Defluviicoccus vanus Glycogen-Accumulating Organisms (DvGAOs) Are Less Competitive Than Polyphosphate-Accumulating Organisms (PAOs) at High Temperature

Glycogen-accumulating organisms (GAOs) have been previously observed to be more competitive in anaerobic volatile fatty acid (VFA) uptake as compared to polyphosphate-accumulating organisms (PAOs) at high temperatures in enhanced biological phosphorus removal (EBPR) systems. However, previous evidence regarding the impact of temperature on GAOs has exclusively focused on Competibacter. Defluviicoccus vanus GAOs (DvGAOs) make up another very important GAO group and have been found in EBPR plants; however, their competitiveness at high temperature for anaerobic VFA uptake was previously unknown. The rate of uptake of VFAs by both DvGAOs reactors enriched with acetate or propionate was much lower than those of Candidatus Accumulibacter phosphatis PAOs operated under similar conditions, showing that PAOs displayed a competitive advantage at high temperature, unlike previous observations with Competibacter. This study provides new insight into our understanding of GAOs in EBPR processes, where the impact of temperature on PAO-GAO competition is highly dependent on the phylogenetic identity of the GAO present in the system. New strategies for promoting EBPR performance at high temperatures are proposed on the basis of the results of this work.