Screening of hydrocarbon-degrading strains and study on the reinforcement of bioremediation to petroleum polluted soil

A bacterial strain, named KL2-13 was isolated by means of enrichment culture from soil contaminated by heavy oil from Karamay of Xinjiang Oilfield. The strain KL2-13 was identified as Bacillus according to its morphological, physiological, biochemical, and 16S rDNA sequence characteristics. The biodegradation experiments were made to research whether the bacterial strain KL2-13 could accelerate the biodegradation progress. The influence of inoculum concentration, N, P sources and the amount of wheat bran on the degradation ability of the strain was investigated. The petroleum polluted soil collected from Karamay was treated by the strain KL2-13 for 90 days at the definite water content. The results showed that the petroleum hydrocarbon pollutants degraded faster. The bioremediation effect was best when the inoculum concentration of the strain KL2-13 was 10%. There was an optimum matching value between the growth of microbe and the amount of the nutrients added, the optimum content of N was 0.2%, and P 0.05%. The degradation rate of hydrocarbon pollutants enhanced along with the increasing amount of wheat bran, when the amount of wheat bran was 25 % of the soil volume, the degradation rate of oil arrived at 56.8 % after 90 days´ bioremediation.