2,3-Butanediol production from cellobiose using exogenous beta-glucosidase-expressing Bacillus subtilis

Area of Science:

• Biotechnology
• Microbial Engineering
• Metabolic Engineering

Background:

• Cellobiose utilization by Bacillus subtilis for 2,3-butanediol (23BD) production is less efficient than glucose.
• Native beta-glucosidase activity in B. subtilis is a limiting factor for cellobiose fermentation.

Purpose of the Study:

• To engineer Bacillus subtilis for enhanced 2,3-butanediol (23BD) production from cellobiose.
• To improve the efficiency of cellobiose hydrolysis to glucose for 23BD biosynthesis.

Main Methods:

• Fermentation of B. subtilis with cellobiose as the carbon source.
• Supplementation of fermentation with purified beta-glucosidase (Tfu_0937) from Thermobifida fusca YX.
• Development of an engineered B. subtilis strain expressing exogenous Tfu_0937.

Main Results:

• Addition of purified beta-glucosidase improved 23BD productivity from cellobiose.
• Engineered B. subtilis expressing Tfu_0937 achieved 21.2 g/L of 23BD after 72 hours.
• Productivity and yield reached 0.294 g/L/h and 0.35 g/g cellobiose, respectively.

Conclusions:

• Hydrolysis of cellobiose to glucose is crucial for efficient 23BD biosynthesis in B. subtilis.
• Exogenous expression of beta-glucosidase in B. subtilis enables efficient 23BD production from cellobiose.
• This engineered strain demonstrates a viable strategy for bio-based 23BD production.