Antibacterial Effect Of Vinegar Pei And Interactions Among Dominent Microbes In The Acetic Acid Fermentation Of Zhenjiang Aromatic Vinegar

The production process of Zhenjiang aromatic vinegar is divided into three main processes, namely alcohol fermentation, acetic acid fermentation, and finally storage and aging before bottling. The phase of acetic acid fermentation not only is a process that acids and flavor substances are produced incrementally by the microbial community, but also a process that solid-state fermentation is carried out in semi-open state including multi-species. Ongoing of the process safely and stably is very closed the interaction of the members of the microbial community. In this master thesis, firstly, the agar diffusion method is used to test the effect of culture supernatants of 24 microbes isolated from the fermentation culture and water extract of fermentation culture to 4 environmental microbes. Secondly, the interactions about the 2 acetic acid bacteria and 8 lactic acid bacteria are preliminary investigated by using culture-dependent mothod in un-situ or situ imitated state, respectively. The main contents are as follows:1) The growth of four environmental microbes,namely Escherichia coli, Shigella sp., Staphylococcus aureus and Listeria monocytogenes, are significantly inhibited by culture supernatants of 24 microbes and water extract of fermentation culture. The culture supernatants of microbes from the genera of Acetobacter and Lactobacillus have the strongest inhibition effect amount all the culture supernatants of 24 microbes. And the inhibition effect of water extract of fermentation culture is stronger along with the process.2) Futher, the antibacterial characteristics are analyzed by treat the 48 hours culture supernatants of Acetobacter pasteurianus, A. pomorum, Lactobacillus helveticus and L. plantarum in different ways. And the antibacterial activity of the 48 h culture supernatants are decline in different degrees by heat treatment, protease treatment and dialysis treatment. Compared with the 48 h culture supernatants, the antibacterial activity of equal amount of acids samples are lower. Hence different types of components, including acids, bacteriocins and other potential substances less than 8000 Da, are accumulated in acetic acid fermentation phase and contribute to the antibacterial activities of fermentation culture and microbes.3) Althought the 2 acetic acid bacteria and 8 lactic acid bacteria can co-exist stably, the interaction type chang in different cultivation state. The relationships are positive between A. pasteurianus and L. helveticus, L. plantarum or L. reuteri, respectively, but the effect is negative between A. pasteurianus and L. pontis. While the interaction is negative between A. pomorum and L. paracasei, and the relationships are slight positive between A. pomorum and L. fermentum, L. hilgardii, respectively.4) The volatile components of culture supernatants from the single and co-culture samples are analyzed by GC-MS mothod in situ simulated state. The result show that 2, 3-butanedione is only detected in the co-culture but the single culture. And the content is up to 9.87 and 14.28 mg×L-1.