Quality and Functional Characterization of Acetic Acid Bacteria Isolated from Farm-Produced Fruit Vinegars

Acetic acid bacteria (AAB) form a bacterial film on the surface of alcoholic solutions and ferment ethanol to acetic acid while also producing bioactive compounds. To discover functional AAB for industrial use, we isolated and selected strains from farm-produced vinegars using a CaCO3-containing medium. The seven isolated strains belonged to Acetobacter cerevisiae and Acetobacter pasteurianus. These strains were tolerant to ethanol concentrations up to 12% (v/v). Acidification was seen for GHA 7, GYA 23, JGB 21-17, and GHA 20 strains at a growth temperature of 40 ?. The seven AAB isolates had strong antibacterial activity against Staphylococcus aureus. Antioxidant activity, as assessed using the DPPH and ABTS assays, was two- and four-fold higher than that for the negative control (1% acetic acid), respectively. We also observed 91.3% inhibition of angiotensin-converting enzyme activity for the KSO 5 strain, which was higher than that for the positive control, 0.1% captopril (76.9%). All strains showed complete inhibition of a-glucosidase, except JGB 21-17 and GHA 7, which showed 98.3% inhibition. Our work suggests the usefulness of the selected strains as seed strains for the highly efficient production of functional vinegar and illustrates the identification of useful functional characteristics on a scientific basis.