| Douchi is famous for its abundant nutrition, attractive fragrance, unique flavorand other features all over the world. What’s more, it has gradually been as dietarysupplements products by many people as its physiological function, such asantioxidant, antithrombotic, antidiabetics, lowering blood pressure. It comes to lightthat microorganism is the most critical factor in affecting the nutrition and the flavorof different Douchi. Therefore, further exploration of the microbial composition andits characteristics in Douchi is of great significance for the development offunctional Douchi or other fermented products.In this study, we applied traditional microbial technology to isolate the bacteriafrom “Dao Xiang Yuan” Douchi and evaluated their effect on fermentation processof Douchi, then we adopted vivo experiment to verify that all strains are safe foradministration. At last, in order to screen the potential probiotics from naturalfermented food, we compared the biological properties of lactic acid bacteria (LAB)isolated from Douchi in various aspects.The sequencing results of the16S rDNA gene showed that14fermentativeisolates were obtained from Douchi.2strains were identified as Bacillus (Bacillussubtilis DC01, B. amyloliquefaciens DC02);5strains were Staphylococcus(Staphylococcus epidermidis DC07, S. gallinarum DC11, S. sciuri DC12,Staphylococcus sp DC13, S. warneri DC14);7strains belong to LAB (DC04andDC10were Pediococcus acidilactici; DC05, DC08and DC09were P. pentosaceus,DC03were Weissella paramesenteroides, DC06were Lactobacillus fermentum).To explore the effect of these bacteria on the organ of mice，we compared thedifference of the serum biochemical indexes between the control group and theexperimental group which was gavaged with2×108CFU/d bacteria dose. It turnedout that, almost all bacteria had no effect on the level of alanine aminotransferase(ALT), aspartate aminotransferase (AST), total bilirubin (TBIL), direct bilirubin(DBIL), creatinine (CREA), urea nitrogen (BUN), uric acid (UA), blood glucose (GLU), triglyceride (TG) and total cholesterol (TC), indicating the safe properties ofthose isolates from Douchi. However, Bacillus amyloliquefaciens DC02couldsignificantly (p<0.01) decrease the level of blood glucose (GLU) in mice afterintragastric administration. This strain is expected to be the potential strain for thetreatment of antidiabetics.The structure of intestinal flora in mice could be as another indicator to judgethe safety of these bacteria and as a powerful reference to screening probiotics. Theresults of viable counting method revealed that5Staphylococcus strains didn’texhibit any influence on the intestinal flora, but a part of bacteria strains isolatedfrom Douchi could improve it significantly with the potential of probioticperformance. The result of PCR-DGGE showed that P. pentosaceus (DC05andDC09) could also keep the balance of intestinal flora by improving the biodiversityindex (S and H’) of the total bacteria, Enterobacterium and Lactobacillus.For further exploring the LAB resources in Douchi, we investigated theproperties of acid resistance, bile salt resistance, acid producing ability, antibacterialability, salt and heat resistance among7strains of LAB, respectively.2strains ofPediococcus pentosaceus (DC05and DC09) were found to be the potential strainsfor further application.This study laid a powerful and experimental data support for the development offunctional Douchi with special flavor. It also provides a new thought to realize themodern production of the traditional Chinese food. |
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