Highly efficient bioconversion of methane to methanol using a novel type I Methylomonas sp. DH‐1 newly isolated from brewery waste sludge

Background Methane is the major component of natural and shale gas. Methane can be converted into methanol via a bioprocess using methanotrophs, and methanol is a valuable chemical feedstock for the production of value‐added chemicals. This work demonstrates highly effective bioconversion of methane to methanol using a newly isolated novel methanotroph, Methylomonas sp. DH‐1. Results A novel methanotroph strain was isolated from activated sludge from a brewery plant and characterized using phylogenetic analysis, electron microscopy and chemotaxonomic analysis. This aerobic, Gram‐negative, non‐motile rod‐shaped type I methanotroph was designated as Methylomonas sp. DH‐1. The growth condition of Methylomonas sp. DH‐1 and batch methane‐to‐methanol bioconversion conditions such as methane concentration, pH, biocatalyst loading, concentration of formate and MDH inhibitor were analyzed and optimized. Methanol was produced from methane with a 1.340 g L−1 titer, a 0.332 g L−1 h−1 volumetric conversion rate and a 0.0752 g g−1 cell h−1 specific methanol conversion rate. Conclusion It was demonstrated that isolation and application of a new methanotroph strain is a practical way of improving bioconversion efficiency in the conversion of methane to methanol. Moreover, one promising feature of Methylomonas sp. DH‐1 for methanol production was its extremely high tolerance to methanol up to 7%(v/v), which is advantageous for high‐titer methanol production. © 2016 Society of Chemical Industry