Characterization of three native Streptomyces that inhibit the growth of fluconazole-resistant Candida spp.

Abstract

Most fungal infections are caused by species of Candida, especially C. albicans, and the number of strains that acquire resistance to antifungals is increasing, which represents many failures in the treatment of these infections. The search for new antifungals is urgent, and since many bacteria of the genus Streptomyces produce molecules that inhibit the growth of fungi, this work sought to determine the antifungal activity of three native isolates obtained from a rhizosphere and an artisanal composting system. Based on the 16S RNA gene sequences and biochemical and morphological traits, it was determined that the species closest to S1H, S40 and S41 isolates were S. globisporus, S. bacillaris and S. cavourensis, respectively, all reported as producers of antifungals. The Candida inhibition by antagonisms was greater as the incubation time of the Streptomyces increased and no differences were found according to the Candida species. Few studies simultaneously evaluate the inhibitory activity of different Candida strains, however, in this study the isolates inhibited growth of C. albicans, C. krusei, C. guilliermondii, C. glabrata, and C. lusitaniae, including some resistant to fluconazole.