Antioxidant Activity and Other Characteristics of Lactic Acid Bacteria Isolated from Korean Traditional Sweet Potato Stalk Kimchi

The aim of this study was to examine the biological activity and probiotic properties of lactic acid bacteria (LAB) isolated from sweet potato stalk kimchi (SPK). Various LAB and <i>Bacillus</i> spp. are active in the early stages of the fermentation of kimchi made from sweet potato stalk. Four strains of LAB were identified, including SPK2 (<i>Levilactobacillus brevis</i> ATCC 14869), SPK3 (<i>Latilactobacillus sakei</i> NBRC 15893), SPK8 and SPK9 (<i>Leuconostoc mesenteroides</i> subsp. <i>dextranicum</i> NCFB 529). SPK2, SPK3, SPK8, and SPK9 showed 64.64-94.23% bile acid resistance and 78.66-82.61% pH resistance. We identified over 10⁶ CFU/mL after heat treatment at 75 °C. Four strains showed high antimicrobial activity to <i>Escherichia coli and Salmonella</i> Typhimurium with a clear zone of >11 mm. SPK2 had the highest antioxidative potentials, higher than the other three bacteria, with 44.96 μg of gallic acid equivalent/mg and 63.57% DPPH scavenging activity. These results demonstrate that the four strains isolated from sweet potato kimchi stalk show potential as probiotics with excellent antibacterial effects and may be useful in developing health-promoting products.