Study On Fermentation Of Butanol From Corn Stover Hydrolysis Solution For Substrate

Corn straw is a kind of biomass with rich cellulose, production of chemical and biological energy base on corn straw as raw materials have been paid attention.Clostridium can grow and produce metabolites,such as butanol, ethanol, and acetone,depend on corn straw hydrolyzate as substrate,therefore there is great potential for industrial application.After 72-96 hours,the concentration of reducing sugar in the hydrolysate is about14% higher in the case of citrate acid-sodium citrate instead of acetic acid-sodium acetate as the buffer in hydrolyzing pretreated corn stover system. By adding the following five substances to corn stover hydrolyzate: charcoal, Ca(OH)2, charcoal + Ca(OH)2, sodium sulfite, sodium hydrosulfite, we studied the effects of different methods on the components and inhibitors of hydrolyzate, and also fermentation. The results showed that the removal rate of inhibitor in descending order: charcoal + Ca(OH)2 > charcoal >Ca(OH)2 > sodium sulfite and sodium hydrosulfite, which is consistent with the loss of reducing sugar.We used C.beijerincii 8052 to ferment the detoxified hydrolyzate, the result from good to bad were: Ca(OH)2> charcoal > charcoal + Ca(OH)2 > sodium sulfite and sodium dithionite. Although method of charcoal + Ca(OH)2 achieved the the greatest removal of inhibitors, but the residual components in the hydrolyzate have a bad impact on the anaerobic fermentation.Inhibitors, such as furfural and HMF, are removed by adding Ca(OH)2 under the condition of 110 rpm and 50 °C. The detoxified hydrolysate is fermented by C.beijerinckii 8052. Butanol production can reach the amount of 8.7 g/L which is 51.8%higher than that in the non-detoxified hydrolysate. In order to make C. beijerinckii 8052 consume more sugar and produce more butanol, UV mutagenesis is used to isolate mutants. A mutant named CM20 is obtained after 20 rounds of consequent mutagenesis. It is able to consume 14% more sugar than the parental strain. CM20 produces 19 g/L of ABE(acetone, butanol and ethanol), including 10.8 g/L of butanol using detoxified carbohydrate of corn stover.And we also find that fermentation with C.beijerinckii 8052 under blowing of CO,the ratio of products(butanol:ethanol:aceton) change significantly.