PCBs降解菌的筛选及其降解特性研究

Isolation and Degradation Characteristics of PCB-degrading Strain

采用富集培养的方法从多氯联苯(PCBs)污染土壤中筛选到1株高效降解PCBs的细菌,命名为PS-11.经16S rDNA初步鉴定,此菌株属于嗜麦芽寡养单胞菌(Stenotrophomonas maltophilia).结果表明,菌株PS-11能够以PCBs作为唯一碳源生长并且能够降解PCBs,菌株PS-11对2 mg.L-1PCB52 4 d的降解率为31.1%,7 d的降解率可达52.9%;对难降解的高氯代多氯联苯PCB153 7 d的降解率为10.9%.此外,该菌株的环境耐受性比较好,在30℃、pH为7～9、PCB52浓度为2～10 mg.L-1的条件下生长较快、降解效果较好,尤其在pH 7、PCB52浓度为2 mg.L-1时降解率最高;碳源种类不同,菌株PS-11的生长能力也不同,其中在以蔗糖为碳源时PS-11的生长能力最强,以葡萄糖为碳源时PS-11的适应期最短,且蔗糖、葡萄糖和Tween-80均可提高PS-11对PCB52的降解率;同时菌株PS-11还可耐受一定浓度的重金属,其耐受性大小为Pb2+>Cd2+>Zn2+>Cu2+.

A new PCB-degrading bacterial strain named PS-11 was isolated from soil contaminated with PCBs by enrichment culture.The strain was identified as Stenotrophomonas maltophilia according to the results of the analyses of 16S rDNA sequence.It was observed that the degradation rate of PCB52 by strain PS-11 was 31.1% after 4 days and 52.9% after 7 days in cultures containing 2 mg·L-1 PCB52.The degradation rate was 10.9% for 2 mg·L-1 refractory PCB153 after 7 days.In addition,the strain showed very good environmental tolerance.It could grow and degrade PCB52 in the culture medium at 30℃ and pH 7-9 with PCB52 concentrations of 2-10 mg·L-1,especially,pH 7 and 2 mg·L-1 PCB52 was found to be the best condition for cell growth and degradation.The growth of strain PS-11 was affected by different carbon sources.The strain showed best growth when sucrose was used as carbon source and the shortest lag time was observed when glucose was used as carbon source.In addition,sucrose,glucose and Tween-80 could increase the degradation rate of PCB52 by PS-11.Further study showed that the strain PS-11 could resist some heavy metal ions at high concentrations,the tolerance in a descending order was： Pb2＋Cd2＋Zn2＋Cu2＋.