The research, led by Nor Jumanah Said Mohamed of Universiti Kebangsaan Malaysia together with colleagues including Ahmad Razi Othman, Siti Rozaimah Sheikh Abdullah and Nur ‘Izzati Ismail, with Clara Manno of the British Antarctic Survey and Mohd Yunus Abd Shukor of Universiti Putra Malaysia, focuses on chitosan, a biopolymer derived from chitin. Chitin is the structural material that gives crustacean shells their strength, and it is abundantly available as waste from the seafood industry. When chitin is deacetylated, meaning that acetyl groups are chemically removed from its long molecular chains, it becomes chitosan, a positively charged polymer that can bind negatively charged particles suspended in water and draw them into settleable clumps. That charge behaviour is precisely what makes chitosan attractive as a coagulant for microplastics, which tend to carry surface charges that keep them dispersed.

The catch lies in how chitosan is produced. Conventional extraction relies on strong acids and alkalis, processes that consume chemicals and energy and can themselves create environmental burdens that offset the benefits of using a bio-based coagulant. The Malaysian team therefore turned to deep eutectic solvents, or DESs, a family of designer solvents formed by mixing a hydrogen bond donor and a hydrogen bond acceptor, in this case all based on choline chloride. The resulting liquids have unusual solvation properties, low volatility and a reputation for being far gentler on the environment than traditional industrial solvents. Because their composition can be tuned by choosing different donor molecules, DESs offer chemists a kind of molecular dial for controlling extraction outcomes.

The researchers tested four choline chloride-based deep eutectic solvents, pairing the choline chloride with glycerol, malonic acid, glucose or urea. Each combination interacts differently with the mineral and protein components of shrimp shells, and the team wanted to know which would best liberate chitin and convert it toward chitosan. The winner was choline chloride combined with malonic acid, abbreviated CCMA. Shells of the whiteleg shrimp Litopenaeus vannamei, one of the most farmed shrimp species in the world and therefore a plentiful waste stream, treated with this solvent yielded 19.09 percent chitosan with a solubility of 90.68 percent, the best figures among the four solvents examined.

Characterisation confirmed that the extracted material was genuine chitosan with useful structural properties. Fourier transform infrared spectroscopy, which probes the chemical bonds in a sample, verified the functional groups expected of deacetylated chitin. X-ray diffraction revealed a semicrystalline structure, a balance of ordered and disordered regions that is typical of chitosan and relevant to how the polymer behaves in solution. Scanning electron microscopy added a striking visual detail: the DES-extracted chitosan displayed a porous, honeycomb-like morphology. Such an open architecture increases the surface area available for contact with suspended particles, a feature that plausibly supports the material’s performance as a coagulant.

Getting the most out of the extraction required careful optimisation. The team first used a one-variable-at-a-time approach, adjusting temperature, reaction time and the ratio of shrimp shell material to solvent individually, and then refined the process with response surface methodology, a statistical technique that maps how several variables interact simultaneously and locates the true optimum rather than a series of local improvements. The optimal conditions emerged as a temperature of 93.91 degrees Celsius, a reaction time of 8.15 hours and a shell-to-solvent ratio of 0.042 grams per millilitre, corresponding to 21 grams of shell per 500 millilitres of solvent. Under these conditions the chitosan reached a degree of deacetylation of 89.05 percent, and the statistical model describing the process showed a strong fit with an R-squared value of 0.9521, indicating that the chosen variables explain most of the variation in the outcome.

The degree of deacetylation matters enormously for coagulation. The more acetyl groups removed, the more free amino groups the polymer carries, and at acidic to neutral pH these amino groups become protonated, giving the chain its positive charge. A chitosan with nearly 90 percent deacetylation is therefore a highly charged molecule, well suited to neutralising the negative surface charges that keep microplastic particles suspended. Charge neutralisation and the subsequent bridging of particles by long polymer chains are the two principal mechanisms by which coagulants turn a cloudy suspension into settleable flocs.

With the optimised chitosan in hand, the team put it to the test against polyethylene, one of the most common plastics in the waste stream and a frequent component of microplastic pollution. In a controlled suspension of polyethylene microparticles in deionised water, the CCMA-derived chitosan achieved a maximum reduction of 58.10 percent in turbidity and 63.55 percent in total suspended solids at a dose of 50 milligrams per litre. Importantly, these figures were corrected against a no-coagulant control, ensuring that the measured removal reflected genuine coagulation rather than simple settling. The performance was comparable to that of commercial chitosan under the same conditions, a significant result for a material produced through a greener extraction route.

