Study On Influence Of Oxygen For Bacillus Butanol Fermentation And Sporulation

In this study we used Bacillus sp.C2 as fermentation strain to research the influence on the fermentation products by the different dissolved oxygen and concentration grads of substrate so as to explore the relationship between butanol producing and bacterial morphology.The C2 took a short time to reach stable phase in facultative anaerobic environment compare to anaerobic environment,and biomass(OD600 expressing)is higher than in an anaerobic environment.So the strict anaerobic environment was not suit for C2.In facultative anaerobic environment the concentration of total solvent and the production of butanol was higher than in anaerobic environment with the same concentration of glucose,The concentration of butanol and total solvent were 12.93 and 18.6g/L respectively with 5% initial glucose,The utilization rate of glucose in facultative anaerobic fermentation was 91~98% compare to83~89% in anaerobic fermentation.The p H of fermentation broth declined both in facultative anaerobic and anaerobic while logarithmic phase.On the contrary,the p H rised in stable phase.The concentration of methane acid in facultative anaerobic was higher than that in anaerobic at the end of fermentation with the same concentration of glucose.The concentration of butyric and undissociated butyric acid in facultative anaerobic was lower than in an aerobic outstandingly.The difference of acetic acid,undissociated formic and acetic acid is not obvious regularity.In aerobic bacteria grew badly with low biomass and there was not a typical S growth curve.Butanl production was very little,and the p H of fermentation broth became low gradually which was positive relativity to the initial concentration of glucose.The cell growth rate in LCS fermentation while logarithmic phase was higher than in that in normal fermentation,and the concentration of solvent was 55%~70% lower than in normal fermentation.The regularity of formic,butyric,total acid and undissociated formic,butyric,total acid changing was not significant.The concentration of acetic and undissociated acetic acid in LCS fermentation while logarithmic phase was lower than in normal fermentation,on the contrary,was higher in solventogenic than in normal fermentation.This expressed the mechanization of LCS phenomenon was different from acid crash phenomenon.