邻苯二甲酸二甲酯及其异构体的好氧微生物降解

Aerobic degradation of dimethyl phthalate ester and its isomers

3种苯二甲酸二甲酯异构体(邻、间和对苯二甲酸二甲酯)主要应用于化学工业,作为增塑剂和生产聚酯的原料。用邻苯二甲酸二丁酯为惟一碳源,从红树林底泥中驯化、富集、培养、分离得到的微生物对邻苯二甲酸二甲酯(Dimethylphthalate,DMP)及其异构体对苯二甲酸二甲酯(Terephthalate,DMT)和间苯二甲酸二甲酯(Isophthalate,DMI)具有较强的降解作用。此菌株16SrDNA分子生物学的鉴定为Rhodococcusruber1k。实验得出该菌能够在苯二甲酸二甲酯作为惟一碳源和能源的培养基中生长。浓度为50mg·L-1的DMP、DMI和DMT分别在6、10、11d内可以完全被降解;DMP能够在好氧条件下被该菌快速降解,生成邻苯二甲酸一甲酯(monomethylphthalate,MMP)和邻苯二甲酸(phthalicacid,PA)2种主要中间产物,最终可以完全矿化成CO2和H2O;该菌对DMI和DMT的降解速度则比DMP慢。两者的降解中间产物间苯二甲酸一甲酯(MMI)和对苯二甲酸一甲酯(MMT)却不能被Rhodococcusruber1k继续降解而在培养基中积累。结果表明苯二甲酸二甲基酯的3种异构体能够被红树林底泥中的土著微生物降解。降解速度及降解途径与底物的化学结构有密切关系。

The microbial degradative characteristics of three phthalate ester isomers （ortho , meta , and para-benzene dicarboxylic esters, DMP,DMI, and DMT respectively for short） by a degrading bacterium isolated from mangrove soil were investigated. The bacterium was identified as Rhodococcus ruber with 16S rDNA sequencing. Experimental results showed that as the sole source of carbon and energy, DMP could be degraded and the degradation intermediates were identified as mono-methyl phthalate （MMP） and phthalic acid （PA）. The tentative pathway proposed for degradation of DMP by the bacterium under aerobic condition was through monoester initially, and further degradation of monoester produced phthalic acid, and finally CO2 and H2O. DMI and DMT at a concentration of 50mg·L^-1 were degraded within 10 days by Rhodococcus ruber, but the intermediates accumulated in the culture medium, the results suggest that the degradation of phthalate ester isomers was related to the structures of chemicals.