Sustainable biosynthesis of chemicals from methane and glycerol via reconstruction of multi‐carbon utilizing pathway in obligate methanotrophic bacteria

Abstract

Obligate methanotrophic bacteria can utilize methane, an inexpensive carbon feedstock, as a sole energy and carbon substrate, thus are considered as the only nature-provided biocatalyst for sustainable biomanufacturing of fuels and chemicals from methane. To address the limitation of native C1 metabolism of obligate type I methanotrophs, we proposed a novel platform strain that can utilize methane and multi-carbon substrates, such as glycerol, simultaneously to boost growth rates and chemical production in Methylotuvimicrobium alcaliphilum 20Z. To demonstrate the uses of this concept, we reconstructed a 2,3-butanediol biosynthetic pathway and achieved a fourfold higher titer of 2,3butanediol production by co-utilizing methane and glycerol compared with that of methanotrophic growth. In addition, we reported the creation of a methanotrophic biocatalyst for one-step bioconversion of methane to methanol in which glycerol was used for cell growth, and methane was mainly used for methanol production. After the deletion of genes encoding methanol dehydrogenase (MDH), 11.6 mM methanol was obtained after 72 h using living cells in the absence of any chemical inhibitors of MDH and exogenous NADH source. A further improvement of this bioconversion was attained by using resting cells with a significantly increased titre of 76 mM methanol after 3.5 h with the supply of 40 mM formate. The work presented here provides a novel framework for a variety of approaches in methanebased biomanufacturing.

Biotechnological Valorization of Waste Glycerol into Gaseous Biofuels—A Review

“…Another added benefit is the large variety of glycerol-metabolizing microorganisms that have been identified [10]. Glycerol generates more reducing equivalents than other carbon sources (e.g., glucose or xylose), thus making it possible to produce biofuels and reduced chemicals at higher efficiency [11]. The abundance, relatively low price, and high reduction capacity of glycerol have made it an attractive feedstock to exploit for the production of various biofuels [12].…”