[Formation of Ag/AgCl Nanoparticles in the Matrix of the Exopolysaccharide of a Diazotrophic Strain Azotobacter chroococcum XU1].

A complex of Ag/AgCl nanoparticles was synthesized on the basis of the extracellular polysaccharide of Azotobacter chroococcum XU1 and 10 mM AgNO3 solution. The complex was characterized by UV spectroscopy, X-ray diffraction, and scanning electron microscopy. Colloidal solutions of the complex had absorption peaks at 260 and 420 nm, indicating the formation Ag/AgCl nanoparticles. The size of the nanoparticles varied from 6 to 50 nm. The nanobiocomposite consisting of the exopolysaccharide matrix and Ag/AgCl nanoparticles exhibited a fungicidal effect against such plant pathogens as Fusarium oxysporum f. sp. vasinfectum and Verticillium dahliae.

[Plasmids of Salt-tolerant Rhizosphere Microorganisms].

Five plasmid DNAs were detected in three of microorganisms, which formed microbial composition «Ð—амин-М¼. One plasmid (23.1 kb) was found in Bacillus megaterium СКБ-310 cells and another one (55.0 kb) was found in cells of Pseudomonas stutzeri СКБ-308, but cells of Bacillus subtilis СКБ-309 contained 3 plasmids (48.5 kb, 30.0 kb and 13.3 kb). It was assumed that these plasmids may carry genes of resistance to adverse environmental conditions, including the high content (10 %) of ions Cl- and SO4(2-).

[Purification of extracellular proteinases from B. subtilis SKB 256 by biospecific chromatography].

Abstract-A simple and efficient method of preparing highly purified extracellular proteinases of B. subtilis B-1 (SKB 256) has been developed. A sorbent based on sorsilen impregnated with hemoglobin or cytochrome c has been synthesized for this purpose. A significant difference between the efficiency of hemoglobin and cytochrome c as biospecific ligands has been observed: the enzyme yield amounted to 40.6 and 65.6% of the total amount of enzyme adsorbed, respectively. The culture was shown to contain two major proteinase forms with different molecular masses that could be separated by chromatography on a Sephadex G-50 but gave only one band with MW 27 kDa upon denaturing electrophoresis in 12.5% PAG in the presence of 0.1% SDS. The influence of eluent pH, ionic strength and ethanol concentration on the sorption of the proteinases on the biospecific sorbent, as well as on the desorption from it, has been investigated. Positive influence of 20% ethanol on proteinase desorption has been demonstrated.

[The effect of acid proteinases on the activity and stability of glucoamylase preparations].

It was demonstrated that the presence of acid proteinases in the preparation isolated from Aspergillus awamori decreased the activity and stability of glucoamylase. Patterns of changes in the enzymatic activity and stability of glucoamylase at increased temperature and various pH values were studied over a long-term storage. A biospecific sorbent for removal of acid proteinases was synthesized, and glucoamylase preparations free of proteolytic activity were produced.

[Effects of nutrient medium composition and temperature on the germination of conidia and the entomopathogenic activity of the fungi].

The effects of nutrient medium composition and temperature on the germination of conidia of the fungi Beauveria bassiana (strain AlG) and Metarhizium anisopliae (strain M-99) and their entomopathogenic activity have been studied. It was demonstrated that the presence of carbohydrates alone was sufficient for the spores of M. anisopliae M-99 to germinate, whereas the germination of B. bassiana AlG spores was inhibited by carbohydrates. Addition of KJ, ZnSO4, or KBr into the Czapek medium increased the entomopathogenic activity of B. bassiana. The optimum temperature for spore germination was 20-35 degrees C in both fungal species.

[Conditions for cultivation of the fungus Penicillium melinii UzLM-4 and its biosynthesis of lipases]. / Usloviia kul'tivirovaniia i biosintez lipaz gribom Penicillium melinii UzLM-4.

