Biomass Deacetylation at Moderate Solid Loading Improves Sugar Recovery and Succinic Acid Production

Abstract

Biomass deacetylation with alkali prior to dilute acid pretreatment can be a promising approach to reduce the toxicity of the resulting hydrolysates and improve microbial fermentation. In this study, the effect of mild alkaline treatment of oil palm trunk (OPT) biomass on succinic acid production was evaluated. Deacetylation was carried out under different conditions: NaOH loadings (1–5%, w/v) and reaction times (15–90 min) at 100 °C. Deacetylation using 1% (w/v) NaOH within 15 min was sufficient to achieve a high acetic acid removal of 5.8 g/L with minimal sugar loss. Deacetylation under this condition resulted in a total sugar concentration of 55.8 g/L (18.0 g/L xylose and 37.8 g/L glucose), which was 37% higher than that of non-deacetylated OPT. Subsequently, succinic acid production using Actinobacillus succinogenes was also improved by 42% and 13% in terms of productivity and yield, respectively, at 10% (w/v) solid loading. This further demonstrated that mild alkaline treatment prior to dilute acid pretreatment is a promising strategy to improve succinic acid production. This study provides a facile approach for reducing the most influential inhibitory effect of acetic acid, and it can be applied to the exploitation of lignocellulosic biomass resources for succinic acid, biofuels, and/or other biochemical co-production in the future.