In the cheese-making industry, commonly chymosin is used as the main milk-clotting enzyme. Bactrian camel (Camelus bactrianus) chymosin (BacChym) has a milk-clotting activity higher than that of calf chymosin for cow’s, goat’s, ewes’, mare’s and camel’s milk. A procedure for obtaining milk-clotting reagent based on recombinant camel chymosin is proposed here. Submerged fermentation by a recombinant yeast (Pichia pastoris GS115/pGAPZαA/ProchymCB) was implemented in a 50 L bioreactor, and the recombinant camel chymosin was prepared successfully. The activity of BacChym in yeast culture was 174.5 U/mL. The chymosin was concentrated 5.6-fold by cross-flow ultrafiltration and was purified by ion exchange chromatography. The activity of the purified BacChym was 4700 U/mL. By sublimation-drying with casein peptone, the BacChym powder was obtained with an activity of 36,000 U/g. By means of this chymosin, cheese was prepared from cow’s, goat’s, ewes’, camel’s and mare’s milk with a yield of 18%, 17.3%, 15.9%, 10.4% and 3%, respectively. Thus, the proposed procedure for obtaining a milk-clotting reagent based on BacChym via submerged fermentation by a recombinant yeast has some prospects for biotechnological applications. BacChym could be a prospective milk-clotting enzyme for different types of milk and their mixtures.

Xylanase is one of industrial enzymes with diverse applications including the paper-bleaching industry and feed additives. Here, a strain having xylanolytic activity and identified as Bacillus sonorensis T6 was isolated from soil. A secretory enzyme was identified by mass-spectrometry as a xylanase of glycosyl hydrolase family 11, with a molecular weight of 23.3 kDa. The xylanase gene of Bacillus sonorensis T6 was cloned and expressed in Escherichia coli (yielding an enzyme designated as rXynT6-E) and in Pichia pastoris (yielding rXynT6-P). The recombinant xylanases were found to have optimal activity at 47–55°C and pH 6.0–7.0. The recombinant xylanase expressed in P. pastoris has 40% higher thermal stability than that expressed in E. coli. The recombinant xylanases retained 100% of activity after 10 h incubation in the pH range 3–11 and 68% of activity after 1 h at pH 2.0. The xylanase activities of rXynT6-E and rXynT6-P under optimal conditions were 1030.2 and 873.8 U/mg, respectively. The good stability in a wide range of pH and moderate temperatures may make the xylanase from Bacillus sonorensis T6 useful for various biotechnological applications, e.g., as an enzyme additive in the feed industry.

Environmental safety and economic factors necessitate a search for new ways of processing poultry farm feathers, which are 90% β-keratin and can be used as a cheap source of amino acids and peptones. In this study, feather-decomposing bacteria were isolated from a site of accumulation of rotten feathers and identified as Bacillus. Among them, the Bacillus sp. A5.3 isolate showed the best keratinolytic properties. Scanning electron microscopy indicated that Bacillus sp. A5.3 cells closely adhere to the feather surface while degrading the feather. It was found that Bacillus sp. A5.3 secretes thermostable alkaline proteolytic and keratinolytic enzymes. Zymographic analysis of the enzymatic extract toward bovine serum albumin, casein, gelatin, and β-keratin revealed the presence of proteases and keratinases with molecular weights 20–250 kDa. The proteolytic and keratinolytic enzymes predominantly belong to the serine protease family. Proteome analysis of the secreted proteins by nano-HPLC coupled with Q-TOF mass spectrometry identified 154 proteins, 13 of which are proteases and peptidases. Thus, strain Bacillus sp. A5.3 holds great promise for use in feather-processing technologies and as a source of proteases and keratinases.

Amylases are enzymes that are known to hydrolyze starch. High efficiency of amylolytic enzymes allows them to compete in the industry with the technology of chemical hydrolysis of starch. A Bacillus licheniformis strain with high amylolytic activity was isolated from soil and designated as T5. The gene encoding α-amylase from B. licheniformis T5 was successfully expressed in both Escherichia coli (rAmyT5-E) and Pichia pastoris (as rAmyT5-P). According to the study, the recombinant α-amylases rAmyT5-E and rAmyT5-P exhibited the highest activity at pH 6.0 and temperatures of 70 and 80 °C, respectively. Over 80% of the rAmyT5-E enzyme activity was preserved following incubation within the pH range of 5–9; the same was true for rAmyT5-P after incubation at pH 6–9. N-glycosylation reduced the thermal and pH stability of the enzyme. The specific activity and catalytic efficiency of the recombinant AmyT5 α-amylase were also diminished by N-glycosylation.

Next-generation prebiotics are increasingly recognized for their ability to modulate gut microbiota and promote host health. Xylo-oligosaccharides (XOS) and malto-oligosaccharides (MOS), derived from cereal biomass, are particularly promising due to their structural stability, low effective dosages, and selective stimulation of beneficial gut microorganisms. This review synthesizes current knowledge on XOS and MOS, with emphasis on enzyme-enabled production technologies, microbial fermentation behavior, and health outcomes in humans and animals. Recent advances in tailored enzyme cocktails and sequential bioconversion strategies enable precise control over oligosaccharide yield and degree of polymerization, facilitating targeted production of functionally distinct fractions. Comparative analyses demonstrate that XOS and MOS offer greater microbial selectivity than conventional prebiotics, such as fructo- and galacto-oligosaccharides, and consistently enhance short-chain fatty acid production. These effects contribute to improved metabolic regulation, immune function, and resistance to enteric pathogens. A distinctive contribution of this review is the valorization of Kazakhstan’s underutilized cereal residues, including wheat, rice, barley, and millet straw and bran, as sustainable feedstocks for prebiotic production. Integrating regional biomass with engineered enzyme systems provides a scalable and environmentally sound platform. Furthermore, combined XOS–MOS formulations may exert synergistic microbiota-modulating effects through complementary fermentation dynamics. Collectively, these insights position enzyme-based conversion of cereal biomass as a novel, regionally relevant strategy for advancing next-generation prebiotics.

The growing amounts of agricultural residues require sustainable solutions for their use. Here, wheat, rice, barley, and oat straw were evaluated as renewable feedstocks for the enzymatic production of xylooligosaccharides (XOS). Hydrolysis used recombinant xylanase from Bacillus sonorensis T6 under optimized conditions (40 °C, pH 7.0), with stepwise enzyme addition. Subsequently, hydrolysis efficiency was found to vary by substrate, with wheat straw producing the highest reducing sugar yield (up to 40.1 g kg⁻¹), followed by barley, oat, and rice straw. As hydrolysis progressed, the influence of enzyme concentration became less pronounced, suggesting that substrate accessibility and the accumulation of hydrolysis products may increasingly affect the overall hydrolysis efficiency. FTIR, NMR, SEM, and TLC analyses confirmed substantial structural changes in the biomass and the formation of carbohydrate-rich hydrolysis products. TLC analysis indicated the presence of low-degree polymerization oligosaccharides with migration behavior similar to X2 and X3 standards, while FTIR and NMR spectra were consistent with β-(1→4)-linked carbohydrate structures. The xylanase from Bacillus sonorensis T6 hydrolyzed all substrates, revealing broad specificity and suitability for diverse lignocellulosic feedstocks, despite differences in biomass structure. Overall, the results highlight the importance of substrate-dependent factors in enzymatic hydrolysis and demonstrate that xylanase from Bacillus sonorensis T6 converts cereal straw into value-added oligosaccharide-rich products, thereby supporting the development of cost-effective, region-specific biorefinery strategies.