Isolation And Characterization Of Crude Oil-degrading Enterobacter Sp.Strains ODB01

Petroleum as a strategic energy brought great revolution to economic development of human beings. However, a large amount of crude oil enters ecological environment during the exploration, mining, transportation, storage and processing, resulted in great threat and hard to the ecological environment and human beings health. Physical methods and chemical methods dealing with crude oil pollution is restricted due to take temporary solution not effect a permanent cure, microbial bioremediation technology paid widespread attention due to the economic, efficient, friendly environment, and no secondary pollution. Therefore, screening high efficient degradation of crude oil bacteria and study on its biodegradation characteristics, providing technical support for future development high performance crude oil degrading bacteria. In this paper, crude oil degrading strains were isolated from crude oil-contaminated soil (changing oilfield, China). The results are as follow:(1) Out of 14 strains were isolation from crude oil-contaminated soil by enrichment cultivation, capable of utilizing crude-oil as the sole source of carbon for growth, four strains of them (NO.:105?109?112?178, respectively)have good stability. Among four strains, further research was performed for 109 strains due to the best biodegradation and named ODB01.(2) Based on morphology observation, iological characteristics, analysis of 16S rDNA gene sequence and phylogenetic tree indicated that the strain ODB01 belonged to Enterobacter sp..(3) Antibiotic susceptibility test results showing that the ODB01 strains has strong drug resistance to rythromycin, penicillin, novobiocin, ampicillin and benzene, and extremely sensitive to rbenicillin, chloramphenicol, kanamycin, cefazolin, cefuroxime, ceftazidime, piperacillin and cefoperazone.(4) The optimization of crude oil degradation condition was carried out by response surface methodology (Box-Behnken), the results are as follows:pH,8.91; NaCl concentration,1.19%; oil-bacteria liquid proportion,1=4.12; temperature,36.78 1?, the degradation rate reaches to 34.6% under optimum condition, and 1.44 times more than before optimization.(5) Both non-ionic surfactant Tween 80 and Triton X-100 could increase crude oil biodegradation of strains ODB01, and optimum surfactant concentration are all 0.05%. The degradation rates of crude oil reach to 42.5% and 46.1% under optimal degradation condition and adding 0.05% Tween 80 and 0.05% Triton X-100, respectively, compared with without adding surfactants degradation rate increased by 15% and 24%, respectively.(6) Genome sequence analysis of crude oil-degrading strains ODB01 show that the genome consists of 4,534,036 bp with a G+C content of 54.81%, a total of 4,117 coding sequences (CDS), out of 27 monooxygenase/dioxygenase genes were identified from annotationed data and may be involved in the biodegradation of crude oil.