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

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.

Quadri I ，Hassani II ，l'Haridon S ，Chalopin M ，Hacène H ，Jebbar M ... -  《-》

[Biodiversity of halophilic archaea isolated from two salt lakes in Xin-Jiang region of China].

Cui HL ，Yang Y ，Dilbr T ，Zhou PJ ，Liu SJ ... -  《-》

Bioprospecting and characterization of pigmented halophilic archaeal strains from Algerian hypersaline environments with analysis of carotenoids produced by Halorubrum sp. BS2.

A set of 110 extremely halophilic archaeal strains were isolated from seven distinct saline habitats located in different regions of Algeria. The physicochemical characterization of the samples showed that these habitats were thalassohaline. The carotenoid production from isolated strains varied from 0.1 to 3.68 µg/ml. Based on their physiological characteristics and pigment production, 43 strains were selected and identified by means of phenotypic tests and 16S ribosomal RNA gene sequencing. Phylogenetic analysis indicated that the isolates corresponded to the class Halobacteria and were closely related to genera Halorubrum, Haloarcula, Haloferax, Natrinema, Halogeometricum, Haloterrigena, and Halopiger. Carotenoids of the highest producer, strain Halorubrum sp. BS2 were identified using high-performance liquid chromatography-diode array detector and liquid chromatography-mass spectrometry. Bacterioruberin and bisanhydrobacterioruberin were the predominant carotenoids. The scavenging activity of these carotenoids reached 99% at a concentration of 18 μg/ml, which was much higher than that of ascorbic acid used as a reference compound. These carotenoids also exhibited significant antibacterial activities against four human-pathogenic strains and four fish-pathogenic strains. Variations in salinity, agitation rate, temperature, and light intensity were found to influence growth and carotenoid production of Halorubrum sp. BS2. Our results suggest that halophilic archaea represent a potential source for carotenoids, which are characterized by high antioxidant and antibacterial activities.

Sahli K ，Gomri MA ，Esclapez J ，Gómez-Villegas P ，Ghennai O ，Bonete MJ ，León R ，Kharroub K ... -  《-》

Extracellular hydrolytic enzymes produced by halophilic bacteria and archaea isolated from hypersaline lake.

Karray F ，Ben Abdallah M ，Kallel N ，Hamza M ，Fakhfakh M ，Sayadi S ... -  《-》

Isolation and characterization from solar salterns of North Algeria of a haloarchaeon producing a new halocin.

Mazguene S ，Rossi M ，Gogliettino M ，Palmieri G ，Cocca E ，Mirino S ，Imadalou-Idres N ，Benallaoua S ... -  《-》