Anlysis Of Bacteria Dynamic Laws And Flocculation Of Lactic Acid Bacteria In Natural Fermentated Sweet Potato Sour Liquid

The sweet potato sour liquid is produced in the natural fermentation process of fans or starch and it is a kind of microbial flocculant.Adding sour liquid in the process of starch production can accelerate the separation of starch and protein.However,traditional sour liquid produces starch is mostly by experience,is often affected by some conditions.So,the quality of sour liquid is very unstable,to a certain extent affect the yield and quality of starch production.Therefore,understanding the influencing factors of fermented sour liquid,grasp the microflora structure of natural fermented sweet potato sour liquid,to improve the quality of sour liquid,develop microbial flocculant,reduce the use amount of sour liquid,solve the problem of environmental pollution are very significant.This study used natural fermented sweet potato sour liquid as the research object,using high throughput sequencing method analysised bacterium dynamic laws of different fermentated periods sour liquid and relationship between various bacterium and sour liquidfermentation.The results showed that:The bacteria from natural fermentated sweet potato sour liquid mainly included Firmicutes 92.6%,Proteobacteria 3.6%and Cyanobacteria 3.4%.In the Firmicutes,Lactobacillus 55.3%,Leuconostoc 23.8%and Bacillus 2.9%were the dominant bacterium;In the Proteobacteria,the dominant bacteria was Pseudomonas 2.0%.Therefore,Lactobacillus was the dominant bacteria in sweet potato sour liquid,Leuconostoc was the second dominant bacteria.With the prolonging of fermentation time,the content of Lactobacillus decreased at first and then increased,and the lowest at the middle stage of fermentation.While the content of Leuconostoc increased at first and then decreased,the highest in the middle of fermentation,and the rate of flocculation in the middle of the natural fermentation of sweet potato sour liquid was the highest,so Leuconostoc was the dominant flocculating bacteria in natural fermented sweet potato sour liquid.According to the results of bacterium dynamic laws in natural fermentated sweet potato sour liquid,isolated and identified bacterium that had flocculability,and verified its function.The results showed that 55 suspected lactic acid bacteria were isolated from the natural fermentatedin sweet potato sour liquid,gram staining were all positive and hydrogen peroxide enzyme reaction were all negative,55 strain was preliminary identified lactic acid bacteria.According to 16SrDNA sequence identification,all were Leuconostoc.Among them,Leuconostoc mesenteroides 76.36%,Leuconostocpseudomesenteroides 20%,Leuconostoc sp.3.64%.Leuconostoc mesenteroides was the dominant bacteria of the whole process of sour liquid fermentation,Leuconostoc mesenteroides was the dominant bacteria when flocculating rate was the highest.