Determination of the dependence of humic acids on the growth parameters of Rhodococcus microorganisms in the presence of hexadecane

The stimulating effect of humic acids of peats of various origin at a concentration of 50 mg / L on the growth and reproduction of oil-degrading microorganisms Rhodococcus erythropolis S67 and Rhodococcus erythropolis X5 was detected by spectrophotometric and gravimetric methods. It was established that the maximum growth parameters (the specific growth rate, the biomass doubling time) were observed for microorganisms Rhodococcus erythropolis S67 in the presence of humic acids of read fen peat. The indicators in the system “microorganism R. erythropolis X5 - hexadecane - humic acids of sphagnum highmoor peat” were 2.6 times higher than in the system “microorganism R. erythropolis X5 -hexadecane”. Growth parameters for R.erythropolis X5 were 2 times higher than the parameters for R.erythropolis S67, which was 2 times higher than the growth parameters of the control. It was found that humic acids in the solution reduced stress conditions for the microorganisms Rhodococcus erythropolis S67 and Rhodococcus erythropolis X5. That contributed to their more rapid biodegradation of the substrate hexadecane, as well as the growth and reproduction of bacteria by increasing the solubility of the organic substrate and creating on the cell surface monolayer screen, which was a mesh filter of humic acid molecules.