To understand the problem, it helps to understand how seaweed gel is actually made. The dominant extraction method is an alkaline process, in which raw seaweed—most importantly the red alga Gracilaria, which contains roughly 30 percent agar and supplies about 53 percent of global agar market demand—is treated with strong alkali. This treatment serves a precise chemical purpose: it converts L-galactose-6-sulfate into 3,6-dehydrated L-galactose, stripping sulfate groups from the polysaccharide chains that would otherwise weaken the gel. The full production line runs from raw seaweed through alkali treatment, neutral cleaning, acidification, bleaching, gel cooking, filtration, cooling, dehydration, and drying. At every stage, chemistry is working to transform a slippery marine plant into a stable, marketable colloid.

That chemistry comes at a cost. During alkali treatment, the alkali attacks the seaweed cell wall, dissolving pigments, polysaccharides, and proteins into the solution, which turns from transparent to a dark liquid known in the trade as black lye. Factories typically reuse industrial lye two or three times, but once the organic concentration climbs too high and the liquid becomes viscous, it can no longer serve. Roughly 30 percent of the alkali remains trapped in the seaweed itself and must be washed out with repeated rinsing and acidification. Producing a single ton of seaweed gel consumes between 8.08 and 10.5 tons of alkali and generates approximately 460 to 600 tons of low-concentration alkali washing wastewater. In Fujian Province, China’s leading seaweed-processing region, nearly 100,000 tons of high-COD waste lye are produced annually; if alkali is reused more than seven times, the chemical oxygen demand can exceed 100,000, making the process unsustainable.

The solid waste stream is equally troubling. Filtration of the gel liquor is hindered by the colloid’s tendency to form a film, so producers add perlite—a porous volcanic glass with a large specific surface area—as a filter aid. The result is a residue that mixes perlite with a substantial load of organic matter. Each ton of seaweed gel generates roughly 2.5 tons of waste residue on a dry basis, and Fujian Province alone produces more than 35,000 dry tons annually. Left to accumulate, this residue decomposes, releasing methane and sulfides and other pollutants. The residue is rich in resources—about 70 percent perlite, along with trehalose, protein, and polyphenols—yet aside from minimal fertilizer recycling and some use as animal feed, most of it ends up as industrial landfill.

The review systematically evaluates the treatment options available for waste lye, and finds most of them wanting. Neutralization followed by activated sludge degradation at sewage plants, the current industrial default, wastes the active substances dissolved in the lye and requires large quantities of acid. Activated carbon adsorption can clean filtered lye, but saturated carbon cannot be reused, creating new disposal problems. Electrochemical oxidation on Ru-iridium titanium electrodes can rapidly strip alkali from seaweed and recover caustic through electrolytic cell reactions—one study reported continuous alkali recovery over 20 days in a bipolar chamber—but it does not recover the organic components. Even green approaches such as using algae to absorb nitrogen and phosphorus from agar wastewater leave the question of concentrated waste lye unresolved.

The most promising lye technology, the authors argue, is electrodialysis combined with membrane concentration. Electrodialysis uses an electric field to drive charged ions selectively across membranes, separating them from the solution; it is already widely used in food processing, salt production, and wastewater treatment. In studies of seaweed-derived waste lye specifically, electrodialysis achieved a cumulative alkali recovery rate of 37 percent while separating alkali from organic matter with low energy consumption and no phase change. The authors’ own group reported a chemical oxygen demand removal rate of 69.97 percent and an alkali recovery rate of 45.31 percent for electrodialysis-treated lye. Membrane concentration adds another layer of capability: multistage membrane systems have recovered tea polyphenols with retention rates of 70 to 83.8 percent, and nanofiltration membranes have cleaned paper-making black lye to reuse standards. New alkali-stable membranes, including quaternized graphene oxide composites that survived 32 days in 2 mol/L sodium hydroxide at 60 degrees Celsius, are making these processes increasingly robust.

For the solid residue, the review champions a hybrid of enzymatic and chemical degradation over calcination, which is costly and can create air pollution, or acid hydrolysis alone, which generates waste acid. Enzymes are gentle catalysts that cleave the glycosidic bonds of polysaccharide macromolecules, producing low-molecular-weight oligosaccharides without generating additional waste. In a key demonstration, the research team enzymatically treated nearly half of the polysaccharides in the residue—excluding the perlite—and recovered specific active oligosaccharides including neoagarobiose, neoagarotetraose, cellobiose, and cellotriose, which initially cleaned the pores of the perlite. Food-grade hydrochloric acid and hydrogen peroxide then degraded the remaining polysaccharides lodged inside the perlite pores, restoring the filter aid’s structure. The recovered perlite achieved a permeability of 2.61 Darcy, meeting reuse standards, and performed comparably to commercial perlite in subsequent gel extraction.

Yet significant scientific puzzles remain, and the review devotes considerable attention to them. During electrodialysis, charges generated in the process are adsorbed by organic substances, which accumulate on the surface of the permeable membrane and reduce the lye recovery rate. Related studies have shown that organic compounds containing benzene rings adsorb especially strongly onto anion exchange membranes, restricting transmembrane ion migration, and that sodium ions alter the internal molecular structure of organic polysaccharides in ways that change how they foul membranes. On the residue side, the structural activity and recovery of organic polysaccharides depend on the specific structure of the enzymes used, and organic material conversion involves energy interactions during solid-liquid separation that are not yet fully understood. These mechanisms, the authors contend, are the critical barriers to industrial-scale recovery of organic active substances from seaweed gel waste.

To crack those mechanisms, the review proposes a concrete analytical toolkit. Trace-charge analysis combined with scanning electron microscopy can quantify how organic active substances aggregate and how charges adsorb and release on membrane surfaces, while charge diffusion models can simulate charge transport during electrodialysis with membrane concentration. For the residue, microcalorimetry and thermodynamic models can track the energy changes that occur as specific enzymes act on organic matter, and Fourier transform infrared spectroscopy, X-ray fluorescence, and X-ray photoelectron spectroscopy can reveal how elemental composition and chemical bonding change during recovery. Analogous work on lignin and sugarcane bagasse has already demonstrated that pyrolysis behavior and potential energy shifts correlate with structural changes during enzymatic hydrolysis, providing a template the seaweed field can follow.

The stakes extend well beyond one industry. Seaweed aquaculture reached approximately 36.3 million tons globally in 2021—97 percent of it cultivated—and China alone produced 2.72 million tons in 2022, with Fujian Province accounting for nearly 48 percent of that output and 60.36 percent of national seaweed gel production. As the blue industry expands, the review’s framework offers a way to close the loop: recover the alkali, reclaim the perlite, extract the oligosaccharides, and return cleaner water to coastal ecosystems. If electrodialysis and enzyme chemistry can be scaled from laboratory benchmarks to factory floors, the mountains of black lye and perlite-laden sludge that currently shadow the seaweed gel industry could become feedstocks rather than liabilities—turning one of aquaculture’s messiest byproducts into one of its most elegant success stories.

Subject of Research: Waste reduction and resource recovery technologies in seaweed gel (agar and carrageenan) production

Article Title: Frontier review of key reduction technologies and resource utilization of waste during the seaweed gel production process

Article References: Luo, X., Wu, Y., Wang, S., Xiong, Z., Du, X., Zheng, M., Zhu, Y., Jiang, Z., Li, Q., Ni, H., Li, Z., & Chen, Z. (2024). Frontier review of key reduction technologies and resource utilization of waste during the seaweed gel production process. Blue Biotechnology, 1(1), Article 12. https://doi.org/10.1186/s44315-024-00013-7

Image Credits: AI Generated

DOI: 10.1186/s44315-024-00013-7

Keywords: seaweed gel, agar, carrageenan, waste lye, electrodialysis, membrane concentration, perlite recovery, enzymatic degradation, polysaccharides, oligosaccharides, wastewater treatment, blue biotechnology

MAAs occupy a unique niche in biology. To date, only cyanobacteria, phytoplankton, and algae are known to synthesize them, and more than 570 species of marine macroalgae are thought to harbor the compounds. Their chemical structures are diverse, their light and thermal stability is excellent, and they are considered non-toxic, qualities that have long made them attractive candidates for cosmetics and pharmaceuticals. Yet their antioxidant behavior has remained surprisingly understudied, particularly in comparison with the polysaccharides, phenols, and pigments that dominate the seaweed antioxidant literature. The Jiangsu team, led by Yingying Sun, set out to close that gap by focusing on six species that are common in Chinese waters and cuisine: Bangia fuscopurpurea, Gelidium amansii, Sargassum fusiforme, Palmaria palmata, Sargassum sp., and Undaria pinnatifida.

