Impact of Influent Carbon to Phosphorus Ratio on Performance and Phenotypic Dynamics in Enhanced Biological Phosphorus Removal (EBPR) System - Insights into Carbon Distribution, Intracellular Polymer Stoichiometry and Pathways Shifts

This study investigated the impact of influent carbon to phosphorus (P) ratio on the variation in P-removal performance and associated intracellular polymers dynamics in key functionally relevant microbial populations, namely, PAOs and GAOs, at both individual and populations levels, in laboratory scale sequencing batch reactor-EBPR systems. Significant variations and dynamics were evidenced for the formation, utilization and stoichiometry of intracellular polymers, namely polyphosphate, glycogen and Polyhydroxyalkanoates in PAOs and GAOs in the EBPR systems that were operated with influent C/P ranged from 20 to 50, presumably as results of phylogenetic diversity changes and, or metabolic functions shifts in these two populations at different influent C/P ratios. Single cell Raman micro-spectroscopy enabled quantification of differentiated polymer inclusion levels in PAOs and GAOs and, showed that as the influent rbCOD/P ratio increases, the excessive carbon beyond stoichiometric requirement for PAOs would be diverted into GAOs. Our results also evidenced that when condition becomes more P limiting at higher rbCOD/P ratios, both energy and reducing power generation required for acetate uptake and PHB formation might shift from relying on both polyP hydrolysis and glycolysis pathway, to more enhancement and dependence on glycolysis in addition to partial/reverse TCA cycle. These findings provided new insights into the metabolic elasticity of PAOs and GAOs and their population-level parameters for mechanistic EBPR modeling. This study also demonstrated the potential of application of single cell Raman micro-spectroscopy method as a powerful tool for studying phenotypic dynamics in ecological systems such as EBPR.\n\n\n\nO_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=97 SRC=\"FIGDIR/small/671081v1_ufig1.gif\" ALT=\"Figure 1\">\nView larger version (37K):\norg.highwire.dtl.DTLVardef@13227d5org.highwire.dtl.DTLVardef@1d52d42org.highwire.dtl.DTLVardef@8e67c4org.highwire.dtl.DTLVardef@13eb1aa_HPS_FORMAT_FIGEXP M_FIG C_FIG