Linearmycin B is novel linear polyene antibiotic isolated from mycelial extracts of Streptomyces sp. Linearmycin A and B have similar, long linear structures terminating with amino and carboxylic acid groups. The carboxylic acid terminal of linearmycin B links to a pentaenone, whereas linearmycin A links to a tetraenone. Linearmycin B has antifungal activity against Candida albicans, and antibacterial activity, causing cellular lysis and colony degradation of the Gram-positive bacterium Bacillus subtilis, acting directly on the cytoplasmic membrane.