Zhang Xinjian, Huang Yujie, Harvey Paul R, Li Hongmei, Ren Yan, Li Jishun, Wang Jianing, Yang Hetong
Shandong Provincial Key Laboratory of Applied Microbiology, Biotechnology Center of Shandong Academy of Sciences, Jinan, Shandong Province, People's Republic of China.
PLoS One. 2013 Oct 1;8(10):e74810. doi: 10.1371/journal.pone.0074810. eCollection 2013.
Carbendazim (methyl 1H-benzimidazol-2-yl carbamate) is one of the most widely used fungicides in agriculture worldwide, but has been reported to have adverse effects on animal health and ecosystem function. A highly efficient carbendazim-degrading bacterium (strain dj1-11) was isolated from carbendazim-contaminated soil samples via enrichment culture. Strain dj1-11 was identified as Rhodococcus erythropolis based on morphological, physiological and biochemical characters, including sequence analysis of the 16S rRNA gene. In vitro degradation of carbendazim (1000 mg·L(-1)) by dj1-11 in minimal salts medium (MSM) was highly efficient, and with an average degradation rate of 333.33 mg·L(-1)·d(-1) at 28°C. The optimal temperature range for carbendazim degradation by dj1-11 in MSM was 25-30°C. Whilst strain dj1-11 was capable of metabolizing cabendazim as the sole source of carbon and nitrogen, degradation was significantly (P<0.05) increased by addition of 12.5 mM NH4NO3. Changes in MSM pH (4-9), substitution of NH4NO3 with organic substrates as N and C sources or replacing Mg(2+) with Mn(2+), Zn(2+) or Fe(2+) did not significantly affect carbendazim degradation by dj1-11. During the degradation process, liquid chromatography-mass spectrometry (LC-MS) detected the metabolites 2-aminobenzimidazole and 2-hydroxybenzimidazole. A putative carbendazim-hydrolyzing esterase gene was cloned from chromosomal DNA of djl-11 and showed 99% sequence homology to the mheI carbendazim-hydrolyzing esterase gene from Nocardioides sp. SG-4G.
多菌灵（甲基1H-苯并咪唑-2-基氨基甲酸酯）是全球农业中使用最广泛的杀菌剂之一，但据报道它对动物健康和生态系统功能有不利影响。通过富集培养从多菌灵污染的土壤样品中分离出了一种高效降解多菌灵的细菌（菌株dj1-11）。基于形态学、生理学和生化特征，包括16S rRNA基因序列分析，菌株dj1-11被鉴定为红平红球菌。在基本盐培养基（MSM）中，dj1-11对多菌灵（1000 mg·L(-1)）的体外降解效率很高，在28°C时平均降解速率为333.33 mg·L(-1)·d(-1)。dj1-11在MSM中降解多菌灵的最佳温度范围是25-30°C。虽然菌株dj1-11能够将多菌灵作为唯一的碳源和氮源进行代谢，但添加12.5 mM硝酸铵可显著（P<0.05）提高降解率。MSM的pH值（4-9）变化、用有机底物替代硝酸铵作为氮源和碳源，或者用锰（2+）、锌（2+）或铁（2+）替代镁（2+），均不会显著影响dj1-11对多菌灵的降解。在降解过程中，液相色谱-质谱联用（LC-MS）检测到了代谢产物2-氨基苯并咪唑和2-羟基苯并咪唑。从djl-11的染色体DNA中克隆出了一个推测的多菌灵水解酯酶基因，其与诺卡氏菌属SG-4G的mheI多菌灵水解酯酶基因的序列同源性为99%。
