Isolation and characterization of three <i>Lactiplantibacillus plantarum</i> strains with high activity and broad antifungal spectrum

The introduction of lactic acid bacteria (LAB) to treat mycoses can be a natural alternative to chemical antifungal agents. This research aims to screen and characterize the antifungal properties of LAB isolates that have been collected from food against fungal species involved in human mycoses. 300 LAB isolated from 35 distinct biotopes were tested in vitro for antifungal activity against six different fungi. Among these, three LAB strains, designated in this study, 2GP, 4FB, and 10SB demonstrated effective antifungal activity and showed the ability to grow under varying pH (3–11), temperature (20–45°C), and sodium chloride concentrations (0–8%), are identified as <i>Lactiplantibacillus plantarum</i> by rDNA16s gene sequencing. They were further subjected to various treatments to identify the nature of the antifungal substances they produced, by measuring the diameter of the zone of inhibition, which decreased from 19.333±1.528 mm to 4.333±1.155 mm for 2GP, from 20.667±1.155 mm to 5±1 mm for 4FB, and from 19.667±2.082 mm to 5.667±1.155 mm for 10SB. Their cell-free supernatant (CFS) enzymatic treatment and its analysis by FTIR, UV-visible as well HPLC-UV revealed the production of various active compounds, including organic acids, peptide compounds, and hydrogen peroxide. Additionally, scanning electron microscopy (SEM) showed that these strains caused damage to filamentation, biofilm formation, and yeast cell morphology. The results obtained suggest that the antifungal activity of these three LAB strains can offer a biological alternative to treat fungal diseases including those due to <i>Candida albicans</i>, by applying their CFS.