Studies On Isolation And Characterization Of Oil Degrading Bacteria

With the development of morden petroleum industry, the pollution caused by oil becomes more and more serious. The oil pollution not destroy the environmetal ecological balance but also threaten the human's health, so more and more countries pay attention to the oil pollution problem and make great efforts to find a better treating method to resolve it. Microbiological remediation technology has been considered a sate, economical and reliable method to remediate oil in soil and oil-degradating microorganisms play a important role in the technology.A series laboratory studies have been conducted to evaluate the economic effection of gasoline to the microorganisms in the sludge, indentify the gasoline -degradating strains islated from gasoline-contaminanted environment, evaluate the factors those will affect the degradation rate of strains.The resultes show: 2 gasoline-degradating strains (named as X and Z) isolated from the sludge discharged from a Chang-Sha oil factory have been identified as Pseudomonas sp(X) and Bacillus sp(Z) by morphological and physiological -biochemical identification. The 16S rDNA sequence of Z shared 99% homologies with Bacillus cereus (AH1134), which was a published sequence of relative bacteria from GenBank, and both sequences constituted a branch in phylogenetic tree.Therefore, the strain Z was considered as one strain of Bacillus cereus. The optium condition for the gasoline degradation by the 2 strains in shaking flask is: the intional pH of the incubation media is 7.0～8.0, the incubation temperature is 37℃, the shaker speed is 180r/min,the seed volume 15%, the concentration of gasoline is 500mg/L, the NaCl concentration is 10g/L, the optimal centration SDS is 100mg/L, Cu2+ is 0.1mg/L; The ptimum carbon and nitrogen sources for X are glucose and NH4Cl, Z are sugar and (NH4)2SO4. The mutants by ultraviolet radiation treatment had greater degrading efficiency than the original ones, with 15W ultraviolet lighe having better mutation effect on the strains than 30W ultraviolet light.