Investigation of Optimized Microbial Oligofructans Production by Bacillus subtilis TISTR 001 Using Response Surface Methodology

Oligofructans are a combination of fructo-oligosaccharides and fructose polymers that are linked by β-glycosidic bonds. Because of their distinctive properties and potential health benefits, they are widely used in many industries. This study optimized microbial oligofructans fermentation using Bacillus subtilis TISTR 001. Fermentative parameters (pH, temperature, shaking rate, sucrose concentration, and fermentation time) were investigated in a one-factor-at-a-time (OFAT) experiment using surface response methodology to determine the predicted model and optimization. Different carbon sources (sucrose, raw sugar, sugarcane juice, and molasses) were studied under the optimized conditions. The results from the Box–Behnken experimental design with four factors and three levels and the predicted model showed the optimum fermentation conditions were 35°Brix of substrate concentration at pH 6.5, 32.5 °C, and 250 rpm shaking speed for 48 h to obtain 88.64 g/L of oligofructans. The predicted oligofructans content (88.64 g/L) was higher than the actual production using sucrose (75.86 g/L), which was the best substrate for oligofructans production. Raw sugar and sugarcane juice could be alternative substrates for oligofructans production based on these optimized conditions, while molasses had the lowest production due to its impurities that negatively affected oligofructans production.