Convertion Of Corncob Into2,3-butanediol Production By Klebsiella Oxytoca

2,3-Butanediol has a wide range of industrial applications, such as being used as a chemical intermediate for the productions of printing inks, perfumes, fumigants, moistening and softening agents, explosives and plasticizers, and as a carrier for pharmaceuticals. Facing shortage of crude oil supply and sharply rising oil prices biological production of2,3-butanediol from abundant and available biomass has become one of the worldwide focuses. Corncob as an abundant lignocellulosic resource can be used in2,3-butanediol production by microbial fermentation. Dilute acid hydrolysis is a favourable method for the conversion of lignocellulose to sugars, especially for hemicellulose to xylose. Cellulase can degrade cellulose to xylose. Klebsiella oxytoca can use glucose and xylose produce2,3-butanediol by fermentation.In this article, pretreatment and enzymolysis of corncob in high substrate concentration were studied. The results show that:the best ratio of solid to liquid was1:3in the pretreatment, and0.25g xylose can be obtained after1g corncob pretreatment, the hemicellulose degradation rate was67.64%. The the best of solid to liquid was1:4during enzymatic hydrolysis. Concentration of glucose and xylose were60.46g/L and64.28g/L respectively. Cellulose hydrolysis rate and hemicellulose hydrolysis rates were74.93%and69.57%respectively.Effect of acetic acid, furfural and5-hydroxymethylfurfural on production of2,3-butanediol by Klebsiella oxytoca was studied. The metabolites of furfural and5-hydroxymethylfurfural were measured. The results show that when acetic acid, furfural and5-hydroxymethylfurfural was individually added, tolerance threshold for Klebsiella oxytoca was30g/L,4g/L and5g/L, respectively. Acetic acid was likely used as substrate to produce2,3-butanediol. The yield of2,3-butanediol increased when acetic acid concentration was lower than30g/L In the fermentation, more than70%5-hydroxymethylfurfural was converted to2,5-furandimethanol. All furfural and the rest of5-hydroxymethylfurfural were metabolized by Klebsiella oxytoca. It showed that in the detoxification process of2,3-butanediol production using lignocelluloses hydrolysate, furfural should be given priority to remove and a certain concentration of acetic acid is not need to removal.The effect of the combination of acetic acid, furfural and5-hydroxymethylfurfural(HMF) on2,3-butanediol fermentation of Klebsiella oxytoca was studied by statistical analysis. A central composite design was used to investigate the influences of these compounds on2,3-butanediol yield and biomass formation. Two models were developed for describing the effect of the combination of acetic acid, furfural and5-hydroxymethylfurfural on biomass and product yield in2,3-butanediol fermentation. The proposed model is suited to fit experimental data and to simulate the cell growth and2,3-butanediol yield, which was confirmed by2,3-butanediol production using the real hydrolysate as substrate.Use corncob which after the pretreatment and enzymatic hydrolysis to produce2,3-butanediol by Klebsiella oxytoca. Two higher concentration of2,3-butanediol were obtained. The concentration of2,3-butanediol were38.7g/L and37.38g/L in two groups of test.