Biodiversity of Polyphosphate Accumulating Bacteria in Eight WWTPs with Different Modes of Operation

AbstractEnhanced biological phosphorous removal (EBPR) from wastewater has been successfully used for more than three decades and is considered to be an environmentally friendly wastewater-treatment process. Biologically, this process is realized by incorporation of phosphate as polyphosphate (polyP) granules in activated sludge bacteria. Important groups of bacteria responsible for P removal have been identified, but the full microbial diversity involved in this process is still unknown. This paper reports on the microbial composition of activated sludge communities in eight wastewater-treatment plants (WWTPs) with different sizes and modes of operation. The polyphosphate accumulating organisms (PAOs) within this complex biocenosis were identified by fluorescent dye staining and classified by in situ hybridization techniques. Of the bacteria in the aerobic basin, 5–13% contained polyP granules. In addition, flow cytometry was used to quantify PAOs after tetracycline staining and to separate these cells. ...