苄嘧磺隆降解菌的分离及生长降解特性研究

Isolation,Growth and Degradation Characteristics of Bensulfuron-methyl Degrading Strain

苄嘧磺隆是一种磺酰脲类除草剂,被广泛应用于稻田土壤中防除一年生和多年生阔叶杂草。在土壤中的持效期较长,大量施用后易对后茬敏感作物产生药害,微生物降解是土壤中苄嘧磺隆转化的主要方式。本研究从长期施用该除草剂的稻田土壤中分离筛选到1株苄嘧磺隆降解菌株75B,经形态学及生理生化特征、16S rRNA基因扩增测序构建系统发育树分析,鉴定为Klebsiella pneumoniae(肺炎克雷伯氏菌)。75B菌株对环境的适应能力较强,在p H 5.0!9.0、0.5!5.0%Na Cl浓度下、培养温度为26!38℃的范围内生长良好。将该菌株按5%接种量置于p H 7.0、以苄嘧磺隆为唯一碳源的无机盐培养基(2.0%Na Cl浓度)中、34℃条件下培养,对50 mg/L苄嘧磺隆的5 d降解率为74.11%,培养至10 d时的降解率为97.65%。结果表明75B菌株可以有效地降解苄嘧磺隆,具有应用于该除草剂污染环境修复的潜力。

Bensulfuron-methyl（ BSM） is a kind of sulfonylurea herbicide and widely used to control broad-leaf weeds in paddy fields. Over-utilization can have negative impact on damaging sensitive succeeding crops because of BSM＇s long persistence. Microbial degradation was considered to be the main mechanisms of reducing bensulfuron-methyl herbicide in soil. In this study,A BSM-degrading bacterium,strain 75 B,was isolated from paddy soil used this herbicide several years. It was identified as Klebsiella pneumoniae based on its morphological,physiological,biochemical properties,and phylogenetic analysis of 16 S r DNA sequences.Strain 75 B grew well at p H 5. 0 to 9. 0,0. 5% to 5. 0% Na Cl concentration and temperature range from 26℃to 38℃. Under optimal conditions（ 5% inoculum size,p H 7. 0 minimal salt medium containing 2. 0% Na Cl concentration,culture temperature 34℃）,74. 11% of the initially added BSM（ 50 mg/L） was degraded after 5 days and almost complete degradation（ 97. 65%） could be achieved after 10 days. These results revealed that 75 B can biodegrade bensulfuron-methyl efficiently and could potentially be used to bioremediate sulphonylurea herbicides contamination.