Weissella cibaria is one of the bacteria in charge of the initial fermentation of kimchi and has beneficial effects such as immune-modulating, antagonistic, and antioxidant activities. In our study, we aimed to estimate the safety of W. cibaria JW15 for the use of probiotics according to international standards based on phenotypic (antibiotic resistance, hemolysis, and toxic metabolite production) and genotypic analysis (virulence genes including antibiotic resistance genes). The results of the safety assessment on W. cibaria JW15 were as follows; (1) antibiotic resistance genes (ARGs) (kanamycin and vancomycin etc.) were intrinsic characteristics; (2) There were no acquired virulence genes including Cytolysin (cylA), aggregation substance (asa1), Hyaluronidase (hyl), and Gelatinase (gelE); (3) this strain also lacked β-hemolysis and the production of toxic metabolites (D-lactate and bile salt deconjugation). Consequently, W. cibaria JW15 is expected to be applied as a functional food ingredient in the food market.

The production of good Meju soybean paste primarily depends on the selection of raw materials and fermenting microorganisms, which together influence its characteristic metabolites, taste, and aroma. In this study, we analyzed the relationship between properties and metabolites in Meju samples fermented by Aspergillus oryzae alone or with Bacillus velezensis. We developed fast-stable processing techniques to obtain Meju from A. oryzae and B. velezensis using the inoculation method, thereby ensuring safety in the production of soybean paste. The amino-type nitrogen content increased from an initial 180–228 mg% to a final 226–776 mg% during fermentation and was higher in Meju inoculated separately with the fungi and bacteria (C group) than in Meju co-inoculated with both the starters concurrently (D group). The levels of metabolites such as glucose, myo-inositol, glycerol, and fatty acids (palmitic, stearic, oleic, and linoleic acids) in Meju fermented by A. oryzae with B. velezensis were higher than those in Meju fermented by A. oryzae alone. Fungal growth was affected by the inoculated bacteria, which often occurs during the fermentation of co-inoculated Meju.

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.

The fermentation of traditional vinegar is a spontaneous and complex process that involves interactions among various microorganisms. Here, we used a microbiome approach to determine the effects of networks, such as fermentation temperature, location, physicochemical and sensory characteristics, and bacterial profile, within traditional grain vinegar samples collected from various regions of Korea. Acetic acid and lactic acid were identified as the major metabolites of grain vinegar, and sourness and umami were determined as taste fingerprints that could distinguish between vinegar samples. Acetobacter ghanensis and Lactobacillus acetotolerans were the predominant bacterial species, and the functional composition of the microbiota revealed that the nucleotide biosynthesis pathway was the most enriched. These results reveal that vinegar samples fermented outdoors are more similar to each other than vinegar samples fermented at 30 °C, when comparing the distance matrix for comprehending bacterial networks among samples. This study may help obtain high-quality vinegar through optimized fermentation conditions by suggesting differences in sensory characteristics according to the fermentation environment.

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 CaCO3, 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°C, respectively; however, some strains of AAB presented reasonable growth even at 40°C. 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.

Traditional yeast (Saccharomyces cerevisiae) has been used for its benefits in various fermentation processes; the benefits of non-Saccharomyces yeast as a material for food, feed, and pharmaceuticals have been studied recently. This study evaluated the anti-inflammatory activity and extracellular functional characteristics of wild-type yeasts isolated from traditional fermented foods (doenjang (common name: soybean paste) and nuruk) in Korea. The viability of the yeast and lipopolysaccharide (LPS)-stimulated RAWBlue™ cells was improved, similar to unstimulated RAWBlue™ cells, and the isolates demonstrated NF-κB inhibitory activity. Yeast suppressed the nitric oxide production in LPS-stimulated RAWBlue™ cells, which was attributed to the inhibition of iNOS or COX-2 mRNA expression depending on the strain. Although there were differences depending on the strain, the production of anti-inflammatory cytokines was reduced in the yeast and LPS-stimulated RAWBlue™ cells, some of which were demonstrated at the mRNA level. In addition, the isolates exhibited high antioxidant and antihypertensive activities (similar to the positive control), which varied depending on the strain. This suggests that yeast can be used for fermentation with enhanced antioxidant and antihypertensive activities. Furthermore, the isolates inhibited the growth of pathogenic Gram-negative bacteria, indicating that yeast can inhibit food spoilage and the growth of pathogenic bacteria during fermentation. Consequently, utilizing raw materials to cultivate yeast strains could be a promising avenue for developing functional foods to prevent and treat inflammatory reactions; such foods may exhibit antioxidant, antihypertensive, and antibacterial properties.