The research, carried out by Federico Lasagni, Robab Ezazi, Marilisa Giavalisco, Stefano Cassanelli, Alessandro Ulrici, Maria Gullo and Teresa Zotta, was funded by the PRIN 2022 project SynBioCell, which targets sustainable bacterial cellulose production for food and health applications, and was supported by the Italian national node MIRRI-IT of the European Research Infrastructure MIRRI-ERIC. The work addresses a well-recognized bottleneck. Acetic acid bacteria, or AAB, are acknowledged as high producers of bacterial cellulose, but the amount they synthesize fluctuates considerably depending on the strain and on a range of environmental and nutritional factors. That variability has practical consequences: any strategy that makes cellulose production more reliable and more productive is of immediate relevance to bioprocess developers.

Instead of relying on trial and error, the team turned to design of experiments, a chemometric framework that allows many variables to be screened and optimized with a statistically controlled number of trials. Their strategy unfolded in two sequential stages. First, two Plackett-Burman designs, screening designs prized for their efficiency in identifying which factors among many actually matter, were used to construct and screen synthetic microbial communities, or SynComs. These communities were assembled from three functional groups: acetic acid bacteria, lactic acid bacteria, and yeasts. In total, twelve different SynComs were built and tested, spanning combinations of AAB alone, AAB with lactic acid bacteria, AAB with yeasts, and communities containing all three groups.

The logic behind mixing species is ecological as much as biochemical. In natural fermentation ecosystems, such as those governing vinegar and kombucha production, acetic acid bacteria rarely act alone. Lactic acid bacteria and yeasts can alter the pH, consume or release metabolites, and create conditions that either help or hinder cellulose-producing strains. By treating community composition itself as an experimental variable, the researchers could ask a question that monoculture studies cannot address: does the identity of the neighbors matter as much as the identity of the producer? The Plackett-Burman screening answered emphatically that it does. The composition of the SynComs significantly affected bacterial cellulose production, and several communities outperformed some of the acetic acid bacteria monocultures tested alongside them.

Having narrowed the field, the researchers moved to the second stage: a circumscribed central composite design, or CCC, a response-surface methodology that fits a mathematical model describing how the response, in this case cellulose titre, changes across a continuum of culture conditions. This allowed the team not merely to pick the best condition among those tested, but to predict where the true optimum lies, including at combinations of factor levels never directly run in the experiment. The factors optimized included glucose concentration, temperature, and cultivation time, three of the most influential levers in any microbial fermentation process.

The outcome was a consortium containing both lactic acid bacteria and yeasts as helper strains alongside the cellulose producer. Under the optimized conditions, 50 grams per liter of glucose, a temperature of 32 degrees Celsius, and a cultivation period of seven days, this SynCom reached a bacterial cellulose titre of 10.40 plus or minus 0.40 grams per liter. For comparison, the best performer among the acetic acid bacteria monocultures, a strain carrying a deletion in the gdh gene, designated the AAB monoculture Δgdh K2G30, produced 10.79 plus or minus 0.36 grams per liter. The difference between the engineered community and the single best strain was within experimental uncertainty, meaning the consortium effectively matched the champion monoculture.

Just as important for process development, the measured production level agreed closely with the model’s forecast. The circumscribed central composite design’s regression model predicted a cellulose titre of 10.53 grams per liter under the same conditions, a figure the experimental result confirmed within its error range. That agreement matters because it validates the entire statistical pipeline: if the response-surface model had diverged sharply from reality, the optimization would have been little more than an elaborate curve fit. Instead, the researchers can now use the model to explore neighboring conditions and to reason about scale-up with quantitative confidence.

The study’s authors are careful about what remains unknown. Although the community-level results are striking, the roles and interactions among the individual community members have not yet been resolved. Whether the lactic acid bacteria and yeasts are supplying growth factors, buffering acidity, scavenging inhibitory byproducts, or reshaping the metabolic flux of the cellulose producer is a question for future metabolic and population dynamics analyses. Such work, tracking which species persist, in what proportions, and what they exchange over the course of a seven-day fermentation, will be essential before synthetic communities can be deployed reliably at industrial scale, where community stability under continuous operation becomes a critical concern.

Even so, the conceptual advance is considerable. Bacterial cellulose is chemically identical to plant cellulose but free of lignin and hemicellulose, which makes it attractive for wound dressings, tissue engineering scaffolds, and novel food textures. Production costs, however, have limited its adoption, and much of the field has focused on genetic engineering of producer strains such as Komagataeibacter xylinus. This study offers a complementary route: rather than modifying the producer’s genome, modify its social environment. The finding that several SynComs outperformed some acetic acid bacteria monocultures suggests that helper organisms can unlock productivity that a single strain cannot reach on its own, and that this effect can be captured systematically rather than stumbled upon.

