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Unique biodiversity and biotechnological potential of microorganisms in the Antarctic region contributes to the intensive search among them of enzymes producers with new properties and a wide range of stability. The aim of the work was to study the glycosidase activity in 26 strains of psychrotolerant UV-resistant yeast isolated from soil-plant сenosis of the Antarctic and evaluate their biotechnological potential as a producer of enzymes. Methods. Yeast cultures were grown in submerged conditions (15-42 °C). Enzymes activities were determined in the culture supernatant. Synthetic monosaccharide derivatives were used to measure glycosidase activity. Casein and elastin-congo red were used as substrates for the determination of proteolytic activity. Results. A spectrum of 12 glycosidase activities (α- and β-D-glucosidase, β-D-galactosidase, β-D-glucuronidase, α-L-fucosidase, α-L-ramnosidase, α-D-mannosidase, α- and β-D-xylosidase, α- and β-Nacetylglucosaminidase, β-N-acetylgalactosaminidase) was studied in Antarctic yeast. The most common were β-N-acetylglucosaminidase and β-glucosidase activities (65 and 58% of strains respectively). 4 strains (6p1s, 2299, 31s and 4p5s2) showed high activity of the complex of cellulose-degrading enzymes. 5p5s1 strain, isolated from the Deshampcia antarctica grass, showed high β-D-xylosidase activity (2.8 U/ml). Rhodotorula mucilaginosa 33c strain showed a spectrum of ten activities, including high α-L-rhamnosidase activity (6.2 U/ml). Conclusion. Yeast cultures from the Antarctic phytocenosis can be used for the directional search for microbial glycosidases with new properties and a wide range of activity. [ABSTRACT FROM AUTHOR]

The optimum irradiation parameters of EHF EMR for Saccharomyces cerevisiae M-09 yeast culture are experimentally determined. In the alcoholic brew, fermented with the irradiated yeast, the accumulation of biomass, alcohol and the amount of carbon dioxide emissions increased compared to control. Simultaneously the amount of nonfermented sugars decreased. The yeast vigor for the filtered brew yeast, their a-glucosidase and zymase activity enhanced. The effect of the EHF EMR action on the yeast culture remained for three generations and gradually weakened, which can be connected with Saccharomyces cerevisiae adaptation to the influence of external factors. [ABSTRACT FROM AUTHOR]

The temperature optimum and thermal stability of endo-beta-glucanase, beta-glucanase, pentosanase and cellobiase from the enzymic preparations used in the brewing industry to treat high amounts of unmalted barley--citorosemin Px, citorosemin P10x, amylosubtilin G10x and brew-n-zyme--were measured. In order to determine the termerature optimum the enzyme activity was assayed under standard conditions. It was found that the temperature optimum for endo-beta-glucanase of all preparations was 50 degrees, for beta-glucanase and pentosanase--40 degrees, for cellobiase--70 degrees C. The thermal stability of endo-beta-glucanase from amylosubtilin G10x and brew-n-zyme in the aqueous solution was higher than that from ditorosemin Px and P10x. The thermal stability of the latter preparations noticeably increased in the presence of substrates.

The paper is concerned with conditions of glucoamylase binding with silanized silochrome using gossypol, dialdehyde isolated from cotton-plant. Kinetic properties of the immobilized enzyme are studied. The enzyme pH optimum does not change with immobilization and the temperature optimum is shifted from 50 degrees to 60 degrees C; a certain increase of the seeming Km is also observed. A high yield of the enzyme activity in immobilization evidences for the possibility of using gossypol as a binding agent in glucoamylase immobilization.

Catalytic activity and stability of glucoamylases immobilized by different methods (adsorption, covalent binding) are studied comparatively. The highest stability is shown to be obtained under covalent binding. The binding efficiency and immobilized glucoamylase properties depend on the nature of insoluble carrier and a purification degree of the enzyme preparations. The choice of the cross-linking agent promoting a binding between the enzyme and the carrier is very significant. The activity and stability of immobilized glucoamylases obtained when using different cross-linking agents rise in such a sequence: 2,4-toluylenediisocyanate, cyanurochloride, glutaric dialdehyde, gossypol. Catalytic properties and stability are determined for soluble and immobilized glucoamylase forms from different sources.