Li Tinggang, Liu Junxin, Bai Renbi, Ohandja Dieudonne-Guy, Wong Fook-Sin
Institute of Environmental Science and Engineering, Nanyang Technological University, Singapore 637723, Singapore.
Water Res. 2007 Aug;41(15):3465-73. doi: 10.1016/j.watres.2007.04.033. Epub 2007 May 8.
A microbial process for the degradation of three types of structurally distinct organonitriles (i.e., saturated and unsaturated aliphatic nitrile and aromatic nitrile) was studied. Microorganisms were enriched from the activated sludge of a pharmaceutical wastewater treatment plant and adapted through providing acetonitrile as the sole carbon and nitrogen source for their growth. The adapted mixed culture was then examined for their capability of degrading acetonitrile, acrylonitrile and benzonitrile under various operational conditions. The performance of biodegradation and the metabolic intermediate- and end-products in the process were monitored. The results show that an average removal rate of 0.083 g acetonitrile g(-1)-VSS h(-1), 0.0074 g acrylonitrile g(-1)-VSS h(-1) or 0.0029 g benzonitrile g(-1)-VSS h(-1) was achieved in the batch bioreactor under the common operational condition of 25 degrees C and pH 7. The biodegradation of acetonitrile and acrylonitrile showed a two-step pathway, with the generation of acetamide followed by acetic acid and ammonia for acetonitrile or acrylamide followed by acrylic acid and ammonia for acrylonitrile. However, the biodegradation of benzonitrile appeared to have only one step, with the direct production of benzoic acid and ammonia, but without benzamide being detected in the process. The results suggest that, depending on the substrates, the adapted mixed culture can develop very different degradation pathways, such as nitrile hydratase plus amidase for acetonitrile or acrylonitrile and nitrilase for benzonitrile. Therefore, the adapted mixed culture has a great potential and flexibility for actual applications in biodegradation of various organonitrile compounds.
研究了一种微生物降解三种结构不同的有机腈（即饱和脂肪腈、不饱和脂肪腈和芳香腈）的过程。从制药废水处理厂的活性污泥中富集微生物，并通过提供乙腈作为其生长的唯一碳源和氮源进行驯化。然后考察驯化后的混合培养物在各种操作条件下降解乙腈、丙烯腈和苯甲腈的能力。监测该过程中生物降解的性能以及代谢中间产物和终产物。结果表明，在25℃和pH 7的常见操作条件下，间歇式生物反应器中乙腈、丙烯腈和苯甲腈的平均去除速率分别为0.083 g乙腈·g(-1)-VSS·h(-1)、0.0074 g丙烯腈·g(-1)-VSS·h(-1)或0.0029 g苯甲腈·g(-1)-VSS·h(-1)。乙腈和丙烯腈的生物降解呈现两步途径，乙腈生成乙酰胺，随后生成乙酸和氨；丙烯腈生成丙烯酰胺，随后生成丙烯酸和氨。然而，苯甲腈的生物降解似乎只有一步，直接生成苯甲酸和氨，过程中未检测到苯甲酰胺。结果表明，根据底物不同，驯化后的混合培养物可产生非常不同的降解途径，如乙腈或丙烯腈通过腈水合酶加酰胺酶降解，苯甲腈通过腈水解酶降解。因此，驯化后的混合培养物在实际应用中对各种有机腈化合物进行生物降解具有很大的潜力和灵活性。
