Aerobic degradation of dimethyl phthalate ester and its isomers

Abstract

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 CO_ 2 and H_ 2O. 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.