Bio-preservative potential of lactic acid bacteria metabolites against fungal pathogens

Bio-preservative potential of the secondary metabolites produced by lactic acid bacteria (LAB) isolated from fermented cassava was assessed against fungal pathogens associated with spoilage of fresh fruits and vegetables. Twenty LAB isolates were identified according to standard morphological and biochemical methods and ten were subjected to phenotypic and genotypic identifications. The metabolites produced were tested for anti-fungal activity using agar-dilution and agar-well diffusion methods. The metabolites were used as sanitizers and biopreservatives by applying them on fresh fruits and vegetables for inhibition of the growth of spoilage fungi and extension of shelf-life. The LAB isolates were identified as Lactobacillus pentosus strains PIS23 and Reyan20, Lactobacillus plantarum strains PON10014, CTBRBL268 and N3114, Lactobacillus brevis strain NS25, Lactobacillus delbrueckii strain NS9, Lactobacillus fermentum strain NS9, Lactococcus lactis strain NS32 and Leuconostoc mesenteroides strain NS73. When fresh fruits and vegetables were inoculated with the metabolites, there was strong inhibition of the radial growth and spores of the fungal pathogens. This study shows that metabolites from fermented cassava are a good source of lactic acid bacteria with the ability to inhibit wide range of spoilage fungi, and can be employed in prolonging the shelf-life of fresh fruits and vegetables.