Co-culture Of Intestinal Bifidobacteria And Escherichia Coli Using Trehalose As Carbon Source

Bifidobacteria is a common probiotics,which can inhibit the growth of intestinal harmful bacteria and regulate body health.Escherichia coli is a common foodborne pathogen,Which can cause diarrhea,disturb the balance of intestinal flora,even endanger life health.In the intestinal microenvironment,Bifidobacteria and Escherichia coli can compete for the substrate carbon source,especially the nondigestible oligosaccharide food components.Trehalose is a nonreducing disaccharide linked by ?,?-1,1glycosidic bonds.Due to its appropriate food processing properties,trehalose is widely used in the food industry.However,there are few studies on the regulation of intestinal flora in structure by trehalose,especially the nutritional competition between intestinal bifidobacteria and Escherichia coli.Therefore,this paper is aimed to explore the competitive rejection of bifidobacteria and Escherichia coli when trehalose is used as carbon source.In this paper,Bifidobacteria breve?Bifidobacteria animal?Bifidobacteria lactics?Bifidobacteria bifidum?Bifidobacteria infantis and Escherichia coli were used as research objects to preliminarily explore the interaction mechanism between bifidobacteria and Escherichia coli.Then,Bifidobacteria infantis and Escherichia coli were used as research objects to study the competitive rejection of infant bifidobacteria to Escherichia coli when trehalose was used as carbon source,To explain the mechanism of them.The study showed that:(1)The supernatant of Bifidobacteria breve?Bifidobacteria animal?Bifidobacteria lactics?Bifidobacteria bifidum?Bifidobacteria infantis at 12 h,24 h and 48 h can inhibit the growth of Escherichia coli,and five kinds of supernatant of bifidobacteria at 48 h have the best effect on Escherichia coli.But the supernatant of Escherichia coli cultured for 12 h,24h and 48 h didn't inhibit the growth of bifidobacteria.(2)Microbial growth curve showed that 0.5%,1% and 2% concentration trehalose could promote the growth of bifidobacteria.The results of RT-q PCR showed that when trehalose was used as the only carbon source to culture bifidobacteria,bifidobacteria could grow well with trehalose.The number of bifidobacteria with 0.5% trehalose was the highest after 72 h of fermentation.Bifidobacteria proliferates rapidly when trehalose is added so that acetic acid is produced earlier.(3)Microbial growth curve showed that 0.5%,1% and 2% concentration trehalose could promote the growth of Escherichia coli.The results of RT-q PCR showed that when trehalose was used as the only carbon source to culture the Escherichia coli,the Escherichia coli could grow with trehalose,The number of Escherichia coli with 1% trehalose was hightest after 72 h of fermentation.Escherichia coli could produce acetic acid by trehalose proliferation,but the content of acetic acid was lower than that of the group without trehalose.(4)Microbial growth curve showed that when 0.5%,1% and 2% concentration trehalose were used for bifidobacteria and Escherichia coli co-culture,the bacteria in the co-culture system could use trehalose to grow well.RT-q PCR results showed that when trehalose was added,both Bifidobacteria and Escherichia coli proliferated in the co-culture system.However,In the first 12 h,Escherichia coli grew rapidly in the whole co-culture system,and the growth rate of Escherichia coli was higher than that of Bifidobacteria.After 12 h,bifidobacteria growed rapidly,and the growth rate of bifidobacteria was higher than that of Escherichia coli.There is competitive inhibition between them.Among them,the effect of 2% trehalose was best in promoting the growth of bifidobacteria in the co-culture system,followed by 1% trehalose and 0.5% trehalose.Due to the addition of trehalose,the content of acetic acid in the fermentation broth of the co-culture system was higher.(5)When trehalose was the sole carbon source,with the concentration was 0.5%,1% and 2% to mono-culture and co-culture bifidobacteria and Escherichia coli,We found that the growth ability of co-culture group in Escherichia coli and bifidobacterial is the highest,the growth ability of monoculture group in Escherichia coli is the next > the growth ability of mono-culture group in Bifidobacteria is the last.As mentioned above,trehalose,as an oligosaccharide has the potential of prebiotics and can promote the proliferation of bifidobacteria and inhibit the growth of Escherichia coli,which has great significance for the treatment of diarrhea caused by Escherichia coli.