Harnessing tobacco stem biomass for eco-friendly xylo-oligomers production via hydrothermal treatment and succinic acid via fermentation

The integration of processes offers promising avenues for valorization of the tobacco waste, enabling the production of commercially significant compounds beyond traditional tobacco leaves designation. This research delves into the feasibility of extracting xylo-oligosaccharides (XOS) from tobacco stems via hydrothermal pretreatment. Emphasis was laid on XOS release kinetics from high solid loads (20% w/v) during pretreatment. The optimal conditions, which facilitated maximum oligomer recovery with minimal degradation compounds and reducing sugar solubilization, were then scaled up. The resultant solid fraction underwent enzymatic hydrolysis at varied solid loads (5%, 10%, and 15% w/v). Subsequent to this, succinic acid production was targeted, propelling the optimal enzymatic hydrolysate towards fermentation using the bacterium Actinobacillus succinogenes. Key findings revealed that a temperature of 190 °C during 8-min emerged as the most effective pretreatment conditions, yielding XOS at 49.54% with a concentration of 11.11 g.L-1. Enzymatic hydrolysis remained relatively uninfluenced by variations in solid loads, thereby permitting the use of high solid loads (15% w/v) to obtain concentrated hydrolysates at 49.37 g.L-1 with a conversion yield of 62.90%. Markedly, this study pioneered the demonstration of tobacco waste as a viable precursor for succinic acid synthesis. Succinic acid concentration stood at 16.88 g.L-1, achieving a yield of 42%. A comprehensive mass balance evaluation spotlighted the potential to derive 56 kg of XOS and 78 kg of succinic acid per 1000 kg of tobacco raw biomass by the process developed herein.