The first hurdle was cosmetic in the most literal sense. In the researchers’ earlier work, MAA extracts from several of these algae came out stained black-red or black-green by co-extracted pigments, which muddied subsequent activity assays and complicated any practical application. Their solution was elegantly simple: wash the dried, powdered algae with anhydrous ethanol before the real extraction begins, discarding the pigment-laden supernatant. Spectrophotometric scans confirmed the wash was pulling out chlorophyll, phycobiliproteins, and beta-carotene, the compounds responsible for the unwanted color. Only then did the team extract the MAAs themselves using 25 percent methanol at 45 degrees Celsius, followed by repeated rounds of cold ethanol precipitation to strip away remaining non-target material.

The results of this pretreatment were striking. The purified extracts emerged a transparent reddish hue rather than an opaque dark sludge, and for two species the yield actually improved rather than suffered. Bangia fuscopurpurea delivered 1.5 times its previous MAA output, reaching a yield of 23.62 percent of the dried algal powder, while Gelidium amansii improved by a factor of 1.1. For the brown algae, the trade-off was less favorable: yields of Sargassum fusiforme, Sargassum sp., and Undaria pinnatifida declined significantly, suggesting that some MAAs were lost during the extra purification steps and that the protocol will need species-specific refinement. High-performance liquid chromatography coupled with mass spectrometry showed that the cleanup did not alter the underlying chemistry. The extracts were dominated by four familiar MAAs: palythine, palythenic acid, shinorine, and porphyra-334. Notably, the team reports the first detection of palythenic acid in Palmaria palmata, a compound previously known mainly from phytoplankton and a handful of other macroalgal species.

With clean extracts in hand, the antioxidant testing began. Using a Trolox-based assay, the researchers found that the total antioxidant capacity of the extracts from Bangia fuscopurpurea and Sargassum fusiforme towered over the rest, running 1.8 to 5.1 times higher than the other four species. The superoxide anion scavenging assay told a similar story. At a concentration of 50 milligrams per milliliter, the extracts from Sargassum fusiforme, Bangia fuscopurpurea, and Sargassum sp. neutralized more than 93 percent of the superoxide radicals in solution, while the remaining three species still managed above 64 percent. The half-maximal effective concentrations for the two standouts hovered around 30 milligrams per milliliter. Vitamin C, it should be said, remains the benchmark, achieving over 96 percent scavenging at a mere 0.035 milligrams per milliliter, so the MAAs are not about to displace ascorbic acid on potency alone.

But potency is not the whole story, and the authors point to a mechanistic nuance that could change the calculus. Earlier studies have shown that although porphyra-334 and shinorine score modestly in DPPH radical assays, they are remarkably effective at quenching free radicals through hydrogen atom transfer, a different chemical pathway. The relatively low concentration of active MAAs within the crude extracts may also be masking their true capability, and the researchers anticipate that further purification could substantially boost performance. There is even suggestive evidence that MAA antioxidant activity contributes to inhibiting cancer cell activity, though that frontier remains exploratory.

Perhaps the most immediately practical finding concerns browning, the enzymatic discoloration that turns a sliced apple or yam an unappetizing brown within hours and drives consumer rejection of fresh-cut produce. When the team soaked yam slices and red Fuji apple slices in dilute MAA solutions and tracked them over three days, the untreated controls browned dramatically while the treated slices stayed visibly fresh. The extracts from Bangia fuscopurpurea and Sargassum fusiforme performed best, and a component isolated from the Bangia extract via silica gel chromatography outdid them all, suppressing browning in more than 52 percent of yam and apple slices after 48 hours. That performance exceeded what has been reported for green tea extract, a standard natural anti-browning agent. The researchers speculate the effect may be linked to the impressive moisture-absorption and retention properties previously documented for Bangia MAAs, though the precise mechanism awaits further study.

Safety and formulation matter just as much as activity for any food additive, and here the mineral analysis delivered reassuring news. Inductively coupled plasma optical emission spectrometry revealed that the extracts are rich in essential macro-elements such as calcium, potassium, magnesium, sodium, and phosphorus, along with beneficial trace elements including iron, zinc, copper, and molybdenum. Critically, no harmful heavy metals, lead, cadmium, arsenic, or mercury, were detected, and copper levels sat far below the limits set by the Chinese Pharmacopoeia. The team then stress-tested the two star extracts against five common food additives over 40 days at both 25 and 48 degrees Celsius. Citric acid proved destructive, cutting absorbance by more than 23 percent for the Bangia extract and over 40 percent for the Sargassum extract by the experiment’s end, while sodium glutamate also destabilized the Bangia extract. Agar and carrageenan, by contrast, actually enhanced stability, making them natural formulation partners.

The convergence of these findings, cleaner and higher-yielding extraction, demonstrated antioxidant and anti-browning activity, a benign mineral profile, and compatibility with common food hydrocolloids, sketches a credible path from laboratory bench to grocery shelf. The authors are careful to note the limitations: yields for the brown algae need improvement, antioxidant potency trails vitamin C, and the anti-browning mechanism remains unexplained. Future work will expand the evaluation to weight loss, texture, color, and visual quality of treated produce, and will probe the health-food applications of the Sargassum fusiforme and Bangia fuscopurpurea extracts in greater depth. Still, the study marks a first on several fronts, from the mineral content analysis to the food-additive stability data, and it strengthens the case that the ocean’s humble seaweeds, already hailed as biorefineries and super plants of sustainable development, hold molecules capable of keeping our food fresher and perhaps our bodies healthier.

Subject of Research: Optimized extraction and antioxidant application of mycosporine-like amino acids from marine macroalgae

Article Title: Research on the optimization of preparation and the application analysis of antioxidant activity of mycosporine-like amino acids derived from marine macroalgae

Article References: Li, Y., Wang, J., Wang, S., Jiang, X., Shi, S., & Sun, Y. (2025). Research on the optimization of preparation and the application analysis of antioxidant activity of mycosporine-like amino acids derived from marine macroalgae. Blue Biotechnology, 2(1), Article 2. https://doi.org/10.1186/s44315-025-00023-z

Image Credits: AI Generated

DOI: 10.1186/s44315-025-00023-z

Keywords: mycosporine-like amino acids, marine macroalgae, antioxidant activity, seaweed, food preservation, anti-browning, palythine, shinorine, porphyra-334, extraction optimization, food additives, blue biotechnology

The researchers began with the fundamentals. Freshly collected G. debilis was cleaned, frozen, dried, and milled into a fine powder before being extracted overnight in either water or 60 percent methanol. Water pulled out roughly 67.6 percent of the biomass by weight, while methanol recovered about 62.3 percent, a difference the authors attribute to the abundance of hydrophilic macromolecules such as polysaccharides and proteins in the algal cell walls. Physical testing of the crude powder revealed impressive functional properties: the material held 8.99 grams of water per gram of dry weight, swelled to 13.53 milliliters per gram, and bound 6.19 grams of oil per gram. These figures exceed those reported for several related Gracilaria species and matter enormously for food formulation, because water and oil holding capacities govern texture, mouthfeel, viscosity, and satiety in low-fat products.

The proximate analysis exposed a striking solvent divide. The water extract was dominated by total sugars at 34.78 percent of dry weight, consistent with its role in dissolving polar carbohydrates and organic acids. The methanol extract, by contrast, was richer in nearly everything else: proteins at 0.827 percent, lipids at 6.50 percent, total phenolics at 27.80 milligrams of gallic acid equivalents per gram, flavonoids at 104.1 milligrams of quercetin equivalents per gram, chlorophyll at 13.79 percent, and carotenoids at 0.586 percent. Sulfate group content, a marker of bioactive sulfated polysaccharides with known anticoagulant and antioxidant properties, peaked in the methanol extract at 55.94 percent. The crude fiber content of the raw seaweed, 19.34 percent, adds another nutritional dimension, since dietary fiber is associated with improved gastrointestinal function and cholesterol reduction.

