[Effect of sulfur-containing compounds on the ultrastructural organization of the cell wall of Candida utilis yeasts]. / Vliianie serosoderzhashchikh soedinenii na ul'trastrukturnuiu organizatsiiu kletochnoi stenki drozhzhei Candida utilis.

The effect of sulfur-containing compounds (cysteine, homocysteine, glutathione, cystine, and methionine) on the ultrastructural organization of the cell wall was studied in Candida utilis 295t by electron microscopy with the aid of staining SH groups by HgCl2. Treatment of the cells with cysteine and homocysteine was found to modify the ultrastructure of the cell wall: the capsule was damaged and the porosity increased, which facilitated the penetration of these compounds into the periplasm. Their further conversion in the cell has been studied.

[Characteristics of lipases in the culture fluid of Penicillium roqueforti]. / Kharakteristiki lipaz, soderzhashchikhsia v kul'tural'noi zhidkosti Penicillium roqueforti.

Lipases were isolated from the cultural broth of Penicillium roqueforti 141, purified and their properties were studied. The lipases differed in their amino acid composition and had a high content of polar amino acids , in particular aspartic and glutamic acids. The lipases contained also carbohydrates (1.4-3.3%): mannose, xylose and glucosamine. The lipases were stable to heating (up to 55 degrees C) and within a wide pH range. The optimal activity of lipases I and III was observed at 40 degrees C and pH 7.0, that of lipase II at 45 degrees C and pH 6.0. The effect of metal ions and various inhibitors on the activity of the lipases was studied. Ca2+, Mg2+ and Fe2+ ions did not activate the lipases. These were inhibited by a broad spectrum of reagents for sulfhydryl groups and by a phosphoorganic compound. This fact suggest that the lipases belong to "serine" enzymes containing sulfhydryl groups.

[Isolation and characteristics of Penicillium roqueforti lipases]. / Vydelenie i nekotorye svoistva lipaz Penicillilum roqueforti.

Lipase were isolated from Penicillium roqueforti 141, purified and their properties were studied. Proteins were precipitated with (NH4)2SO4 from the cultural broth of this organism, and then subjected to gel filtration through Sephadex G-100 and chromatography on DEAE-cellulose; the procedure yielded a purified preparation consisting of three lipolytically active proteins. Disc electrophoresis in polyacrylamide gel confirmed the homogeneity of the lipases. The molecular weights of the enzymes were 7930, 9100 and 11 420 respectively, according to the data of gel filtration through Sephadex G-150. The lipases differed in their substrate specificity. Lipase III was most active in hydrolysis of plant oils containing mainly unsaturated fatty acids. Lipase II most effectively hydrolyzed synthetic triglycerides containing saturated fatty acids, in particular, tricaproin, tricaprilin and trimyristin. Tributyrin was more actively hydrolyzed with lipase I as compared to lipases II and III.

[Effect of emulsifiers on the hydrolysis of solid fats by microorganism lipases]. / Vliianie émul'gatorov na gidroliz tverdykh zhirov lipazami mikroorganizmov.

The object of this work was to select emulsifiers and techniques for preparing emulsions of triglycerides of saturated fatty acids. It was found that not only the degree of dispersity of an emulsion influenced the activity of lipase with respect to a lipid being emulsified, but also the nature of an emulsifier affected hydrolysis of solid fats by microbial lipases.

[Lipolytic activity of microorganisms isolated from different sources]. / Lipoliticheskaia aktivnost' mikroorganizmov bydelennykh iz razlichnykh istochnikov.

From different natural sources (samples of raw and pasteurized milk, fresh and melted butter, cheese, industrial and nonindustrial sewage containing fats and surface active substances) 650 microorganisms were isolated. Measurements of their lipolytic activity on milk fat (20% cream), tristearin and olive oil indicated that 27 microorganisms had no lipolytic activity on either substrate. A hundred cultures showed the highest activity. Out of them 40 most active cultures belonging to different systematic groups (fungi, yeast, bacteria) were identified as representatives of certain genera or species. Lipolytic activity varied significantly in microorganisms belonging to the same species. The use of several substrates (cream, tristearin, olive oil) helped to discriminate microorganisms that preferentially hydrolyzed either substrate.