Whole-genome Sequencing of Two Streptomyces Strains Isolated From Sand Dunes of Sahara

Abstract

Background. Sahara is one of the largest deserts in the world. The hard conditions especially high temperature and aridity lead to unique adaptation of organisms that could be a potential source of new metabolites. In this respect, two Saharan soils from El Oued Souf and Beni Abbes in Algeria were collected. The bacterial isolates were selected by screening the antibacterial, antifungal, and enzymatic activities. The whole genomes of the two native Saharan strains were sequenced to study the desert Streptomyces microbiology and ecology from genomic perspective. Results. The strains Babs14 (from Beni Abbes, Algeria) and Osf17 (from El Oued Souf, Algeria) were initially identified by 16S rRNA sequence as belonging to the Streptomyces genus. The whole genome sequencing of the two strains was performed by using Pacific Biosciences Sequel II technology (PacBio) and it showed that Babs14 and Osf17 have a linear chromosome of 8.00 Mb and 7.97 Mb, respectively. The number of identified proteins is 6910 in Babs14 and 6894 in Osf17. No plasmids were found in Babs14, whereas three plasmids were detected in Osf17 and no genome duplications were detected in the two strains. Although the strains have different phenotypes and are from different regions, they are slightly different from each other in protein sequence level but, differ more from their earlier published relatives. 29 biosynthetic gene clusters (BGCs) coding for secondary metabolites were predicted in each strain indicating antifungal, antibiotic, and other activities of Babs14 and Osf17. Moreover, many other BGCs were related to biosynthesis of factors needed in response to environmental stress in temperature, UV light and osmolarity. Conclusion. The genome sequencing of Saharan Streptomyces strains revealed factors that are related to their adaptation to an extreme environment and stress conditions. The genome information gives tools to study the ecological adaptation in desert environment and to explore the bioactive compounds of these microorganisms. The two whole genome sequences are among the first ones for the Streptomyces genus of Algerian Sahara. The present research was undertaken as a first step to explore more profoundly the desert microbiome.