Isolation of HAA degrading bacteria from drinking water using complex media

This study used alternative microbial cultivation methods other than enrichment cultures to explore haloacetic acid (HAA) degrading bacteria from both biofilm and free-floating bacteria in drinking water. Instead of enrichment culture with high HAA concentration, biofilm from the rapid sand surface and suspended cells in finished water were directly plated on three different media (Reasoner's 2A, nutrient agar, and Lysogeny broth agar). After bacterial purification, HAA biodegradability and degradation kinetics were investigated from each of the isolates. Thirty-four strains of bacteria were retrieved and 13 of them were successfully identified as HAA degraders. Porphyrobacter sp., Sinorhizobium sp., and Aquabacterium sp. showed higher monochloroacetic acid (MCAA) degrading rates (2.46-2.91 µg mg^-1 protein h^-1) among other isolated strains. In addition, Porphyrobacter sp. and Aquabacterium sp. also expressed higher dichloroacetic acid (DCAA) degrading rates (1.44 and 1.0 µg mg^-1 protein h^-1). For isolates with both MCAA and DCAA biodegradability, HAA degradation by bacterial isolates occurs in succession rather than in simultaneity. These results could provide a better understanding on HAA degrading bacteria in drinking water systems.