Engineering New-to-Nature Biological Pathways for β,γ-Alkanediol Synthesis.

Area of Science:

• Biotechnology
• Metabolic Engineering
• Synthetic Biology

Background:

• Linear chain β,γ-alkanediols are valuable chemicals with applications in solvents, biofuels, and cosmetics.
• While some are naturally occurring, their biosynthetic pathways are not well understood.
• Exploring novel biosynthetic routes is crucial for sustainable chemical production.

Purpose of the Study:

• To expand acetohydroxyacid synthase (AHAS)-mediated carboligation for synthesizing linear chain β,γ-alkanediols.
• To develop and optimize pathways for producing hexane-2,3-diol (2,3-HDO) and pentane-2,3-diol (2,3-PDO) in Escherichia coli.
• To demonstrate the versatility of AHAS-mediated carboligation for producing diverse diols.

Main Methods:

• Engineered E. coli using AHAS-mediated carboligation.
• Developed two distinct pathways for 2,3-HDO production: a redesigned clostridial pathway and an artificial reversal β-oxidation pathway.
• Disrupted endogenous thioesterases in E. coli to enhance diol yield.

Main Results:

• Achieved significant production of 2,3-HDO (152.2 mm or 17.98 g/L) from glucose in fed-batch bioreactors.
• Successfully synthesized 2,3-PDO (15.5 mm or 1.61 g/L) in shake flask cultures.
• Demonstrated high yields and titers for both target diols, validating the engineered pathways.

Conclusions:

• AHAS-mediated carboligation is a versatile platform for synthesizing linear chain β,γ-alkanediols.
• Engineered E. coli strains can efficiently produce 2,3-HDO and 2,3-PDO from renewable feedstocks.
• This work lays the foundation for the future production of other linear chain β,γ-diols.