Screening for non-polyenic antifungal antibiotics produced by rare Actinomycetales

Strains of Actinomycetales (286 in toto) belonging to thirteen genera other than Streptomyces were isolated from different ecosystems in the Algerian Sahara. Among these strains, 32 showed antibiotic activity against at least one of the test organisms comprising four bacteria, two yeasts and several filamentous fungi, and twelve were antagonistic against both bacteria and fungi. The characteristic UV spectra of active extracts revealed that six strains produced non-polyenic antifungal substances and four synthetized polyenic substances. One strain of Spirillospora produced a pentaene antifungal substance. The only antibiotic so far known to be produced by this genus is spirillomycin.