Isolation, identification and breeding of petroleum-degrading bacteria in oilfield produced water by UV-plasma complex mutagenesis

Abstract:

[Objective] In order to solve the environmental pollution problem caused by total petroleum hydrocarbons (TPHs), the wild type strains’ degradation rate of TPHs was enhanced in this study. [Methods] Based on bioremediation technique, the strains, which can degrade TPHs effectively, were isolated from the oilfield produced water and selected out by enrichment culture, prescreening and rescreening. Then, the strains were identified through morphological, physiological, biochemical, and phylogenetic (16S rRNA gene) characterization. In order to obtain highly efficient THPs-degrading strains, after being mutated by UV-plasma and 96-pore plate fermentation, the isolated strains were screened by high-throughput screening method, with the use of multi-functional microplate reader based on the dual wavelength ultraviolet spectrum. At last, the mutants’ hereditary stability was tested by analysis of variance. [Results] The wild strain PW04, which was isolated from produced water, was identified as Sphingobacterium multivorum. After the compound mutation, three highly efficient THPs-degrading strains (S. multivorum PW04-H10, S. multivorum PW04-G9 and S. multivorum PW04-A6) were obtained, which the degradation rate of THPs can reach to 85.1%, 82.7% and 82.9% respectively. As was shown in the result of hereditary stability analysis, the three mutants all had stable genetic stability. [Conclusion] Through the isolation and mutation breeding, the TPHs degradation rate of the highly efficient THPs-degrading strain reached to 85.1%, increased by 48% compared with wild type strains. The highly efficient THPs-degrading strain can reduce the TPHs contents in the environment significantly and restore the oil-contaminated environment effectively.