| Alcohol culture is prevalent all over the world.Alcohol and alcohol products are widely shipped around the world.However,excessive intaking of alcoholic beverages can lead to epilepsy,fatty liver,stomach bleeding and other diseases,but also cause traffic accidents,violence and other social problems.Therefore,there is an urgent need of a product which is able to assist the body to rapidly degrade alcohol.The key to solving alcoholism lies in the breakdown of acetaldehyde into acetic acid by acetaldehyde dehydrogenase.At present,the anti-alcoholic products on the market are mainly aimed at enhancing people's immunity,limited by gene different distribution of acetaldehyde dehydrogenase in humans,and can not effectively solve the problem from the fundamental principle of alcoholism.There are studies found the presence of acetaldehyde dehydrogenase in some microorganisms,such as Lactobacillus,Acetobacter aceti and Yeast.Lactobacillus,as a probiotic,has a long history of being added to fermented milk to make probiotic fermented dairy products.This study is committed to finding the lactic acid bacteria being capable of expressing acetaldehyde dehydrogenase and domesticating it with acetaldehyde,which increases the expression of acetaldehyde dehydrogenase,and increases the activity of acetaldehyde dehydrogenase.After domestication,it will be applied to fermented dairy products to produce a probiotic dairy product which can efficiently dispel the effects of alcohol and relieve the discomfort of drinking probiotic in the human body.The main results are as follows:1)This study screened and isolated and did 16S rDNA sequencing to the Lactobacilli in natural environment and fermentation products.We found a Lactobacillus plantarum with acetaldehyde dehydrogenase gene ald H,and named it Lactobacillus plantarum YLA.The domestication of Lactobacillus plantarum YLA using the method of adding gradient concentrations of ethanol and acetaldehyde to the medium has enabled it to tolerate high concentrations of ethanol and acetaldehyde and maintain good growth at the same time.Presently,Lactobacillus plantarum YLA1 that can tolerate 7%(v/v)concentration of ethanol and 8‰(w/v)concentration of acetaldehyde was obtained.2)The activity of acetaldehyde dehydrogenase of YLA1was determined,a plant lactobacillus domesticated by acetaldehyde,and it has high-efficiency acetaldehyde dehydrogenase activity.This study also cloned the ald H gene in the YLA1 genome,constructed a recombinant plasmid carrier which can express acetaldehyde dehydrogenase,and transformed it to E.coli to obtain an E.coli strain with acetaldehyde dehydrogenase gene ald H.This study tested the transformed E.coli and the YLA1 for expression of acetaldehyde dehydrogenase,and the transformed E.coli can express acetaldehyde dehydrogenase,the YLA1 can express acetaldehyde dehydrogenase in large quantities when being in acetaldehyde pressure.3)Low pH tolerance determination was carried out on Lactobacillus plantarum YLA1,and YLA1 was able to tolerate a minimum pH of 2.5.When human takes food or water,gastric acid pH can be around 3.5 in stomach,proving that YLA1 can withstand the stomach acid environment in the human body and successfully reach the intestine and play a role.In this study,two fermented dairy products schemes were developed,including YLA1 mono-bacterial fermented acid milk and YLA1,Lactobacillus bulgaricus and Streptococcus thermophilus mixed-bacterial fermented yogurt.The determination of the number of live bacteria was carried out on Lactobacillus plantarum YLA1 in fermented acid milk.We found that YLA1 remained highly active within 19 days of being refrigerated at 4?,and the number of live bacteria can be kept above 4.3×10~7 CFU/m L.We set the shelf life of YLA1-adding mono-bacterial fermented acid milk at 19 days. |
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