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麦草畏是理想的抗除草剂转基因工程的靶标除草剂;发掘新的麦草畏高效降解菌株和基因具有非常重要的理论和应用价值.从南京土壤样品中分离到一株麦草畏高效降解菌株,命名为3-3.根据生理生化特征和16S r DNA序列相似性分析,将其初步鉴定为苍白杆菌属(Ochrobactrum sp.).菌株3-3在48 h内完全降解100 mg/L的麦草畏.该菌株降解麦草畏的最适温度为30℃,最适p H为7.0.代谢产物高效液相和质谱鉴定结果表明该菌株降解麦草畏的起始步骤是脱甲基,形成没有除草活性的3,6-二氯水杨酸(DCSA).菌株粗酶液只在NADH存在时才有麦草畏脱甲基酶活性.PCR扩增和该菌基因组生物信息学分析表明该菌株没有已报道的麦草畏脱甲基酶基因DMO、Mtv及Dmt或其同源序列.总之,本研究首次分离筛选到苍白杆菌属的麦草畏降解菌,且该菌可能存在一个新的氧化酶类麦草畏脱甲基酶基因.
Dicamba is an ideal target herbicide for herbicide-tolerant transgenic engineering.It is of great theoretical and practical value to discover new high-degradation strains and genes of dicamba.A strain of dicamba-degrading strain was isolated from soil samples from Nanjing, Was 3-3, which was initially identified as Ochrobactrum sp. On the basis of physiological and biochemical characteristics and similarity analysis of 16S r DNA sequences. Strain 3-3 completely degraded 100 mg / L dicamba within 48 h. The optimal temperature for the degradation of dicamba was 30 ℃, and the optimum pH was 7.0.The HPLC and mass spectrometry identification of the metabolites showed that the initial step of this strain in degrading dicamba was demethylation to form 3 , 6-dichlorosalicylic acid (DCSA) .The crude enzyme activity of the strain only had dicamba demethylase activity in the presence of NADH.PCR amplification and genome bioassay analysis of the strain showed that the strain did not have the reported wheatgrass In addition, the DMO, Mtv, Dmt or their homologous sequences of the methylase genes were weakened.At last, we isolated and isolated the dicamba bacteria from the genus Corynebacterium for the first time in this study, and a new oxidase-like dicamba-demethylated Enzyme gene.