Role of the non-ribosomal peptide synthetase siderophore enzyme (Rfs) of Mucor lusitanicus in controlling the growth of fungal phytopathogens.

Dimorphic species of Mucor, which are cosmopolitan fungi belonging to subphylum Mucoromycotina, are metabolically versatile. Some species of Mucor are sources of biotechnological products, such as biodiesel from M. circinelloides and expression of heterologous proteins from M. lusitanicus. Furthermore, M. lusitanicus has been described as a model for understanding mucormycosis infections. However, little is known regarding the relationship between M. lusitanicus and other soil inhabitants. In this study, we investigated the potential use of M. lusitanicus as a biocontrol agent against fungal phytopathogens, namely Fusarium oxysporum f. sp. lycopersici, Fusarium solani, and Alternaria solani, which destroy economically important crops. Results showed that aerobic cell-free supernatants of the culture broth (SS) from M. lusitanicus inhibited the growth of the fungal phytopathogens in culture, soil, and tomato fruits. The SS obtained from a strain of M. lusitanicus carrying the deletion of rfs gene, which encodes an enzyme involved in the synthesis of siderophore rhizoferrin, had a decreased inhibitory effect against the growth of the phytopathogens. Contrary, this inhibitory effect was more evident with the SS from an rfs-overexpressing strain compared to the wild-type. This study provides a framework for the potential biotechnological use of the molecules secreted from M. lusitanicus in the biocontrol of fungal phytopathogens.