Nybomycin is a fungal metabolite originally isolated from Streptomyces sp. A717 and has antibacterial activity. It is active against B. subtilis, B. cereus, B. mycoides, M. smegmatis, and K. pneumoniae (MICs = 0.025, 2, 0.8, 0.2, and 0.003 μg/ml, respectively). Nybomycin is also active against M. tuberculosis and M. bovis (MICs = 4.5 and 1 μg/ml, respectively).