Cellulose fermentation: effect of substrate pretreatment on microbial growth

Area of Science:

• Biochemistry
• Biotechnology
• Agricultural Science

Background:

• Rice straw and sugarcane bagasse are abundant lignocellulosic biomass resources.
• Efficiently converting cellulose from these materials is crucial for biofuel and biochemical production.
• Current pretreatment methods require optimization for enhanced microbial digestibility.

Purpose of the Study:

• To investigate the impact of various chemical, physical, and enzymatic treatments on the microbial digestibility of cellulose.
• To identify optimal conditions for pretreating rice straw and sugarcane bagasse for improved cellulose breakdown.

Main Methods:

• Treatments included sodium hydroxide (NaOH), ammonia (NH3), sulfuric acid, crude cellulase, grinding, and high-pressure cooking.
• Microbial digestibility was assessed using the Cellulomonas species.
• Cellulose digestibility percentages were measured before and after treatment.

Main Results:

• 4% NaOH treatment at 100°C for 15 min increased cellulose digestibility from 29.4% to 73%.
• 5.2% NH3 treatment improved digestibility to 57.0%.
• Sulfuric acid and crude cellulase solubilized cellulose but did not enhance microbial digestibility; physical methods showed minimal impact.

Conclusions:

• Alkaline pretreatment, particularly with NaOH, is highly effective in enhancing the microbial digestibility of cellulose in rice straw and sugarcane bagasse.
• Optimized chemical pretreatment is essential for maximizing cellulose accessibility for microbial fermentation.
• Further research can focus on refining alkaline pretreatment parameters for industrial-scale applications.