Application of a fermentation strategy to produce succinic acid usingActinobacillus succinogenes ; Application d'une stratégie de fermentation pour la production d'acide succinique en utilisant Actinobacillus succinogenes

This PhD work integrates the succinic acid production, in a pioneer study using pure culture, co-culture and electro-fermentation that involves selection of substrates, microorganisms and electrode potential. In this process, glucose and fructose were chosen as organic substrates, while MgCO3 was used as co-substrate providing inorganic carbon source in anaerobic fermentations using Actinobacillus succinogenes. The results showed that during anaerobic batch fermentation (250 mL), the highest succinic acid concentration was obtained from an equal ratio of glucose and fructose recording a succinic acid value of 0.22 mol L-1 equivalent to a yield of 0.94 mol-C/ mol-C and a productivity of 0.27 g L-1 h-1 after 96 h. The subsequent fermentations carried out with fumaric acid as enhancer, confirmed the efficiency of the process with global succinic acid production of 0.5 mol L-1 and a productivity of 0.48 g L-1h-1. A lab scale-up studies showed the best results in bench scale reactor (3 L) after 96 h of fermentation recording a value of 0.88 mol-C/mol-C and 0.5 g L-1h-1 for succinic acid yield and productivity, respectively. Preliminary results of bioelectro-based process showed high succinic acid productivity, 1.01 g L-1 h-1, after only 48 h. The last part of this work was dedicated to the co-culture fermentation process of two microorganisms in 250 mL bottles. It was based on the utilization of carbon dioxide produced from Saccharomyces cerevisiae in the fermentation by the succinate producing-bacteria (Actinobacillus succinogenes). Results showed that MgCO3 and N2 sparging could be substituted by applying a sequential co-culture leading to 0.27 molL-1 of succinic acid and a productivity of 0.3 g L-1 h-1. This work proved the production of succinic acid by glucose and fructose as feedstock in pure culture, in co-culture and electro-fermentation in batch mode. ; La production d'acide succinique en culture pure, en co-culture et par électrofermentation a été examinée dans cette étude; ce qui implique la sélection des ...