Escherichia coli-based biorefining process yields optically pure lactic acid from fermented second-generation...

Area of Science:

• Biotechnology
• Microbial Engineering
• Circular Economy

Background:

• Optically pure lactic acid (LA) production from 2nd generation feedstocks is crucial for a circular bioeconomy but remains challenging.
• Current methods for LA resolution are often inefficient or costly.

Purpose of the Study:

• To develop genetically engineered Escherichia coli strains for the efficient resolution of racemic lactic acid (LA).
• To demonstrate the feasibility of using these engineered strains for biorefining LA from diverse 2nd generation feedstocks.

Main Methods:

• Genetic engineering of Escherichia coli to create strains capable of consuming specific LA stereoisomers.
• Cultivation of engineered strains on fermented organic waste and grass silage leachates containing racemic LA.
• Monitoring of LA stereoisomer concentrations to assess refining efficiency.

Main Results:

• Engineered E. coli strain JSP0005 successfully refined racemic LA solutions, completely removing L-lactic acid (L-LA).
• Optically pure D-lactic acid (D-LA) was obtained, with concentrations increasing up to 248.6% to 38 g/L.
• Demonstrated effective LA refining using 2nd generation feedstocks like fermented household waste and grass silage.

Conclusions:

• The developed microbial strains represent a significant advancement in biorefining racemic LA.
• This approach offers a promising pathway towards sustainable and efficient production of optically pure D-LA from waste streams.
• Further development of these microbial strains could enable a scalable, bio-based LA biorefining process.