克雷伯氏菌和伯克霍尔德氏菌复合菌群催化三硝基甲苯降解

 通过摇瓶实验研究了克雷伯氏菌 (S1) 和伯克霍尔德氏菌 (S2) 复合菌群 (简称 S) 降解三硝基甲苯 (TNT) 的特性和机理. 结果表明, 在外加碳源和氮源时, 100 mg/L TNT 在 16 h 内可被菌群 S 完全去除. 只外加碳源时, TNT 的最高去除率为 80%; 只加入氮源时, 仍可除去 12% 的 TNT. 在 S1 催化体系中检测到较高活性硝基还原酶的存在, 该酶催化 TNT 转化为缩合中间产物二硝基双偶氮甲苯, 其分子量为 326. 但是只有 S1 和 S2 共存才能产生高活性的甲苯双加氧酶和邻苯二酚 2,3-双加氧酶, 两类酶共同催化中间产物的开环分解. 伴随着二硝基双偶氮甲苯的开环分解, 硝基脱落生成 NO2–, 后者进一步氧化生成 NO3–. 通过 S1 和 S2 的协同作用, 实现了 TNT 的好氧开环和硝基脱落, 该结果表明在 TNT 生物催化降解中复合菌群比单一菌株更具优势和潜力.

Biodegradation of Trinitrotoluene by a Bacterial Consortium Containing Kleb-siella sp. and Burkholderia sp.

The biodegradation characteristic and mechanism of trinitrotoluene (TNT) by a bacterial consortium S consisted of Klebsiella sp. S1 and Burkholderia sp. S2 were investigated by shaking-flask culture. The results show that the consortium S can completely biodegrade 0.1 g/L TNT in solution in the presence of both external carbon and nitrogen sources, whereas the biodegradation efficiency of TNT reaches 80% and 12%, respectively, with external carbon source only and nitrogen source only. Highly active nitroreductase was detected in the S1 catalyst system. This enzyme transformed TNT into a condensation product, diazodinitrotoluene, which was further degraded through ring cleavage catalyzed by the combined action of highly active toluene dioxygenase and catechol dioxygenase produced in the case of coexistence of S1 and S2. Nitro groups in TNT were released during the ring cleavage of diazodinitrotoluene, resulting in the formation of NO₂^–, which was further oxidized into NO₃^–. This bacterial consortium has greater potentials in biodegradation of TNT than the single bacterium.