Localization and Identification of Populations of Phosphatase-Active Bacterial Cells Associated with Activated Sludge Flocs.

Abstract The majority of phosphatase (PO(4)ase) activity detected in fresh aerobic activated sludge from a municipal wastewater treatment plant was associated with suspended floc material. PO(4)ase activity appeared to be localized in discrete bacteria-containing areas of the floc matrix based on the distribution of nucleic acid-stained cells and precipitated fluorescent crystals produced as a result of reaction of the enzyme(s) with the artificial substrate ELFtrade mark-PO(4). Of the total floc-associated bacterial cells that stained positive with the nucleic acid-binding fluorochrome acridine orange (AO), 8.8 +/- 1.2% displayed PO(4)ase activity based on the proximity of AO-stained cells to precipitated ELF crystals. Using a 16S rRNA oligonucleotide probe specific for the cytophaga-flavobacteria group, it was determined that 17-20% of the floc-associated bacteria that probed positive also displayed PO(4)ase activity. Furthermore, 35-45% of the ELF fluorescence was associated with bacterial cells that probed positive for the cytophaga-flavobacteria group. The results suggest that the cytophaga-flavobacteria, as a group, is important in mediating the liberation of inorganic orthophosphate (P(i)) from phosphomonoesters of detrital organic phosphate (organic-P) in the aerobic activated sludge process of wastewater treatment.http://link.springer-ny.com/link/service/journals/00248/bibs/38n3p201.html</hea