Isolation and identification of Lactobacillus plantarum 4F, a strain with high antifungal activity, fungicidal effect, and biopreservation properties of food

A total of 270 lactic acid bacteria (LAB) was isolated and screened for their antifungal activity against Penicillium expansumMUCL2919240. Fourteen isolates showed wide antifungal spectrum against seven molds involved in food spoilage. Among these, three LAB strains named 4F, 4JC, and 3MI3 were selected for their high activity and broad antifungal spectrum. To identify these isolates, API CH50 and 16S rRNA gene sequencing were performed. Results showed that 4F and 4 JC were identified as lactobacillus plantarum and 3MI3 as lactobacillus paracasei. Various treatments of Cell‐free supernatant (CFS) from LAB showed that the inhibitory effect was due to proteinaceous substances, organic acids, and hydrogen peroxide. Scanning electron microscope (SEM) was carried out to assess the effects of CFS on the morphology of fungi. Efficacy of the CFS as biopresevative in tomato paste, bread, black olives, and grapes was tested and showed fungal inhibition suggesting its use in different food technologies. Practical applications Food spoilage caused by molds and yeasts represents an important issue in industries. The preservation of these products is done through the use of chemicals that are harmful. And with the trend toward the consumption of natural products and the demand for clean labels it becomes essential to research natural preservative. In our study we report the improvement of quality and shelf life of tomato paste, bread, black olives, and grapes using antifungal lactobacillus plantarum 4F against Penicillium expansum and Aspergillus fumigatus, by producing antifungal substances that cause mycelial breakage of target mold.