Antifungal Activity of Lactobacillus plantarum and Lactobacillus fermentum Isolated from Agadagidi and Ogi against Spoilage Fungi of Plantain

Background: There has been an increase in public health concern over post-harvest spoilage fungi in plantain. This study aimed to explore the role of Lactic Acid Bacteria (LAB) from fermented foods against spoilage fungi of plantain. Methods: Seventy-five LAB were isolated from agadagidi and ogi between February and April 2021. Cell-Free Supernatants (CFS) of the broth cultures were obtained by centrifugation. Spoilage fungi were obtained from plantain with visible mould growth. Initial screening of the LAB isolates for antifungal activities was carried out using the agar overlay method. The agar well diffusion method was used to assay the inhibitory spectrum of the CFS. Data obtained for the inhibition diameters were analysed using descriptive statistics (IBM SPSS 22). LAB isolates with the highest antifungal activity were assessed for their safety via the DNase, gelatinase, and haemolysis tests, and were identified by 16S rRNA sequencing. Results: Twenty-six LAB isolates exhibiting antifungal activity were obtained from the samples. The isolated spoilage fungi included Aspergillus flavus, Fusarium oxysporum, Fusarium verticilliodes, Penicillium sp, and Rhizopus sp. Nine of the 26 LAB isolates produced inhibition zones >14 mm in diameter. The CFS of isolate 5AG8 had antifungal activity against the spores of A. flavus, F. oxysporum, and Penicillium sp. The CFS of isolate AG1 inhibited the mycelial growth of F. verticilliodes and Penicillium sp, while the CFS of isolate OP was active against the spores of A. flavus and Penicillium sp. None of the isolates tested positive in the safety assessment tests. The isolates were identified as Lactobacillus plantarum OP, L. plantarum AG1, and Lactobacillus fermentum 5AG8. Conclusion: This study revealed that LAB strains from agadagidi and ogi are safe for use in food matrices and their metabolites can be used in the control of spoilage fungi in plantain.