Mineral profiling by inductively coupled plasma mass spectrometry reinforced the picture of a nutritionally dense organism. The water extract carried the highest concentrations of sodium, magnesium, potassium, and phosphorus, with potassium reaching 3363 milligrams per 100 grams, while the methanol extract was the better source of calcium and iron. Encouragingly from a food-safety standpoint, heavy metals such as arsenic and chromium were present only at low levels, and no mercury or lead was detected in any extract, keeping the material within FDA safety limits. The sodium-to-potassium ratio, a parameter relevant to cardiovascular health, varied widely across preparations, from 6.05 in the methanol extract to 0.33 in the crude sample, underscoring how processing shapes the final mineral balance a consumer would ingest.

Antioxidant performance split along solvent lines in a way that the authors link directly to compound polarity. In the ABTS radical scavenging assay, the water extract was far superior, with a half-maximal effective concentration of just 76.41 micrograms per milliliter compared with 294.19 for methanol, a result the team attributes to hydrophilic antioxidants such as sulfated polysaccharides. The methanol extract flipped the script in the DPPH assay, achieving an EC50 of 435.9 micrograms per milliliter, roughly half that of the water extract, and it also showed about twice the ferric reducing antioxidant power, with an EC50 of 16.35 micrograms per milliliter. The total antioxidant capacity assay favored water again. This dual-profile behavior suggests that a two-solvent strategy could be used deliberately to harvest complementary antioxidant fractions from the same biomass.

Un-targeted metabolite profiling by gas chromatography-mass spectrometry made the solvent effect vivid. Water extracts were enriched in organic acids, including lactic acid at 419.12 micrograms per milligram and oxalic acid at 427.03 micrograms per milligram, along with sugars such as D-mannose and D-xylose. Methanol extracts instead concentrated fatty acids and amino acids: palmitic acid reached 502.32 micrograms per milligram, L-isoleucine 383.35 micrograms per milligram, and the specialized metabolite butyrolactone appeared exclusively in the methanol fraction at 239.75 micrograms per milligram. Targeted fatty acid analysis detected fourteen fatty acids in the crude sample but only five in the water extract, while amino acid profiling found phenylalanine at a remarkable 40.99 milligrams per gram in the methanol extract. Multivariate statistics, including principal component analysis and PLS-DA, cleanly separated the three preparations along polarity-driven lines, confirming that extraction protocol is effectively a dial for selecting which metabolite class to prioritize.

The most eye-catching results came from the cell biology. Using the MTT viability assay, the team tested both extracts against three cell lines: Huh-7 human hepatoma carcinoma cells, HeLa cervical cancer cells, and Chinese hamster ovary cells. The methanol extract showed half-maximal inhibitory concentrations of 167.73 micrograms against Huh-7, 223.26 against CHO, and 145.08 against HeLa cells. These values are higher than those of the standard chemotherapy drug 5-fluorouracil, meaning the extracts are less cytotoxic, which the authors interpret as evidence of a gentler, more selective bioactivity profile rather than blunt toxicity. Hoechst 33342 nuclear staining provided visual confirmation of apoptosis: treated cells displayed chromatin condensation, shrunken and fragmented nuclei, and the small bright blue dots characteristic of DNA damage and late-stage programmed cell death.

Perhaps the most clinically suggestive finding came from the wound healing assay, a standard proxy for metastatic potential. When a scratch was made across a confluent monolayer of CHO cells, the methanol extract allowed only 7.61 percent wound closure at twelve hours and 14.36 percent at twenty-four hours, substantially less than the water extract, which permitted 29.57 percent closure by twenty-four hours. Because cancer spread depends on cell migration, this antimigratory effect hints at possible antimetastatic activity, though the authors are careful to frame it as an in vitro observation requiring in vivo validation. The mechanistic backdrop they sketch is consistent with broader seaweed literature: sulfated polysaccharides and phenolics can trigger the intrinsic apoptotic pathway by modulating Bcl-2 family proteins, disrupting mitochondrial membrane permeability, releasing cytochrome c, and activating caspase cascades.

Safety considerations were not ignored. The team quantified antinutritional factors, compounds that can interfere with mineral absorption or digestion, and found them at acceptable levels. Phytic acid, which chelates essential minerals, was actually lowest in the methanol extract at 3.01 micrograms per milligram, while saponins and terpenoids, though present, remained within ranges considered tolerable for food supplements. Taken together with the favorable heavy metal profile, the data support the argument that G. debilis could be safely incorporated into functional foods, at least at the formulation stage. The authors caution, however, that translating these laboratory findings into real products demands rigorous validation of health benefits, including cholesterol-lowering effects, gastrointestinal improvements from fiber, and dose-specific anticancer activity, all of which require animal and eventually human studies assessing bioavailability, safety, and efficacy.

The broader significance of the study lies in its demonstration that seaweed chemistry is not a fixed property but a designable one. By choosing water, a producer obtains a fraction rich in sugars, organic acids, and hydrophilic antioxidants suited to fermentation or sweetener applications; by choosing methanol, one harvests phenolics, flavonoids, terpenoids, fatty acids, and the fractions with the strongest showing in cancer cell assays. As the global seaweed hydrocolloid market is projected to grow from 610 million dollars in 2023 to 997 million dollars by 2033, and as consumer demand for natural, sustainable, evidence-based health ingredients accelerates, species like G. debilis sit at a compelling intersection of aquaculture, nutrition, and medicine. The next challenge, the researchers note, is scaling up: refining solvent systems to maximize bioactive yields while minimizing antinutrients, standardizing extraction protocols, and stabilizing delicate compounds during processing, so that a seaweed once valued mainly for agar can take its place on the functional food shelf.

Subject of Research: Nutraceutical and bioactive characterization of the red seaweed Gracilaria debilis

Article Title: Proximate, physicochemical, bioactive and antiproliferative characteristics of Gracilaria debilis extract reveal its nutraceutical potential

Article References: Khandwal, D., Maniar, J. N., Pandey, A. K., Gupta, N. K., & Mishra, A. (2025). Proximate, physicochemical, bioactive and antiproliferative characteristics of Gracilaria debilis extract reveal its nutraceutical potential. Blue Biotechnology, 2(1), Article 10. https://doi.org/10.1186/s44315-025-00031-z

Image Credits: AI Generated

DOI: 10.1186/s44315-025-00031-z

Keywords: Gracilaria debilis, red seaweed, nutraceuticals, antioxidants, phenolics, flavonoids, antiproliferative activity, cell migration, functional foods, metabolite profiling, sulfated polysaccharides, blue biotechnology

The enzyme at the heart of the work is phenylalanine dehydrogenase from Natranaerobius thermophiles, a microorganism originally isolated from marine environments that thrives at elevated temperatures and in extremely salty, alkaline conditions. Enzymes from such extremophiles are prized in industry precisely because they tolerate conditions that would destroy ordinary proteins. Yet even these rugged biocatalysts can benefit from a supportive scaffold. Immobilizing enzymes on solid carriers is a classic strategy in biotechnology: it allows the catalyst to be recovered and reused, protects its three-dimensional structure, and simplifies product purification. The challenge has always been finding carriers that are cheap, biocompatible, and mechanically useful at the same time.

The Xiamen team, led by Shizhen Wang, turned to wool keratin extracted through a reduction-dissolution process using sodium sulfide, urea, and sodium dodecyl sulfate. Keratin is no ordinary protein. Its three-dimensional network is stabilized by disulfide bonds, hydrogen bonds, and ionic interactions, and it is studded with functional groups including amino, carboxyl, and sulfhydryl moieties. These groups make keratin inherently biocompatible and give it a rich chemical surface for binding other molecules. Graphene oxide, meanwhile, is a two-dimensional carbon sheet decorated with oxygen-containing groups, widely used in biosensors and drug delivery because of its heterogeneous surface chemistry and enormous surface area.

The assembly strategy was elegantly simple. The researchers first mixed the purified enzyme with keratin solution, then added graphene oxide and stirred the mixture at low temperature. The resulting GO-WK-NT composite self-organized into a layer-by-layer sandwich structure, with keratin and enzyme complexes interleaved between graphene oxide sheets. Spectroscopic and microscopic evidence supported this architecture: Fourier transform infrared spectroscopy revealed a new peak at 500 cm−1 indicating fresh interactions among the three components, while X-ray diffraction showed distinctive peaks at 31.82 and 41.2 degrees, reflecting keratin chains rearranging in parallel or folded configurations between the oxide lamellae. Scanning electron microscopy confirmed that graphene oxide was uniformly dispersed throughout the keratin-enzyme matrix rather than clumping, as it tends to do on its own.