Cultivation of the fungus Penicillium melinii UzLM-4 on a Raistrick's medium of our own modification made it possible to increase the biosynthesis of lipases three to four times. The following conditions ensured a high rate of synthesis of the extracellular lipase: age of the inoculum, 15 days; concentration of the inoculum, 15 x 10(6) conidia per 100 ml medium; initial pH of the nutrient medium, 8.0; and cultivation in a shaker at 150 rpm (25 degrees C).

[Effect of culture medium composition on peroxidase biosynthesis by the fungus Pleurotus ostreatus UzBI-I105]. / Vliianie sostava pitatel'noi sredy na biosintez peroksidazy gribom Pleurotus ostreatus, shtamm UzBI-I105.

Production of extracellular peroxidase during submerged cultivation of the xylotrophic bazidiomycete Pleurotus ostreatus UZBI-I105 in nutrient media with lignocellulosic wastes, exhausted cottonseed oil cake, cotton stalks, rice husks, or ambary hemp was studied. The enzyme production increased threefold to fivefold in the presence of exhausted cottonseed oil cake extract in the nutrient medium. The dynamics of peroxidase production in various media was investigated.

[Insecticidal activity of Bacillus thuringiensis cells]. / Entomotsidnaia aktivnost' bakterial'nykh kletok Bacillus thuringiensis.

The influence of sixteen different nutrient media on the entomopathogenic activity of three Bacillus thuringiensis strains was studied. The medium composition based on potato, yeast extract, and molasses was optimized. B. thuringiensis No 1 grown on the media No 7 and 9 displayed the highest entomopathogenic activity (94.3 and 90.6%, respectively).

[Enzymatic utilization of cotton soap stock]. / Frmentativnyi sposob utilizatsii khlopkovogo soapstoka.

Enzymatic hydrolysis of neutral fat of cotton oil soap stock with a nonspecific lipase produced by Oospora lactis F-500 was designed. The culture liquid and a preparation of enzyme obtained by precipitation with isopropanol from a filtrate of the culture liquid were used. Utilization of cotton oil soap stock as the only source of carbon during cultivation of the fungus was studied. The rate of hydrolysis of soap stock fat strongly depended on the way of biological conversion of cotton oil soap stock. The most effective utilization was observed during cultivation of the fungus in the medium containing soap stock.

[Multiplicity of lipase forms from Rhizopus microsporus]. / Priroda mnozhestvennosti form lipazy Rhizopus microsporus.

The lipase from Rhizopus microsporus of glycoprotein origin is represented by five forms differing in their molecular weights and localization in the cell. The lipase forms are distinguished by their relative content of A and B subunits (AB, 2A + B, A + 2B, 4A + B, 3A + 2B). Only three isoenzymes containing the bulk of the non-protein moieties were detected in the culture fluid. The other two forms can exist only as intracellular proteins.

[Lipase activity of Oospora lactis protoplasts]. / Lipaznaia aktivnost' protoplastov Oospora lactis.

The paper describes how to prepare osmotically sensitive forms from the fungus Oospora lactis. The lytic enzyme from actinomycetes at a concentration of 25 mg/ml causes abundant formation of protoplasts at 36 degrees C and pH 7.5 within 10--15 min. The best stabilizing agent is 1 M NaCl solution or a mixture of 1 M NaCl with 1 M mannitol solution (1:1). In order to induce lysis of cell walls by the enzyme from Helix pomatia, the cells must be pretreated with a solution containing 40 mM tris (hydroxymethyl)-aminomethane, 5 mM EDTA and 0.2 M cysteine. The production of Oospora lactis protoplasts was accompanied with the liberation of lipase from the periplasmic space. The activity of lipase was 90% of the overall intracellular activity as was confirmed by the results of differential centrifugation of a homogenate prepared by mechanical disintegration of the cells. Since the Rf in disc electrophoresis, the pH optimum and the substrate specificity of exocellular lipase were identical with those of periplasmic lipase, the enzyme must be liberated without a change in the molecular weight.