Microbial Biotechnology and Protein Research Laboratory, Department of Molecular Biology and Biotechnology, Tezpur University, Tezpur, 784 028 Assam, India.
Environ Sci Pollut Res Int. 2012 Sep;19(8):3380-8. doi: 10.1007/s11356-012-0862-8. Epub 2012 Apr 15.
The major aromatic constituents of petroleum products viz. benzene, toluene, and mixture of xylenes (BTX) are responsible for environmental pollution and inflict serious public concern. Therefore, BTX biodegradation potential of individual as well as formulated bacterial consortium was evaluated. This study highlighted the role of hydrogen peroxide (H(2)O(2)), nitrate, and phosphate in stimulating the biodegradation of BTX compounds under hypoxic condition.
The individual bacterium viz. Bacillus subtilis DM-04 and Pseudomonas aeruginosa M and NM strains and a consortium comprising of the above bacteria were inoculated to BTX-containing liquid medium and in soil. The bioremediation experiment was carried out for 120 h in BTX-containing liquid culture and for 90 days in BTX-contaminated soil. The kinetics of BTX degradation either in presence or absence of H(2)O(2), nitrate, and phosphate was analyzed using biochemical and gas chromatographic (GC) technique.
Bacterial consortium was found to be superior in degrading BTX either in soil or in liquid medium as compared to degradation of same compounds by individual strains of the consortium. The rate of BTX biodegradation was further enhanced when the liquid medium/soil was exogenously supplemented with 0.01 % (v/v) H(2)O(2), phosphate, and nitrate(.) The GC analysis of BTX biodegradation (90 days post-inoculation) in soil by bacterial consortium confirmed the preferential degradation of benzene compared to m-xylene and toluene.
It may be concluded that the bacterial consortium in the present study can degrade BTX compounds at a significantly higher rate as compared to the degradation of the same compounds by individual members of the consortium. Further, addition of H(2)O(2) in the culture medium as an additional source of oxygen, and nitrate and phosphate as an alternative electron acceptor and macronutrient, respectively, significantly enhanced the rate of BTX biodegradation under oxygen-limited condition.
石油产品中的主要芳香族成分，如苯、甲苯和二甲苯混合物（BTX），是造成环境污染的元凶，引发了公众的严重关切。因此，我们评估了 BTX 的生物降解潜力，包括单个细菌和组合细菌的生物降解潜力。本研究强调了在缺氧条件下，过氧化氢（H₂O₂）、硝酸盐和磷酸盐在刺激 BTX 化合物生物降解方面的作用。
我们分别使用枯草芽孢杆菌 DM-04 菌株和铜绿假单胞菌 M 和 NM 菌株作为单个细菌，以及包含上述两种细菌的组合细菌，接种到含有 BTX 的液体培养基和土壤中。在含有 BTX 的液体培养物中进行了 120 小时的生物修复实验，在 BTX 污染的土壤中进行了 90 天的生物修复实验。在有氧和无氧条件下，通过生物化学和气相色谱（GC）技术分析了 BTX 降解的动力学。
与单一菌株相比，细菌组合在土壤或液体培养基中降解 BTX 的效果更好。当液体培养基/土壤外源添加 0.01%（v/v）的 H₂O₂、磷酸盐和硝酸盐时，BTX 的生物降解速率进一步提高。GC 分析了细菌组合在土壤中 90 天的 BTX 生物降解情况，结果证实了苯的优先降解，其次是间二甲苯和甲苯。
本研究中的细菌组合可以比单一菌株以更高的速率降解 BTX 化合物。此外，在培养基中添加 H₂O₂作为额外的氧气来源，以及硝酸盐和磷酸盐作为替代电子受体和宏量营养素，在缺氧条件下显著提高了 BTX 的生物降解速率。
