多氯联苯污染土壤好氧降解菌群的分离与鉴定

Isolation and Identification of Aerobic Polychlorinated Biphenyls-Degrading Bacterial Strains in PCBs-contaminated Soils

从浙江温岭和萧山长期受多氯联苯污染的土壤中,以联苯为唯一碳源和能源进行菌类的富集筛选共得到35株纯菌,其中革兰氏阴性菌占细菌总数的60%。对得到的35株菌株进行16SrRNA基因序列分析,结果显示温岭和萧山土壤中的优势菌属分别为寡养单胞菌(Stenotrophomonas sp.)和潘多拉菌属(Pandoraea sp.)。挑选的4株细菌棒状杆菌(Corynebacterium sp.)WL8、芽孢杆菌(Bacillus sp.)WL10、微杆菌属(Microbacterium sp.)XS4和柠檬酸杆菌(Citrobacter sp.)XS7均可在联苯存在情况下共代谢降解2,3,4,5-四氯代多氯联苯(PCB61),其中从温岭土壤中筛选到的Corynebacteriumsp.WL8对PCB61的5d去除率达到了50%。

Growth of microorganisms was stimulated by incubating polychlorinated biphenyl-polluted soils in Wenling and Xiaoshan with biphenyl as sole carbon and energy source. After 4 weeks, a total of thirty five strains of bacteria which were able to grow on biphenyl-containing minimal medium plates were isolated. Sixty percent of them are gram-negative bacteria. The results of 16S rRNA gene sequencing showed that the dominant strains are Stenotrophomonas sp. and Pandoraea sp.. We chose two well growing strains from each soil to further study PCB-degradation. The four strains are Corynebacterium sp. WL8, Bacillus sp. WL10, Microbacterium sp. XS4 and Citrobacter sp. XS7. All of them were cultured in fresh mineral medium containing 100 mg·L-1 biphenyl and 2 mg·L-1 2, 3, 4, 5-tetrachlorobiphenyl （PCB61）for five days. The residual concentrations of PCB61 determined by gas chromatography showed all the strains could degrade PCB61. Especially,the transformation rate of PCB61 by Corynebacterium sp.WL 8, isolated from Wenling soil, reached 50%.This result will benefit further research of genetic screening, cloning and restructuring, as well as providing guidance for the cultivation of PCBs-degrading bacteria.