The authors are careful about the limits of their findings. The coagulation experiments were conducted in deionised water, a clean and simplified matrix that lacks the organic matter, salts and competing particles found in real wastewater. Natural waters can dramatically alter coagulation behaviour, since dissolved organic carbon competes for the polymer’s binding sites and ionic strength changes the electrostatic interactions at play. The study itself notes that further validation under representative wastewater conditions is required before the approach can be considered ready for practical deployment. That caveat is standard for laboratory-scale coagulation research, but it is an essential one for readers hoping to gauge how quickly this technology might reach treatment plants.

Even with those caveats, the study contributes a meaningful piece to the puzzle of sustainable microplastic remediation. It links two waste streams in a single solution: shrimp shells that would otherwise be discarded become a high-performance coagulant, and the solvent used to extract it is designed to be environmentally benign and potentially recoverable. It also demonstrates a rigorous workflow, from solvent screening through statistical optimisation to materials characterisation and application testing, that other groups can adapt to different feedstocks and different pollutant targets. As regulators and utilities worldwide grapple with how to remove microplastics from effluents and drinking water, approaches that avoid swapping one pollution problem for another will be increasingly valuable. This work suggests that the answer to a plastic problem might, in part, come from the seafood counter, provided the chemistry behind it stays as green as the ambition.

Subject of Research: Green extraction of chitosan from shrimp shell waste with deep eutectic solvents for microplastic coagulation

Article Title: Deep eutectic solvent-assisted extraction of chitosan for polyethylene microplastic coagulation

Article References: Mohamed, N. J. S., Othman, A. R., Manno, C., Shukor, M. Y. A., Abdullah, S. R. S., & Ismail, N. I. (2026). Deep eutectic solvent-assisted extraction of chitosan for polyethylene microplastic coagulation. Environmental Science and Pollution Research. https://doi.org/10.1007/s11356-026-38253-2

Image Credits: AI Generated

DOI: 10.1007/s11356-026-38253-2

Keywords: chitosan, deep eutectic solvents, microplastics, polyethylene, coagulation-flocculation, shrimp shell waste, chitin, degree of deacetylation, response surface methodology, water treatment, green chemistry, Litopenaeus vannamei

Chitin is the star of this story. It is the second most abundant natural polymer on Earth after cellulose, forming the tough exoskeletons of crustaceans and insects as well as the cell walls of fungi. Chitinase enzymes break chitin down into smaller, soluble fragments that have uses ranging from agricultural biocontrol agents and fertiliser components to cosmetic ingredients and pharmaceutical precursors. The bottleneck has always been production: chitinase made by fermenting microbes is expensive, and purifying chitin from shrimp shells traditionally requires harsh chemical treatments that generate their own pollution. The Egyptian team set out to solve both problems at once by letting bacteria ferment raw shrimp shell waste directly, using the waste as the sole source of both carbon and nitrogen.

The researchers began by screening four thermophilic bacterial strains from their culture collection: Bacillus amyloliquefaciens BT 2022, Bacillus licheniformis Basma87, Priestia megaterium AMD 2024, and the actinobacterium Streptomyces maritimus MSQ-2021. Thermophiles were a deliberate choice. Growing at elevated temperatures reduces the risk of contamination by ordinary mesophilic microbes, lowers cooling costs in an industrial fermenter, and often coincides with faster enzyme kinetics. When the four strains were grown on media containing nothing but shrimp shell waste, Priestia megaterium AMD 2024 emerged as the clear winner, degrading the chitin matrix most vigorously and releasing the highest chitinolytic activity into the culture broth.

With the champion strain identified, the team turned to optimisation, first using the familiar one-variable-at-a-time approach, in which a single fermentation parameter is adjusted while everything else is held constant. This systematic sweep identified a sweet spot: shrimp shell waste at a concentration of 5 percent, incubation at 60 degrees Celsius for 72 hours, a neutral pH of 7.0, shaking at 200 revolutions per minute, and an inoculum size of 2 percent. Under these conditions the culture produced 93.24 units per millilitre of chitinase activity, a respectable figure that confirmed the concept. But OVAT has a well-known weakness. It cannot detect interactions between variables, and in fermentation biology those interactions are often where the real gains hide. A temperature that works at one pH may fail at another, and substrate concentration can shift the entire response surface.

