Metabolisms of Microlunatus phosphovorus NM-1 Using Glucose, Glutamate, and Aspartate as Carbon Sources for Enhanced Biological Phosphorus Removal

Abstract

Here, we present the first systematic and comprehensive analysis of the biochemical and transcriptomic characteristics of Microlunatus phosphovorus NM-1 with glucose and amino acids as carbon sources for enhanced biological phosphorus removal (EBPR). Glucose-induced the highest P release rate, followed by aspartate and glutamate. Its anaerobic P release and glucose uptake and aerobic P uptake kinetics exceeded those of Tetrasphaera and Candidatus Accumulibacter (with acetate). Anaerobic glucose uptake and activation were achieved via the phosphoenolpyruvate-dependent phosphotransferase system and bifunctional glucokinases, contributing to its exceptionally high glucose uptake rates. Aspartate and glutamate uptake was driven by proton motive force. Glucose and those amino acids were mainly stored as glycogen. Novel pathways (beta-oxidation and fatty acid biosynthesis) were encoded by NM-1 for polyhydroxyalkanoate generation. Transcriptomic analysis revealed significantly transcribed genes in the glyoxylate cycle in anaerobic glucose metabolism. Glutamate and aspartate were deaminized and routed into the TCA cycle for glycogen and polyhydroxyvalerate generation. Two low-affinity phosphate transporter genes were distinctly transcribed in the anaerobic and aerobic phases, benefiting enhanced P release and uptake. Collectively, this study provides a comprehensive understanding of the glucose and amino acid metabolism of NM-1, benefiting an improved description and modeling of the M. phosphovorus-mediated EBPR process.