微囊藻毒素降解菌S3的分子鉴定及其降解毒素的研究

Molecular identification of a microcystin-degrading bacteria strain S3 and its biodegradation of microcystin

对一株具有强降解微囊藻毒素MC-LR能力的细菌S3进行了分子鉴定.测得该菌16Sr DNA为1396bp,GenBank序列登录号为DQ836314.序列比对结果显示,该菌与类芽孢杆菌Paenibacillus validus的相似性达98%.微囊藻毒素降解实验结果表明,该菌能在以微囊藻毒素为唯一碳、氮源的培养基中生长,微囊藻毒素在72h内减少78.3%,菌株S3的最适生长温度是30℃,最适生长pH值为7.0.

More than 18 microcystin-degrading bacterial strains were isolated from water bodies with cyanobacteria blooms. The strain with the highest degrading capacity was strain S3. To identify the species, 16S rDNA of S3 was amplified by PCR. The PCR product was sequenced and the data submitted to GenBank under accession number DQ836314. BLAST sequence analysis showed that it had a 98% similarity to Paenibacillus validus. S3 could grow on mineral medium supplied with microcystins （ mainly MC-LR）, extracted from Microcystis PCC 7806, as sole carbon and nitrogen sources （micrecystins were substituted for NH4＋ and glucose in M9 medium）. S3 could degrade and metabolize 78.3% of 5 mg· L^-1 MC-LR in 72 h. To find suitable conditions for the bacterial degradation of MC-LR, we investigated the effects of temperature and pH on cell growth and MC-LR degradation rate. The results showed that 30 ℃ and pH 7.0 were the best conditions, which are similar to the environmental conditions for Microcystis blooms. So S3 may be useful in removing MCs from water during algal blooms.