To capture those hidden interactions, the researchers moved to response surface methodology, a statistical framework that models the output of a process as a mathematical surface over multiple input dimensions. The first stage used a Plackett–Burman design, an efficient screening tool that evaluates many factors simultaneously with a minimal number of runs, allowing the team to identify which variables exerted the strongest influence on enzyme yield. The significant factors then fed into a central composite design, which samples the response surface around an optimal region and fits a quadratic model to locate the true maximum. The outcome was dramatic: chitinase activity climbed to 273.3 units per millilitre, a 2.93-fold increase over the OVAT baseline. For bioprocess engineers, the result is a textbook demonstration of why statistical design has largely replaced trial-and-error optimisation in modern industrial biotechnology.

The enzyme then had to be recovered from the broth. The team used ammonium sulphate precipitation, a classic low-cost purification step in which increasing salt concentrations progressively crash proteins out of solution. The 60 to 80 percent saturation fraction proved the richest, delivering 260.0 units per millilitre of activity while retaining 95.13 percent of the original enzymatic function. This partial purification strikes a pragmatic balance for industrial applications: the enzyme is concentrated and freed from the bulk of unwanted proteins without the expense of chromatographic polishing that would be unnecessary for many agricultural and cosmetic uses.

Perhaps the most consequential finding for commercial prospects came from the safety testing. The purified enzyme was applied to HFB4, a normal human skin cell line, in cytotoxicity assays. Even at the maximum concentration tested, equivalent to 260.0 units per millilitre of activity, the enzyme showed no toxic effects on the skin cells, confirming its biocompatibility. That single result opens doors well beyond waste management. Chitinases with demonstrated skin safety can be considered for cosmetic formulations, where chitin-derived oligosaccharides are prized as moisturising and film-forming agents, and for biomedical applications where contact with living tissue is unavoidable.

The broader significance of the study lies in its circular economy logic. Shrimp processing generates enormous quantities of shell waste that is rich in chitin, protein, and minerals, and disposal of that waste is a genuine environmental burden for coastal nations, including Egypt’s rapidly growing aquaculture and seafood sectors. By feeding the waste directly to a thermophilic bacterium, the process simultaneously treats a pollutant and manufactures a product, converting a disposal cost into a revenue stream. Because the bacteria use the shells as their only feedstock, the process avoids the chemical demineralisation and deproteinisation steps of conventional chitin processing, cutting reagent consumption and effluent load. The authors frame the work explicitly as an eco-friendly solution, and the numbers support that framing: a waste-derived substrate, a low-energy thermophilic fermentation, and a benign purification route.

There are, of course, steps between a well-optimised laboratory fermentation and an industrial process. Scale-up will require confirming that the statistical optimum holds in larger vessels, where mixing, oxygen transfer, and heat removal behave differently from shake flasks. Downstream processing will need to be tailored to each target market, since an enzyme destined for a cosmetic cream faces stricter purity requirements than one sprayed on a field to suppress fungal pathogens. Nonetheless, the study provides a complete proof of concept, from strain selection through statistical optimisation to purification and safety assessment, and it identifies a robust thermophilic producer in Priestia megaterium AMD 2024 that can serve as a platform for further engineering. As industries everywhere search for biologically based alternatives to petrochemical processes, studies like this one show that some of the most promising feedstocks are already piling up behind seafood processing plants, waiting for the right microbe to come along.

For the researchers, the message is straightforward: chitinase production no longer needs to depend on expensive purified substrates or energy-intensive conditions. A waste product that once cost money to throw away can, with the right bacterium and the right experimental design, become the foundation of a sustainable enzyme industry serving agriculture, manufacturing, and cosmetics alike. The 2.93-fold boost achieved through response surface methodology is not merely a laboratory curiosity; it is the kind of quantitative improvement that makes the difference between a process that stays in a paper and one that attracts investment. And with the enzyme shown to be safe for human skin cells, the path from shrimp shell heap to shelf-ready product has never looked shorter.