The methodological lesson may prove as influential as the biological one. Sequential design of experiments, moving from Plackett-Burman screening to central composite response-surface optimization, gave the researchers a disciplined path from twelve candidate communities to one optimized recipe and one validated set of culture conditions, all with a manageable number of experiments. As synthetic microbial communities attract growing interest across biotechnology, from waste valorization to probiotic formulation, the ability to assemble and tune them statistically, rather than intuitively, could become standard practice. For bacterial cellulose specifically, the results point toward more versatile fermentation processes in which consortia, not lone strains, do the manufacturing, a perspective the authors present as a new direction for future development in food and biomedical applications.

Subject of Research: Design-of-experiments-guided assembly of synthetic microbial communities to optimize bacterial cellulose production

Article Title: DOE-guided assembly and optimization of Synthetic Microbial Communities for bacterial cellulose production

Article References: Lasagni, F., Ezazi, R., Giavalisco, M., Cassanelli, S., Ulrici, A., Gullo, M., & Zotta, T. (2026). DOE-guided assembly and optimization of Synthetic Microbial Communities for bacterial cellulose production. Applied Microbiology and Biotechnology. https://doi.org/10.1007/s00253-026-14059-7

Image Credits: AI Generated

DOI: 10.1007/s00253-026-14059-7

Keywords: bacterial cellulose, synthetic microbial communities, acetic acid bacteria, lactic acid bacteria, yeasts, design of experiments, Plackett-Burman design, central composite design, Komagataeibacter xylinus, fermentation optimization, biopolymer, industrial microbiology

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

Alpha-amylases are the workhorses of the industrial enzyme market, accounting for roughly 30 percent of global enzyme production. These endo-1,4-alpha-D-glucan glucohydrolases randomly hydrolyse the internal bonds of starch chains, depolymerising polysaccharides into reducing sugars in the alpha-configuration. Unlike glucoamylases, which peel glucose units from the non-reducing ends of starch molecules step by step, alpha-amylases act throughout the polymer, making them invaluable for rapid starch liquefaction. Both enzyme classes are calcium-dependent metalloenzymes, with calcium ions playing a critical structural role. Today, they underpin processes ranging from food manufacturing and detergent formulation to wastewater treatment and emerging clinical applications, and demand for them continues to climb.

The commercial enzymes currently used in starch saccharification, which operates at 70 to 110 degrees Celsius, are mesophilic GH-13 amylases that lack sufficient heat tolerance and specificity. This forces manufacturers to make costly pH adjustments and to supplement reactions with calcium. Thermal stability offers real economic rewards: substrates dissolve more readily at high temperature, medium viscosity drops, microbial contamination risk falls, and accompanying non-enzymatic reactions accelerate. For these reasons, the hunt is on for calcium-independent, thermostable, acid-stable amylases that can function near starch’s native pH of approximately 4.5, a combination that would make starch processing cheaper and more energy-efficient. The enzyme from THS-K1, with its broad pH tolerance and robust thermal endurance, is a serious candidate.

Optimising enzyme production from microbial sources is a bioprocess engineering challenge in itself. The researchers began with one-variable-at-a-time screening but quickly moved to statistical designs that capture interactions between factors. A Plackett-Burman design assessed ten medium parameters, including starch concentration, calcium chloride, beef extract, sodium chloride, peptone, pH, yeast extract, and phosphate salts, at two levels each. Regression analysis produced a first-order polynomial model with an R-squared value of 0.79 and a highly significant F-value of 14.39. Three variables emerged as dominant: soluble starch concentration, medium pH, and yeast extract concentration. Starch serves as both inducer and carbon source, while yeast extract supplies a complex blend of nitrogenous compounds and growth factors that inorganic salts cannot replicate.

With the key factors identified, the team applied a Central Composite Design under the Response Surface Methodology framework. Twenty experimental runs, each performed in triplicate, explored combinations of starch from 1.5 to 2.5 grams percent, pH from 6.5 to 7.5, and yeast extract from 0.1 to 1 grams percent. A second-order polynomial model fitted the data with adjusted and experimental R-squared values of 0.99 and 0.98 respectively, indicating an exceptionally strong agreement between predicted and observed responses. Three-dimensional surface plots confirmed meaningful interactions between the variables, with starch and pH jointly shaping the response landscape. Under the optimum conditions, a medium containing 2 percent soluble starch, 0.55 percent yeast extract, calcium chloride, phosphate salts, peptone, magnesium sulphate, and sodium chloride at pH 7 and 50 degrees Celsius for 72 hours, enzyme production rose from 1.1 units per millilitre to 4.94 plus or minus 0.05 units per millilitre, an increase of roughly 4.5-fold.

