Abstract
AbstractLignocellulosic biomass is the most abundant bio‐resource on earth, mainly composed of D‐glucose, D‐xylose and L‐arabinose. It is widely considered to be a promising alternative feedstock for biotechnological processes. Here we evaluated its potential to be the carbon source for growth of broadly distributed and well‐established Escherichia coli laboratory and protein expression strains as well as a classic probiotic E. coli strain. E. coli DH5α, E. coli K12‐MG1655, E. coli K12‐W3110, E. coli BL21(DE3) and E. coli Nissle 1917 were cultivated in mineral media containing single lignocellulosic sugar components. Sugar consumption in these cultures and growth parameters of the different strains were characterized. enhanced green fluorescent protein (eGFP) was chosen as a first easy to measure and prominent model recombinant target protein to demonstrate lignocellulose‐dependent recombinant protein production in E. coli. To open new production routes for high value food proteins based on lignocellulose, structural genes encoding bovine αS1‐casein and human αS1‐casein were synthesized, cloned and then expressed in an E. coli T7 expression system in different media based on single sugars and a synthetic wheat straw mixture. Successful recombinant production of both bovine and human αS1‐caseins in E. coli under these experimental conditions was demonstrated and quantified by densitometric analysis after protein separation in polyacrylamide gels. Finally, efficient casein production in E. coli based on a real hydrolysate obtained by steam explosion of wheat straw lignocellulose in a bioreactor‐based batch production process was successfully demonstrated. We believe that this proof‐of‐concept presented here is a promising starting point to open new routes for the production of food or feed proteins with high nutritional and economic value. As such, a valorization of bulk residual biomass like lignocellulose is envisioned as a key support of a growing and truly sustainable bioeconomy.
Highlights
Promising economic and ecologic options arising from the use of renewable energies and resources have raised attention all over the world, due to the mostly undoubted rising global challenges as posed to mankind by the climate change, decline of environmental integrity and diversity, energy prices, energy long-run supply problems and impacts of these challenges on human health (Hansen et al, 2006; McMichael et al, 2006; Schröter et al, 2005)
To open new production routes for high value food proteins based on lignocellulose, structural genes encoding bovine αS1-casein and human αS1-casein were synthesized, cloned and expressed in an E. coli T7 expression system in different media based on single sugars and a synthetic wheat straw mixture
As the main objective of this study we have demonstrated the recombinant production of bovine and human αS1-casein proteins on sugar mixtures emulating lignocellulosic hydrolysates from wheat straw residues as sole carbon sources
Summary
Promising economic and ecologic options arising from the use of renewable energies and resources have raised attention all over the world, due to the mostly undoubted rising global challenges as posed to mankind by the climate change, decline of environmental integrity and diversity, energy prices, energy long-run supply problems and impacts of these challenges on human health (Hansen et al, 2006; McMichael et al, 2006; Schröter et al, 2005). As the main objective of this study we have demonstrated the recombinant production of bovine and human αS1-casein proteins on sugar mixtures emulating lignocellulosic hydrolysates from wheat straw residues as sole carbon sources. Zoonoses such as the current Coronavirus disease 2019 and salmonellosis and others stress the need for animal-free alternatives of high-value protein supply in combination with climate-neutral production We believe that this proof-of-concept presented here may be a promising starting point to open general new routes for the production of food or feed proteins with high nutritional and economic value based on bulk residual biomass like lignocellulose for the support of a growing and truly sustainable bioeconomy
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