Subject of Research: Microbial production and statistical optimization of chitinase from shrimp shell waste using thermophilic bacteria

Article Title: Harnessing shrimp shell waste: enhanced chitinase production through optimization techniques for ecofriendly solutions using bacteria

Article References: Abd-Elhalim, B. T., & Ashour, M. A. (2026). Harnessing shrimp shell waste: enhanced chitinase production through optimization techniques for ecofriendly solutions using bacteria. Biotechnology for Biofuels and Bioproducts, 19(1), Article 73. https://doi.org/10.1186/s13068-026-02808-9

Image Credits: AI Generated

DOI: 10.1186/s13068-026-02808-9

Keywords: chitinase, shrimp shell waste, Priestia megaterium, response surface methodology, Plackett-Burman design, central composite design, thermophilic bacteria, biowaste valorization, partial purification, cytotoxicity, circular economy, green biotechnology

Chitosan is a cationic polysaccharide derived from chitin, the second most abundant natural polymer on Earth after cellulose and the structural backbone of crustacean exoskeletons. Chemically, chitosan consists of repeating units of D-glucosamine and N-acetyl-D-glucosamine linked by beta-(1,4) glycosidic bonds, and its native amine groups become protonated at physiological pH. This positive charge allows the polymer to interact electrostatically with negatively charged cell membranes, modulating cell adhesion, migration and proliferation. Because of these properties, chitosan has long attracted interest as a wound-dressing material that can promote tissue regeneration, stimulate fibroblast activity, accelerate hemostasis and suppress microbial infection. The single most important quality parameter is the degree of deacetylation, the proportion of deacetylated glucosamine units in the chain; a chitin sample with more than 50 percent deacetylation is generally classified as chitosan, and higher values typically improve solubility, antimicrobial performance and biological interactions.

The catch has always been how to make it. Conventional extraction subjects shrimp shell powder to concentrated sodium hydroxide at high temperatures for hours, an energy-intensive process that risks degrading the polymer backbone and inflating production costs. Alternative technologies each carry their own burdens: ultrasound can accelerate extraction but may cleave polymer chains and reduce molecular weight, enzyme-assisted routes offer selectivity at the price of costly catalysts and long processing times, and deep eutectic solvents reduce harsh chemical use but complicate solvent recovery at industrial scale. Microwave-assisted extraction promises shorter reaction times, lower electricity consumption, simpler equipment and easier scalability, because microwave radiation heats the reaction mixture directly and uniformly through dipole rotation and ionic conduction rather than through slow conduction and convection.

The research team, working with shrimp shell waste from Indonesian processing of Litopenaeus vannamei, ground and sieved the dried shells to 74 to 150 micrometers and then optimized each of the three extraction stages under microwave irradiation. Demineralization with hydrochloric acid proved to be governed mainly by acid concentration rather than microwave power: at 0.5 M HCl more than 72 percent of the calcium remained, while both 1 M and 2 M HCl achieved complete calcium removal across 400, 500 and 600 watts within just five minutes. Deproteinization with sodium hydroxide followed a similar pattern, with protein removal rising from 99.18 percent at 2 percent NaOH to a full 100 percent at 10 percent NaOH, regardless of the power level applied.

Deacetylation, the step that transforms chitin into chitosan, responded strongly to both alkali concentration and microwave power. At a fixed 600 watts, increasing NaOH from 40 to 80 weight percent pushed the degree of deacetylation toward 80 percent even in five-minute treatments, and extending the reaction to ten minutes at 600 watts and 80 percent NaOH lifted the value to nearly 85 percent. FTIR spectroscopy, using the ratio of absorbance bands at 1320 and 1420 inverse centimeters, confirmed a degree of deacetylation of 85 percent for microwave-synthesized chitosan versus 80 percent for the conventionally produced material. More striking was the yield: microwave processing converted 10 percent of the starting shell mass into final chitosan, compared with only 1.6 percent for the conventional route, a six-fold improvement in material efficiency.

