Exopolysaccharide (EPS)-producing lactic acid bacteria are used in the dairy industry to obtain products with appropriate sensorial properties. Specific EPS act as stabilizers, thickeners, and/or fat-replacers, and are considered as natural biopolymers. The autochthonous microbiota of foods provides a rich reservoir of biodiversity to find biopolymers for novel applications. In this study, a collection of LAB isolated from homemade Algerian dairy products was screened for a rational selection of EPSproducing strains. Six isolates, identified as Lactobacillus plantarum, presented a stable mucoid/ropy phenotype after several sub-cultivations and they were used to ferment skimmed milk. Those fermented with strains LBIO1 and LBIO28 had higher viscosity, a smooth/ creamy texture and presented lower syneresis. The kinetics of growth and EPS-production, followed for 48 h, showed that both strains had similar behaviour, the molar mass (about 2x10 6 Da) and radius of gyration (about 80 nm) of the polymers being also similar. However, LBIO28 was able to increase the apparent viscosity of the fermented milk to a higher extent than LBIO1, which could be related with the earlier accumulation of EPS in the first strain in relation to the gelation point. Thus, these two ropy EPS-producing strains are suitable for different applications in dairy fermentations.

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.

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.

The genus Geobacillus is comprised of a diverse group of spore-forming Gram-positive thermophilic bacterial species and is well known for both its ecological diversity and as a source of novel thermostable enzymes. Although the mechanisms underlying the thermophilicity of the organism and the thermostability of its macromolecules are reasonably well understood, relatively little is known of the evolutionary mechanisms, which underlie the structural and functional properties of members of this genus. In this study, we have compared 29 Geobacillus genomes, with a specific focus on the elements, which comprise the conserved core and flexible genomes. Based on comparisons of conserved core and flexible genomes, we present evidence of habitat delineation with specific Geobacillus genomes linked to specific niches. Our analysis revealed that Geobacillus and Anoxybacillus share a high proportion of genes. Moreover, the results strongly suggest that horizontal gene transfer is a major factor deriving the evolution of Geobacillus from Bacillus, with genetic contributions from other phylogenetically distant taxa.

Two extremely halophilic archaea, strains 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 6C 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 (5CECT 7257 T 5DSM T).The extremely halophilic archaea are found in hypersaline environments such as the Dead Sea, the Great Salt Lake, sabkhas and natural and artificial salterns. They are classified within the family Halobacteriaceae. Halobacteria are considered to be the most extremely halophilic microorganisms and require at least 1.5 M NaCl for their growth (Grant et al., 2001). Currently, members of the aerobic, extremely halophilic archaea are classified in 26 genera: The genus Halomicrobium was proposed by Oren et al. (2002) and currently contains only one species, Halomicrobium mukohataei, which was first isolated from the soils of the Argentine salt flats (Ihara et al., 1997). In this study, the characterization of two halophilic strains that represent a novel species of the genus Halomicrobium is described.Strain Al-5 T was isolated from Lake Tebenquiche of the Atacama Saltern, Chile, and strain K-1 was isolated from water samples collected from Ezzemoul sabkha located in the north-east of Algeria. They were isolated independently from each other on hypersaline agar medium containing (per litre): 5 g proteose-peptone no. 5 (Difco), 5 g yeast extract (Difco), 1 g glucose with 25 % (w/v) total salts. The stock of total salts at 30 % (w/v) was prepared as described by Subov (1931): 234 g NaCl, 42 g MgCl 2 . 6H 2 O, 60 g MgSO 4 . 7H 2 O, 1 g CaCl 2 . 2H 2 O, 6 g KCl, 0.2 g NaHCO 3 , 0.7 g NaBr, 0.005 g FeCl 3 and 1000 ml distilled water. The medium was brought to pH 7.0 and incubation was at 40 u C. Phenotypic tests of strains T and K-1 were performed according to the proposed minimal standards for the desc...