Abstract

Sudanese soil is an unexplored source of antibiotic-producing microorganisms. Here, we reported the screening of soil samples from Sudan for actinomycetes that have antibacterial activity. Two isolates, AH11.4 and AH47, displaying a broad antimicrobial spectrum were selected for further study. Morphological, physiological and biochemical studies indicated that the two isolates are Streptomyces spp. 16S rDNA sequencing confirmed that the closest matches were to other Streptomyces, but phylogenetic analysis demonstrated that the Sudanese strains were on a different node to previously identified strains. The antibiotic activity was isolated by preparative High-performance liquid chromatography (HPLC) and determined to be primarily actinomycin D on the basis of UV, 1H- and 13C-NMR, and MS analyses. One strain also produced actinomycin X2 and aB. These strains are distinct from the known producers of actinomycin, thus are new sources of these antibiotics.

Key words: Screening, antibiotic, antitumour, identification.