Sustainable succinic acid production from rice husks

In this study, an investigation was carried out into the production of succinic acid by Actinobacillus succinogenes using the residual biomass rice husks as a sustainable carbon source. The rice husks were submitted to acid hydrolysis in autoclave and in a pressurized polytetrafluorethylene vessel. The hydrolysis conditions were optimized with the aid of a factorial design. The best results were obtained with a pressurized reactor using HCl 2.2% (v v^?1), at a temperature of 174 °C (59 bar), 46 min reaction time, and producing 19.0 g L^?1 glucose and 3.01 g L^?1 xylose. The hydrolysate was detoxified through a combination of pH regulation and adsorption on active carbon; it was subsequently, fermented in anaerobic medium at 37 °C; the nutrient concentration and the agitation speed were also optimized by factorial design. After 54 h static fermentation of the rice husks hydrolysate, supplemented with 8.40 g L^?1 yeast extract and 1.40 g L^?1 NaHCO₃, an amount of 12.5 g succinic acid L^?1 was produced, which corresponds to a yield of 59.9%. This confirms that, rice husks can definitely be used as substrate to produce succinic acid and other priority chemicals