The binding forces holding this sandwich together are multiple and cooperative. Hydrogen bonds and electrostatic interactions link the charged groups of keratin to both the enzyme surface and the oxidized carbon sheets, while hydrophobic and π-π interactions contribute additional grip. Zeta potential measurements tracked the progressive accumulation of negative surface charge, from −2.18 millivolts for the free enzyme to −7.28 millivolts for the full composite, consistent with stepwise layering. This web of weak, redundant interactions is precisely what makes the material soft yet stabilizing: it cradles the enzyme without covalent modification that might distort its active site.

Performance testing showed that the composite outperformed both the free enzyme and a simpler graphene-oxide-only formulation. While the free enzyme displayed an activity of 4.48 units per milligram, the graphene oxide immobilizate reached 5.22 and the keratin hybrid reached 6.36 units per milligram. Reusability, a key economic criterion for industrial biocatalysts, was equally impressive: after five cycles of recovery and reuse, the hybrid retained 73.5 percent of its initial activity, slightly ahead of the 72.1 percent retained by the simpler composite, whose performance decays as enzyme desorbs from bare oxide surfaces.

Thermal resilience told an even clearer story. After two and a half hours of incubation at 70 degrees Celsius and pH 9.0, the free enzyme retained only 46.1 percent of its activity, whereas the keratin-graphene hybrid kept 69.4 percent, with a measured half-life of 4.7 hours. The authors attribute this to the keratin’s functional groups forming multi-site bonds that lock the enzyme’s structure in place, while its hydrophilic groups preserve the crucial hydration shell that keeps proteins folded. The keratin matrix also acts as a local buffer: at pH 11.0, the immobilized enzyme retained 57.1 percent activity compared with just 34.8 percent for the free enzyme, because the amino, carboxyl, and sulfhydryl groups moderate the pH microenvironment surrounding the active site.

Kinetic analysis using Hanes-Woolf plots revealed that immobilization increased both the maximum reaction velocity and the apparent Michaelis constant, the latter reflecting added diffusion resistance through the layered structure. Nevertheless, the catalytic efficiency, expressed as kcat/Km, rose from 2.72 to 3.32 mM−1·s−1 for the hybrid enzyme. One striking finding emerged from solvent testing: in 30 percent cyclohexane, the immobilized enzyme actually reached 130.6 percent of its baseline activity, while the free enzyme dropped to 48.6 percent. The researchers explain that cyclohexane prevents agglomeration of graphene oxide and dissolves the hydrophobic substrate, ethyl 2-oxo-4-phenylbutyrate, more effectively, while the keratin coating shields the enzyme from direct solvent attack.

The practical target of all this engineering is L-homophenylalanine, an unnatural amino acid used as a chiral building block in pharmaceutical synthesis. The enzyme catalyzes the reductive amination of the keto-acid ester substrate using NADH as a cofactor, a green route that avoids the metal catalysts and harsh conditions of traditional chemical synthesis. An immobilized, reusable, solvent-tolerant version of this catalyst could make such bioprocesses considerably more economical, and the fact that one of its key ingredients is textile waste adds a circular-economy dimension that is increasingly demanded by both regulators and consumers.

Looking beyond chemical manufacturing, the authors point toward biosensing and wearable technology. Graphene oxide is an excellent electrode material, and keratin-based graphene composites have already been spun into flexible strain-sensor inks. A soft, biocompatible enzyme-carrier that functions at 70 degrees Celsius and in high salt could underpin enzyme electrodes for extreme environments or conformal health-monitoring devices. The work, funded by the National Natural Science Foundation of China, thus transforms two humbling feedstocks, landfill-bound wool and a sheet of oxidized carbon, into a precisely layered biological machine, showing how materials science and extremophile biology can converge on chemistry that is simultaneously tougher, greener, and cheaper.

Subject of Research: Immobilization of an extremophile phenylalanine dehydrogenase on a wool keratin and graphene oxide hybrid biomaterial for enzyme stabilization and green biosynthesis

Article Title: Hybrid soft biomaterial of wool keratin and graphene oxide for immobilization of thermophilic and halophilic dehydrogenase from extremophile

Article References: Zeng, X., Lei, H., Zhang, J., Xie, B., Jiang, L., & Wang, S. (2025). Hybrid soft biomaterial of wool keratin and graphene oxide for immobilization of thermophilic and halophilic dehydrogenase from extremophile. Blue Biotechnology, 2(1), Article 25. https://doi.org/10.1186/s44315-025-00049-3

Image Credits: AI Generated

DOI: 10.1186/s44315-025-00049-3

Keywords: wool keratin, graphene oxide, enzyme immobilization, extremophile, phenylalanine dehydrogenase, Natraanaerobius thermophilus, L-homophenylalanine, biocatalysis, thermostability, biomaterials, waste valorization, blue biotechnology

The economic stakes are considerable. Polysaccharides, proteins, lipids, pigments, and polyphenols harvested from marine microalgae have been shown to exhibit anti-inflammatory, antimicrobial, and antitumor activities, while pigments and unsaturated fatty acids contribute antioxidant properties and help meet human nutritional needs. Among the most commercially significant are omega-3 polyunsaturated fatty acids, a market valued at 2.3 billion US dollars in 2019 and expected to grow at an annual rate of 7.44 percent through 2027, with microalgae-derived omega-3 products growing even faster at 11.9 percent per year. High-value pigments such as lutein, beta-carotene, astaxanthin, and fucoxanthin command premium prices as natural food colorants, dietary supplements, and nutraceutical ingredients, and compounds like the polysaccharide chrysolaminarin and beta-glucan add further value to algal biomass.

There is also a pressing environmental driver behind the shift toward microalgal sources. The human body cannot synthesize the omega-3 fatty acids eicosapentaenoic acid, or EPA, and docosahexaenoic acid, or DHA, and must obtain them through diet. Traditionally these have come from fish, but overfishing has disrupted marine ecological balance, and contamination incidents have raised safety concerns about seafood products. Deep-sea fish extraction suffers from poor product stability and off-flavors, while bioaccumulation concentrates pollutants such as methylmercury, copper, polychlorinated biphenyls, and dioxins in fish bodies. Microalgae sidestep many of these problems: species such as Nannochloropsis can synthesize EPA efficiently through photosynthetic autotrophy, with the fatty acid accounting for twenty to thirty percent of total cellular lipids, and their oils are odorless, cholesterol-free, and contain squalene and phytosterols with additional health benefits.

Yet the path from algal pond to finished product is obstructed by a formidable biological barrier: the cell wall. Despite their tiny size, microalgae possess complex polysaccharide-protein composite cell walls whose high mechanical strength causes low energy efficiency and incomplete extraction with conventional disruption methods, and the variability among species means no single approach works universally. Without proper pretreatment, extraction efficiency is severely limited. The review catalogs the main pretreatment strategies in detail, dividing them into mechanical methods, including high-pressure homogenization, ultrasonication, microwave treatment, and pulsed electric fields, and chemical methods such as acid hydrolysis, surfactant treatment, and enzymatic hydrolysis. Drying itself is a pretreatment decision, with freeze-dried samples of species like Chlorella variabilis and Scenedesmus regularis typically showing higher extraction efficiency than spray-dried material, though sun drying remains the cheapest option for large volumes.

The numbers illustrate how difficult cell disruption can be. High-pressure homogenization, one of the few techniques scalable to industrial volumes, achieves only a forty percent lysis rate for Nannochloropsis even at pressures up to 900 bar. Ball milling, which uses friction and collision between microspheres to shatter cell walls, requires careful temperature control because frictional heat can inactivate delicate products; optimized conditions for the lipid-rich organism Schizochytrium sp. DT3 used beads of 0.4 to 0.6 micrometers at 4500 rpm for just four minutes. Enzymatic pretreatment offers a gentler alternative, as enzyme preparations selectively hydrolyze cell wall structures, avoid equipment corrosion, reduce energy consumption, and protect heat-sensitive compounds in a mild aqueous environment. The evidence is striking: combining the enzymes Cellulyve and Feedlyve GMA increased oil extraction from Microcystis by nearly 1.8 times, while a crude mixture of cellulase and amylase doubled protein extraction and boosted sugar extraction by 41 percent in Oocystis sp. The catch is cost, since enzyme preparations are expensive, must be matched precisely to each species’ cell wall chemistry, and demand strict control of reaction parameters.

