Engineered yeast tolerance enables efficient production from toxified lignocellulosic feedstocks

Area of Science:

• Biotechnology
• Synthetic Biology
• Metabolic Engineering

Background:

• Lignocellulosic biomass is a promising renewable resource for fuels and chemicals.
• Biomass deconstruction yields hydrolysates containing inhibitors toxic to fermentation microorganisms.
• Toxicity limits the industrial-scale utilization of lignocellulosic feedstocks.

Purpose of the Study:

• To engineer Saccharomyces cerevisiae for enhanced tolerance to lignocellulosic hydrolysate inhibitors.
• To enable efficient production of biofuels and chemicals from toxified biomass feedstocks.
• To demonstrate the transferability of engineered tolerance to other microbial chassis.

Main Methods:

• Engineered aldehyde reduction pathways in Saccharomyces cerevisiae.
• Optimized extracellular potassium and pH conditions for fermentation.
• Tested engineered strains on diverse, highly toxified genuine lignocellulosic feedstocks.

Main Results:

• Achieved near-parity production titers between inhibitor-laden and inhibitor-free feedstocks.
• Demonstrated industrial-scale cellulosic ethanol titers exceeding 100 g/L with toxified feedstocks.
• Successfully transferred multifeedstock tolerance to xylose-consuming and lactic acid-producing strains.

Conclusions:

• Targeted engineering of aldehyde reduction and environmental conditions confers broad hydrolysate tolerance.
• The developed strain exhibits robust performance on diverse, toxic lignocellulosic feedstocks.
• This 'drop-in' capability facilitates cost-effective, large-scale biomass valorization for fuels and chemicals.