Transvalencin A, a thiazolidine zinc complex antibiotic produced by a clinical isolate of Nocardia transvalensis. I. Taxonomy, fermentation, isolation and biological activities.

A new thiazolidine-type antibiotic with zinc in its structure, designated transvalencin A, was isolated from Nocardia sp. IFM 10065, a clinical isolate from a patient with actinomycotic mycetoma. The strain was identified as Nocardia transvalensis based on its morphological, phenotypic and phylogenetic characteristics. Transvalencin A showed antimicrobial activity against fungi such as Trichophyton mentagrophytes and Cryptococcus neoformans. The antibiotic is also active against Gram-positive bacteria such as Micrococcus luteus. We observed higher activity for fungi in an acidic medium than in a neutral medium.