Agro-industrial wastes as feedstock for sustainable bio-production of butanol by Clostridium beijerinckii

• Clostridium beijerinckii NRRL B-466 used for ABE fermentation.
• Use of different agro-industrial wastes to butanol production.
• Pretreatment and glucose supplement to enhance butanol production.
• Screening of substrate concentration to get higher production.
• Carbon balance to show utilization of biomass for production.

Three different inexpensive, abundant agro-industrial wastes: suspended brewery liquid waste (BLW), starch industry wastewater (SIW) and apple pomace ultra-filtration sludge (APUS) have been explored for biobutanol production. Physicochemical analysis of biomass for carbohydrate and nutrient pool, acid hydrolysis, fermentation of raw extracts and hydrolysates by Clostridium beijerinckii NRRL B-466 for ABE production and glucose supplementation to increase butanol production have been studied. The efficiency of the microorganism to produce butanol and other metabolites was explored via carbon balance. Inhibitory effects were minimized by dilution and detoxification method. Pretreated diluted extracts having reducing sugar content of 30 g/L gave optimum butanol production of 4.68 g/L, 1.4 g/L and 1.8 g/L from SIWH, APUSH and BLWH, respectively, as compared to 5.1 g/L obtained from control. Reducing sugar concentration in each diluted extract was increased to 60 g/L by 3% (w/v) glucose supplement and the butanol production was increased to 11.04 g/L (0.27 g/g), 9.3 g/L (0.24 g/g) and 8.06 g/L (0.25), respectively. For SIWH, the maximum yield of butanol (0.27 g/g) and acetone–butanol–ethanol (ABE) (0.46 g/g) was obtained. Thus, production of butanol, with 3% glucose supplement demonstrated that these inexpensive agro-industrial wastes could have important implications in stimulating energy-economics.

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