Actinobacteria Derived from Algerian Ecosystems as a Prominent Source of Antimicrobial Molecules

Actinobacteria, in particular “rare actinobacteria” isolated from extreme ecosystems, remain the most inexhaustible source of novel antimicrobials, offering a chance to discover new bioactive metabolites. This is the first overview on actinobacteria isolated in Algeria since 2002 to date with the aim to present their potential in producing bioactive secondary metabolites. Twenty-nine new species and one novel genus have been isolated, mainly from the Saharan soil and palm groves, where 37.93% of the most abundant genera belong to Saccharothrix and Actinopolyspora. Several of these strains were found to produce antibiotics and antifungal metabolites, including 17 new molecules among the 50 structures reported, and some of these antibacterial metabolites have shown interesting antitumor activities. A series of approaches used to enhance the production of bioactive compounds is also presented as the manipulation of culture media by both classical methods and modeling designs through statistical strategies and the associations with diverse organisms and strains. Focusing on the Algerian natural sources of antimicrobial metabolites, this work is a representative example of the potential of a closely combined study on biology and chemistry of natural products.

Taxonomy and antimicrobial activity of streptosporangium strain SG163 isolated from a Saharan soil

n a continuing search fornew antimicrobial products from actinobacteriacollected in Algerian Saharan soils, an isolateof actinobacteria,designated Sg163, was selected for its interesting antimicrobial activity.The isolate wasidentified to the genus Streptosporangium by phenotypicand molecular criteria. The cultural and physiological characterizations as well as phylogenetic analysis indicated that the isolate was different from known members of the genus Streptosporangium. Analysis of the 16S rRNA sequence showed 97.09to 98.27% similarity with those of Streptosporangium type strains. The strainSg163 produced antifungal and antibacterial activities on several culture media. The highest antimicrobial activities were obtained in ISP2 medium. Three active products C1, C2 and C3 with both antifungal and antibacterial activities were isolated and purified by chromatographic methodswith C2, as the major compound. The data of the infraredspectroscopy andthe chemical revelations, suggested that the active molecules were glycosylatedaromaticcompounds.