[Use of bacteria of the genus Azotobacter for biodegradation of oil-contaminated soils]. / Ispol'zovanie bakterii roda Azotobacter pri bioremediatsii neftezagriaznennykh pochv.

The rate of self-purification of oil-contaminated soil increases after introduction of bacteria of the genus Azotobacter. The bacteria can assimilate oil hydrocarbons as the sole source of carbon and energy, both in the presence of fixed nitrogen and during nitrogen fixation. The species Azotobacter chroococcum activates growth of hydrocarbon-oxidizing bacteria present in Devoroil.

[The effect of yeast autolysates on the level and distribution of free amino acids in yeast cells of the Candida genus]. / Vliianie drozhzhevogo avtolizata na soderzhanie i raspredelenie svobodnykh aminokislot v kletkakh drozhzhei roda Candida.

The work was aimed at studying the effect of yeast autolysate on the content and subcellular distribution of free amino acids in yeast cells. The overall pool of free amino acids decreased 1.5-2 times when mineral nitrogen in the growth medium was substituted either completely or partly by yeast autolysate. As was shown using the technique of differential extraction, the vacuolar pool of the cell is mainly responsible for the decrease in the content of free amino acids.

[Composition of the microorganism population in an unprotected fermentation process]. / Zusammensetzung der Mikroorganismenpopulation im ungeschützten Fermentationsprozess.

An accompanying flora of the production strains always develops in each unprotected continuous fermentation process. In the process of production of fodder biomass from gas oil the high specific growth rate provides sufficient selection advantages to the production strain Lodderomyces elongisporus "D" EH 15 against substrate competitors. The accompanying flora uses products of metabolism and lysis as carbon and energy sources. The concentration of these compounds in the medium and consequently the development of the accompanying flora depends on the process conditions. During a period of more than ten years the taxonomic-diagnostic and technological properties of the production strain Lodderomyces elongisporus "D" EH 15 did not change, caused by the permanent selection stress in the continuous fermentation process.

[Cultivation of feed yeasts on media with carbohydrates]. / Kul'tivirovanie kormovykh drozhzhei na sredakh s uglevodorodami.

The different culture of yeasts oxidizing hydrocarbons and the accompanying microflora are, under certain physico-chemical conditions, in metabiotic relationships which provide stability of the system. These relationships were studied with yeast cultures belonging to the Candida genus and oxidizing hydrocarbons. The relationships between the hydrocarbon oxidizing yeast Candida guilliermondii and other species of the genus Candida were determined by a combination of active and passive antogonism, as the result of which strains of this species completely dominated in the cenosis of fermenters.

[Metabolic products of hydrocarbon-oxidizing strains of Mycococcus lactis and Pseudomonas fluorescens and their influence on culture growth]. / Produkty metabolizma uglevodorodokisliaiushchikh shtammov Mycococcus lactis i Pseudomonas fluorescens i ikh vliianie na razvitie kul'tur.

The effect of concentrations of organic acids in the cultural broth on growth was studied with the strains of Mycococcus lactis and Pseudomonas fluorescens oxidizing hydrocarbons. The ratio between the acid and neutral fractions in the cultural broth of Mycococcus lactis was also investigated as well as their action on the bacterial growth. Mycococcus lactis growing on paraffin was found to produce acid and neutral products at a ratio of 1:2. The acid and neutral products of metabolism produced different action on the growth of the carbohydrate oxidizing bacteria. The acid products inhibited the growth at a concentration of organic acids in the medium above 500 mg/litre. The neutral products were partily assimilated by Mycococcus lactis.

[Zinc consumption from the nutrient medium of Trichosporon capitatum and Aspergillus niger]. / Pogloshchenie tsinka iz pitatel'noi sredy kul'turami Trichosporon capitatium i Aspergillus niger

The sorption capacity of the cultures Trichosporon capitatum and Aspergillus niger towards zinc dissolved in the culture liquid was studied by radio active labelling. The curves of sorption kinetics and the so-called sorption quasi-isotherms showing the dependence of zinc sorption by the microbial biomass upon zinc concentration in the liquid medium were derived. For the Aspergillus niger culture at zinc concentrations of 0.5 to 52 mug/ml the sorption quasi-isotherm was linear. The zinc extraction by microorganisms was related not only to the physico-chemical sorption but also to the zinc accumulation in the cell biopolymers. The paper presents calculations of the microbiological purification of sewage waters from zinc by means of the Aspergillus niger culture.