Continuous cellulosic bioethanol fermentation by cyclic fed-batch cocultivation.

Area of Science:

• Biotechnology
• Microbial Fermentation
• Bioenergy

Background:

• Cocultivation of microbial consortia enhances bioethanol production from cellulosic materials.
• Previous studies confirmed cocultivation's effectiveness in batch fermentation systems.

Purpose of the Study:

• To evaluate a semicontinuous cyclic fed-batch fermentor for improved cellulose fermentation efficiency.
• To optimize bioethanol production using cocultures of Clostridium thermocellum and Thermoanaerobacter pseudethanolicus.

Main Methods:

• Utilized a semicontinuous cyclic fed-batch fermentor with cocultures of Clostridium thermocellum LQRI and Thermoanaerobacter pseudethanolicus X514.
• Investigated the impact of initial cellulose concentration and pH control on fermentation performance.
• Assessed bioethanol production under controlled conditions over 96 hours.

Main Results:

• pH control increased ethanol concentration by 4.5-fold at an initial cellulose concentration of 40 g/L.
• Sustained efficient cellulosic bioethanol production in the semicontinuous configuration.
• Achieved 474 mM bioethanol in 96 hours with 80 g/L initial cellulose and controlled pH (6.5-6.8).

Conclusions:

• The cyclic fed-batch process offers advantages for cellulosic bioethanol fermentation via microbial cocultivation.
• Optimized process parameters like initial cellulose concentration and pH are critical for maximizing yield.
• Semicontinuous fermentation is a viable strategy for efficient and sustained bioethanol production.