Abstract
The existence of marine polyphosphate-accumulating organisms (PAOs) living under high salinity environments is little known. We attempted to make an enrichment culture of the uncultured marine PAOs by using a closed down-flow hanging sponge (DHS) reactor. The DHS reactor inoculated with some tidal flat sediment was fed with a synthetic seawater containing phosphate. After 130 days of the operation, a stable phosphorus release and uptake were observed in the anaerobic and aerobic phases, respectively, indicating that the enrichment of marine PAOs was successfully made. Microbial community analysis by 16S rRNA gene targeted cloning revealed that under the acetate and propionate feeding condition, Accumulibacter, which is the major PAO in wastewater treatment plants, was dominant in the DHS reactor. When the anaerobic substrate was changed to only acetate, the percentage of Accumulibacter decreased, and an unknown filamentous PAO dominated. These results suggest a possibility of the enhanced biological phosphorus removal even under high salinity conditions.
