METABOLIC PROCESSES AND GENOME-SCALE METABOLIC MODELLING OF METHANOCCOCUS MARIPALUDIS S2

Abstract

Methanococcus maripaludis S2 is a fast-growing, hydrogenotrophic, mesophilic methanogen with the potential applications in biological fixation of CO2. This thesis focuses on its metabolic activities, encompassing three areas: growth behaviours under diazotrophy, aqueous metabolites, and characterization of the associated enzyme. Our study showed that growth under diazotrophy resulted in a prolonged growth phase, higher CO2 utilization and methane production. Acetate was determined to be one of the metabolites produced by the methanococci. The compound was produced in the early growth phase, and then assimilated in the late growth phase. This behaviour is called an acetate switch, a phenomenon which has only been reported for heterotrophs prior to this study. The enzyme involved in acetate production was produced via the ligation-independent cloning technique and its kinetics were characterized. Based on the experimental results above and existing literature, a genome-scale metabolic model iMR557 was developed.