Biodegradation of bisphenol A in the aquatic environment

Biodegradation potential of bisphenol A (BPA) in the aquatic environments was investigated using 3 activated sludge and 44 river water microcosms. The biodegradation potential was exhibited by most of the tested microcosms; 3 activated sludge and 40 river water microcosms. However, only 8 river water microcosms could completely mineralize BPA, and the others showed accumulation of common metabolites which were detected as 2 peaks according to a high-pressure liquid chromatograph. In total 19 BPA-degrading bacteria were isolated from activated sludge and river water samples, and their BPA degradation property was also investigated. Although all the BPA-degrading bacteria could grow on BPA and remove about 70-80% of TOC derived from BPA, they accumulated 2 common metabolites, and they could not be removed by the prolonged cultivation up to more than 1 month. These 2 metabolites were identified as 2,3-bis(4-hydroxyphenyl)-1,1-propanediol and p-hydroxyphenacyl alcohol in the culture of a typical BPA-degrading bacterium. The experimental results suggested that BPA-degrading bacteria ubiquitously exist in the aquatic environments, but that they cannot completely degrade BPA, leading to the accumulation of more recalcitrant metabolites. For complete BPA degradation, the presence of microbes which can degrade the metabolites seems necessary together with SPA-degrading bacteria.