Biotransformation of Methane and Carbon Dioxide Into High-Value Products by Methanotrophs: Current State of Art and Future Prospects

Abstract

Conventional chemical methods to transform methane and carbon dioxide into useful chemicals are plagued by the requirement for extreme operating conditions and expensive catalysts. Exploitation of microorganisms as biocatalysts is an attractive alternative to sequester these C1 compounds and convert them into value-added chemicals through their inherent metabolic pathways. Microbial biocatalysts are advantageous over chemical processes as they require mild-operating conditions and do not release any toxic by-products. Methanotrophs are potential cell-factories for synthesizing a wide range of high-value products via utilizing methane as the sole source of carbon and energy, and hence, serve as excellent candidate for methane sequestration. Besides, methanotrophs are capable of capturing carbon dioxide and enzymatically hydrogenating it into methanol, and hence qualify to be suitable candidates for carbon dioxide sequestration. However, large-scale production of value-added products from methanotrophs still presents an overwhelming challenge, due to gas-liquid mass transfer limitations, low solubility of gases in liquid medium and low titer of products. This requires design and engineering of efficient reactors for scale-up of the process. The present review offers an overview of the metabolic architecture of methanotrophs and the range of product portfolio they can offer. Special emphasis is given on methanol biosynthesis as a potential biofuel molecule, through utilization of methane and alternate pathway of carbon dioxide sequestration. In view of the gas-liquid mass transfer and low solubility of gases, the key rate-limiting step in gas fermentation, emphasis is given toward reactor design consideration essential to achieve better process performance.

From renewable energy to sustainable protein sources: Advancement, challenges, and future roadmaps

“…However, pure cultures have shown lower affinity to substrate, having higher inhibition levels to potential inhibitors and also to auxotrophy compared to the growth of mixed methanotrophic consortia [56]. For example, if methanol dehydrogenase (MDH) is inhibited, the fermentation of pure cultures can lead to methanol accumulation [57], ceasing MOB growth. On the contrary, mixed cultures can alleviate the challenges triggered by inhibitor accumulation, since a consortium member can take up the inhibitor(s) produced by another co-worker, stabilizing the MP production process.…”

“…Gas transfer to the water phase is the main factor limiting the production of MP given the low solubility of bothmethane and hydrogen [46]. Thus, the design and operation of bioreactors aim at maximizing mass transfer [57,232,233], thereby maximizing bacterial biomass productivity.…”

Choice of Microbial System for In-Situ Resource Utilization on Mars

“…Some also present an explosion hazard. Integrated setups can, however, avoid explosive gas mixtures and achieve significant production rates (Kracke et al, 2020;Sahoo et al, 2021). To completely avoid these problems, methane could be further converted to methanol (Zakaria and Kamarudin, 2016;Latimer et al, 2018)-albeit poor conversion efficiency is a century old unsolved problem.…”

In Vitro One-Pot 3-Hydroxypropanal Production from Cheap C1 and C2 Compounds

“…The production of value-added products from cheap C1 or C2 compounds via chemical processes has been extensively studied [ 3 , 4 ]. However, these chemical processes occur under high temperatures and pressures and release toxic by-products [ 5 ]. Recently, enzymatic processes using biocatalysts have been developed to substitute chemical synthesis [ 6 , 7 , 8 ].…”