Hydrogenotrophic Methanogenesis and Autotrophic Growth ofMethanosarcina thermophila

Abstract

Although Methanosarcinales are versatile concerning their methanogenic substrates, the ability ofMethanosarcina thermophilato use carbon dioxide (CO2) for catabolic and anabolic metabolism was not proven until now. Here, we show thatM. thermophilaused CO2to perform hydrogenotrophic methanogenesis in the presence as well as in the absence of methanol. During incubation with hydrogen, the methanogen utilized the substrates methanol and CO2consecutively, resulting in a biphasic methane production. Growth exclusively from CO2occurred slowly but reproducibly with concomitant production of biomass, verified by DNA quantification. Besides verification through multiple transfers into fresh medium, the identity of the culture was confirmed by 16s RNA sequencing, and the incorporation of carbon atoms from13CO2into13CH4molecules was measured to validate the obtained data. New insights into the physiology ofM. thermophilacan serve as reference for genomic analyses to link genes with metabolic features in uncultured organisms.