[Effect of shale kerogen oxidation products on biodegradation of petroleum and petroleum products in soil and water]. / Vliianie produktov okisleniia kerogena slantsev na biodestruktsiiu nefti i nefteproduktov v pochve i vode.

Effect of oxidation products of shale kerogen (high-molecular-weight acids with 6-22 carbon atoms) on biodegradation of oil and oil products in soil and water was studied. High-molecular-weight acids (HMWA) not only affected the layer of oil and/or oil products and dispersed it into small particles, but also stimulated growth of Rhodococcus erythropolis VKM AS-1339D, degraders of oil and oil products. Addition of 0.001-0.003% HMWA to a medium to be purified from oil products increased the extent of bacterial biodegradation by a factor of 1.1-5.0.

[Natural and induced variability of pathogen, producing antifungal antibiotic, imbrimycin]. / Estestvennaia i indutsirovannaia izmenchivost' produtsenta protivogribkovogo antibiotika imbritsina.

Natural and induced variation of Streptomyces imbricatus LIA 0112, an organism producing imbricin, a nonpolyene antifungal antibiotic, was studied. The culture was shown to be homogeneous by the morphological and cultural properties and consisted of one (rarely two) morphological type depending on the medium composition. The effect of some mutagens such as UV light, N-nitroso-N-methyl biuret in a concentration of 0.05 per cent and 1,4-bisdiazoacetyl butane in a concentration of 0.1 per cent on the actinomycete culture was investigated. It was found that the imbricin-producing culture was stable to the effect of both the physical and chemical mutagens. As a result of multistep selection of the actinomycete culture its productivity increased by 22 per cent.

[Effect of aeration and redox potential on the biosynthesis of the antibiotic imbricin]. / Vliianie aératsii i okislitel'no-vosstanovitel'nogo potentsiala na biosintez protivogribkogo antibiotika imbritsina.

The relationship between imbricin biosynthesis by Streptomyces imbricatus and the medium aeration and redox potential (Eh) was studied. The influence of the oxygen dissolution velocity within the ranges of 2.9 to 0.5 g O2/l.h was investigated and it was shown that the highest yield of the antibiotic was provided by the maximum velocity. At the background of the intensive aeration (2.9 g O2/l.h) decreasing of Eh by reducing agents such as ascorbic acid, L-thyrosin or K4Fe(CN)6 stimulated the biosynthesis whereas at the lower velocities the process proved to be inhibited. Under conditions of insufficient aeration the biosynthesis stimulation could be provided by increasing the medium Eh by acidifying agents such as K2Cr2O7, K3Fe(CN)6 or KMnO4. It was concluded that intensive synthesis of imbricin required not only efficient aeration but also definite levels of the medium redox potential.