Synthetic Methylotrophy: A Practical Solution for Methanol-Based Biomanufacturing

Synthetic methylotrophy, which integrates natural or artificial methanol assimilation pathways in platform microorganisms, can be exploited to produce fuels and chemicals using methanol as a feedstock. Enzyme engineering strategies, including enzyme mining, directed evaluation, and construction of multifunctional enzyme complexes, are being applied to overcome the rate-limiting steps of methanol bioconversion. Metabolic engineering approaches guided by systems and synthetic biology, including in silico pathway design and construction of synthetic methanol-dependent strains, are being used to enhance methanol utilization. Recent advances in bioproduction using synthetic methylotrophs are expanding the portfolio of products that can be produced from methanol. The increasing availability and affordability of natural gas has renewed interest in using methanol for bioproduction of useful chemicals. Engineering synthetic methylotrophy based on natural or artificial methanol assimilation pathways and genetically tractable platform microorganisms for methanol-based biomanufacturing is drawing particular attention. Recently, intensive efforts have been devoted to demonstrating the feasibility and improving the efficiency of synthetic methylotrophy. Various fuel, bulk, and fine chemicals have been synthesized using methanol as a feedstock. However, fully synthetic methylotrophs utilizing methanol as the sole carbon source and commercially viable bioproduction from methanol remain to be developed. Here, we review ongoing efforts to identify limiting factors, optimize synthetic methylotrophs, and implement methanol-based biomanufacturing. Future challenges and prospects are also discussed. The increasing availability and affordability of natural gas has renewed interest in using methanol for bioproduction of useful chemicals. Engineering synthetic methylotrophy based on natural or artificial methanol assimilation pathways and genetically tractable platform microorganisms for methanol-based biomanufacturing is drawing particular attention. Recently, intensive efforts have been devoted to demonstrating the feasibility and improving the efficiency of synthetic methylotrophy. Various fuel, bulk, and fine chemicals have been synthesized using methanol as a feedstock. However, fully synthetic methylotrophs utilizing methanol as the sole carbon source and commercially viable bioproduction from methanol remain to be developed. Here, we review ongoing efforts to identify limiting factors, optimize synthetic methylotrophs, and implement methanol-based biomanufacturing. Future challenges and prospects are also discussed. a process of sequential serial cultivation of microorganisms under a specific selection pressure for selection of mutants with preferred phenotypes, such as enhanced substrate uptake or tolerance to toxic compounds. a manufacturing process that utilizes biological systems to convert feedstocks to useful chemicals. Examples include fermentation using microorganisms and catalytic synthesis using enzymes. single carbon atom chemicals that can be used as feedstocks for biomanufacturing. It can be categorized into gas C1 chemicals such as carbon dioxide and methane and liquid C1 chemical such as formic acid, formaldehyde, and methanol. a protein engineering strategy that encourages the evolution of enzymes towards a user-defined goal, such as catalyzing commercially useful reactions. a cellular control mechanism in which an enzyme’s activity is inhibited when its product has accumulated to a certain level. a method for constructing an atomic-resolution model of a target protein using its amino acid sequence and an experimental 3D structure of a template homologous protein. the entire set of small molecule compounds within a biological sample. engineered microbial cells that produce recombinant proteins, chemicals, and various products of commercial interest. a reagent used for specific detection of formaldehyde, consisting of ammonium acetate, acetyl acetone, and acetic acid. microorganisms with a natural capability to utilize methane or methanol as the sole carbon and energy source. microorganisms with clear genetic background, extensive metabolic knowledge, and advanced genome engineering tools. Platform microorganisms have been widely used as biological models or engineered for industrial applications. the entire set of proteins expressed by a genome in a cell. a type of chemical that serves as the electron donor in redox reactions and becomes oxidized when it donates electrons to electron acceptors. Carrier molecules of reducing equivalents include NADH, FADH2, etc. an interdisciplinary branch of biology and engineering that aims to design and build biological modules, systems, and organisms for useful purposes. non-native methylotrophs that are created by building methane or methanol utilization pathway in non-methylotrophic platform microorganisms such as E. coli and C. glutamicum. design and engineering non-native methylotrophs that can utilize methane or methanol as a substrate to produce useful chemicals. a discipline of biology that studies complex biological systems at a system-wide level via mathematical, computational, and multiomics analyses. metabolic engineering integrated with synthetic biology, systems biology, and evolutionary engineering. Systems metabolic engineering is a powerful strategy allowing engineering biological systems at a systemic level for highly efficient production of useful chemicals. the complete set of transcripts (RNA molecules) in a cell.