Effects Caused By Exposing Saccharomyces Cerevisiae To Lactobacillus Plantarum Cell Wall In Ethanol Productivity

Compared with traditional fossil fuels,bioethanol has an advantage for being clean and renewable;and to make use of straw and other non-food agricultural waste biomass fermentation in producing bioethanol can also reduce the environmental pollution caused by the burning of these agricultural wastes.Therefore,it is of practical economic and social significance to study how to improve the efficiency of bioethanol fermentation and further increase ethanol production.However,industrial-scale bioethanol fermentation is not an absolute aseptic process.It is often accompanied by the contamination of bacteria such as lactic acid bacteria,resulting in a decline in the production of bioethanol,which in turn causes significant economic losses.Although there are various competitions among different kinds of microorganisms,there is active identification between them that can promote growth.Therefore,contaminated bacteria in bioethanol fermentation may also positively regulate bioethanol fennentation in some way.In this subject,in order to determine whether the cell wall contact of Lactobacillus plantaru,m can promote the efficiency of yeast ethanol production,it is added with the dead cells of Lactobacillus plantarum or its cell wall(the Lactobacillus plantarum cell wall contact group)and the dead cell protoplast of Lactobacillus plantarum(Lactobacillus cell wall limit)into the Saccharomyces cerevisiae culture system.And the pure culture of Saccharomyces cerevisiae was set as the control group.The growth of yeast,the yield of ethanol and the amount of residual sugar were measured to evaluate the ethanol production ability of yeast under different contact conditions.The results showed that compared with the limited contact group,the Saccharomyces cerevisiae biomass in Lactobacillus plantarum cell wall contact group decreased,but the final yield of ethanol was not significantly different,which indicated that the ethanol fermentation efficiency of the limited contact group was higher,and the lactobacillus cell wall might play a positive role in the bio-ethanol fermentation process.In addition,the changes in intracellular metabolites of Saccharomyces cerevisiae caused by Lactobacillus plantarum cell wall contact were studied by using the metabonomics based on gas chromatography mass spectrometry(GC MS),in order to explain the reasons for the increase of ethanol efficiency under contact.By using Principal component analysia(PCA),Partial least-squares-discriminant analysis(PLS-DA)and other data analysis methods,13 different metabolites of Saccharomyces cerevisiae related to the cell wall contact of Lactobacillus plantarum were identified,and the changes of these metabolites were expressed.As the content of short chain fatty acids is down,the content of amino acids and short peptides,which are involved in the protective function of sterols,is higher,which may be the stress response of Saccharomyces cerevisiae cells under acid stress and the inhibition of Lactobacillus plantarum metabolism.Finally,this paper simulates the batch fermentation to verify whether the cell wall of Lactobacillus plantarum is of practical significance to the positive regulation of Saccharomyces cerevisiae ethanol fermentation process.The results showed that in the case of adding Lactobacillus plantarum cell wall,Saccharomyces cerevisiae had higher bioethanol efficiency(the increase of bio ethanol production of single Saccharomyces cerevisiae),and higher ethanol tolerance,thus higher bio ethanol production.Through an orthogonal test,the survival rates of Saccharomyces cerevisiae cells under 10%ethanol stress were increased by 4.08%,24.98%and 34.85%,respectively,by adding xylose,Lactobacillus plantarum cell wall and adding xylose and Lactobacillus plantarum cell wall respectively.The positive regulatory mechanism of this new discovery indicates that the efficiency of bio ethanol fermentation in industrial production can be improved by controlling the proper degree of infection or artificially simulating the bacteria to a certain extent.At the same time,people's understanding of the interaction and co-evolution of the bacteria can be improved.