The phylogeny, ecology and ecophysiology of the glycogen accumulating organism (GAO) Defluviicoccus in wastewater treatment plants

• Published in: Water research (Oxford) 2022-08, Vol.221, p.118729-118729, Article 118729
• Main Authors: Maszenan, Abdul M., Bessarab, Irina, Williams, Rohan B.H., Petrovski, Steve, Seviour, Robert J.
• Format: Article
• Language: English
• Subjects: Activated Sludge; Ca. accumulibacter; Ca. competibacter; Defluviicoccus; Enhanced biological phosphorus removal; Glycogen accumulating organisms; Phosphate accumulating organisms
• ISSN: 0043-1354; 1879-2448
• DOI: 10.1016/j.watres.2022.118729

•This comprehensive review examines critically.•what is known about the ecophysiology of the glycogen accumulating organism Defluviicoccus.•which factors affect its relative abundance in EBPR wastewater treatment plants.•its interactions with other functionally important members of plant communities.•problems arising from incomplete phylogenetic identification of its populations.•which areas of research are needed to address current gaps in our knowledge. This comprehensive review looks critically what is known about members of the genus Defluviicoccus, an example of a glycogen accumulating organism (GAO), in wastewater treatment plants, but found also in other habitats. It considers the operating conditions thought to affect its performance in activated sludge plants designed to remove phosphorus microbiologically, including the still controversial view that it competes with the polyphosphate accumulating bacterium Ca. Accumulibacter for readily biodegradable substrates in the anaerobic zone receiving the influent raw sewage. It looks at its present phylogeny and what is known about it's physiology and biochemistry under the highly selective conditions of these plants, where the biomass is recycled continuously through alternative anaerobic (feed); aerobic (famine) conditions encountered there. The impact of whole genome sequence data, which have revealed considerable intra- and interclade genotypic diversity, on our understanding of its in situ behaviour is also addressed. Particular attention is paid to the problems in much of the literature data based on clone library and next generation DNA sequencing data, where Defluviicoccus identification is restricted to genus level only. Equally problematic, in many publications no attempt has been made to distinguish between Defluviicoccus and the other known GAO, especially Ca. Competibacter, which, as shown here, has a very different ecophysiology. The impact this has had and continues to have on our understanding of members of this genus is discussed, as is the present controversy over its taxonomy. It also suggests where research should be directed to answer some of the important research questions raised in this review. [Display omitted]