Genomic insights into the metabolism of 'Candidatus Defluviicoccus seviourii', a member of Defluviicoccus cluster III abundant in industrial activated sludge

Filamentous cluster III Defluviicoccus (DF3) are known to proliferate and cause bulking issues in industrial wastewater treatment plants. Members of the genus Defluviicoccus are also known to exhibit the glycogen accumulating organism (GAO) phenotype, which is suggested to be detrimental to enhanced biological phosphorus removal (EBPR). Despite the reported negative impact members of the DF3 have on activated sludge wastewater treatment systems, limited research has focused on understanding the physiological traits that allow them to compete in these environments. In this study, a near complete genome of an abundant filamentous DF3 named 'Candidatus Defluviicoccus seviourii' was obtained from a full-scale sequencing batch reactor (SBR) treating winery wastewater. Annotation of the 'Ca. D. seviourii' genome revealed interesting metabolic features that help to understand the abundance of this microorganism in industrial wastewater treatment plants. Their potential for the storage of polyhydroxyalkanoates (PHA) is suggested to favour these organisms with the intermittent availability of carbon in these systems. An ability to fix nitrogen and take up urea may provide them with an additional advantage with the characteristically high carbon to nitrogen content of industrial waste. The genome and preliminary findings of this study provide a foundation for further research into these biotechnologically relevant organisms.