Study On Fermentative Production Of Succinic Acid From Sugarcane Bagasse

Succinic acid,as one of most important platform chemicals, has been widely used in food, agriculture, chemical industry and pharmaceutical industries etc. Sugarcane bagasse(SB) is the main by-product of sugar industry,and it is rich in large amounts of cellulose and hemicellulose. China has a wealth of sugarcane bagasse material resources asa large country of sugarcane planting, thus it has a very important practical significance to sdudy of fermentative production of succinic acid using SB as provides a new way of untillization of.cheap raw material. In this study, pretreatment of SB, enzymatic bydrolysis of pretreated SB(PSB), fermentative production of succinic acid with hydrolysate of pretreated SB(HPSB) and the reuse of SB residue(SBR) was studied. Specific results from this paper were showed as followed:First of all, comparing Na OH and H2SO4 pretreatment of SB, Na OH had the better effect in lignin removal and cellulose and hemicellulose retention rate. When the SB was pretreaed with 1% Na OH concentration, lignin removal rate of SB reached 93.3%, and the retention rate of cellulose and hemicellulose were 97.9% and 87.3%Second, the influence of cellulase, xylanase, glucanase and pectinase on hydrolysis of PSB was investigated and the condition of muti-enzyme complex hydrolysis were optimized Optimizing. The total reducing sugar could be 65.6 g·L-1 with a yield of 90% under the condition of 75 g·L-1 substrate concentration with 20 FPU.g-1 of cellulase, 85 U.g-1 of xylanase, 50 U.g-1 of β-glucanase and 20 U.g-1 of pectinase addition.Next, HPSB as a carbon source for succinic acid fermentation was investigated. Results showed: the optimum concentration of sugar and corn steep liquor for fermentation were 55 g·L-1 and 20 g·L-1. When fermentation was performed in a 3 L stirred bioreactor using Mg CO3 to control fermentation p H about 6.2, and 39.95 g·L-1 succinic acid concentration was achieved with a succinic acid yield of 0.82 g·g-1(reducing sugar) at 29 h. While fed-batch fermentation was carried out, 71 g·L-1 succinic acid concentration was achieved with a succinic acid yield of 0.81 g·g-1(reducing sugar) at 50 h with succinic acid productivity of1.42 g·L-1.h-1.Finally, reuse of SBR as the carriers to attach A. succinogenes during fermentation was studied. Succinic acid concentration was about 40 g·L-1 after three times of repeated batch fermentation with SBR concentration of 10 g·L-1. Na HCO3 could replace Mg CO3 as p H controlling for fermentation of succinic acid. When repeated batch fermentation in 3 L fermentor was performed 3 times, the average succinic acid concentration was 35 g·L-1with a succinic acid yield of 0.81 g·g-1and succinic acid productivity of 1.65 g·L-1.h-1, This indicated SBR could use in repeated batch fermentation by immobilization cells, so that saving seed cultivation operation.As in conclusion, SB is a promising raw material for succinic acid production.