Glycine-mediated microbial interactions in biological phosphorus removal systems

Amino acids are less studied substrates in enhanced biological phosphorus removal (EBPR) systems. Glycine, a prevalent amino acid in wastewater, was used in this study to evaluate its role in EBPR processes. We operated a sequencing batch reactor (SBR) for over three months with glycine as the sole carbon source to investigate phosphorus removal performance and microbial dynamics using chemical and molecular analyses. The reactor supported EBPR activity, with glycine enabling anaerobic phosphorus release followed by aerobic uptake. The dissolved organic carbon to phosphorus (DOC:P) removal ratio of 100:9.9 closely matched values reported for systems dominated by polyphosphate-accumulating organisms (PAOs), and net phosphorus removal (20 mg PO₄-P L^-1) fell within the range reported for laboratory-scale EBPR systems fed with mixed carbon sources. Community analyses showed enrichment of Saccharimonadales alongside putative PAOs, including Ca. Phosphoribacter and Ca. Propionivibrio. Genome-resolved analyses indicate distinct but complementary metabolic potentials, including glycine transformation and lactate-related pathways, suggesting distributed carbon processing within the community. Together, these findings expand the understanding of amino acid utilization in EBPR systems and identify potential metabolic linkages that influence phosphorus removal under glycine-fed conditions.