Search

Four halophilic archaeal strains YCN1 T , YCN58 T , LT38 T , and LT62 T were isolated from Yuncheng Salt Lake (Shanxi, China) and Tarim Basin (Xinjiang, China), respectively. Phylogenetic and phylogenomic analyses showed that these four strains tightly cluster with related species of Halobacterium, Natronomonas, Halorientalis, and Halobellus, respectively. The AAI, ANI, and dDDH values between these four strains and their related species of respective genera were lower than the proposed threshold values for species delineation. Strains YCN1 T , YCN58 T , LT38 T , and LT62 T could be differentiated from the current species of Halobacterium, Natronomonas, Halorientalis, and Halobellus, respectively, based on the comparison of diverse phenotypic characteristics. The polar lipid profiles of these four strains were closely similar to those of respective relatives within the genera Halobacterium, Natronomonas, Halorientalis, and Halobellus, respectively. The phenotypic, phylogenetic, and genome-based analyses indicated that strains YCN1 T , YCN58 T , LT38 T , and LT62 T represent respective novel species within the genera Halobacterium, Natronomonas, Halorentalis, and Halobellus, for which the names Halobacterium yunchengense sp. nov., Natronomonas amylolytica sp. nov., Halorientalis halophila sp. nov., and Halobellus salinisoli sp. nov. are proposed, respectively., (© 2024. The Author(s), under exclusive licence to Springer Nature Japan KK.)

A halophilic archaeal strain, designated C46 T , was isolated from an inland salt lake in Qinghai Province, PR China. Results of phylogenetic analysis based on 16S rRNA gene sequences indicated that strain C46 T belongs to the genus Halobaculum , and the closest phylogenetic relative is Halobaculum gomorrense DSM 9297 T with 97.7 % similarity. Despite this, strain C46 T was more related to Halobaculum saliterrae WSA2 T than other members of the genus Halobaculum based on genome comparison and analysis, and the average nucleotide identity, in silico DNA-DNA hybridization, amino acid identity and percentage of conserved protein values between the two strains were 89.1, 53.3, 89.2 and 75.6 %, respectively, which are lower than the cutoff values proposed for species delimitation. The physiological, biochemical, genetic and genomic characteristics of strain C46 T were different from those of its closest phylogenetic neighbours, which indicated that this strain represents a novel species of the genus Halobaculum , for which the name Halobaculum rubrum sp. nov. is proposed. The type strain is C46 T (=CGMCC 1.13737 T =JCM 32959 T ).

Two halophilic archaeal strains, Gai3-2 T and NJ-3-1 T , were isolated from salt lake and saline soil samples, respectively, collected in PR China. The 16S rRNA gene sequences of the two strains were 97.5% similar to each other. Strains Gai3-2 T and NJ-3-1 T had the highest sequence similarities to ' Halobonum tyrrellense ' G22 (96.7 and 97.8%, respectively), and displayed similarities of 91.5-93.5% and 92.3-94.7%, respectively, to Halobaculum members. Phylogenetic analysis revealed that the two strains formed different branches and clustered tightly with ' H. tyrrellense ' G22 and Halobaculum members. The average nucleotide identity (ANI), in silico DNA-DNA hybridization ( is DDH) and amino acid identity (AAI) values between the two strains were 83.1, 26.9 and 77.9%, respectively, much lower than the threshold values proposed as a species boundary. These values between the two strains and ' H. tyrrellense ' G22 (ANI 77.9-78.2%, is DDH 22.5-22.6% and AAI 68.8-69.3%) and Halobaculum members (ANI 77.53-77.63%, is DDH 21.8-22.3% and AAI 68.4-69.4%) were almost identical, and much lower than the recommended threshold values for species delimitation. These results suggested that strains Gai3-2 T and NJ-3-1 T represent two novel species of Halobaculum . Based on phenotypic, chemotaxonomic and phylogenetic properties, strains Gai3-2 T (=CGMCC 1.16080 T =JCM 33550 T ) and NJ-3-1 T (=CGMCC 1.16040 T =JCM 33552 T ) represent two novel species of the genus Halobaculum , for which the name Halobaculum halophilum sp. nov. and Halobaculum salinum sp. nov. are proposed.

A haloalkaliphilic strain JWXQ-INN-674 T was isolated from the water sample of a soda lake in Inner Mongolia Autonomous Region, China. Cells of the strain were coccoid, motile, and strictly aerobic. The strain was able to grow in presence of 2.6-5.4 M NaCl (optimum concentration is 3.4 M) at 30-50 °C (optimum temperature is 42 °C) and pH 7-9.5 (optimum pH is 9.0). The 16S rRNA gene sequence of strain JWXQ-INN-674 T showed 95.3-96.6% similarity to members of the genus Natronorubrum of the family Natrialbaceae. The whole genome sequencing of strain JWXQ-INN-674 T revealed a genome size of 4.56 M bp and a DNA G + C content of 62.5 mol%. Genome relatedness of strain JWXQ-INN-674 T and other species in the genus Natronorubrum was analyzed by average nucleotide identity and digital DNA-DNA hybridization with the values of 76.8-90.6 and 23.1-39.3%, respectively. The strain possessed the polar lipids phosphatidylglycerol and methylated phosphatidylglycerol phosphate lipid. No glycolipids were detected. Based on phylogenetic analysis, phenotypic characteristics, chemotaxonomic properties and genome relatedness, the isolate was proposed as the type strain of a novel species of genus Natronorubrum, Natronorubrum halalkaliphilum sp. nov. (type strain JWXQ-INN-674 T  = CGMCC 1.17283 T  = JCM 34245 T ).

