Optimization of bio-succinic fermentation process from crude glycerol by Actinobacillus succinogenes

Bio-succinic acid is a commodity chemical with potent application in bioplastic and food industries which can be produced from renewable resources. In this study, bioprocess for production of bio-succinic from glycerol by Actinobacillus succinogenes was studied. The maximum succinic acid concentration in small-scale serum bottle experiments was 6.8 and 6.5 g/L using pure and crude glycerol, respectively, with supplemented MgCO3. The ratio of acetic acid to succinic acid (AA/SA) implied the increased carbon flux to the C4 pathway using crude glycerol supplemented with MgCO3 compared to that with CaCO3.The carbonate salts tended to induce C3 metabolic pathway in fermentation using pure glycerol which was in accordance with the ratio of acetic acid to glycerol (AA/GL). The highest succinic acid concentration of 17.9 g/L from crude glycerol was achieved from batch fermentation in a lab-scale fermenter with the maximum glycerol utilization of 99.9% which were higher than those obtained from fed- batch and semi-continuous processes. Acetic acid tended to increase throughout the fermentation process in fed-batch and semi-continuous operations, which resulted in the lower product yield and substrate utilization efficiency. The time for initial purging of CO2 showed effects on succinic acid production and internal metabolic pathways. This work provided a basis for process development on bio-succinic acid production from crude glycerol in industry.