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In Algeria, many salt lakes are to be found spread from southern Tunisia up to the Atlas Mountains in northern Algeria. Oum Eraneb and Ain El beida sebkhas (salt lakes), are located in the Algerian Sahara. The aim of this study was to explore the diversity of the halobacteria in this type of habitats. The physicochemical properties of these shallow saline environments were examined and compared with other hypersaline and marine ecosystems. Both sites were relatively alkaline with a pH around 8.57- 8.74 and rich in salt at 13% and 16% (w/v) salinity for Oum Eraneb and Ain El beida, respectively, with dominant ions of sodium and chloride. The microbial approach revealed the presence of two halophilic archaea, strains JCM13561 and A33T in both explored sebkhas. Growth occurred between 10 and 25% (w/v) NaCl and the isolates grow optimally at 20% (w/v) NaCl. The pH range for growth was 6 to 9.5 with an optimum at pH 7.5 for the first strain and 7 to 9.5 with an optimum pH at 8.5-9 for the second strain. On the basis of 16S rRNA gene sequence analysis, strains JCM13561 and A33T were most closely related to Halorubrum litoreum and Natronorubrum bangense (99% and 96% similarity, respectively).

Two extremely halophilic archaea, strains Al-5(T) and K-1, were isolated from Lake Tebenquiche (Atacama Saltern, Chile) and Ezzemoul sabkha (Algeria), respectively. Cells of the two strains were short-rod-shaped and Gram-negative; colonies were orange-pigmented. They grew optimally at 37-40 degrees C and pH 7.0-7.5 in the presence of 25 % (w/v) NaCl. Magnesium was not required. Polar lipid analysis revealed the presence of phosphatidylglycerol and phosphatidylglycerophosphate methyl ester, the absence of phosphatidylglycerosulfate, and the presence of sulfated diglycosyl diether and diether diglycosyl as the sole glycolipids. DNA G+C contents of strains Al-5(T) and K-1 were 52.4 and 52.9 mol% (T(m) method), respectively. 16S rRNA gene sequence comparison with database sequences showed that strains Al-5(T) and K-1 were most closely related to Halomicrobium mukohataei DSM 12286(T) (similarities of 97.5 and 96.9 %, respectively). DNA-DNA hybridization indicated that strains Al-5(T) and K-1 were members of a single species. However, DNA-DNA relatedness to Halomicrobium mukohataei was 55.7+/-2.5 %. A comparative analysis of phenotypic characteristics and DNA-DNA hybridization between the isolates and Halomicrobium mukohataei DSM 12286(T) supported the conclusion that Al-5(T) and K-1 represent a novel species within the genus Halomicrobium, for which the name Halomicrobium katesii sp. nov. is proposed. The type strain is Al-5(T) (=CECT 7257(T)=DSM 19301(T)).

A novel extremely halophilic archaeon was isolated from Ezzemoul sabkha, Algeria. The strain, designated 5.1(T), was neutrophilic, motile and Gram-negative. At least 15 % (w/v) NaCl was required for growth. The isolate grew at pH 6.5-9.0, with optimum growth at pH 7.0-7.5. Mg(2+) was required for growth. Polar lipids were C(20)C(20) derivatives of phosphatidylglycerol and phosphatidylglycerol phosphate methyl ester, and phosphatidylglycerol sulfate and sulfated diglycosyl diether. The genomic DNA G+C content of strain 5.1(T) was 61.9 mol% (T(m)). Phylogenetic analysis based on comparison of 16S rRNA gene sequences revealed that strain 5.1(T) clustered with Halorubrum species. The results of DNA-DNA hybridization and biochemical tests allowed genotypic and phenotypic differentiation of strain 5.1(T) from other Halorubrum species. The name Halorubrum ezzemoulense sp. nov. (type strain 5.1(T)=CECT 7099(T)=DSM 17463(T)) is proposed.