Research of selection of microorganisms for decomposition of petroleum products with increased nitrogenase activity in laboratory bioreactor

Abstract

The article presents the results of studies on decomposition of petroleum products, on the example of diesel fuel, the investigation having been carried out in a bioreactor with loading of immobilized microorganisms specially selected and adapted to the destruction of hydrocarbons. In the course of the investigation, 25 micro-organism culture strains were isolated from crude oil by selection, the strains had different destructive activity relative to hydrocarbons of the paraffin fraction of diesel fuel and nitrogen-fixing ability. Further, selection was carried out along with oxidation of hydrocarbons and according to the ability of microorganisms to nitrogen fixation. Such microorganisms during oxidation of hydrocarbons will allow reducing the content of biogens in purified water. Part of the microorganisms was identified and the nitrogenase activity of pseudomonades was investigated. When growing on diesel hydrocarbons in a bioreactor, nitrogen assimilation is most active in Rhodococcus erythopoltis R-2 culture and equals 10.52 nmol C2H4/mg protein per hour. The maximum nitrogenase activity has the association of bioreactor destructive cultures obtained by the authors, which, when growing on diesel oil products is 23.7 nmol C2H4/mg protein per hour, which is 2.3 times higher than the nitrogen-fixing capacity of Rhodococcus erythropoltis R-2. There was studied the rate of hydrocarbon degradation, оn the seventh day of cultivation, the degradation of paraffinic hydrocarbons in nitrogen-free media is 68%, whereas in the presence of ammonium nitrogen it reached - 87 %. These investigations have determined the ability of isolated cultures of oil-oxidizing bacteria to use hydrocarbons under atmospheric nitrogen assimilation conditions.