Extraction and Isolation of Antioxidant-Antibacterial Compounds From Lactobacillus casei Strain K1C by Thin-Layer Chromatography

Background: Nowadays, searching for natural bioactive compounds with potential use in food industries is a major issue. Because of simple purification, natural compounds from microbial sources attract more attention. These encompass antioxidant and antibacterial materials derived from probiotics. Methods: In this study, Lactobacillus strains were isolated from kefir specimens. The antioxidant and antibacterial activity of the methanol extract of the supernatants was determined using 2, 2-diphenyl-picyril hydrazil (DPPH) and minimum inhibitory concentration (MIC) methods, respectively. In order to increase the antioxidant properties, a minimum medium fermented aerobically was used. Results: Antibacterial activity of Lactobacillus supernatant increased against E. coli ATCC 11303 in case of minimum medium (25.32 mg/mL) compared to MRS broth (32 mg/mL); however, aerobic condition decreased antibacterial production (65.44 mg/mL). After fractionation by thin-layer chromatography (TLC), this value reached the highest level (500 mu g/mL). Production analysis at different times showed that maximum antibacterial activity was obtained in the middle of the logarithmic growth phase until the beginning of the stationary growth phase. The antioxidant traits increased significantly in minimum culture media and anaerobic condition (492.1 +/- 0.25 mu g/mL) compared to the similar condition in MRS broth (880.96 +/- 0.05 mu g/mL). The highest antioxidant production was observed in the stationary growth phase of the aerobically fermented minimum medium (266.82 +/- 0.17 mu g/mL). Conclusions: The findings of this study showed that the best antibacterial and antioxidant-producing isolate, L. casei strain K1C (accession no.: KU954559), could be useful as a natural preservative in food industries.

Automated summary

This study isolated Lactobacillus strains with antioxidant and antibacterial activity from kefir, with L. casei strain K1C identified as the best producer of these properties. This strain has potential for use as a natural preservative in food industries.