The present study evaluated the cultural and functional characteristics of six strains of acetic-acid bacteria (AAB), namely, GHUR-A11-2, SR-A24, GY-A26, GHF-A37, JS-B7, and JS-C1, which were isolated from farm-made fermented vinegars. The six bacterial strains exhibited high acetic acid production capability via the decomposition of CaCO 3 , and they were identified as Acetobacter pasteurianus based on the 16S rDNA sequences. The initial pH and optimal growth temperature for acetic acid production were determined to be 4.0 and 30℃, respectively; however, some strains of AAB presented reasonable growth even at 40℃. Four bacterial strains (except SR-A24 and GHF-A37) exhibited alcohol degradation activities of more than 90%. Bacillus cereus presented high susceptibility to the antibacterial activity of the six strains of AAB. The antioxidant activity evaluated using DPPH and ABTS was 5-15 times and 4-5 times higher for the six strains of AAB than that for the control group, respectively. GHUR-A11-2, SR-A24, and JS-C1 exhibited higher ACE activities, with inhibition rates of 154%-175%, as compared to those exhibited by the positive control of 0.1% captopril (inhibition rate of 138%). Furthermore, the fibrinolysis activity of SR-A24 (93.3%) was markedly higher than that of 0.5 U plasmin. Four bacterial strains (except GHF-A37 (75.3%) and JS-B7 (68.0%)), exhibited α-glucosidase inhibition activities of more than 100%. It was concluded that the six strains of AAB exhibited excellent physiologically active characteristics, which facilitated their use as seed strains for the synthesis of high-efficiency functional vinegar by harnessing the functional characteristics that fit the scientific basis.

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 °C. 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 α-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.

Traditional grain vinegar is fermented using multiple acetic acid bacteria (AAB) at various temperatures. A single AAB showed high acid-producing ability at 30 °C with a 5% alcohol concentration and an initial pH adjusted to 4.0. Multiple AAB were similar to a single AAB; however, the optimal initial pH was 3.0. Acid production ability according to the type of AAB was higher in multiple AAB than in single AAB. That is, using multiple AAB helped increase the titratable acidity of traditional grain vinegar. In addition, increasing the titratable acidity and content of volatile flavor compounds was advantageous when two, rather than four, AAB types were mixed and used. The titratable acidity was high at medium temperatures (30 °C); however, volatile flavor compounds increased at low temperatures (20 °C) under multiple AAB. A 16S rDNA-based microbiome taxonomic profiling analysis identified differences in beta diversity due to multiple AAB and fermentation temperatures. In particular, beta diversity analysis revealed a specific pattern when a mixture of Acetobacter ascedens GV–8 and Acetobacter pasteurianus GV–22 was fermented at a low temperature (20 °C). Therefore, we propose the application of multiple AAB with acidic and flavor-producing properties in traditional grain vinegar.

This study was conducted to evaluate the alcohol-producing abilities and functional characteristics of five strains of non-Saccharomyces cerevisiae (NSC), namely, Kluyveromyces marxianus KJ-L, Wickerhamomyces anomalus KJ-1, W. anomalus CP-2, Pichia anomalus HAN-1, and Meyerozyma guilliermondii SU-L, which were isolated from Korean traditional nuruk. The selected yeast strains produced large amounts of alcohol using a carbon source of 20% glucose and were identified as NSC based on their 18S rDNA sequences. The optimal growth temperature and pH of the NSC except for M. guilliermondii SU-L were 25°C and 4.0, respectively. Two NSC strains, KJ-L and CP-2, produced 5–10% more alcohol compared to that produced by S. cerevisiae LP (SC LP) control. Although the α-amylase and ß-glucosidase activities were slightly lower in the NSC strains than in the SC LP, glucoamylase activity was 1.4-fold higher in the NSC strains than in the SC LP. The α-glucosidase inhibition activity evaluated using 1% acarbose was 29-fold higher for K. marxianus KJ-L and P. anomalus HAN-1 than that of SC LP. The five strains of NSC exhibited higher angiotensin-converting enzyme inhibitory activity with inhibition rates of 51.7–61.7% compared to that of SC LP (37.3%). The tyrosinase inhibition activities of NSC (86.4-91.5%) and SC LP (94.9%) were significantly higher than that of the positive control, kojic acid. These NSC yeast show high potential for industrial application as domestic starters for manufacturing fermented foods and cosmetics based on their physiological activities and functional characteristics.

Fungi were isolated and identified from nuruk produced in six regions, and the growth characteristics and various physiological functions of the five selected strains were investigated. These fungi exhibited optimum growth characteristics at 28-35°C and pH 5, and were acid resistant. The antibacterial activity of the five fungi against four types of harmful bacteria was determined using Salmonella typhimurium (57.9-71.4%) and Staphylococus aureus (57.5-70.0%), respectively. The antihypertensive activity showed ACE inhibitory activity of 98.9-99.6% and relatively high thrombolytic activity of 84.7-91.9%, compared to the positive control. The antidiabetic effect of five strains of the fungus showed α-amyloglucosidase inhibitory activity ranging from 20.4 to 26.6% of 0.5% acarbose. The fungi (Lichtheimia ramosa KJ-WF, Aspergillus oryzae SU-Y, and Lichtheimia panacisoli SU-BF) were confirmed to reduce the production of two or more types of cytokines by treating Raw 264.7 cells with LPS. In particular, Lichtheimia panacisoli SU-BF exhibited the best anti-inflammatory effect. Therefore, the five strains of fungus showed potential to be used as a functional material in food manufacturing and pharmaceuticals industries.