Once cells are opened, the choice of solvent becomes the next critical decision, and this is where the green chemistry revolution is most visible. Traditional extractions rely on solvents such as chloroform, methanol, and hexane, which are volatile, flammable, explosive, or toxic. The review highlights two leading alternatives. Ionic liquids, composed entirely of cations and anions, feature low vapor pressure, high solvating power, and excellent chemical and thermal stability, and their polarity, hydrophobicity, and viscosity can be tuned by pairing different ions. Researchers evaluated fifteen cholinium and amino acid-based ionic liquids for disrupting the hydrogen-bond network of Nannochloropsis cell walls and found that cholinium arginate performed best, likely because it offers six hydrogen bonding sites. Pairing hydrophilic ionic liquids with microwave assistance increased lipid yield from Nannochloropsis oculata by 34.9 percent compared with the classic Bligh-Dyer chloroform-methanol method, and, importantly, worked on wet algae, eliminating the energy-intensive drying step.

Deep eutectic solvents, or DES, represent an even newer class of green solvents. These form when hydrogen bond acceptors such as choline chloride combine with hydrogen bond donors such as urea or lactic acid to create low-melting mixtures that are biodegradable, easy to synthesize, non-volatile, and non-flammable. Their natural variants, nDES, offer food-grade safety, meaning extracts can be used directly in food systems without solvent purification, a significant simplification of production. Responsive DES go further, allowing solvent polarity to be reversed on demand through external triggers such as pH or temperature, solving the persistent problem of separating target products from solvent. The review also covers supercritical fluid extraction, in which carbon dioxide above its critical point acts as a non-toxic solvent at near-ambient temperature, and pressurized liquid extraction, which cuts processing time by more than half while slashing solvent consumption; one PLE protocol with dimethyl sulfoxide at 103.4 bar recovered lutein, beta-carotene, fucoxanthin, and diatoxanthin from algal biomass in a single pass.

Physical intensification methods can be coupled with these solvent systems to dramatic effect. Microwave technology exploits electromagnetic energy in the 0.3 to 300 gigahertz band to rapidly heat and rupture cells, with optimized conditions of 1.47 minutes of treatment yielding efficient lutein extraction from Chlorella sorokiniana. Ultrasound generates cavitation, microfluidics, and bubble collapse that tear cell walls apart; freezing and thawing combined with ultrasonication pushed C-phycocyanin yield to 109.57 milligrams per gram, well above either technique alone and with the highest purity. A triphasic separation strategy applied to wet marine Chlorella sp. NITT 02 used ultrasonication followed by ammonium sulfate and tert-butanol to split biomass into an oil layer, a protein layer, and a sugar-containing salt layer in one operation. However, the review is candid that green extraction remains difficult: ethanol is less toxic than methanol or chloroform but delivers lower yields, and microwave and ultrasound processes are energy-intensive or limited in scale.

Economics ultimately decide which technologies survive, and here the authors turn to life cycle assessment, a four-step framework covering goal definition, inventory analysis, impact assessment, and interpretation. The figures are sobering: freeze-drying consumes about 1080 megajoules, ultrasonic disruption 108 to 324 megajoules, and solvent recovery 210 to 588 megajoules, while harvesting costs a mere 0.02 megajoules. A multi-product roadmap for marine Chlorella variabilis showed sugar extraction as the most energy-hungry step at 160.8 megajoules per kilogram, compared with just 5.9 for lipid extraction and 5.2 for harvesting. The authors argue that complete separation of every component is unnecessary; extracting only the highest-value products and converting residues through fermentation or thermal conversion achieves better economics, and integrating cultivation with wastewater treatment further improves sustainability.

Perhaps the most forward-looking section of the review concerns artificial intelligence and computational screening. Extraction obeys thermodynamic principles, but phase equilibrium data for multi-component systems containing salts, ionic liquids, and polymers remain scarce, making solvent selection largely empirical. Theoretical tools such as COSMO-RS have guided the design of solvents for extracting lutein, phycobiliproteins, EPA, fucoxanthin, and lipids, with researchers screening databases of roughly 8,000 molecules and narrowing thousands of candidate deep eutectic solvents down to 712 using constraints on boiling point, melting point, greenness, and solubility. Machine learning applied to the wealth of existing laboratory data promises to close the loop between experimental science, theoretical calculation, and AI analysis, accelerating solvent discovery. The authors identify three priorities for the field: standardized pilot-scale extraction test suites, quantified solvent life-cycle impacts, and open databases of extraction yields for machine learning training. If those pieces fall into place, the green extraction of marine microalgal compounds could finally deliver on the promise of blue biotechnology at industrial scale, turning sunlight, seawater, and carbon dioxide into medicines, supplements, and sustainable materials.

Subject of Research: Green extraction of bioactive compounds from marine microalgae

Article Title: Green extraction of active compounds in marine microalgae

Article References: Green extraction of active compounds in marine microalgae. (n.d.). https://doi.org/10.1186/s44315-025-00051-9

Image Credits: AI Generated

DOI: 10.1186/s44315-025-00051-9

Keywords: marine microalgae, green extraction, ionic liquids, deep eutectic solvents, supercritical CO2, pressurized liquid extraction, cell disruption, omega-3 fatty acids, bioactive compounds, blue biotechnology, life cycle assessment, machine learning

Compensatory growth is the accelerated phase of growth that follows a period of food deprivation when adequate nutrition is restored. During re-feeding, fish commonly exhibit hyperphagia, an elevated appetite, along with improved feed conversion efficiency and enhanced nutrient utilization, allowing them to partially or fully recover the growth lost during starvation. The magnitude of this recovery depends on the species, the severity and duration of restriction, environmental conditions, and the structure of the feeding regime itself. While the phenomenon has been documented extensively in laboratory settings across carp, tilapia, seabream, sturgeon, and crustaceans, field data from real pond ecosystems, where plankton and other natural food organisms contribute meaningfully to fish nutrition, have remained scarce. The new study, published in Blue Biotechnology, addresses that gap directly by testing cyclic restriction protocols across an entire ten-month production cycle under commercial-style pond conditions.

The experimental design was deliberately rigorous. Twelve earthen ponds of 0.04 hectares each were prepared according to the standard pre-stocking protocols of ICAR-CIFA, including drying, liming, and fertilization, and stocked with rohu fingerlings at 7,500 fish per hectare with three replicate ponds per treatment. Fertilization followed a uniform fifteen-day schedule using urea, single superphosphate, and composted cow dung to sustain natural food production identically across all ponds, ensuring that any differences among treatments could be attributed to the feeding regime rather than variations in pond productivity. Fish received a sinking pelleted diet formulated from groundnut oil cake, sesame oil cake, and rice bran, delivering 25.63 percent crude protein, 7.26 percent ether extract, and a digestible energy of 17.08 megajoules per kilogram, and were fed at 1.5 to 3.0 percent of body weight depending on size, with monthly sampling to adjust rations.

Three cyclic restriction schedules were tested against a continuously fed control over the ten-month trial. The T-1 protocol combined two months of feeding, one month of starvation, one month of re-feeding, a further month of starvation, and five months of re-feeding. T-2 extended the first starvation to two months and shortened the final re-feeding to four months, while T-3 stretched the initial deprivation to three months with only three months of re-feeding at the end. The outcomes diverged sharply. T-1 fish reached a final weight of 662.61 grams and a production of 5,494 kilograms per hectare, statistically indistinguishable from the control and actually representing approximately 4.6 percent greater weight gain and about nine percent higher fish production relative to the control, despite the lower feed input. In contrast, T-2 and T-3 achieved only partial compensation of 81.88 percent and 76.28 percent respectively, with significantly reduced final weights and yields.

