Turning waste into biofuel: Non-sterile fermentation of molasses using immobilized cells of Bacillus licheniformis BD43 for efficient 2,3-Butanediol production

2,3-Butanediol (2,3-BD) is a high-value chemical compound with various applications in the industry. Conversion of agricultural wastes or by-products into 2,3-BD via microbial fermentation processes would be an environmentally friendly approach to reduce waste and sustain the production of biotechnologically important chemicals. Therewithal, sterilization of waste feedstock, which is usually required before fermentation to prevent any contamination, is not a cost-effective step because of energy consuming. The present study was performed to produce 2,3-BD from molasses using immobilized cells of locally isolated and nonpathogenic Bacillus licheniformis BD43 strain under non-sterile fermentation conditions. Sodium alginate was used as entrapping agent for cell immobilization. The highest production of 2,3-BD was obtained at temperature of 55 ⁰C, pH 7, molasses concentration of 100 mL/L, bead number of 150 beads/100 mL, 5 mm bead size and incubation time of 24 h. In optimized non-sterile batch fermentation of 100 mL/L molasses (48.3 g sugar), 31.6 g/L of 2,3-BD was obtained with a yield of 0.65 g/g. Non-sterile fermentation of molasses using immobilized cells of B. licheniformis in the production of 2,3-BD was investigated for the first time. The study indicates that thermophilic B. licheniformis BD43 is a suitable candidate for non-sterile and energy-saving processes to convert waste feedstock to value-added chemicals.