College of Chemistry and Environmental Science, Hebei University, Baoding City, Hebei Province, 071002, PR China.
College of Chemistry and Biological Engineering, University of Science and Technology Beijing, Beijing, 100083, PR China.
J Hazard Mater. 2018 Jul 15;354:225-230. doi: 10.1016/j.jhazmat.2018.04.067. Epub 2018 Apr 27.
Pyraclostrobin has been widely and long-termly applicated to agricultural fields. The removal of pyraclostrobin from ecological environment has received wide attention. In this study, using sequential enrichments with pyraclostrobin as a sole carbon source, two microbial communities (HI2 and HI6) capable of catabolizing pyraclostrobin were obtained from Hawaiian soils. The microfloras analysis indicated that only Proteobacteria and Bacteroides could survive in HI2-soil after acclimatization, whereas the number of Proteobacteria in HI6-soil accounted for more than 99%. The percentages of Pseudomonas in the HI2 and HI6 microfloras were 69.3% and 59.3%, respectively. More than 99% of pyraclostrobin (C = 100 mg L) was degraded by the HI2 and HI6 microorganisms within five days. A unique metabolite was identified by high performance liquid chromatography tandem quadrupole time-of-flight mass spectrometry (HPLC-QTOF-MS/MS). A metabolic pathway involving carbamate hydrolysis was proposed. The tertiary amine group of pyraclostrobin was hydrolyzed to primary amine group with the decarboxylation, which facilitated pyraclostrobin detoxification because carboxylester was an important functional group. The metabolic mechanism suggested that Pseudomonas expressing carboxylesterase might be able to degrade carbamate chemicals. Therefore, Pseudomonas might be an ideal candidate for expression and cloning of carbamate-degrading gene in genomics studies. The current study would have important implications in detoxification and bioremediation of carbamates through the CN bond cleavage of methyl carbamate.
吡唑醚菌酯已被广泛且长期应用于农业领域。吡唑醚菌酯从生态环境中的去除已受到广泛关注。在这项研究中，使用以吡唑醚菌酯为唯一碳源的连续富集方法，从夏威夷土壤中获得了两种能够代谢吡唑醚菌酯的微生物群落（HI2 和 HI6）。微生物群落分析表明，只有在适应后 HI2-土壤中才能生存 Proteobacteria 和拟杆菌，而 HI6-土壤中 Proteobacteria 的数量占比超过 99%。HI2 和 HI6 微生物群落中假单胞菌的比例分别为 69.3%和 59.3%。HI2 和 HI6 微生物在五天内将超过 99%的吡唑醚菌酯（C=100mg/L）降解。通过高效液相色谱串联四极杆飞行时间质谱（HPLC-QTOF-MS/MS）鉴定出一种独特的代谢产物。提出了一种涉及氨基甲酸酯水解的代谢途径。吡唑醚菌酯的叔胺基团在脱羧作用下水解为伯胺基团，这有助于吡唑醚菌酯解毒，因为羧酸盐是一个重要的功能基团。代谢机制表明，表达羧酸酯酶的假单胞菌可能能够降解氨基甲酸酯类化学物质。因此，假单胞菌可能是在基因组学研究中表达和克隆降解氨基甲酸酯基因的理想候选者。本研究对于通过 CN 键断裂对甲基氨基甲酸酯进行解毒和生物修复具有重要意义。