Survival ranged from 83.55 to 92.11 percent and did not differ significantly among treatments, indicating that even the harshest restriction schedule remained within the physiological tolerance of the species. Apparent feed conversion ratio and protein efficiency ratio likewise showed no significant differences, though the highest specific growth rate was recorded in the moderate restriction group. Perhaps most striking were the nutrient retention results: protein productive value and lipid productive value were both significantly higher in all restricted feeding groups than in the control, signaling that restricted fish converted dietary protein and lipid into body tissue with markedly greater efficiency during re-feeding. Effect sizes for the key growth variables were enormous, with partial eta-squared values between 0.94 and 0.99, meaning the feeding regime accounted for nearly all of the variance in growth outcomes, a statistical signal the authors describe as biologically as well as statistically meaningful.

The digestive physiology data illuminate the mechanism behind the recovery surge. Protease and lipase activities in the intestinal tissue were significantly higher in the control and T-1 groups than in the longer-restriction treatments, with effect sizes exceeding 0.90. Elevated protease activity in T-1 suggests that moderate deprivation primes the digestive system for accelerated protein digestion once food returns, a well-documented adaptive response in fish recovering from fasting. Conversely, the suppression of both enzymes in T-2 and T-3 reflects the down-regulation of gastrointestinal function during prolonged starvation, when limited substrate availability forces the gut into a metabolically conservative state that cannot be instantly reversed when feeding resumes, ultimately constraining the speed and completeness of growth recovery.

Blood chemistry added a stress dimension to the picture. Haemoglobin concentrations did not differ significantly among groups, indicating that none of the feeding regimes compromised the fish’s oxygen-carrying capacity or hematological health. Blood glucose, however, told a sharper story. Levels were significantly lower in the control and T-1 fish than in T-2 and T-3, and elevated glucose is widely recognized as a physiological stress marker in fish, reflecting enhanced gluconeogenesis and the mobilization of endogenous energy reserves during extended fasting. The authors argue that blood glucose therefore serves as a sensitive indicator of nutritional stress severity under cyclic feeding regimes, and the lower glucose values in the moderate restriction group point to better metabolic adaptation and homeostatic stability.

Carcass composition shifted in revealing ways. Dry matter and crude protein were highest in the T-2 group, and crude lipid rose in all restricted treatments, with the greatest accumulation in the longest-restricted fish. This pattern is consistent with the physiology of recovery: during starvation, fish burn stored glycogen, lipid, and eventually protein to maintain essential metabolism, and during re-feeding, anabolic pathways sweep nutrients into tissue storage with unusual efficiency. Yet the increased protein and lipid deposition in T-2 and T-3 did not translate into superior production, a finding the researchers emphasize as a caution against reading improved nutrient retention alone as evidence of successful feeding management. Tissue deposition, however efficient, cannot compensate for the somatic growth lost to prolonged deprivation.

The practical implications extend well beyond the experimental ponds. Because rohu is cultured extensively in composite carp farming systems across India and beyond, a feeding schedule that maintains full productivity while trimming supplemental feed by roughly nine percent carries substantial economic weight in an industry where feed costs dominate budgets. The savings compound further when reduced feeding labor and lower nutrient loading into pond water are considered. The authors note that their apparent feed conversion ratios excluded the nutrient contribution of plankton, which was assumed equivalent across uniformly fertilized ponds, and they recommend validation in composite culture, integrated multi-trophic aquaculture, recirculating systems, and biofloc-based setups. Broader digestive enzyme profiling and gut morphology studies would also strengthen the mechanistic picture. Still, the core message is clear: in fertilized pond aquaculture, the strategy that wins is not maximum feeding but precisely timed feeding, letting a fish’s own compensatory biology do a measurable share of the work.

Subject of Research: The effects of cyclic feed restriction and re-feeding on compensatory growth, nutrient utilization, digestive enzyme activity, and physiology of Labeo rohita cultured in fertilized ponds.

Article Title: Effects of feed restriction and refeeding on compensatory growth of Labeo rohita in fertilized ponds

Article References: Mohanta, K. N., Khalasi, Y., Prakash, P., Kumari, R., & Chandan, N. K. (2026). Effects of feed restriction and refeeding on compensatory growth of Labeo rohita in fertilized ponds. Blue Biotechnology, 3(1), Article 12. https://doi.org/10.1186/s44315-026-00063-z

Image Credits: AI Generated

DOI: 10.1186/s44315-026-00063-z

Keywords: compensatory growth, Labeo rohita, feed restriction, aquaculture, pond culture, carp, nutrient utilization, digestive enzymes, refeeding, fish nutrition, feed conversion ratio, Blue Biotechnology

The most striking finding documented in the retraction notice concerns the article’s reference list. The editor determined that the majority of the references cited in the paper appear to be non-existent. In practical terms, this means that a large share of the studies underpinning the review’s claims could not be traced to any real publication. Fabricated or hallucinated references of this kind have become a hallmark of text generated by large language models, which can produce fluent, plausible-looking citations that dissolve under scrutiny. When reviewers or readers attempt to locate the cited works, they find no matching titles, authors, journals or digital object identifiers. In this case, the density of apparently fictitious citations was judged sufficient to suggest that generative AI had been used in writing the manuscript, although that use was never disclosed by the authors.

The second pillar of the retraction concerned citation behaviour. The notice states that the authors numerously cited their own previous works, none of which were judged to be relevant to the published paper. Self-citation is not inherently improper; researchers frequently build on their own earlier findings, and in specialised fields a degree of self-referencing is expected. What troubled the editor in this instance was the combination of irrelevance and volume. Citation recycling of this sort can artificially inflate an author’s bibliometric profile, boost journal-level metrics and create a misleading impression of scholarly consensus around a topic. When the self-citations are also tangential to the subject matter, they add noise rather than substance, and they deprive readers of the genuinely relevant literature they would expect a review article to survey.

The retracted paper had been positioned as a synthesis of nutrigenomics research in fish, a field that sits at the intersection of genomics, nutrition and aquaculture science. Nutrigenomics, broadly defined, seeks to understand how dietary components interact with an organism’s genome, transcriptome, proteome and metabolome, and how those interactions shape growth, health and nutritional quality. Applied to farmed fish, the field promises to inform feed formulations that improve growth performance, disease resistance and the nutritional value of the final product for human consumers. With capture fisheries at or near their sustainable limits, aquaculture has become the fastest-growing animal food production sector worldwide, and the genetic optimisation of farmed species is a major research priority. A credible review of this landscape would have been a valuable resource for the community, which makes the integrity failure all the more consequential.

The authors of the retracted article were affiliated with several Indian research institutions, including the ICAR-Central Institute of Fisheries Education in Mumbai, the Sher-E-Kashmir University of Agricultural Sciences and Technology of Kashmir, the ICAR-Central Institute of Brackishwater Aquaculture in Chennai, and the College of Fisheries in Kishanganj under the Animal Science University in Patna. The retraction notice records that all authors disagree with the retraction. Disagreement is not unusual in retraction cases, and it does not by itself reverse an editorial decision. Under the guidelines that most publishers follow, the retraction notice remains permanently linked to the article, which stays online but is clearly watermarked as retracted so that readers who encounter it are not misled. The notice itself, published as an open-access document, has already recorded hundreds of accesses, reflecting the attention such cases now attract.

For the journal, the case underscores the difficulty of screening submissions in an era when generative AI tools can produce manuscripts that pass superficial readability checks. Peer review was designed to evaluate scientific merit, not to authenticate reference lists or detect machine-generated prose. Fabricated citations are often discovered only after publication, when readers attempt to follow up on the sources. Journals and publishers have been rolling out additional safeguards, including reference verification at submission, disclosure policies requiring authors to declare any use of AI in manuscript preparation, and clearer rules reserving authorship for humans who take responsibility for the work. The retraction notice in this case makes explicit that the undeclared nature of the suspected AI use was central to the decision, alongside the reliability problems it created.

The episode also highlights why retractions, though painful, are an essential part of the scientific ecosystem. The retracted review concerned a topic with real-world stakes: sustainable aquaculture and the nutritional improvement of farmed fish. Researchers, feed companies and policymakers who consult the literature on fish nutrigenomics rely on reviews to orient their work. A review built substantially on non-existent references cannot support that function, because its synthesis rests on evidence that does not exist. Leaving such a paper uncorrected would risk propagating false claims into downstream research, extension materials and even feed development decisions. By retracting the article and publishing a transparent notice, the journal protects the integrity of the record, even at the cost of acknowledging that a flawed publication slipped through.

