苄嘧磺隆降解菌的分离及生长降解特性研究

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。

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

Bensulfuron-methyl(BSM) is a kind of sulfonylurea herbicide and widely used to control broadleaf 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 75B,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 16S rDNA sequences.Strain 75B grew well at pH 5.0 to 9.0,0.5％ to 5.0％ NaCl concentration and temperature range from 26℃ to 38℃.Under optimal conditions (5％ inoculum size,pH 7.0 minimal salt medium containing 2.0％ NaC1concentration,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 75B can biodegrade bensulfuron-methyl efficiently and could potentially be used to bioremediate sulphonylurea herbicides contamination.