Comparative analysis of biological phosphate removal (BPR) and non-BPR activated sludge bacterial communities with particular reference to Acinetobacter

The bacterial community of a biological phosphate removal (BPR) activated s ludge process was studied and compared to that of a non-BPR process treatin g the same municipal waste water. Bacterial isolates from the BPR process, as characterized by whole cell fatty acids, belonged to more than twenty ge nera, with Micrococcus, Staphylococcus and Acidovorax scoring highest. Acin etobacter spp represented 4% of cultured bacteria, less than or equal to 3% as estimated by fluorescence in situ hybridization, and well under 10% on the basis of the proportion of ubiquinone Q9 in the sludge, The mole propor tions of ubiquinones, Q8 : Q10: Q9 in the sludge were maintained fairly sta ble at approximately 9:4:1, The spectra of the isolated strains and the pro portions of ubiquinones in the processes (BPR vs non-BPR) were otherwise si milar, but a significant number of isolates related to actinomycetes were o btained from the BPR sludge only. The BPR process did not enrich Acinetobac ter, Pure cultures of Acinetobacter isolated from the sludge stained for po lyphosphate, but Acinetobacter cells responding to the ACA probe in native sludge from the BPR process did not. Instead, the bulk of the polyphosphate in the BPR sludge was located in a distinct morphotype of large, coccoid, highly clustered cells.