1. Escherichia coli-based biorefining process yields optically pure lactic acid from fermented second-generation feedstocks.
- Author
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Visentin, Anna, Murphy, Cormac D., Alvarado-Morales, Merlin, Angelidaki, Irini, and Sweeney, Joseph B.
- Subjects
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TARTARIC acid , *ENANTIOMERIC purity , *RACEMIC mixtures , *ESCHERICHIA coli , *ACID solutions - Abstract
Within the circular bioeconomy the production of optically pure LA from 2nd generation feedstocks would be ideal but it is very challenging. In this paper genetically engineered Escherichia coli strains were created to resolve racemic LA solutions synthesised and produced from the fermentation of organic waste or ensiled grass. Refining LA racemic mixtures into either a D- or L-LA was achieved by cells being able to consume one LA isomer as a sole carbon and energy source while not being able to consume the other. A D-LA refining strain JSP0005 was grown on fermented source-sorted organic household waste and different grass silage leachates, which are 2nd generation feedstocks containing up to 33 g/L lactic acid racemate. In all growth experiments, L-LA was completely removed leaving D-LA as the only LA stereoisomer, i.e. resulting in optically pure D-LA, which also increased by as much as 248.6 % from its starting concentration, corresponding to 38 g/L. The strains resulting from this study are a promising first step towards a microbial based LA biorefining process. [Display omitted] • Genetically engineered Escherichia coli strains yield optically pure lactic acid from racemic mixtures. • These strains could allow racemic lactic acid solutions to be obtained from cheap and abundant 2nd generation feedstocks. • D‐lactic acid was produced while all L-lactic acid was removed from grass silage leachates and fermented organic wastes. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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