The broader context is a rising tide of AI-related integrity cases across scientific publishing. Publishers have reported growing numbers of retractions in which fabricated references, nonsensical text or undisclosed AI assistance played a role. The phenomenon is not confined to any single discipline or region, and it has prompted international bodies to refine their guidance on authorship, disclosure and the responsible use of AI tools. At the same time, many researchers use AI legitimately, for language polishing, literature discovery or data analysis, provided that such use is transparent and that humans verify and take responsibility for the final content. The line drawn in this case was between undisclosed use that compromised the reliability of the manuscript and the disclosed, supervised use that publishers generally accept. The retraction notice suggests the authors crossed that line in ways that could not be remedied by correction.

For the aquaculture and nutrigenomics communities, the practical lesson is one of vigilance. Review articles shape research agendas, funding priorities and teaching materials, and their authority depends on the verifiability of every citation. Readers evaluating reviews in this field, as in any other, are increasingly advised to check that cited studies exist and genuinely support the claims attached to them, and to treat reference lists with the same critical attention once reserved for methods sections. The retracted paper’s promise, decoding the fish genome to make aquaculture more sustainable and more nutritious, remains a legitimate and active research goal pursued by many groups worldwide. What the retraction removes is not that goal, but a document that claimed to summarise it on unreliable foundations. The scientific record, corrected through the retraction notice now permanently attached to the article, is the mechanism by which that distinction is made clear to everyone who comes after.

Subject of Research: Retraction of a fish nutrigenomics review article over undeclared generative AI use and fabricated references

Article Title: Retraction Note: Fish nutrigenomics: unravelling the genetic code for sustainable aquaculture and improved nutritional benefits

Article References: Retraction Note: Fish nutrigenomics: unravelling the genetic code for sustainable aquaculture and improved nutritional benefits. (n.d.). https://doi.org/10.1186/s44315-026-00053-1

Image Credits: AI Generated

DOI: 10.1186/s44315-026-00053-1

Keywords: retraction, fish nutrigenomics, generative AI, research integrity, fabricated references, self-citation, aquaculture, Blue Biotechnology, Springer Nature, peer review, open access, sustainable aquaculture

A new landmark editorial launching Ocean Microbiology, an open-access journal dedicated to marine and aquatic microorganisms, argues that the field stands at a unique crossroads. The publication, authored by Ramiro Logares of the Institute of Marine Sciences in Barcelona, describes a golden age of marine microbial research, powered by an extraordinary convergence of technologies that have transformed what scientists can see and measure. Over the past two decades, high-throughput DNA sequencing, high-resolution imaging, microfluidics and single-cell technologies, advanced bioinformatics, autonomous monitoring systems, predictive modeling and new theoretical frameworks have together revealed the diversity and complexity of ocean microbes at unprecedented scales, opening windows onto a world that was almost entirely hidden a generation ago.

The technical achievements of this era have been stunning in their scope. Large-scale sequencing campaigns have uncovered millions of novel microbial genes, dramatically expanding understanding of the metabolic potential harbored in ocean waters—genes that hint at undiscovered biochemistries operating in every liter of seawater. Surveys of plankton across ocean basins have exposed the existence of a vast ‘rare biosphere,’ an enormous collection of low-abundance microbial taxa that nonetheless perform ecologically relevant roles in nutrient cycling and energy flow. Completely new lineages of microorganisms have been described, some of which are forcing biologists to redraw portions of the tree of life itself. And beneath the boundaries of species definitions, researchers are detecting a large but still overlooked diversity within microbial populations, revealing evolutionary dynamics occurring at fine genetic scales that classical methods could never resolve.

Equally transformative has been the growing appreciation of microbial ecology as a web of interactions rather than a roster of species. Scientists are now characterizing the myriad ecological relationships that sustain marine food webs and underpin ocean ecosystem functioning, including newly mapped interaction networks, syntrophic associations in which different microbes cooperate metabolically to complete chemical transformations neither could achieve alone, and symbioses that bind microorganisms to hosts ranging from corals to fish larvae. These interactions play key roles in ecosystem functioning and nutrient cycling, and their disruption—by warming, acidification or pollution—could cascade through marine ecosystems in ways scientists are only beginning to anticipate. The editorial emphasizes that unveiling these interaction networks is one of the central tasks facing the next generation of marine microbiologists.

But the same editorial does not celebrate unreservedly. It arrives at a moment when accelerating climate change, including ocean warming and acidification, together with other anthropogenic pressures such as pollution, is impacting marine ecosystems at an unprecedented pace. Because microbes mediate the biogeochemical reactions that determine how much carbon the ocean absorbs, how efficiently nutrients are recycled, and how productive fisheries will be, understanding how microbial communities respond and adapt to these pressures has become a matter of global urgency. The convergence of unprecedented technological capability with unprecedented environmental stress, the editorial argues, creates both opportunities and responsibilities for the marine microbiology community worldwide.

The technical toolkit for meeting that responsibility is maturing rapidly. Long-term ocean observatory programs now monitor microbial communities across years and decades, producing time series that can distinguish genuine trends in microbial abundance and composition from natural seasonal and interannual variability. When coupled with new predictive models—drawing on machine learning, ecosystem modeling and increasingly sophisticated representations of microbial metabolism—these observatories are expected to yield essential insights into how the ocean microbiome may be changing over time, and into its resistance, resilience, or potential fragility in the face of multiple simultaneous stressors. Such forecasting capability is exactly what policymakers and ocean managers will need as climate impacts intensify through the middle of the century.

Timing matters in another sense as well. The editorial notes that as the United Nations Decade of Ocean Science for Sustainable Development, running from 2021 to 2030, reaches its midpoint, advancing understanding of microbial responses to global change has become essential for forecasting the future health of the ocean. International frameworks like the Ocean Decade have elevated the microbiome from a specialist concern to a central pillar of ocean sustainability science, reflecting the recognition that no meaningful model of the future ocean can be built without representing the microbial processes that regulate it. The launch of a dedicated, open-access venue for the field is framed as part of this broader institutional shift toward treating ocean microbes as infrastructure of the biosphere.

The new journal is explicitly designed around the interdisciplinary character of modern marine microbiology. The editorial stresses that the field requires integration across scales: from molecular mechanisms inside single cells to ecosystem processes spanning whole basins, from tightly controlled laboratory experiments to global ocean observations gathered by ships, floats and satellites, and from micro- to macroecological perspectives. Accordingly, the journal welcomes research spanning microbial diversity, genomics and evolution; biogeochemical cycles and microbial metabolism; host–microbe interactions; microbial responses to global change; marine biotechnology and applied microbiology, including so-called blue biotechnology and nature-based solutions to societal challenges; methodological and theoretical advances; and microbial oceanography, including studies of large-scale ecological patterns across the ocean.

The applied dimension of the field deserves particular attention, because the same microbial capabilities that run the planet’s cycles also represent a resource for human society. Marine microbes are a reservoir of enzymes, natural products and metabolic pathways with potential uses in medicine, industry and environmental remediation. Nature-based solutions inspired by microbial processes—harnessing communities that degrade pollutants, cycle nutrients in aquaculture systems or buffer coastal ecosystems against climate impacts—form a growing frontier where fundamental ocean microbiology translates directly into tools for sustainability. The editorial signals that such translational research will sit alongside discovery-driven science in the new journal’s scope, reflecting the field’s expanding societal relevance.

The invitation to the community is broad. The editorial calls on marine microbiologists across all career stages, in every region of the world, to submit their research, contribute as reviewers and help shape a publication intended not merely to document progress but to influence the future direction of marine and aquatic microbial science. As Logares writes in closing, sitting by the ocean one wonders what new secrets it will unveil in the coming years. Given the pace of discovery, the accelerating pressures of global change, and the sheer scale of the microbial world that remains unexplored, that question may well define ocean science for the rest of the decade.

