[Effect of the nutrient medium composition on biotin biosynthesis by an Actinomyces species 313-152 culture]. / Vliianie sostava pitatel'noi sredy na biosintez biotina kul'turoi Actinomyces species 313-152.

The effect of the composition of the nutrient medium on the biosynthesis of biotin by the culture Actinomyces species 313-152 was investigated. This microorganism can synthesize biotin on simple and complex media. The biotin synthesis is stimulated by oleic acid and Tween-80 utilized by the culture as a carbon source. The exogenous biotin added at concentrations of 1 x 10(-8) M to 1 x 10(-6) M to the medium containing fodder yeast hydrolyzate and Tween-80 did not inhibit the synthesis by the culture Actinomyces species 313-152.

[Coenzyme-induced slow transitions of NADP-sorbitol dehydrogenase from Gluconobacter oxydans]. / Indutsiruemye kofermentom medlennye perekhody NADP-sorbitoldegidrogenazy iz Gluconobacter oxydans.

The kinetic properties of NADP-dependent sorbitol dehydrogenase from G. oxydans cell extract were studied at pH 8.8 and 9.3 in the direction of D-sorbitol oxydation. It was shown that the shape of the kinetic curves of NADPH accumulation in time is characterised by initial burst whose magnitude depends on the concentration of the enzyme extract used. Preincubation of the enzyme with NADP or D-sorbitol eliminated the initial burst on these curves and transformed them into straight lines coming from the start of co-ordinates. The dependence of the stationary reaction rate on the enzyme extract concentration is not a linear one. The kinetic dependences of stationary rate of the reaction catalysed by the enzyme on the concentration of D-sorbitol and NADP at pH 8.8 and 9.3 were examined under all conditions studied; the shape of these kinetic curves altered to considerable extent with the alteration of the enzyme extract concentration in the reaction mixture and pH. At pH 9.3 several intermiediate plateaux were found on the curves of the D-sorbitol concentration dependent stationary rate of the reaction. The preincubation of the enzyme extract with NADP during 1.5 h removed the intermediate plateau on these curves and made them hyperbolic. Disk-electrophoresis of the enzyme extract in PAAG concentration gradient showed that at pH 8.8 the enzyme exists in one active form, while at pH 9.3 it exists in three major and three minor active forms of the enzyme differing in their molecular weights are found. It is assumed that the enzyme from G. oxydans cell extract can exist in a great number of molecular equilibrium forms, the rate of quilibrium being comparable or significantly less than that of the enzymatic reaction. NADP significantly influences on the equilibrium of the molecular forms of the enzyme.

[Formation of vitamin B6 by by the fungus Cladosporium resinae on media with n-dodecane or glucose]. / Obrazovanie vitamins B6 gladosporium resinae na sredakh s n-dodekanom ili gliukozoi.

Accumulation of vitamin B6 by the fungus Cladosporium resinae str. Moscow University eas investigated on media containing n-dodecane or glucose. Vitamin B6 was built up in the mycelium and the culture liquid filtrate. Under stationary condiditions of growth the maximum amount was found on the 28th day and reached 750/mkg and 925/mkg per 1 of the culture liquid on the glucose and n-dodecane containing medium, respectively.