Structural characterization reinforced the case for the microwave route. X-ray diffraction showed that both products were semi-crystalline, but the conventionally synthesized sample exhibited a broadened and weakened peak near 2 theta of 10 degrees, indicating loss of crystallinity, whereas the microwave product retained a well-defined crystalline peak, suggesting that rapid volumetric heating minimizes disruption of the polymer backbone. Scanning electron microscopy revealed characteristic lamellar flake morphologies with smooth surfaces and dense packing for both materials, consistent with a high density of free amino groups. At the molecular level, the researchers explain the difference through kinetics: hydroxide ions attack the electrophilic carbonyl carbon of chitin’s acetamide groups, cleaving the C–N bond and releasing acetate, and microwave-driven dipolar heating accelerates this nucleophilic attack throughout the crystalline core instead of forcing slow diffusion from a hot surface inward.

The biological evaluation focused on RAW 264.7 murine macrophage-like cells, key players in the inflammatory phase of wound repair. In MTT cytotoxicity assays, microwave-derived chitosan at concentrations from 0.1 to 10 milligrams per milliliter did not significantly reduce cell viability over 24 or 48 hours of incubation, demonstrating excellent cytocompatibility. In scratch assays, monolayers cultured on the chitosan-coated substrates showed progressive wound closure beginning around 12 hours, with the cell-free gap nearly completely closed after 48 hours. The authors attribute this activity in part to positively charged calcium ions released from the biopolymer, which may enhance cell proliferation, and to the hydrophilic character of the chitosan surface. They caution, however, that macrophage results represent only one facet of a process that also depends on fibroblasts, keratinocytes, endothelial cells and extracellular matrix remodeling, and that fibroblast and keratinocyte models plus in vivo studies are needed to confirm therapeutic efficacy.

To probe mechanism, the team performed molecular docking of chitosan malate against AKT1, a protein kinase central to the PI3K/AKT signaling pathway that drives cell proliferation, migration and angiogenesis during tissue repair. Chitosan malate showed a predicted binding affinity of minus 9.6 kilocalories per mole toward AKT1, stronger than the known AKT activator SC79 at minus 7.9, with predicted contacts at residues Thr81, Thr82 and Arg273 in the PH domain and near the kinase domain interface. The researchers stress that these are exploratory computational estimates: the study did not measure AKT1 expression or phosphorylation, so any involvement of the pathway in the observed wound-closure behavior remains a hypothesis requiring experimental validation.

The economic case may prove equally consequential. By integrating equipment power ratings over operating times, the team calculated that microwave-assisted synthesis consumed up to 94.6 percent less energy than conventional heating. A techno-economic analysis anchored to Indonesian market conditions yielded a positive net present value of approximately USD 10.73 million, an annual profitability investment of 18.62 percent, and a benefit-cost ratio of 17.72, comfortably above the feasibility threshold of unity. Sensitivity analyses varying the product selling price by plus or minus 15 percent showed that the project remained profitable even in the worst scenario, with NPV near USD 9 million and a benefit-cost ratio of 15. Taken together, the results position microwave extraction as a commercially viable, energy-efficient pathway for turning one of the seafood industry’s largest waste streams into a biomedical raw material, though the authors note that pilot-scale validation, molecular-weight characterization, in vivo testing and continuous reactor design remain the next hurdles before clinical and industrial adoption.

Subject of Research: Microwave-assisted synthesis of high-quality chitosan from shrimp shell biowaste for wound-healing applications

Article Title: Comparative study of microwave-assisted and conventional methods for the synthesis of high-quality chitosan from shrimp shell biowaste to manipulate cell growth and functions: Supported molecular docking analysis

Article References: Rahmatunnisa, C., Budi, C. S., Ilhami, F. B., Puspitarini, S., Melanie, M., Hapidin, D. A., Kuo, D.-H., Zeleke, M. A., Kurnia, I., Hastuti, L. P., Rahmah, D. M., & Gultom, N. S. (2026). Comparative study of microwave-assisted and conventional methods for the synthesis of high-quality chitosan from shrimp shell biowaste to manipulate cell growth and functions: Supported molecular docking analysis. Case Studies in Chemical and Environmental Engineering, 14, Article 101481. https://doi.org/10.1016/j.cscee.2026.101481

Image Credits: AI Generated

DOI: 10.1016/j.cscee.2026.101481

Keywords: chitosan, shrimp shell waste, microwave-assisted extraction, chitin deacetylation, wound healing, biomaterials, molecular docking, AKT1, techno-economic analysis, biocompatibility, energy efficiency, marine biowaste