Determination of fermentation conditions of Streptomyces sp. VNUA116 to improve the antifungal activities against Fusarium oxysporum f. sp. cubense causing Panama wilt disease on banana plants

Abstract

This study aims to identify medium components (carbon source, carbon concentration, nitrogen source) and fermentation conditions (temperature, pH) to enhance the resistance against Fusarium oxysporum f. sp. cubense Tropical Race 4 (Foc Tr4), causing Panama wilt disease of Streptomyces sp. VNUA116 (VNUA116). By using the agar well diffusion method, it was determined that strain VNUA116 has strong anti-fungal pathogen activities Foc Tr4 under fermentation nutrients: YIM 301 medium, carbon source CB1 (soluble starch 40 g/l: D-glucose 1 g/l, and nitrogen source N1 beef extract 3 g/l: yeast extract 5 g/l: peptone 3 g/l). Additionally, optimal fermentation conditions were established, including pH 7, and
temperature 30^oC. Strain VNUA116 exhibited the highest antifungal activity, reaching a diameter of 30.67±0.58 mm after 10 days of cultivation. Furthermore, under these optimised fermentation conditions, Streptomyces sp. VNUA116 demonstrated an impressive inhibitory capability against Foc-Tr4, reaching up to 93.20%, equivalent to the concentration of the fungicide Ridomil gold 68WG at 3 g/l in laboratory conditions. This affirms
the considerable potential of the VNUA116 strain for applications in the production of biofertilizers for the biological control of Panama wilt disease in banana plants.