Lactic acid production from cellulosic material by synergetic hydrolysis and fermentation

Area of Science:

• Biotechnology
• Biochemical Engineering
• Renewable Energy

Background:

• Corncob residue presents a viable feedstock for biofuel and biochemical production.
• Cellulose hydrolysis is often limited by feedback inhibition from accumulated sugars like cellobiose and glucose.
• Efficient conversion of cellulosic biomass into valuable products like lactic acid is crucial for sustainable industry.

Purpose of the Study:

• To develop a synergistic enzymatic hydrolysis process for corncob residue.
• To couple cellulose hydrolysis with lactic acid fermentation using immobilized microbial cells.
• To optimize the bioconversion process for high yields and productivity.

Main Methods:

• Synergistic hydrolysis of corncob residue using Trichoderma reesei cellulase and immobilized cellobiase.
• Immobilization of Lactobacillus delbrueckii for lactic acid fermentation.
• Coupling of enzymatic hydrolysis and fermentation in batch and fed-batch processes.

Main Results:

• Achieved 82.5% hydrolysis yield with 88.2% glucose in reducing sugar.
• Eliminated feedback inhibition by cellobiose and glucose accumulation.
• Reached 92.4% lactic acid conversion efficiency and 0.938 g/(L.h) productivity in batch process.
• Increased substrate and lactic acid concentrations to 200 g/L and 107.5 g/L in fed-batch, reducing cellulase dosage.

Conclusions:

• Synergistic hydrolysis and coupled fermentation effectively convert corncob residue to lactic acid.
• The developed process overcomes key limitations in cellulosic bioconversion.
• This approach offers a significant advancement in utilizing renewable cellulosic resources.