Organic Acid Pretreatment of Oil Palm Trunk Biomass for Succinic Acid Production

Abstract

Oil palm trunk (OPT) is a promising lignocellulosic biomass for sugar production due to its abundant availability, low-cost and high carbohydrate content. Organic acids have been suggested as an alternative to sulphuric acid pretreatment due to their lower hazardous properties. Various organic acids (citric acid, formic acid and oxalic acid) of different concentration (0.5–5.0%) were assessed to find a suitable catalyst in hydrolysing oil palm trunk biomass (OPTB) for different reaction time (15–120 min) at a fixed temperature (120 °C), and expressed in a combined severity factor (CSF) to allow for xylose selectivity and their performance comparison. Of various organic acids used, oxalic acid was shown to be the most effective in solubilizing hemicellulose of OPTB, recovering a maximum xylose of ~ 61.2% at a CSF of 0.97. Nevertheless, citric acid-derived hydrolysate was more potent for succinic acid fermentation by Actinobacillus succinogenes 130Z, showing optimal succinic acid titer of 10.62 g/L and yield of 0.47 g/g, which were two-fold higher than those without acid pretreatment. The capability of A. succinogenes 130Z in utilising both glucose and xylose of OPTB hydrolysates supports development of bio-based succinic acid using oil palm biomass.