太湖芦苇荡底泥中藻毒素降解菌的筛选及其特性研究

Study on Screening of Microcystins Degrading Bacterial Strain from Reed Marsh Sediment of Taihu Lake and its Degradation Characteristics

针对连年蓝藻暴发造成的饮用水源水微囊藻毒素(Microcystins,MCs)污染问题,从蓝藻暴发时期江苏太湖百渎港芦苇荡的底泥中筛选出一株MC-LR降解菌,命名为CQ5,对该菌株进行形态观察、生理生化试验及16S r DNA分子鉴定,并考察pH值和接菌量对其增殖和降解MC-LR的影响。结果表明,菌株CQ5在系统发育分类学上与耐硼赖氨酸芽孢杆菌(Lysinibacillus boronitolerans)亲缘关系最近,两者同源性高达99%;菌株能以MC-LR为碳、氮源进行生长,且耐弱酸弱碱;当pH值为7,接菌量为3%时,菌株的增殖及降解效果最好,6 d内可使初始质量浓度为14.12μg/L的MC-LR降至1.68μg/L,降解率达87.96%。

To solve the problem of microcystins pollution in drinking water sources due to the alage bloom in last several years,a MC-LR degrading bacterium named CQ5 was screened from the sediment of the reed marshes in the Baihu Harbor of Taihu Lake. The strain was identified by morphological observation,physiological and biochemical tests and 16 S r DNA sequence analysis. The effects of pH and inoculation amount on the growth and degradation of MC-LR were examined. The results show that the strain CQ5 is closely related to Lysinibacillus boronitolerans in phylogenetic taxonomy and the homology between them up to 99%. This strain grows by degrading MC-LR as carbon and nitrogen source and tolerates the mild acid or alkali environmental. The strain performs better in the growth and degradation of MC-LR at pH of 7 with the inoculation amount of 3%,the MC-LR original concentration was substantially reduced from14. 12 μg/L to 1. 68 μg/L and the degradation rate was around 87. 96% within 6 days.