Phosphotriesterase activity in marine bacteria of the genera Phaeobacter, Ruegeria, and Thalassospira

Abstract

Phosphate triester compounds are synthetic organophosphoric acids commonly used as plasticizers and pesticides. Despite their introduction in oceans through river water, the concentrations of phosphate triester compounds in coastal water are low, suggesting that they are naturally degraded by microorganisms. We here provide the first characterization of marine bacteria with enzymatic activities responsible for the degradation of a phosphate triester under coastal oceanic conditions. Bacterial strains belonging to Phaeobacter sp., Ruegeria mobilis, and Thalassospira profundimaris/tepidiphila showed the requisite phosphotriesterase activity for degradation of a phosphate triester (paraoxon-methyl). Further, Ruegeria sp. URN111 and Thalassospira sp. URN109 showed phosphodiesterase and phosphomonoesterase activities. These enzymatic activities of the marine bacteria appear to be lead to the release of phosphate from phosphate triesters. Considering the worldwide distribution of Ruegeria and Thalassospira, our findings suggest that the enzymatic/microbial degradation of phosphate triesters possibly occurs in coastal environments and may provide new material for the bioremediation of phosphate triesters.