Isolation and Characterization of Nonylphenol-degrading Bacteria

To isolate a nonylphenol (NP)-degrading bacterium, we isolated a single colony from the NP-degrading microbial consortium SW-3, which was previously isolated from an aqueous environment. Ten colonies that exhibited different cell morphologies were isolated and the strains were named SW-3-A,-B,-C,-D,-E,-F1,-F2,-G,-H, and-I. The ability of isolates to degrade NP was evaluated by kinetic analysis by the constant of NP degradation rate (k1) and the half-life time of NP degradation (t1/2). SW-3-F1,-F2,-G, and-I strains were superior at degrading NP. The k1 and t1/2 values of the four strains were sixfold higher and one-sixth lower, respectively, than those of the consortium strain. Additionally, SW-3-F1,-G, and-I strains were tested for their ability to degrade NP during coculture. NP degradation by coculture with a combination of all three strains was inferior to that of culture conducted with single isolates, suggesting that the three strains are antagonistic toward each other during NP degradation