Chemistry Division, The Institute of Environmental Toxicology, 4321 Uchimoriya-machi, Joso-shi, Ibaraki, 303-0043, Japan.
Appl Microbiol Biotechnol. 2010 May;86(5):1585-92. doi: 10.1007/s00253-010-2460-3. Epub 2010 Feb 19.
A novel s-triazine-mineralizing bacterium-Nocardioides sp. strain DN36-was isolated from paddy field soil treated with ring-U-(14)C-labeled simetryn ([(14)C]simetryn) in a model paddy ecosystem (microcosm). In a tenfold-diluted R2A medium, strain DN36 liberated (14)CO(2) from not only [(14)C]simetryn but also three ring-U-(14)C-labeled s-triazines: atrazine, simazine, and propazine. We found that DN36 mineralized ring-U-(14)C-cyanuric acid added as an initial substrate, indicating that the bacterium mineralized s-triazine herbicides via a common metabolite, namely, cyanuric acid. Strain DN36 harbored a set of genes encoding previously reported s-triazine-degrading enzymes (TrzN-AtzB-AtzC), and it also transformed ametryn, prometryn, dimethametryn, atraton, simeton, and prometon. The findings suggest that strain DN36 can mineralize a diverse range of s-triazine herbicides. To our knowledge, strain DN36 is the first Nocardioides strain that can individually mineralize s-triazine herbicides via the ring cleavage of cyanuric acid. Further, DN36 could not grow on cyanuric acid, and the degradation seemed to occur cometabolically.
一株新型三嗪矿化细菌——诺卡氏菌 sp. 株 DN36，从稻田土壤中分离得到，该土壤曾在一个稻田模型生态系统（微宇宙）中用环-U-（14）C 标记的西玛津（[（14）C]西玛津）处理过。在十倍稀释的 R2A 培养基中，DN36 不仅能从[（14）C]西玛津中释放（14）CO2，还能从三种环-U-（14）C 标记的三嗪类化合物：莠去津、西玛津和扑灭津中释放（14）CO2。我们发现 DN36 能矿化环-U-（14）C-氰尿酸作为初始底物，这表明该细菌通过一种共同的代谢物，即氰尿酸，矿化三嗪类除草剂。DN36 株携带一套编码先前报道的三嗪类降解酶（TrzN-AtzB-AtzC）的基因，它还能转化莠灭净、扑灭通、二甲戊灵、阿特拉津、赛克津和丙炔恶草酮。这些发现表明，DN36 株可以矿化多种三嗪类除草剂。据我们所知，DN36 株是第一株可以通过氰尿酸的环裂解单独矿化三嗪类除草剂的诺卡氏菌株。此外，DN36 不能在氰尿酸上生长，降解似乎是共代谢发生的。
