Bioprotection of Zea mays L. from aflatoxigenic Aspergillus flavus by Loigolactobacillus coryniformis BCH-4

Fungal infection causes deterioration, discoloration, and loss of nutritional values of food products. The use of lactic acid bacteria has diverse applications in agriculture to combat pathogens and to improve the nutritional values of cereal grains. The current research evaluated the potential of Loigolactobacillus coryniformis BCH-4 against aflatoxins producing toxigenic Aspergillus flavus strain. The cell free supernatant (CFS) of Loig. coryniformis was used for the protection of Zea mays L. treated with A. flavus. No fungal growth was observed even after seven days. The FT-IR spectrum of untreated (T1: without any treatment) and treated maize grains (T2: MRS broth + A. flavus; T3: CFS + A. flavus) showed variations in peak intensities of functional group regions of lipids, proteins, and carbohydrates. Total phenolics, flavonoid contents, and antioxidant activity of T3 were significantly improved in comparison with T1 and T2. Aflatoxins were not found in T3 while observed in T2 (AFB1 and AFB2 = 487 and 16 ng/g each). HPLC analysis of CFS showed the presence of chlorogenic acid, p-coumaric acid, 4-hydroxybenzoic acid, caffeic acid, sinapic acid, salicylic acid, and benzoic acid. The presence of these acids in the CFS of Loig. coryniformis cumulatively increased the antioxidant contents and activity of T3 treated maize grains. Besides, CFS of Loig. coryniformis was passed through various treatments (heat, neutral pH, proteolytic enzymes and catalase), to observe its stability. It suggested that the inhibitory potential of CFS against A. flavus was due to the presence of organic acids, proteinaceous compounds and hydrogen peroxide. Conclusively, Loig. coryniformis BCH-4 could be used as a good bioprotecting agent for Zea mays L. by improving its nutritional and antioxidant contents.