Characterization and antimicrobial potential of extremely halophilic archaea isolated from hypersaline environments of the Algerian Sahara

Inès Quadri, Imene Ikrame Hassani, Stéphane l’Haridon, Morgane Chalopin, Hocine Hacène, Mohamed Jebbar

Cellular and Molecular Biology Laboratory (Team Microbiology), University of Sciences and Technology Houari Boumediene, Bp 32, El Alia, 16111 Bab Ezzouar, Algiers, Algeria.

Abstract

Halophilic archaea were isolated from different chotts and sebkha, dry salt lakes and salt flat respectively, of the Algerian Sahara and characterized using phenotypic and phylogenetic approaches. From 102 extremely halophilic strains isolated, forty three were selected and studied. These strains were also screened for their antagonistic potential and the production of hydrolytic enzymes. Sequencing of the 16S rRNA genes and phylogenetic analysis allowed the identification of 10 archaeal genera within the class Halobacteria: Natrinema (13 strains), Natrialba (12 strains), Haloarcula (4 strains),Halopiger (4 strains), Haloterrigena (3 strains), Halorubrum (2 strains), Halostagnicola (2 strains), Natronococcus, Halogeometricum and Haloferax (1 strain each). The most common producers of antimicrobial compounds belong to the genus Natrinema while the most hydrolytic isolates, with combined production of several enzymes, belong to the genus Natrialba. The strain affiliated to Halopiger djelfamassilliensis was found to produce some substances of interest (halocins, anti-Candida, enzymes). After partial purification and characterization of one of the strains Natrinema gari QI1, we found similarities between the antimicrobial compound and the halocin C8. Therefore, the gene encoding halocin C8 was amplified and sequenced.

Keywords: Algerian sahara; Halophilic archaea; Antimicrobial activities; Halocin.