High-titer bio-succinic acid production from sequential alkalic and metal salt pretreated empty fruit bunch via simultaneous saccharification and fermentation

•Bio-SA is produced from sequential alkalic and metal salts pretreated OPEFB via SSF.•SSF was conducted anaerobically using Actinobacillus succinogenes ATCC 55618.•Biomass and enzyme loading are the significant factors that influence SA yield.•High titer SA was produced at 100 g/L biomass, 5% inoculum and cellulase enzyme 40 FPU/g OPEFB. Bio-succinic acid is produced from inorganic salt pretreated oil palm empty fruit bunch (OPEFB) for the first time through simultaneous saccharification and fermentation (SSF). OPEFB is an agriculture waste that can be converted into succinic acid (SA) which is a high value added product sought after in the chemical industry. In this study OPEFB is pretreated using sequential inorganic salt (sodium phosphate dodecahydrate and zinc chloride) before undergoing SSF using Actinobacillus succinogenes ATCC 55618. Parameters that influenced the SA production such as substrate loading, inoculum size and enzyme loading are investigated using design of experiments. The results revealed that biomass loading and enzyme loading have significant impact in SA yield. Under condition of 100 g/L biomass, 5% inoculum and cellulase enzyme 40 FPU/g OPEFB, maximum concentration of SA (65.2 g/L) and yield (0.65 g/g OPEFB) are obtained. Subsequently the model developed for predicting SA production has been successfully validated.