Biodegradation of phthalate esters by newly isolated Rhizobium sp. LMB-1 and its biochemical pathway of di-n-butyl phthalate.

AIMS

To isolate a novel strain that could degrade many kinds PAEs efficiently and investigate the DBP-degrading pathway in this strain.

METHODS AND RESULTS

Based on its 16S rRNA gene sequence, the strain was identified as Rhizobium sp. This strain, named LMB-1, can also utilize phthalates, such as DEHP, DMP, DBP and DEP. During the degradation of DBP, six possible metabolites, diethyl phthalate, mono-ethyl phthalate, di-methyl phthalate, mono-methyl phthalate, phthalic acid and tartaric acid, were identified by gas chromatography-mass spectrometry (GC-MS) analysis, and the degradation pathway of DBP was also identified in this study.

CONCLUSIONS

In summary, strain LMB-1, identified as Rhizobium sp., was found to be capable of efficiently degrading PAEs, and it was determined that the strain degraded DMP completely within 45 h. DEP, DMP, MEP, MMP, PA and tartaric acid were detected during the course of DBP degradation by LMB-1. We propose that this strain could completely degrade DBP or other PAEs. Our results offer a novel and potential candidate, Rhizobium sp. LMB-1, for use in the bioremediation of cultivated soil contaminated by PAEs.

SIGNIFICANCE AND IMPACT OF THE STUDY

This is the first report concerning the complete degradation of phthalate esters by Rhizobium sp.