Abstract
Methanotrophs have been used to convert methane to methanol at ambient temperature and pressure. In order to accumulate methanol using methanotrophs, methanol dehydrogenase (MDH) must be downregulated as it consumes methanol. Here, we describe a methanol production system wherein MDH expression is controlled by using methanotroph mutants. We used the MxaF knockout mutant of Methylosinus trichosporium OB3b. It could only grow with MDH (XoxF) which has a cerium ion in its active site and is only expressed by bacteria in media containing cerium ions. In the presence of 0 μM copper ion and 25 μM cerium ion, the mutant grew normally. Under conditions conducive to methanol production (10 μM copper ion and 0 μM cerium ion), cell growth was inhibited and methanol accumulated (2.6 μmol·mg−1 dry cell weight·h−1). The conversion efficiency of the accumulated methanol to the total amount of methane added to the reaction system was ~0.3%. The aforementioned conditions were repeatedly alternated by modulating the metal ion composition of the bacterial growth medium.
Highlights
Methane is a principal component of natural and shale gases
Methylosinus trichosporium OB3b wild type and ΔmxaF cultures were grown at 30°C with constant shaking at 130 rpm and under a 1:4 (v/v) methane/air mixture in 30 ml Nitrate mineral salt (NMS) in 200-ml Erlenmeyer flasks fitted with baffles
The mutant presented with nearly the same growth as the wild type under conditions conducive to cell growth and it expressed XoxF in the presence of cerium ion
Summary
Methane is a principal component of natural and shale gases. As its global reserves are vast, it is regarded as a next-generation carbon feedstock. Biogas produced by microbial biomass digestion under anaerobic conditions is composed mainly of methane. Microbial methane fermentation can use carbon dioxide as a carbon source. Methane is expected to be a valuable industrial fuel source as it is renewable and the technologies associated with its collection, production, and consumption are sustainable. Its global warming potential is 25× higher than that of carbon dioxide [U.S Environmental Protection Agency (EPA), 2019]. It is a prime mitigation target in greenhouse gas reduction (Shindell et al, 2012). A major source of atmospheric methane is the anaerobic decomposition of biomass from anthropogenic industrial waste production and agricultural activity (Conrad, 2009). The methane produced by archaea is low concentration and the collectable gas contains
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
