Downscale fermentation for xylooligosaccharides production by recombinant Bacillus subtilis 3610

Area of Science:

• Biotechnology
• Microbial Fermentation
• Carbohydrate Chemistry

Background:

• Growing global demand for prebiotics like xylooligosaccharides (XOS) necessitates efficient production methods.
• Xylooligosaccharides offer significant health benefits, driving research into their synthesis and application.
• Optimizing fermentation processes is key to increasing the yield and purity of XOS.

Purpose of the Study:

• To develop an efficient method for producing xylooligosaccharides (XOS) through direct fermentation.
• To optimize fermentation conditions for maximum XOS yield using a genetically modified Bacillus subtilis strain.
• To characterize the stability and composition of the produced XOS.

Main Methods:

• Engineered Bacillus subtilis 3610 with Trichoderma reesei xylanase gene (xyn2) for direct xylan fermentation.
• Fermentation optimization using a one-time impulse fed-batch strategy.
• Analysis of XOS yield, degree of polymerization, and in vitro digestion stability.

Main Results:

• Achieved a maximum XOS yield of 306 ± 4 mg/g of xylan after 8 hours of fermentation.
• Optimal conditions identified: pH 6.0, 42.5°C, with xylan concentration increased from 2.5 to 5.0 g/L.
• Produced a stable mixture of XOS (DP 4-6), with xylopentaose as the major component (47%).

Conclusions:

• The engineered Bacillus subtilis strain efficiently produces XOS from beechwood xylan.
• The optimized fed-batch fermentation process significantly enhances XOS yield and stability.
• This method provides a promising route for the large-scale production of high-quality XOS for the prebiotic market.