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.