Ni Haiyan, Yao Li, Li Na, Cao Qin, Dai Chen, Zhang Jun, He Qin, He Jian
Key Laboratory of Microbiological Engineering of Agricultural Environment, Ministry of Agriculture, Life Sciences College of Nanjing Agricultural University, Nanjing 210095, China.
China National Center for Biotechnology Development, Beijing 100039, China.
J Environ Sci (China). 2016 Mar;41:121-127. doi: 10.1016/j.jes.2015.04.035. Epub 2015 Sep 3.
A bacterium strain Y3, capable of efficiently degrading pendimethalin, was isolated from activated sludge and identified as Bacillus subtilis according to its phenotypic features and 16S rRNA phylogenetic analysis. This strain could grow on pendimethalin as a sole carbon source and degrade 99.5% of 100mg/L pendimethalin within 2.5days in batch liquid culture, demonstrating a greater efficiency than any other reported strains. Three metabolic products, 6-aminopendimethalin, 5-amino-2-methyl-3-nitroso-4-(pentan-3-ylamino) benzoic acid, and 8-amino-2-ethyl-5-(hydroxymethyl)-1,2-dihydroquinoxaline-6-carboxylic acid, were identified by HPLC-MS/MS, and a new microbial degradation pathway was proposed. A nitroreductase catalyzing nitroreduction of pendimethalin to 6-aminopendimethalin was detected in the cell lysate of strain Y3. The cofactor was nicotinamide adenine dinucleotide phosphate (NADPH) or more preferably nicotinamide adenine dinucleotide (NADH). The optimal temperature and pH for the nitroreductase were 30°C and 7.5, respectively. Hg(2+), Ni(2+), Pb(2+), Co(2+), Mn(2+) Cu(2+), Ag(+), and EDTA severely inhibited the nitroreductase activity, whereas Fe(2+), Mg(2+), and Ca(2+) enhanced it. This study provides an efficient pendimethalin-degrading microorganism and broadens the knowledge of the microbial degradation pathway of pendimethalin.
从活性污泥中分离出一株能够高效降解二甲戊灵的细菌菌株Y3，根据其表型特征和16S rRNA系统发育分析，鉴定为枯草芽孢杆菌。该菌株能够以二甲戊灵作为唯一碳源生长，在分批液体培养中，2.5天内可降解100mg/L二甲戊灵的99.5%，其降解效率高于其他任何已报道的菌株。通过HPLC-MS/MS鉴定出三种代谢产物，即6-氨基二甲戊灵、5-氨基-2-甲基-3-亚硝基-4-(戊-3-基氨基)苯甲酸和8-氨基-2-乙基-5-(羟甲基)-1,2-二氢喹喔啉-6-羧酸，并提出了一条新的微生物降解途径。在菌株Y3的细胞裂解物中检测到一种催化二甲戊灵硝基还原为6-氨基二甲戊灵的硝基还原酶。辅助因子是烟酰胺腺嘌呤二核苷酸磷酸(NADPH)，更优选的是烟酰胺腺嘌呤二核苷酸(NADH)。该硝基还原酶的最适温度和pH分别为30°C和7.5。Hg(2+)、Ni(2+)、Pb(2+)、Co(2+)、Mn(2+)、Cu(2+)、Ag(+)和EDTA严重抑制硝基还原酶活性，而Fe(2+)、Mg(2+)和Ca(2+)则增强其活性。本研究提供了一种高效降解二甲戊灵的微生物，拓宽了对二甲戊灵微生物降解途径的认识。
