Induced production of BE-31405 by co-culturing of Talaromyces siamensis FKA-61 with a variety of fungal strains

While isolating fungal strains from soil samples, two strains, Talaromyces siamensis FKA-61 and Phomopsis sp. FKA-62, were found to produce a black pigment near the boundary with an adjoining colony on agar plates. Moreover, strain FKA-61 inhibited the growth of strain FKA-62. Co-culture of T. siamensis FKA-61 with Phomopsis sp. FKA-62 resulted in the production of an antifungal agent, BE-31405, which proved active against Phomopsi s sp. FKA-62. We screened for fungal genera that have the ability to induce production of antifungal BE-31405. Surprisingly, production of BE-31405 was induced only by co-culturing T. siamensis FKA-61 with a variety of BE-31405-sensitive fungal strains but never with BE-31405-insensitive strains. This is the first report of the induced production of a specific antibiotic active against antibiotic-sensitive fungal strains by co-culturing with them.