Microbial treatment of bis (2-ethylhexyl) phthalate in polyvinyl chloride with isolated bacteria

In this study, we investigated the use of microbes to degrade and remove bis (2-ethylhexyl) phthalate (DEHP), a common plasticizer and a suspected endocrine disruptor, exuding from polyvinyl chloride. Four species of bacteria that utilize DEHP as their sole carbon source were isolated from garden soil, one of which, strain NK0301, was markedly more efficient than the others in degrading DEHP and was chosen for further studies. Strain NK0301 was a coryneform bacterium (1.5x1.0 microm) identified as Mycobacterium sp. from its 16S rDNA sequencing homology. It readily degraded DEHP to two major products determined by gas chromatography/mass spectrometry to be 2-ethylhexanol and 1,2-benzenedicarboxylic acid. Other phthalate esters, suspected of being endocrine disruptors, were also tested and all except two could be utilized by strain NK0301 as their sole source of carbon. When strain NK0301 was cultivated on polyvinyl chloride sheets containing DEHP as the plasticizer, it removed up to 90% of DEHP in 3 d. Following this treatment, the polyvinyl chloride sheets did not exude DEHP to artificial saliva.