Identification and classification of the Tetrasphaera genus in enhanced biological phosphorus removal process: a review

Abstract

Tetrasphaera are an attractive putative group of polyphosphate accumulating organisms (PAOs) that may play an important role in the enhanced biological phosphorus removal (EBPR) process. Unlike conventional PAOs that mostly rely on volatile fatty acids (VFAs), Tetrasphaera can assimilate a wide range of carbon substrates including glucose and various amino acids (e.g., glycine, glutamate, and aspartate). In addition, they have the ability to produce VFAs. This functional versatility confers significant performance and economic benefits for its application in EBPR processes. However, before the wastewater industry can harness these benefits, fundamental knowledge of their taxonomy, classification and identification in EBPR and activated sludge systems must be understood. This review provides a summary of the polyphasic approach: use of phenotypic, genotypic, and chemotaxonomic methods for bacterial classification and its application in the classification of Tetrasphaera. A review of molecular tools currently used to identify Tetrasphaera in activated sludge systems is also provided. In addition, this review discusses how challenges with molecular tools limit our understanding and application of Tetrasphaera in EBPR processes.