Biodegradation of bisphenol A by cells and cell lysate from Sphingomonas sp strain AO1

The capacity and pathway of bisphenol A [BPA; 2,2- bis(4-hydroxyphenyl) propane] degradation in Sphingomonas sp. strain AO1, which was isolated from the soil of a vegetable-growing field in Japan, were investigated. The bacterial strain was able to grow in a basal mineral salt medium containing BPA as the sole carbon source ( BSMB medium), and was able to degrade 115 mug ml(-1) BPA in 6 h in L medium. Several BPA metabolites were detected in the culture supernatant by HPLC and then identified by GC-MS and LC-MS-MS. These compounds were confirmed to be the same as those reported for other BPA-degrading bacteria. BPA degradation by cells in the basal mineral salt medium was induced by BPA, and activity was detected only in the intracellular soluble fraction in the presence of coenzymes, such as NADH, NAD+, NADPH or NADP+. The addition of metyrapone, a cytochrome P450 inhibitor, to BSMB medium resulted in a decrease in BPA degradation and cell growth. The BPA-degradation activity of the intracellular soluble fraction was also inhibited by the cytochrome P450 inhibitor. Carbon monoxide difference spectra indicated that cytochrome P450 was present in the cells and that the amount of cytochrome P450 corresponded to the cellular BPA-degradation activity. Our results provide evidence that the cytochrome P450 system is involved in BPA metabolism in Sphingomonas sp. strain AO1.