Novel fed-batch process with in-situ product recovery for glycerol fermentation to butanol using Clostridium pasteurianum
Abstract
Butanol, a next-generation biofuel, can be produced by fermenting glycerol using Clostridium pasteurianum. To address product inhibition, an integrated system that combined a fed-batch process with pervaporation was assessed against conventional batch and fed-batch fermentations. This study showed that with the novel process configuration, the productive fermentation time could be extended, translating to a 2.4-fold and 1.9-fold increase in butanol production relative to baseline fed-batch and batch operation, respectively. Further, it was demonstrated that butanol concentrations were able to be maintained below inhibitory levels throughout the fermentation. Despite this outcome, metabolic oscillations were revealed, indicating instability in the process. The introduction of secondary sugar substrates into the modified system improved the butanol selectivity and did not result in fluctuations of the product profile. Overall, these findings provide strong evidence of the advantages of in-situ product recovery in glycerol fermentation which can be aided by the addition of secondary carbon sources.