Subject of Research: The ocean microbiome and its role in Earth system functioning under global change

Article Title: The ocean microbiome on a changing planet

Article References: The ocean microbiome on a changing planet. (n.d.). https://doi.org/10.1186/s44375-025-00004-y

Image Credits: AI Generated

DOI: 10.1186/s44375-025-00004-y

Keywords: ocean microbiome, marine microbiology, climate change, biogeochemical cycles, rare biosphere, microbial genomics, ocean warming, ocean acidification, symbiosis, blue biotechnology, microbial ecology, Ocean Decade

The review, authored by Shao-Wei Ho, Ji-Yu Wu, Yu-Wei Chen, Chieh-Kai Yang and Wen-Ping Tsai of National Cheng Kung University in Taiwan, synthesizes recent advances across the major domains of marine science. Rather than cataloguing individual algorithms, the authors emphasize a common pattern: machine learning and deep learning models are enabling scientists to extract actionable knowledge from vast, high-dimensional and often messy ocean observations at scales that were previously unimaginable. Where traditional conservation relied on labor-intensive field surveys, laboratory analyses and satellite remote sensing that were slow, expensive and geographically constrained, AI-driven systems now process satellite imagery, acoustic recordings, underwater video and sensor streams in near real time. One striking example cited in the review: machine learning-based processing of coral reef imagery can run roughly two hundred times faster than manual analysis, allowing assessments that once took months to be completed in days.

At the technical heart of this transformation sit a handful of architectures, each suited to a different kind of ocean problem. Convolutional neural networks, or CNNs, excel at interpreting grid-like image data, learning hierarchical spatial features that progress from simple edges and textures to complex objects, which makes them the workhorse for classifying fish, corals and benthic invertebrates in underwater photographs. Long Short-Term Memory networks, a specialized form of recurrent neural network, use gating mechanisms to selectively retain information over long intervals, making them ideal for time-series forecasting of wave heights, tides, salinity and dissolved oxygen. Random Forest ensembles, which average predictions from many decorrelated decision trees, offer interpretable models for forecasting fish-habitat suitability and estimating chlorophyll-a concentrations. Segmentation networks such as U-Net and its nested variant U2-Net perform pixel-level delineation of coral reef boundaries, sea ice and oil slicks, while generative adversarial networks fill gaps in satellite time series and super-resolve ocean-color imagery.

The review’s analysis of the literature reveals just how dominant vision-based AI has become. CNN-based frameworks accounted for nearly sixty percent of image-based biodiversity studies, and their reported performance is remarkable. One deep learning system achieved 94.9 percent test accuracy in coral and fish recognition, exceeding the 89.3 percent accuracy of human experts on the same task. Coral image classification studies reported overall accuracies of 94.5 percent, with some classes reaching one hundred percent, and large-scale habitat mapping efforts achieved 83 to 94 percent similarity to expert assessments. Platforms such as TagLab, which applies CNN-based segmentation to annotate coral reef orthomosaics, documented roughly a ninety percent increase in identification speed compared with manual routines, while systems like AquaVision automatically detect invasive fish species in the Mediterranean and continuously update their models as new imagery arrives.

Acoustic monitoring is undergoing a parallel revolution. Marine mammals rely on vocalizations as their primary mode of communication, and passive acoustic monitoring systems now use machine learning classifiers to distinguish species-specific calls with high precision, enabling long-term, non-invasive surveillance of whales and dolphins. Deep learning extends this capability across broader frequency bands, enriching the analysis of entire underwater soundscapes. Meanwhile, autonomous underwater vehicles equipped with AI-based object detection are mapping deep-sea habitats inaccessible to divers, and few-shot learning techniques that generalize from limited labeled samples are helping researchers detect rare and endangered species in ecologically sparse datasets. Initiatives such as Seagrass Finder use deep learning on AUV video to map eelgrass, a critical resource for blue carbon accounting.

Fisheries management, long a battleground between productivity and sustainability, may be the domain where AI delivers the most immediate governance benefits. AI-powered electronic monitoring systems installed on fishing vessels use onboard cameras and deep learning algorithms to identify catch composition in real time, reduce bycatch and verify compliance with regulations. The review highlights AI-RCAS, a real-time catch analysis system that combines YOLOv10 object detection with ByteTrack tracking algorithms on embedded Jetson boards, analyzing catches in situ to support enforcement of total allowable catch limits. A lightweight MobileNet-based classifier reported up to 97 percent species-level accuracy in electronic monitoring pipelines, an edge-efficient design suited to resource-constrained vessels. Beyond enforcement, machine learning models trained on environmental and biological data forecast fish stock fluctuations, and reinforcement learning is being used to design adaptive harvest control rules that balance catch efficiency with conservation needs under uncertainty. Platforms like Global Fishing Watch apply pattern recognition to vessel tracking data to expose illegal, unreported and unregulated fishing, promoting real-time transparency across the global fleet.

In aquaculture, the fastest-growing food production sector on the planet, AI is optimizing everything from feeding to disease prevention. Smart feeding systems that monitor fish appetite, movement and water conditions have achieved feed cost reductions of twenty to thirty percent while improving growth rates. Computer vision algorithms detect early visual signs of disease such as lesions, discoloration and erratic swimming, while time-series models trained on water temperature, pH and oxygen data predict outbreaks before clinical symptoms appear. Hybrid deep learning architectures combining CNNs, LSTM networks and attention mechanisms have been proposed to predict nitrate concentrations in recirculating aquaculture systems, and Internet of Things platforms with edge AI continuously monitor water quality, triggering alerts before dangerous thresholds are breached.

Pollution detection and climate impact assessment round out the review’s application landscape. Deep learning models applied to Sentinel-2 and synthetic aperture radar imagery can distinguish oil slicks from optical lookalikes; one hyperspectral framework integrating CNN classification with DBSCAN clustering achieved 92.12 percent mean pixel accuracy while processing each image in under seven hundred milliseconds. AI models also classify floating plastics from hyperspectral satellite imagery, and machine learning has even outperformed humans in microplastic characterization, revealing labeling errors in infrared spectroscopy data. On the climate front, deep learning forecasters reported prediction accuracies exceeding 96 percent for variables such as dissolved oxygen and temperature in coastal time series, and AI-driven ecosystem models project species range shifts and potential collapse thresholds under different emissions scenarios, giving governments and conservation groups the foresight needed for proactive, climate-resilient planning.

The authors are careful, however, not to oversell the technology. Marine AI faces a web of intertwined challenges: ocean data remain fragmented, sparse and geographically imbalanced, especially in polar regions, the deep sea and developing coastal nations; models trained in one environment often degrade when transferred to waters with different turbidity, light or species composition; and the computational demands of deep learning raise both cost barriers and genuine carbon footprint concerns that could undermine the sustainability goals the technology serves. Many biodiversity-rich but technologically underserved regions lack the connectivity and infrastructure for real-time AI deployment, and the opacity of black-box models erodes trust among policymakers and coastal communities whose livelihoods depend on AI-informed decisions. The review calls for explainable AI techniques such as SHAP and Grad-CAM, human-in-the-loop oversight, lightweight and energy-efficient architectures, and federated learning approaches that train models across decentralized networks of buoys, gliders and autonomous vehicles without shipping raw data to central servers, preserving both privacy and bandwidth.

Looking forward, the most promising frontier may be the fusion of machine learning with physical ocean models through differentiable parameter learning and physics-informed neural networks, approaches that embed conservation laws directly into the training process and can cut calibration costs by orders of magnitude. Combined with multi-modal data integration spanning satellites, sonar, environmental DNA and in-situ sensors, and with federated edge intelligence deployed directly at sea, the authors argue that AI can shift marine governance from reactive crisis response to anticipatory, data-driven stewardship. The stakes could hardly be higher: healthy oceans underpin Sustainable Development Goal 14 and the wellbeing of millions. What this comprehensive review makes clear is that the algorithms are ready. The harder work now lies in building the open data infrastructure, ethical safeguards and international cooperation needed to put them to work for the ocean, everywhere, equitably and at scale.

Subject of Research: Applications of artificial intelligence, machine learning and deep learning techniques for sustainable marine resource management

Article Title: Leveraging artificial intelligence (AI) techniques for sustainable marine resources

Article References: Leveraging artificial intelligence (AI) techniques for sustainable marine resources. (n.d.). https://doi.org/10.1186/s44315-026-00054-0

Image Credits: AI Generated

DOI: 10.1186/s44315-026-00054-0

Keywords: artificial intelligence, machine learning, deep learning, marine biodiversity, sustainable fisheries, ocean conservation, aquaculture, marine pollution, climate change, coral reefs, federated learning, blue biotechnology