A novel halophilic actinobacterium, designated H202T, was isolated from a Saharan soil in the Ahbès region (Béni-Isguen, Ghardaïa province, South Algeria), and its taxonomic position was determined by a genome-based polyphasic approach. Phylogenetic analysis of the 16S rRNA gene sequence revealed that the strain H202T belonged to the genus Actinopolyspora and showed the highest sequence similarity to Actinopolyspora mzabensis DSM 45460T (99.46%). Comparative genomic analysis based on digital DNA-DNA hybridization (dDDH), average nucleotide identity (ANI) and average amino acid identity (AAI) showed values below the recommended species cut-off thresholds of 70% (dDDH) and 95-96% (ANI and AAI), suggesting that the strain H202T represents a novel species. This strain exhibits the typical characteristics of the genus Actinopolyspora. The cell-wall hydrolysates contained meso-diaminopimelic acid, and the diagnostic whole-cell sugars were arabinose and galactose. Phosphatidylcholine was identified as the diagnostic phospholipid, and the predominant menaquinones were MK-9(H4) and MK-10(H4). The major fatty acids (≥10%) were anteiso-C17:0, iso-C15:0, iso-C16:0 and anteiso-C15:0. The genome size of strain H202T was estimated to be 5.2 Mbp, with a G+C content of 67.5%. Based on these findings, strain H202T is proposed as a representative of a novel species within the genus Actinopolyspora, named Actinopolyspora sabaoui sp. nov. The type strain is H202T (=DSM 46671T=CECT 31287T).
Rafika Saker, Mónica Majo-Cuervo, N. Bouras et al.· International Journal of Sys...· 0 citations
Actinobacteria from extreme environments represent a valuable source of novel bioactive secondary metabolites with potential antimicrobial applications. The aim of this study was to isolate, identify, and evaluate the antimicrobial potential of a newly isolated strain of actinobacteria. AHA8 strain, was isolated from an Algerian desert soil sample in the Ahaggar region (Tamanrasset) by the dilution-agar plating method using a chitin-vitamins B medium supplemented with nalidixic acid and actidione. Morphological characterization indicated that this strain belonged to the genus Streptomyces. Phylogenetic analysis based on the 16S rRNA gene showed that the strain is closely related to Streptomyces djakartensis NBRC 15409T (99.57% sequence similarity). Strain AHA8 showed very strong activity against pathogenic staphylococci, including Staphylococcus aureus (MRSA 639c), as well as against other Gram-positive bacteria: Bacillus subtilis (ATCC 663) and Listeria monocytogenes (ATCC 13932). Additionally, the strain exhibited a moderate activity against mycotoxigenic and phytopathogenic fungi, including Aspergillus carbonarius (M333), A. westerdijkiae (ATCC 3174), Fusarium culmorum (Fc), and Umbelopsis ramanniana (NRRL 1829). Almost the same results were observed for Gram-negative bacteria and the pathogenic yeast Candida albicans (M3). Therefore, four solvents (n-hexane, dichloromethane, ethyl acetate, and n-butanol) were used to extract the bioactive secondary metabolites produced by the AHA8 culture on a synthetic starch medium. The highest antibacterial activity was obtained with the butanolic and ethyl acetate extracts. These findings demonstrate that the desert-derived strain AHA8 represents a promising source of antimicrobial secondary metabolites and supports further studies aimed at the purification and characterization of its bioactive compounds.
S. Saadi, Hafsa Yaiche Achour, N. Djemouai et al.· Analele Universitatii din Or...· 0 citations