Electricity from methane by Methylococcus capsulatus (Bath) and Methylosinus trichosporium OB3b

[Display omitted] •Electricity generation from methane was demonstrated by model methanotrophs.•A method of coating rGO/Ni electrodes with methanotrophs was developed.•OB3b biofilms on rGO/Ni electrodes gave13-fold higher power.•Bath biofilms on rGO/Ni electrode promoted methane oxidation.•Cytochrome-based redox reactions were revealed in methane oxidation pathways. Given the difficulties valorizing methane (CH4) via catalytic routes, this study explores use of CH4-oxidizing bacteria (“methanotrophs”) for generating electricity directly from CH4. A preconditioned methanotrophic biofilm on 3D nickel foam with reduced graphene oxide (rGO/Ni) was used as the anode in two-compartment microbial fuel cells (MFCs). This study demonstrates a proof of concept for turning CH4 into electricity by two model methanotrophs including Methylosinus trichosposium OB3b and Methylococcus capsulatus (Bath). Both OB3b (205 mW.m−2) and Bath (110 mW.m−2) strains yielded a higher electricity from CH4 when grown on rGO/Ni compared to graphite felt electrodes. Based on electrochemistry tests, molecular dynamics simulations, genome annotations and interaction analysis, a mechanistic understanding of reasons behind enhanced performance of methanotrophs grown on rGO/Ni are presented.