Multilevel Correlations in the Metabolism of Polyphosphate-Accumulating Organisms

EnhancedEnergy biologicalSystem phosphorus removalEnhanced biological phosphorus removal (EBPREBPR) reliesMetabolism onInorganic polyphosphate activePolymer polyphosphatePolyphosphate-accumulatingCorrelation organismsPhosphoanhydride bond (PAOsPAO). PAOsPAO competeEnrichment for organicOrganics resourcesResource withPolyphosphate glycogenGlycogen-accumulatingConductivity (GAOsGAO) andPolyphosphatase otherMetabolic batch test chemoorganoheterotrophs. PAOsPAO and their metabolismMetabolism werePolyphosphate-accumulating organisms examined across bioreactorBioreactor, microbiomeMicrobiome, genetic, enzymatic, and metabolic scales. Two anaerobicAnaerobic-aerobicAerobic enrichmentsEnrichment of PAOsPAO and GAOsGAO were obtained in sequencing batch reactorsSequencing batch reactor (SBRsSBR). This required the optimizationOptimization of cultureCulture mediaMedium and start-upStart-up conditions by gradually adapting the organicOrganics loadLoad rateRate and anaerobic contact timeAnaerobic contact time. The betaproteobacterial PAOPAO genus “Ca. AccumulibacterAccumulibacter” dominated the PAOPAO-SBRSBR (up to 61%). Gammaproteobacterial “Ca. CompetibacterCompetibacter” (> 35%) and alphaproteobacterial Rhodospirillaceae (> 30%) were the main GAOsGAO in the GAOGAO-SBRSBR. Electrical conductivityElectrical conductivity was used to track the level of enrichmentEnrichment of PAOsPAO in sludgeSludge. PAOsPAO gain energyEnergy by hydrolyzing their intracellular polyphosphatePolyphosphate to take up organicsOrganics under anaerobicAnaerobic conditions. The orthophosphate release is traceable with conductivityConductivity. The biomassBiomass-specific maximum rateRate of conductivityConductivity evolution measured and modelled with PHREEQCPHREEQC in anaerobicAnaerobic metabolic batch testsMetabolic batch test and the polyphosphatasePolyphosphatase activityActivity of cell extracts correlated positively with the fractionFraction of PAOsPAO in defined mixturesMixture of PAOsPAO and GAOsGAO. While the diversityDiversity of genesGene encoding for exopolyphosphatasesExopolyphosphatase (PPX) was attempted using degenerate primers, ppx genesGene were not detected. Since identical enzymatic responses were obtained with samples collected in anaerobicAnaerobic and aerobicAerobic phasesPhase, polyphosphate kinasesPolyphosphate kinase (PPK) can be involved in polyphosphatePolyphosphate utilization. Collectively, online electrical-conductivityConductivity-based metabolic batch testsMetabolic batch test and enzymatic assaysEnzymatic assay are efficient to rapidly measure the relative abundanceRelative abundance of PAOsPAO and the dephosphatationDephosphatation potentialPotential of biomassesBiomass at process lineProcess line.