润滑油降解菌的分离、鉴定及降解特性

以HVI 500润滑油为唯一碳源进行选择性富集培养，从油污染土壤中筛选出3株菌，分别命名为SN0901，SN0902和SN0903. 采用重铬酸钾法测定含HVI 500润滑油培养液的ρ(COD_Cr)，用以评价分离菌对润滑油的降解能力. 结果表明，由于润滑油降解而使培养液ρ(COD_Cr)降低，即3株菌均为HVI 500润滑油降解菌. 根据形态学观察、生理生化试验和16S rDNA基因序列比对分析，初步确定3株菌分别属于假单胞菌属(Pseudomonas)、苍白杆菌属(Ochrobactrum)和博德特氏菌属(Bordetella). 采用倾注平板法对不同温度下降解菌的菌落计数，采用重铬酸钾法测定不同pH下培养液的ρ(COD_Cr). 结果显示，温度和pH对菌株降解作用影响显著，3株菌最适宜的降解温度为30～34 ℃，pH为6.0～7.8，但每株菌的最适宜降解温度和pH稍有不同. 

Isolation, Identification and Degradation Characteristics of Bacterial Strains for Biodegradation of Lubricating Oil

Utilizing HVI 500 lubricating oil as a sole carbon source, three bacterial strains named as SN0901, SN0902 and SN0903 were isolated from the oil-contaminated soil by selective enriched culture. The abilities of the three strains to biodegrade HVI 500 lubricating oil were evaluated by determining COD_Cr mass concentrations of the oil-containing culture fluids by the method of dichromate titration. Results showed that the COD_Cr mass concentrations decreased due to the biodegradation of the lubricating oil, indicating that the three strains were all degrading bacteria for lubricating oils. The three strains were preliminarily identified to be genus Pseudomonas, Ochrobactrum and Bordetella, respectively, based on morphological observations, physiological and biochemical tests, and 16S rDNA sequencing analyses. Degrading-bacteria colonies were counted at different temperatures by the pour plate count method and COD_Cr mass concentrations of the culture fluids in different pH were explored by the method of dichromate titration. Results demonstrated that under the temperatures between 30 and 34 ℃ and pH between 6.0 and 7.8, the three strains exhibited excellent degrading abilities, although the optimum temperatures and pH differed slightly for different strains.