Feasibility study on microencapsulation of anaerobicClostridium acetobutylicumATCC 824 by emulsification method for application in biobutanol production

This work evaluated the feasibility of microencapsulating Clostridium acetobutylicum ATCC 824 cells by emulsification for fermentation to produce biobutanol. The effects of selected emulsification process on viability of the vegetative cells and spores were investigated to enable the selection of appropriate form of bacterium for immobilisation. The spores were found to be more suitable for microencapsulation than the vegetative cells. Design of experiment and mathematical models were then used to evaluate the effects of gellan gum concentration, HLB of surfactant blend, temperature and stirring speed on the properties of the microspheres produced. Using the predicted optimal conditions, the spores were successfully immobilised in spherical microspheres for use in fermentation. The microencapsulated spores were easily revived by heat shock treatment and could produce 8.2 g/l of butanol, which was higher than that generally reported in literature. The microencapsulation method developed provides means of producing reusable microbioreactors for anaerobic spore-forming microorganisms.