A halotolerant Actinobacteria strain HR-4 was isolated from a salt lake soil sample in Algerian Sahara. Analysis of 16S rDNA gene sequence showed that strain HR-4 belonged to the genus Nocardiopsis. The similarity level ranges between 97.45 and 99.20% with Nocardiopsis species and Nocardiopsis rosea being the most closely related one. Morphological, physiological and phylogenetic characteristics comparisons showed significant differences with the nearest species. These data strongly suggest that strain HR-4 represents novel species. The antimicrobial activity of strain HR-4 showed an antibacterial activity against Gram-positive bacteria as well as an antifungal one. Two major natural products including a new one were isolated from the culture broth using various separation and purification procedures. The chemical structure established on the basis of spectroscopic studies NMR and by comparing with spectroscopic data from the literature of the two compounds affirm that they are classified in the group of Angucyclinones. This is the first report of a production of this type of molecules by the genus Nocardiopsis. The new natural compound was established as (-)-7-deoxy-8-O-methyltetrangomycin with a new configuration.
Keywords: Angucyclinone; Antimicrobial activity; Halotolerant; Nocardiopsis; Taxonomy.