Résumé:
The presence and biodiversity of Actinobacteria in four Algerian hot springs was explored using water samples from four thermal springs located in northeastern Algeria. Twenty-three morphologically distinct isolates were isolated and identified. Analysis of the 16S rRNA sequences showed that the isolates were assigned to the Streptomycetaceae, Nocardiaceae and Microbacteriaceae families, the majority being affiliated to the genus Streptomyces. The metabolic diversity of the strains was also explored using the api® galleries (BioMérieux). From the batch of isolated actinobacteria, 4 actinobacteria were selected and studied further. This characterization concerns spore morphology by electron microscopic examination, tolerance to different pH and sodium chloride concentrations, growth at different temperatures and G+C content and chemotaxonomy. The in-depth study revealed that these strains are thermotolerant, halotolerant bacteria and prefer an alkaline pH. The G+C content of these strains is quite low and ranges from 41% to 66%. Their cell walls are type I and their phospholipid profiles are type PII. The characteristic cellular fatty acids detected are AnteisoC15: 0, Iso-C15: 0, Iso-C16: 0, Anteiso-C17: 0 and Iso-C17: 0.The menaquinones present mainly are MK-9 (H6) and MK-9 (H8). These strains have several enzymes which are biotechnologicaly very interesting, such as cellulases, xylanases, lipases and proteases. The antimicrobial activity of these 4 strains was carried out against 6 bacteria and 2 filamentous fungi. These facultative thermophiles actinobacteria are capable of producing antagonist antibiotic compounds against at least one test bacteria studied.
