There has been an increasing consumer demand for cheese along with a search for products with new organoleptic parameters, which has resulted in extensive research on alternative milk coagulants. The ratio of proteolytic activity to milk-clotting activity determines the requirements for proteases used in the cheese making process. To date, plant enzymes have largely been used for this purpose, along with traditional enzymes of animal origin, chymosin and pepsin. The most popular types of proteases used in the food industry, especially in cheese making, are plant proteases belonging to the cysteine (papain, bromelain, ficin), aspartate (cinarase, cardosin), and serine (kukumizin, leucine) group of proteases. The aspartate proteases of microbial origin mucorpepsin and endotyapepsin have found wide application in cheese production due to low production costs and high organoleptic characteristics of the final product. The use of plant and microbial milk-clotting enzymes as an alternative to animal-derived enzymes allows not only to diversify the assortment of cheeses on the market but also to solve ethical and economic issues. In addition, vegetable and microbial preparations meet the requirements of vegetarianism, halal, and kosher food, thus further opening the market.

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Thermostable polymerases play a significant role in molecular biology and diagnostic practice. The most famous and demanded is Polymerase I from the thermophilic bacterium Thermus aquaticus (Taq-pol). This polymerase at one time made a kind of revolution in the polymerase chain reaction. In this work, we attempted to modify this polymerase by attaching an additional Sso7d protein from Sulfolobus solfataricus to Taq-pol, which provides additional binding to the double-stranded DNA of the template. Sso7d-Taq fusion gene was expressed in BL21(DE3) cells. Optimal conditions were selected for maximum production of modified Sso7d-Taq polymerase. The optimal conditions for the intracellular accumulation of Sso7d-Taq polymerase: activation of the T7 promoter when the optical density of the culture reaches OD600 = 0.8-1.0 by adding IPTG at a concentration of 0.2 mM, followed by incubation of the culture at 37°C for 20-24 hours. Recombinant Sso7d-Taq polymerase has been purified and tested by PCR for thermal stability and elongation time. It was found that the Sso7d-Taq enzyme withstands 5 hour incubation at 95°C and 75 minute incubation at 98°C. Comparative analysis with unmodified Taq DNA polymerase showed that the Sso7d-Taq enzyme reduces the elongation rate by several times - up to 15-13 seconds per 1 kbp. The results obtained indicate the prospects of using Sso7d-Taq DNA polymerase in scientific research and diagnostic practice.

For survival in cold conditions, many organisms have developed unique adaptive mechanisms based on the synthesis of antifreeze proteins, peptides and glycoproteins that prevent ice formation at negative temperatures. These molecules tend to bind ice crystals and lower the freezing point of the solution without the formation of large crystals. Antifreeze proteins (AFP) were found in almost all types of living organisms, including insects, fungus, yeasts, bacteria and plants. The gene of antifreeze protein - glucan endo-1,3-beta-D-glucosidase (ScGlu-3) from Secale cereale was cloned into shuttle vector pPICZαA. The competent cells of yeast Pichia pastoris GS115 were transformed and the producer strain was obtained, which secreted of ScGlu-3 into the culture medium using 3% methanol as the only carbon source. It was found by western blotting that the maximum accumulation of ScGlu-3 in the culture occurs after 48 hours of fermentation on a medium with methanol. Established that rScGlu-3 precipitates at 50-65% of ammonium sulfate.