【摘要】 从红树林污泥中通过富集培养分离到4株细菌,鉴定结果是多杀巴斯德菌(PasteurellamultocidaSa)、产酸克雷伯菌(KlebsiellaoxytocaSc)、少动鞘氨醇单胞菌(Sphingomonaspauci mobilisSy)和嗜中温甲基杆菌(MethylobacteriummesophilicumSr)。在纯培养降解间苯二甲酸二甲酯(DMI)时发现,单一纯菌株不能完全矿化间苯二甲酸二甲酯,而2种或3种纯菌株组成的混合菌可以将220mg·L-1的底物在12d内完全矿化。主要的中间产物有间苯二甲酸一甲酯(MMI)和间苯二甲酸(IA)。根据鉴定出的中间产物,DMI的生化降解途径为:DMI→MMI→IA→CO2+H2O。研究结果表明,DMI的2个酯基的水解是决定DMI能否完全矿化的重要步骤,但2个酯基的酶催化水解反应有差异,由不同的细菌分步来完成,说明是酯酶对不同底物的专性所致;第2个酯基的水解对整个降解过程有决定性作用。更多还原

【Abstract】 The biodegradation of dimethyl isophthalate （DMI） by pure species of bacteria isolated from mangrove sediment was conducted in batch experiments after enrichment culture. Four morphologically distinct bacteria isolated from mangrove soil by enrichment culture were identified as Pasteurella multocida Sa, Klebsiella oxytoca Sc, Sphingomonas paucimobilis Sy, Methylobacterium mesophilicum Sr respectively, and tested for their ability to degrade DMI. Observations from our study indicated that none of the single microorganism in pure culture showed capability of completely degrading DMI; however, a consortium of two or three pure strains could completely mineralize DMI at a concentration of 220mg·L^-1 within 12 days. DMI was readily transformed by P. multocida Sa, K. oxytoca Sc or S. paucimobilis Sy with formation of mono-methyl isophthalate （MMI）, which was not further mineralized apparently within 30 days and accumulated in the culture medium. M. mesophilicum Sr was able to mineralize MMI with formation of isophthalate （IA）, but unable to metabolize DMI. Among the diverse reconstituted consortia of the four microorganisms, the one consisting of K. oxytoca Sc, S. paucimobilis Sy and M. mesophilicum Sr displayed the highest ability to completely hydrolyze DMI at a high concentration of 220mg·L^-1 within 12 days through formation of MMI and then IA. Based on the chemical structures of intermediates identified, the possible metabolism pathway of DMI was proposed as DMI→MMI→IA →CO₂ + H₂O. The results obtained from this investigation suggested that initial biodegradation of DMI by microorganism occurred as a series of sequential steps, involving the hydrolysis of both esters’ linkage between the carboxyl groups of the isophthalate and the methyl chain to produce MMI and then IA. The transformation of DMI first to MMI and then to IA involved at least two different strains, and the second step was dominant in the complete degradation of DMI. The results also suggested that DMI and its corresponsive intermediates could be mineralized completely by indigenous bacteria from mangrove sediment.更多还原