Screening Of High-temperature Resistance Bacteria Using Xylose To L-lactic Acid And Study On Lactic Acid Fermentation Of Corn Cob Hydrolysis Product

Xylose is widespread in forest and agricultural residues.Xylose can be fermented to L-lactic acid which is an effective exploitation of renewable materials.In this study,through strain screening method,two Thermophilus Bacteria strain L-8 and L-20 that can high-efficient convert xylose to L-lactic acid were obtained.Through single factor experiment on shaking flask fermentation,the conditions of fermentation were experimented.The Optimized fermentation condition determined that:the best xylose concentration is 8%,the suitable fermentation temperature is 52℃,the inoculum size is 10%,the inoculum age is 14h, the media value is 150ml/250ml,the CaCO₃ suitable quantity is 50g/L,fermentation time is 72 hours.In this study,the conditions of corn cob hydrolysis by dilute sulfuric acid were experimented too.The Optimized hydrolysis condition determined that:the concentration of dilute sulfuric acid of 2%,the hydrolysis reaction time of 30 min and and hydrolysis reaction temperature of 120℃and the ratio of solid/liquid of 1/10.Under the Optimized hydrolysis condition,the concentration of reducing sugar was 49.35g/L.Through thin-layer chromatography of corn cob hydrolysis,the main monosaccharide was xylose.After fermentation for 72 hours using corn cob hydrolysate,L-8 produced 67.06g of L-lactic acid/L, and the conversion rate respectively were 91.03%.