College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, China.
Bioresour Technol. 2013 Nov;148:628-31. doi: 10.1016/j.biortech.2013.09.038. Epub 2013 Sep 16.
Two bacterial strains Sphingobium quisquiliarum DC-2 and Sphingobium baderi DE-13 were isolated from activated sludge. Acetochlor was transformed by S. quisquiliarum DC-2 to a transitory intermediate 2-chloro-N-(2-methyl-6-ethylphenyl)acetamide (CMEPA), which was further transformed to 2-methyl-6-ethylaniline (MEA), and MEA could not be degraded by strain DC-2. S. baderi DE-13, incapable of degrading acetochlor, showed capability of degrading MEA to an intermediate 2-methyl-6-ethylaminophenol (MEAOH). MEAOH was further transformed to 2-methyl-6-ethylbenzoquinoneimine (MEBQI), which was mineralized by strain DE-13. A gene, cmeH, encoding an amidase that catalyzed the amide bond cleavage of CMEPA was cloned from strain DC-2. CmeH was expressed in Escherichia coli BL21 and homogenously purified using Ni-nitrilotriacetic acid affinity. CmeH efficiently hydrolyzed CMEPA and other important herbicide, such as propanil, fenoxaprop-p-ethyl and clodinafop-propargyl.
鞘氨醇单胞菌 DC-2 和鞘氨醇单胞菌 DE-13。乙酰甲胺磷被 DC-2 菌株转化为瞬态中间产物 2-氯-N-(2-甲基-6-乙基苯基)乙酰胺 (CMEPA)，进一步转化为 2-甲基-6-乙基苯胺 (MEA)，而 MEA 不能被菌株 DC-2 降解。不能降解乙酰甲胺磷的鞘氨醇单胞菌 DE-13 表现出降解 MEA 为中间产物 2-甲基-6-乙基氨基酚 (MEAOH)的能力。MEAOH 进一步转化为 2-甲基-6-乙基苯醌亚胺 (MEBQI)，由 DE-13 菌株矿化。从菌株 DC-2 中克隆了编码催化 CMEPA 酰胺键裂解的酰胺酶的基因 cmeH。CmeH 在大肠杆菌 BL21 中表达，并使用 Ni-亚氨基二乙酸亲和进行均相纯化。CmeH 有效地水解 CMEPA 和其他重要的除草剂，如丙草胺、苯氧羧酸和氯氟草醚丙炔。
