Efficient l-lactic acid production from corncob residue using metabolically engineered thermo-tolerant yeast

Area of Science:

• Biotechnology
• Industrial Microbiology
• Metabolic Engineering

Background:

• Lactic acid is a key industrial chemical.
• Lignocellulose offers a sustainable and cost-effective feedstock for chemical production.
• Current methods for lactic acid production face challenges in cost and environmental impact.

Purpose of the Study:

• To develop an efficient yeast platform for producing high-purity l-lactic acid from lignocellulose.
• To engineer Kluyveromyces marxianus for enhanced lactic acid fermentation from corncob residue.

Main Methods:

• Screening of heterologous lactate dehydrogenases (from Plasmodium falciparum and Bacillus subtilis) for l-lactic acid production.
• Genetic modifications including overexpression of transporter and glycolytic enzymes, and disruption of d-lactate dehydrogenase.
• Simultaneous saccharification and co-fermentation (SSCF) using engineered yeast on corncob residue.

Main Results:

• Identified effective lactate dehydrogenases for l-lactic acid synthesis.
• Demonstrated that overexpression of specific genes and disruption of others significantly enhanced lactic acid accumulation.
• Achieved 103.00 g/L of l-lactic acid with 99.5% optical purity at 42°C using the engineered strain YKX071.

Conclusions:

• Successfully engineered Kluyveromyces marxianus for high-yield, high-purity l-lactic acid production from lignocellulosic biomass.
• Established an effective fermentation platform utilizing inexpensive nitrogen sources and corncob residue.
• This work provides a sustainable and economically viable route for industrial l-lactic acid manufacturing.