Purification followed a classical but carefully executed pipeline. The extracellular enzyme was first precipitated with ammonium sulphate, with the active fraction recovered between 50 and 70 percent saturation, then dialysed overnight through a 10 kilodalton cutoff membrane. Size exclusion chromatography on a Bio-Gel P-100 column separated proteins by molecular mass, and a subsequent ion exchange step on DEAE-cellulose, eluted with a sodium chloride gradient, polished the preparation. Together, these steps achieved a 12.8-fold purification with a 25.14 percent yield. SDS-polyacrylamide gel electrophoresis revealed a single band at approximately 25 kilodaltons, a small size for an alpha-amylase, and zymographic analysis, in which a clear band appeared against a dark blue iodine-stained starch background, confirmed that this band was the active enzyme.

Characterisation of the purified enzyme revealed a profile well suited to demanding industrial conditions. Maximum catalytic activity, reaching 3.8 units per millilitre, occurred at 50 plus or minus 1 degree Celsius, although the enzyme remained active across a wide range from 40 to 90 degrees Celsius. The optimum pH was 7, with activity sustained from pH 5 through 10, an unusually broad working window. Thermal stability testing showed half-lives of 13 hours at 50 degrees, 6 hours at 60 degrees, 2 hours at 70 degrees, and an impressive 1 hour and 53 minutes even at 80 degrees. In pH stability trials, the enzyme endured half-lives of 15 to 16 hours between pH 6 and 8 and still retained activity after 8 hours at pH 9. Kinetic analysis using Lineweaver-Burk plots yielded a Michaelis constant of 0.033 milligrams per millilitre, indicating strong substrate affinity, a maximum velocity of 4.18 micromoles per millilitre per minute, a turnover number of 8.71 per second, and a catalytic efficiency of 4.28 times 10 to the fourth per molar per second.

Metal ion profiling added another dimension to the enzyme’s industrial credentials. Divalent cations including copper, iron, calcium, and magnesium significantly enhanced activity, consistent with the metalloenzyme nature of amylases, while monovalent potassium and sodium ions exerted a slight inhibition. To understand the molecular basis of these properties, the team extracted genomic DNA, amplified the amylase gene with Bacillus-specific primers AmyF1 and AmyR1, and recovered a fragment of approximately 1.7 kilobases. Sanger sequencing and BLASTx analysis confirmed that the sequence encodes an alpha-amylase of the conserved cd11315 domain, and translation predicted a polypeptide of roughly 368 amino acids with high sequence identity to the alpha-amylase of Bacillus subtilis. A phylogenetic tree built with the UPGMA method and 1000 bootstrap replicates placed the enzyme firmly within the Bacillus amylase family.

Homology modelling using the SWISS-MODEL server, based on the crystal structure of the Bacillus sp. KR-8104 amylase (PDB entry 3DC0), produced a three-dimensional model showing 61.66 percent sequence identity with a QMEAN quality score of 0.73, indicating reliable local geometry. Ramachandran plotting confirmed that the majority of residues occupy favoured regions, validating the model for structure-function analysis. Comparison with the template revealed multiple amino acid substitutions that the authors suggest may underpin the enzyme’s enhanced thermal stability. Together, the statistical optimisation, biochemical characterisation, kinetic analysis, and in silico modelling represent the first integrated molecular portrait of an amylase from Bacillus stercoris isolated from an Indian hot spring. With its ability to withstand elevated temperatures, function across a broad pH spectrum, and digest starch efficiently, the THS-K1 enzyme and its Amy gene offer a promising foundation for recombinant production and protein engineering aimed at cheaper, greener starch saccharification.

Subject of Research: Bioprocess optimisation and molecular characterisation of a thermostable alpha-amylase from thermotolerant Bacillus stercoris THS-K1

Article Title: Bioprocess optimisation and molecular characterisation of alpha-amylase from thermotolerant Bacillus stercoris THS-K1

Article References: Padia, H. H., Jain, K. S., Goswami, V. C., & Tipre, D. R. (2025). Bioprocess optimisation and molecular characterisation of alpha-amylase from thermotolerant Bacillus stercoris THS-K1. Discover Biotechnology, 2(1), Article 35. https://doi.org/10.1007/s44340-025-00044-9

Image Credits: AI Generated

DOI: 10.1007/s44340-025-00044-9

Keywords: alpha-amylase, Bacillus stercoris, thermostable enzyme, hot spring microbiology, response surface methodology, Plackett-Burman design, central composite design, enzyme purification, starch saccharification, Amy gene, homology modelling, bioprocess optimisation