Development of a novel methanotrophic process with the helper micro-organismHyphomicrobiumsp. NM3

AIMS Microbial consortia can be more efficient at biological processes than single isolates. The purposes of this study were to design and evaluate a synthetic microbial consortium containing the methanotroph Methylocystis sp. M6 and the helper Hyphomicrobium sp. NM3, and develop a novel methanotrophic process for this consortium utilizing a dialysis membrane. METHODS AND RESULTS Hyphomicrobium increased the methane-oxidation rate (MOR), biomass and stability at a dilution rate of 0·067 day-1 in fed-batch co-culture. qRT-PCR showed that Methylocystis population increased gradually with time, whereas Hyphomicrobium population remained stable despite cell washing, confirming synergistic population interaction. At 0·1 day-1 , spiking of Hyphomicrobium effectively increased the methanotrophic activity, after which Hyphomicrobium population decreased with time, indicating that the consortium is optimal at