In vitro antifungal,probiotic and antioxidant properties of novel Lactobacillus plantarum K46 isolated from fermented sesame leaf

This study aimed to describe the diversity of antifungal lactic acid bacteria (LAB) in popular traditional Korean fermented food. A total of 22 LAB strains was selected and subjected to a monophasic identical approach using 16S rRNA gene sequence analysis. Antifungal LAB associated with fermented food was identified as Lactobacillus plantarum (9), Lactobacillus graminis (5), Lactobacillus pentosus (4), Lactobacillus sakei (2), Lactobacillus paraplantarum (1), and Leuconostoc mesenteroides subsp. mesenteroides (1). Novel Lactobacillus plantarum strain K46 exhibited comparatively better antifungal activity against several spoilage fungi, and was deposited in the Korean Collection for Type Cultures (KACC91758P). Antifungal substances from the spent medium in which K46 was cultivated were extracted with ethyl acetate. Antifungal activity was assessed using the broth micro dilution technique. Compounds were characterized based on infrared, ¹³C nuclear magnetic resonance (NMR), and ¹H NMR spectral data. The minimum inhibitory concentration (MIC) of the compounds against Aspergillus clavatus, Aspergillus oryzae, Penicillium chrysogenum and Penicillium roqueforti was 2.5 mg/mL and that against Aspergillus fumigatus, Aspergillus niger, Curvularia lunata and Gibberella moniliformis was 5.0 mg/mL. K46 was able to survive gastrointestinal conditions simulating the stomach and the duodenum passage with the highest percentage of hydrophobicity. In addition, its resistance to hydrogen peroxide and highest hydroxyl radical and 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging activities, with inhibition rates of 43.53 % and 56.88 %, respectively, were to its advantage. An antimicrobial susceptibility pattern was an intrinsic feature of this strain, thus consumption does not represent a health risk to humans. The results showed the potential of K46 strain as an antifungal, probiotic and antioxidant culture, and hence it was determined to be suitable for application in functional foods.