Succinic acid fermentation with immobilized Actinobacillus succinogenes using hydrolysate of carbohydrate-rich microalgal biomass

This work aimed to study the efficiency of polyvinyl-alcohol-immobilized Actinobacillus succinogenes ATCC55618 for succinic acid (SA) production. Batch fermentation (pH 7, 45% CO₂ gas at 0.04 vvm) using glucose (40 g L^-1) resulted in SA titer, 26.7 g L^-1; productivity, 3.33 g L^-1h⁻¹; yield, 0.621 g g⁻1. Fed-batch mode with cyclic extrication of SA from the medium markedly enhanced the yield to 0.699 g g⁻¹ and concentration to 59.5 g L^-1. Batch fermentation using sugars derived from Chlorella vulgaris ESP-31 without yeast extract gave a SA productivity, concentration, and yield of 1.82 g L^-1h⁻¹, 36.1 g L^-1, and 0.720 g g⁻1, respectively. Furthermore, continuous fermentation (at 6 h HRT) with microalgal sugar improved the productivity and yield to 3.53 g L^-1h⁻¹ and 0.62 g g⁻¹, respectively, which is comparable to those obtained by using glucose. This study reports the highest productivity for SA fermentation using microalgae-derived sugars.