Screening Of Oxytolerant Butanol Producing Bacteria And Efficient Conversion Of Liquor Grains To Produce Butanol

At present,there are the main problems in the production of butanol by biological fermentation:?1?Strains are strictly anaerobic,which is not conducive to production operations,and the deoxygenation process leads to increased production costs;?2?Butanol output and yield are low;?3?It is produced using grain-based raw materials and has a relatively high cost.This research starts from obtaining oxygen-resistant butanol-producing bacteria,increasing butanol production and yield,using cheap distiller's grains as raw materials,and improving fermentation technology.The in-depth research is intended to solve the above problems.A butanol-producing strain with oxygen-resistant ability and stable properties was isolated from the Luzhou-style cellar mud.After 16S rDNA identification,the strain was named Clostridium beijerinckii LY-5.Through single factor test,temperature optimization of C.beijerinckii LY-5 was carried out,and it was determined that anaerobic and anaerobic fermentation had no significant effect on the final yield of butanol produced by C.beijerinckii LY-5;from simple operation,high butanol production and equipment utilization Considering the high rate,the fermentation method of C.beijerinckii LY-5 was determined to be oxygen-resistant fermentation at34?for 4 days,and the final butanol production was 12.5 g/L.Through the Plackett-Burman test,it is concluded that the changes in the content of glucose,peptone,and magnesium sulfate heptahydrate have a significant effect on the production of butanol,and the degree of the effect decreases in turn.The data of the central compound test was used to build a model of the neural network,and the genetic algorithm was used to find the optimal solution,and the optimal content of glucose,peptone,and magnesium sulfate heptahydrate was 85,4.3,and 0.18 g/L,butanol The yield is 13.8 g/L.It was verified through experiments that the actual butanol output was 13.6 g/L,which was an increase of 8.8%compared with that before optimization.The test results of the basic components of vinasse showed that the contents of lipids has the potential for the production of butanol by C.beijerinckii LY-5 fermentation.Using 1:4?w/v?material-liquid ratio,according to the quality of vinasse,50 U/g?-amylase was added in turn to hydrolyze at 75?for 3 h,250 U/g saccharification enzyme was hydrolyzed at 60?for 3 h,250 U/g cellulase was hydrolyzed at 50?for 3 h.The concentration of reducing sugar in the hydrolysate was high and the yield was high,respectively 83.4 g/L and 29.8%.The vinasse hydrolysate was best treated with 20 g/L Ca?OH?₂ for 12 h and 20 g/L activated carbon for 6 h.Butanol output reached 4.8 g/L.Scanning electron microscopy results showed that C.beijerinckii LY-5 was degraded in the hydrolysate without pretreatment,and in the hydrolysate of vinasse after pretreatment,the cell shape remained intact.The inhibitor has a removal effect.According to the growth curve of C.beijerinckii LY-5,the optimal culture time of C.beijerinckii LY-5 under oxygen-resistant environment is 21 h.The yield of C.beijerinckii LY-5 fermented butanol in distillers grain hydrolysate was 4.7 g/L.Butyric acid fermentation was added to the distillers grain hydrolysate and co-cultivated with C.butyricum.The yield of butanol was 4.9 and 5.4 g/L,respectively increased by 4.3%and 14.9%.C.beijerinckii LY-5 can improve the yield of butanol when co-cultured with distillers grain hydrolysate and C.butyricum.