Halanaerobacter jeridensis sp nov., isolated from a hypersaline lake
An obligatory anaerobic, moderately halophilic bacterium, designated strain CEJFG43(T), was isolated from a sample of sediment collected below the salt crust on the hypersaline El Jerid lake, in southern Tunisia. The cells of this novel strain were Gram-staining-negative, non-sporulating, motile, short rods. They grew in media with 6-30% (w/v) NaCl (optimum 15%), at 20-60 °C (optimum 45 °C) and at pH 5.5-9.5 (optimum pH 8.3). The micro-organism fermented glucose, fructose, ribose, raffinose, galactose, mannose, sucrose, maltose, xylose, mannitol, pyruvate and glycerol. The products of glucose fermentation were lactate, ethanol, acetate, H(2) and CO(2). The genomic G+C DNA content of strain CEJFG43(T) was 33.3 mol%. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain CEJFG43(T) belonged in the genus Halanaerobacter and was most closely related to Halanaerobacter lacunarum DSM 6640(T) (95.3% gene sequence similarity) and Halanaerobacter chitinivorans DSM 9569(T) (95.3%). The predominant cellular fatty acids were non-branched (C(16:0) and C(16:1)). Based on the phylogenetic and phenotypic evidence, strain CEJFG43(T) represents a novel species in the genus Halanaerobacter for which the name Halanaerobacter jeridensis sp. nov. is proposed. The type strain is CEJFG43(T) ( = DSM 23230(T) = JCM 16696(T)).
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[Show abstract] [Hide abstract] ABSTRACT: Prokaryotic diversity was investigated in a Tunisian salt lake, Chott El Jerid, by quantitative real-time PCR, denaturing gradient gel electrophoresis (DGGE) fingerprinting methods targeting the 16S rRNA gene and culture-dependent methods. Two different samples S1-10 and S2-10 were taken from under the salt crust of Chott El Jerid in the dry season. DGGE analysis revealed that bacterial sequences were related to Firmicutes, Proteobacteria, unclassified bacteria, and Deinococcus-Thermus phyla. Anaerobic fermentative and sulfate-reducing bacteria were also detected in this ecosystem. Within the domain archaea, all sequences were affiliated to Euryarchaeota phylum. Quantitative real-time PCR showed that 16S rRNA gene copy numbers of bacteria was 5 × 10(6) DNA copies g(-1) whereas archaea varied between 5 × 10(5) and 10(6) DNA copies g(-1) in these samples. Eight anaerobic halophilic fermentative bacterial strains were isolated and affiliated with the species Halanaerobium alcaliphilum, Halanaerobium saccharolyticum, and Sporohalobacter salinus. These data showed an abundant and diverse microbial community detected in the hypersaline thalassohaline environment of Chott El Jerid.
- "This is the first report describing the microbial populations present in the water and sediment of Chott El Jerid using molecular methods [denaturing gradient gel electrophoresis (DGGE) and quantitative real-time PCR]. Few ecological studies of this environment based on the cultivation approach have been investigated (Ben Abdallah et al. 2015; Mezghani et al. 2012). The main purpose of this research is to obtain an overview of the abundance, the structure, and microbial diversity of both archaeal and bacterial communities in water and sediment samples of Chott El Jerid using culture-dependent and culture-independent techniques. "
- [Show abstract] [Hide abstract] ABSTRACT: The order Halanaerobiales, families Halanaerobiaceae and Halobacteroidaceae, consists of obligatory anaerobic, moderately halophilic bacteria that require NaCl concentrations between 0.5 and 3.4 M for optimal growth. Representatives have been isolated from anaerobic sediments of salt lakes worldwide, from brines associated with oil reservoirs, and also from fermented salted foods. Some species are thermophilic or alkaliphilic. Although phylogenetically affiliated with the low G+C branch of the Firmicutes, the cells show a Gram-negative wall structure, and most species stain Gram-negative. Some representatives of the Halobacteroidaceae produce endospores. Most species ferment carbohydrates to acetate, ethanol, H2, CO2, and other fermentation products. Within the Halobacteroidaceae, a greater metabolic diversity is found, with some species displaying a homoacetogenic metabolism; growth by anaerobic respiration using different electron acceptors including nitrate, trimethylamine.-oxide, selenate, arsenate, or Fe(III); or chemolithoautotrophic growth on hydrogen and elemental sulfur. © 2014 Springer-Verlag Berlin Heidelberg. All rights are reserved.
- [Show abstract] [Hide abstract] ABSTRACT: Halophilic, obligately anaerobic, Gram-negative bacterial strains were isolated from a sediment sample taken under salt crust of El-Jerid hypersaline lake located in southern Tunisia by using tryptone or glucose as substrate. One of them (strain CEJFT1BT) was characterized phenotypically and phylogenetically. Cells were non-motile, non-spore forming, short rods. Strain CEJFT1BT was able to grow in the presence of 5-30 % (w/v) NaCl (optimum 20 %) and at 30-60 °C (optimum 45 °C). It grew at pH 5.5-7.75 and the optimum pH for growth was 6.75. The isolate required yeast extract for growth. Substrates utilized by strain CEJFT1BT included glucose, fructose, sucrose, pyruvate, casaminoacids and starch. Individual amino acid such as glutamate, lysine, methionine, serine, tyrosine and amino acid mixtures by Stickland reaction such as alanine-glycine, valine-proline, leucine-proline, isoleucine-proline were also utilized. Products of glucose fermentation were acetate (major product), butyrate, isobutyrate, H2 and CO2. The DNA G+C content of strain CEJFT1BT was 32.3 mol%. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain CEJFT1BT could be assigned to the genus Sporohalobacter. The sequence similarity between strain CEJFT1BT and Sporohalobacter lortetii was 98.5%, but DNA-DNA hybridization between the two strains revealed relatedness value of 56.4%, indicating that they are not related at the species level. The combination of phylogenetic analysis, DNA-DNA hybridization data, and differences in substrate utilization supported the view that strain CEJFT1BT represents a new species of the genus Sporohalobacter, for which the name Sporohalobacter salinus sp. nov. is proposed. The type strain is strain CEJFT1BT (DSM 26781 = JCM 19279).