Isolation and characterization of novel bisphenol-A--degrading bacteria from soils

Abstract

One hundred and seven soil samples were collected from various places in Japan, and their bisphenol-A (BPA, 2,2-bis(4-Hydroxyphenyl) propane) degradative capacities were evaluated. Eighty-five soil samples possessed BPA degradative capacities, and 26 bacterial strains could be isolated as BPA-degrading bacterium. Sequence analysis of their 16S rRNA genes indicated that 22 isolates belonged to proteobacteria groups, and three of four Gram-positive bacterial strains, YA27, NO13, and NO15, were classified as Bacilli. All isolates except strain YA27 completely degraded 115 microg/mL BPA in L medium but strain YA27 degraded only 50 microg/mL BPA. Strain YA27 and three Sphingomonas sp. strains could also grow in basal salt media containing BPA as a sole carbon source (BSMB medium). In HPLC analyses, some isolates, including the three Sphingomonas strains, produced some BPA metabolites in their cultures although the others, including strain YA27, produced no detectable metabolite. Furthermore, the Pseudomonas strains SU1 and SU4 produced some BPA metabolites that were different from the metabolites detected in the degradation of BPA by the S. bisphenolicum strain AO1. These results suggested that all isolates could be applicable to the bioremediation of BPA-polluted soil and water. Furthermore, we suggest that Bacillus sp. YA27 and Pseudomonas SU1 and SU4 may exhibit novel BPA metabolism pathways that are distinct from that of S. bisphenolicum AO1.