Current progress on engineering microbial strains and consortia for production of cellulosic butanol through consolidated bioprocessing

Abstract

In the last decades, fermentative production of n‐butanol has regained substantial interest mainly owing to its use as drop‐in‐fuel. The use of lignocellulose as an alternative to traditional acetone–butanol–ethanol fermentation feedstocks (starchy biomass and molasses) can significantly increase the economic competitiveness of biobutanol over production from non‐renewable sources (petroleum). However, the low cost of lignocellulose is offset by its high recalcitrance to biodegradation which generally requires chemical‐physical pre‐treatment and multiple bioreactor‐based processes. The development of consolidated processing (i.e., single‐pot fermentation) can dramatically reduce lignocellulose fermentation costs and promote its industrial application. Here, strategies for developing microbial strains and consortia that feature both efficient (hemi)cellulose depolymerization and butanol production will be depicted, that is, rational metabolic engineering of native (hemi)cellulolytic or native butanol‐producing or other suitable microorganisms; protoplast fusion of (hemi)cellulolytic and butanol‐producing strains; and co‐culture of (hemi)cellulolytic and butanol‐producing microbes. Irrespective of the fermentation feedstock, biobutanol production is inherently limited by the severe toxicity of this solvent that challenges process economic viability. Hence, an overview of strategies for developing butanol hypertolerant strains will be provided.

Insights into the susceptibility of Pseudomonas putida to industrially relevant aromatic hydrocarbons that it can synthesize from sugars

“…The effectiveness of various microbial hosts (e.g., E. coli, Clostridium acetobutylicum, Corynebacteria and yeasts) for the production of chemicals is often limited by the inherent sensitivity of the host to the chemical of interest. This is particularly true when synthetic pathways have been developed to produce aromatic hydrocarbons and medium chain alcohols such as butanol in Clostridium [ 75 , 76 ]; isobutanol in E. coli and yeasts [ 77 , 78 ] and aromatic compounds (e.g., 2-phenylethanol and styrene) in E. coli [ 11 , 23 ].…”

Establishment of synthetic microbial consortia with Corynebacterium glutamicum and Pseudomonas putida: Design, construction, and application to production of γ‐glutamylisopropylamide and l‐theanine

“…The sum of implemented genetic modifications, which is limited to a single strain, is higher, and the desired features of different strains or species can be combined in a coordinated manner (Cui et al., 2019 ; Wang et al., 2018 ). Also, complicated metabolic and genetic manipulation can be reduced by the use of specialised members in the consortia (Re & Mazzoli, 2023 ). A number of design rules exist for this subdivision, comprising availability of transport proteins, inhibition due to substrates, intermediates or products and distinct biochemical requirements of subpathways regarding NADPH, ATP or oxygen (Sgobba & Wendisch, 2020 ).…”

Enhancing Pervaporation Performance for Alcohol Recovery from Aqueous Solutions with Silicalite-1/Polydimethyldiethoxysilane (PDMDES) Nanocomposite Membranes

“…Alcohols, such as methanol, ethanol, and butanol, have been extensively utilized in daily life and industrial processes, − ascribed to their high combustion energy, clean combustion products, and renewable characteristics. These alcohols are usually regenerated in aqueous solutions via chemical processes like photocatalytic reaction and biomass fermentation. , Thus, the recovery of these valuable resources from reaction solution becomes crucial. Pervaporation (PV), a membrane-based separation technique, has been increasingly adopted for the efficient separation of alcohols or volatile organic compounds (VOCs) from dilute aqueous solution, owing to its advantages like lower energy consumption, high efficiency, and environmental friendliness. − …”