Toxoflavin Produced by Burkholderia gladioli from Lycoris aurea Is a New Broad-Spectrum Fungicide

Abstract

Human fungal infections are a growing problem associated with increased morbidity and mortality. Moreover, a growing number of antifungal-resistant fungal isolates have been reported over the past decade. Thus, the need for novel antifungal agents is imperative. In this study, we show that an endophytic bacterium, Burkholderia gladioli , isolated from the medicinal plant Lycoris aurea , is able to abundantly secrete a compound, toxoflavin, which has a strong fungicidal activity not only against plant fungal pathogens but also against human fungal pathogens Aspergillus fumigatus and Candida albicans , Cryptococcus neoformans , and the model filamentous fungus Aspergillus nidulans . More importantly, toxoflavin also displays an efficacious inhibitory effect against azole antifungal-resistant mutants of A. fumigatus . Consequently, our findings provide a promising approach to abundantly produce toxoflavin, which has novel broad-spectrum antifungal activity, especially against those currently problematic drug-resistant isolates.