Kinetics of type I methanotrophs mixed culture enriched from waste activated sludge

Methanotrophs are unique microorganisms that can upgrade the methane produced within wastewater treatment plants into diverse prominent commodities. The determination of the methanotrophic enrichments growth kinetics is a pivotal milestone to develop any methane based biotechnology. In this study, diversified batch incubations were performed to experimentally obtain, for the first time, the microbial growth kinetics for type I methanotrophs enriched from waste activated sludge. The key genus in the enriched culture includes Methylococcus, Methylobacter, Methaylocaldum, Methylomicrobium, Methylomonas, Methylosarcina, Methylosphaera. The attained maximum specific growth rate (μmax) (0.358 h−1) and maximum specific methane biodegradation rate (qmax) (g-CH4,Total g-DCW−1 h−1) were the highest reported in mixed cultures. Furthermore, the low substrate threshold concentration (Smin) (0.033 mg-CH4,aq./hr) observed shows that the microbial activity can be maintained at a very low methane aqueous concentrations. The obtained kinetic parameters confirm the prominence of utilizing type I methanotrophs mixed cultures in resources recovery processes from waste streams.