Proteomics unravels metabolic strategies employed by nitrate reducing bacteria during growth on different carbon sources

Methyloversatilis universalis FAM5 is a facultative methylotroph that has been found in denitrifying activated sludge systems using both C1 and muticarbon electron donors. To obtain a global overview of the proteomic and transcriptional responses of FAM5 to different electron donors, the strain was cultured in anoxic chemostats with nitrate as the electron acceptor, methanol and ethanol as the electron donors, respectively. Lower cell growth yield was found under methanol growth, where cells also displayed elevated concentrations of the enzymes involved in C1 transfer, formate oxidation and C1 assimilation. In contrast, primary alcohol oxidation, central metabolism and PHB synthesis related proteins were enerally induced by ethanol. Proteomics result also revealed similar expressions of N reductases under the two growth conditions, therefore explained the metabolic versatility of M. universalis in denitrification systems and its role in meeting effluent nitrogen discharge goals during carbon transition.