Antifungal potential of eco-friendly chitosan-sodium benzoate to inhibit the development of Rhizopus stolonifer isolated from jackfruit

Jackfruit (Artocarpus heterophyllus L.)) is prone to be attacked by various pathogens during the postharvest stage, mainly by fungi of the Rhizopus genus that cause the disease known as soft rot, causing large pre- and post-harvest losses. Normally, R. stolonifer is controlled by using synthetic fungicides that have noxious effects that are detrimental to jackfruit consumption. Natural substances considered as Generally Recognized as Safe have potential fungicidal activity and serve as alternative green fungicides. In this study, the antifungal activity of chitosan (Chi) and sodium benzoate (SB) was investigated individually or in combination at different concentrations, evaluating mycelial growth, sporulation, spore germination, and morphological changes of R. stolonifer by scanning electron microscopy (SEM). Chi at 2.5% slowed mycelial growth by 48%, which meant fewer spores and less germination than in the control. The application of SB at 2.0% showed MG inhibition of 98%. However, the combined treatment of Chi-SB inhibited the development of the fungus in 100% of the evaluated in vitro tests. The SEM images showed changes in the development of the mycelium and external morphology of the spores. Therefore, the application of the Chi-SB combination is an alternative to inhibit the growth of R. stolonifer.

Automated summary

This study investigated the antifungal activity of chitosan (Chi) and sodium benzoate (SB) individually or in combination at different concentrations against R. stolonifer. Chi at 2.5% slowed mycelial growth and resulted in fewer spores and less germination. SB at 2.0% showed 98% inhibition of spore formation. However, the combined treatment of Chi-SB inhibited the growth of the fungus in 100% of the evaluated tests. Scanning electron microscopy images showed changes in the development of the mycelium and external morphology of the spores. Therefore, the combined application of Chi-SB is an alternative method to inhibit the growth of R. stolonifer.