Fan Jieyu, Yang Guoxia, Zhao Haoyu, Shi Guanying, Geng Yucong, Hou Taiping, Tao Ke
Key Laboratory of Bio-resources and Eco-environment of Ministry Education, College of Life Sciences, Sichuan University, Chengdu, 610064, P.R. China.
J Gen Appl Microbiol. 2012;58(4):263-71. doi: 10.2323/jgam.58.263.
A bacterial strain named CB4, with highly effective glyphosate degradation capability, was isolated from soil after enrichment. On the basis of the Biolog omniLog identification system (Biolog) and 16S ribosomal RNA (rRNA) gene sequencing methods, strain CB4 was identified as Bacillus cereus. Further experiments were carried out to optimize the growth of strain CB4 and the glyphosate degradation activity by high performance liquid chromatography (HPLC). The optimal conditions were found as follows: initial pH 6.0, incubation temperature 35°C, glyphosate concentration 6 g L(-1), inoculation amount 5% and incubation time 5 days. Under the optimal conditions, stain CB4 utilized 94.47% of glyphosate. This is the first report on B. cereus with a capacity to utilize herbicide glyphosate, and it can degrade glyphosate concentrations up to 12 g L(-1). Metabolization of glyphosate by strain B. cereus CB4 was studied. Results indicated that two concurrent pathways were capable of degrading glyphosate to AMPA, glyoxylate, sarcosine, glycine and formaldehyde as products. Glyphosate breakdown in B. cereus CB4 was achieved by the C-P lyase activity and the glyphosate oxidoreductase activity.
从富集后的土壤中分离出一株名为CB4的细菌菌株，其具有高效的草甘膦降解能力。基于Biolog全细胞鉴定系统（Biolog）和16S核糖体RNA（rRNA）基因测序方法，菌株CB4被鉴定为蜡样芽孢杆菌。通过高效液相色谱法（HPLC）进一步开展实验以优化菌株CB4的生长及草甘膦降解活性。发现最佳条件如下：初始pH 6.0、培养温度35℃、草甘膦浓度6 g L(-1)、接种量5%以及培养时间5天。在最佳条件下，菌株CB4利用了94.47%的草甘膦。这是关于蜡样芽孢杆菌具有利用除草剂草甘膦能力的首次报道，并且它能够降解高达12 g L(-1)的草甘膦浓度。研究了蜡样芽孢杆菌CB4对草甘膦的代谢作用。结果表明，两条并行途径能够将草甘膦降解为产物氨甲基膦酸、乙醛酸、肌氨酸、甘氨酸和甲醛。蜡样芽孢杆菌CB4中草甘膦的分解是通过C-P裂解酶活性和草甘膦氧化还原酶活性实现的。
