Cometabolic degradation of bisphenol A by pure culture of Ralstonia eutropha and metabolic pathway analysis.

Bisphenol A (BPA) is a toxic compound emitting to the environment mainly by polycarbonate production facilities. In this research, BPA with the initial concentrations in the range of 1-40 mg l-1 was degraded by Ralstonia eutropha. The bacteria were unable to use BPA as the sole carbon source. Therefore, resting and growing cells of phenol-adapted R. eutropha were used for cometabolic biodegradation of BPA with phenol at the concentration of 100 mg l-1. The optimum initial concentrations of BPA were 20 mg l-1 in both approaches of cometabolism. By using resting cells, BPA removal efficiency (RE) reached to 57%, however, RE decreased to 37% by growing cells in the presence of phenol. BPA-degrading activity was inhibited at BPA concentrations >20 mg l-1. Liquid chromatography-mass spectrometry technique was used to identify some metabolic intermediates generated during BPA degradation process as 1,2-bis(4-hydroxyphenyl)-2-propanol, 4-(2-propanol)-phenol, 4-hydroxyacetophenone, 4-isopropenylphenol, and 4-hydroxybenzoic acid. Finally, metabolic pathways for BPA degradation were proposed in this study.