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【目的】阐明紫金牛叶杆菌Phyllobacterium myrsinacearum RC6b及其诱变菌株对二苯砷酸(Diphenylarsinic acid,DPAA)的降解特征与代谢产物。【方法】以紫金牛叶杆菌RC6b为出发菌株,分别以蔗糖、葡萄糖和乙酸钠为外加碳源,优化共代谢降解条件;采用亚硝基胍(N-methyl-N′-nitro-N-nitrosoguanidine,NTG)对出发菌株进行化学诱变,比较诱变前后菌株对DPAA降解能力的变化,鉴定诱变菌株对DPAA的降解代谢产物。【结果】以DPAA为唯一碳源时,培养28 d后RC6b菌株对DPAA的降解率低于2%;分别添加蔗糖、葡萄糖和乙酸钠为外加碳源培养28 d后,DPAA的降解率显著提高,分别达到14.08%、15.21%和15.05%;采用250μg/m L的NTG诱变后获得3株诱变菌,在以DPAA为唯一碳源培养28 d后,3株诱变菌对DPAA的降解率与出发菌株相比均显著提高,其中N-RC6b2对DPAA的降解率最高,达36.71%;代谢产物鉴定结果表明,诱变菌株N-RC6b2对DPAA的代谢产物中有单羟基化DPAA的生成。【结论】RC6b出发菌株难以直接利用DPAA为唯一碳源生长,外加蔗糖、葡萄糖和乙酸钠等共代谢碳源可显著提高菌株RC6b对DPAA的降解率;NTG化学诱变可进一步提高RC6b菌株对DPAA的降解效果,代谢产物为单羟基化DPAA。
【Objective】 The objective of this study is to elucidate the degradation characteristics and metabolites of dipyrnameolanic acid (DPAA) by Phyllobacterium myrsinacearum RC6b and its mutants. 【Method】 Using the Bacillus thuringiensis RC6b as starting strain, sucrose, glucose and sodium acetate were added as carbon sources respectively to optimize the conditions of catabolism and degradation. N-methyl-N’-nitro-N-nitrosoguanidine , NTG) were used to mutagenize the starting strain. The changes of DPAA degrading ability were compared before and after mutagenesis, and the degradation metabolites of DPAA were identified. 【Result】 The results showed that the DPAA degradation rate of RC6b strain was less than 2% when cultured for 28 days with DPAA as sole carbon source. The degradation rate of DPAA was significantly increased after 28 days of addition of sucrose, glucose and sodium acetate , Respectively, reached 14.08%, 15.21% and 15.05% respectively. Three mutagens were obtained after NTG mutagenesis with 250μg / mL Lactobacillus plantarum and DPAA degradation was induced by three strains of mutants after DPAA as sole carbon source for 28 days The rate of N-RC6b2 to DPAA was the highest (36.71%). The results of metabolite identification showed that the production of mono-hydroxylated DPAA in DPAA metabolites was induced by N-RC6b2 . 【Conclusion】 The RC6b strain could not directly utilize DPAA as the sole carbon source. The addition of sucrose, glucose and sodium acetate could significantly improve the degradation rate of DPAA by strain RC6b. NTG chemical mutagenesis could further enhance the effect of RC6b on DPAA The degradation products, metabolites of monohydroxylated DPAA.