Two halophilic archaeal strains, C90 T and YPL13 T , were isolated from a salt lake and a salt mine in PR China. The two strains were found to form two clusters (97.5 and 89.5 % similarity between them, respectively) separating them from the three current members of the genus Natronomonas (95.4-97.0 % and 86.6-89.3 % similarity, respectively) on the basis of the 16S rRNA and rpoB' gene sequence similarities and phylogenetic analysis. Diverse phenotypic characteristics differentiate strains C90 T and YPL13 T from current Natronomonas members. The polar lipids of strain C90 T were phosphatidic acid, phosphatidylglycerol (PG), phosphatidylglycerol phosphate methyl ester (PGP-Me), phosphatidylglycerol sulphate, two unidentified glycolipids, a major glycolipid and a minor glycolipid, while those of strain YPL13 T were PG, PGP-Me, two unidentified phospholipids and a glycolipid. The average nucleotide identity (ANI) and in silico DNA-DNA hybridization ( is DDH) values between the two strains were 79.8 and 27.1 %, respectively, which were much lower than the threshold values proposed as a species boundaries (ANI 95-96 % and is DDH 70 %), which revealed that the two strains represent two novel species; these values (ANI 76.6-80.0 % and is DDH 21.6-27.0 %) of the strains examined in this study and the current members of Natronomonas are much lower than the recommended threshold values, suggesting that strains C90 T and YPL13 T represent two genomically different species of Natronomonas . These results showed that strains C90 T (=CGMCC 1.13738 T =JCM 32961 T ) and YPL13 T (=CGMCC 1.13884 T =JCM 31111 T ) represent two novel species of Natronomonas , for which the names Natronomonas halophila sp. nov. and Natronomonas salina sp. nov. are proposed.

A haloarchaeal strain (ESP3B_9 T ) was isolated from the salt pan of Sambhar salt lake, Rajasthan, India. Cells were coccoid, non-motile, Gram-stain-negative and formed reddish-pink pigmented colonies. The strain was aerobic, able to grow at 35-55 °C (optimum, 40 °C), in 20-35 % (25 %) NaCl and pH 8-10 (pH 9). Mg 2+ not required for growth. The cells were lysed in distilled water and the minimum NaCl concentration that prevented cell lysis was 5 % w/v. The 16S rRNA gene sequence similarities between strain ESP3B_9 T and Natrialba hulunbeirensis JCM 10989 T and Natrialba magadii ATCC 43099 T were 96.53 and 96.25 % respectively. The similarities of the RNA polymerase subunit B gene between strain ESP3B_9 T and N. hulunbeirensis JCM 10989 T and N. magadii ATCC 43099 T were 84.47 and 84.9 % respectively. Genome sequencing revealed a genome size of 4.20 Mbp with DNA G+C content of 62.5 mol%. The major polar lipids were phosphotidylglycerol and phosphatidylglycerol phosphate methyl esters with minor amounts of unidentified lipids. The results of polyphasic analysis determined that strain ESP3B_9 T represents a novel species of the genus Natrialba , for which the name Natrialba swarupiae sp. nov. is proposed. The type strain is ESP3B_9 T (MCC 3419 T =JCM 33002 T =KCTC 4279 T =CGMCC 1.16737 T ).

Eight pure cultures of alkaliphilic haloaloarchaea capable of growth by dissimilatory sulfur reduction (previously only shown for neutrophilic haloarchaea) were isolated from hypersaline alkaline lakes in different geographic locations. These anaerobic enrichments, inoculated with sediments and brines, used formate, butyrate and peptone as electron donors and elemental sulfur as an electron acceptor 4 M total Na + and at pH 9-10. According to 16S rRNA gene sequencing, the isolates fell into two distinct groups. A major group, comprising seven obligate alkaliphilic isolates from highly alkaline soda lakes, represents a new species-level branch within the genus Natronolimnobius (order Natrialbales ), while a single moderately alkaliphilic isolate from the less alkaline Searles Lake forms a novel genus-level lineage within the order Haloferacales . The cells of the isolates are either flat rods or coccoid. They are facultative anaerobes using formate or H 2 (in the presence of acetate or yeast extract as carbon source), C 4 -C 9 fatty acids or peptone (the major group) as electron donors and either sulfur or DMSO (the major group) as electron acceptors. Aerobic growth is only possible with organic acids and peptone-yeast extract. All isolates are extreme halophiles, growing optimally at 4 M total Na + . On the basis of their unique physiological properties and distinct phylogeny, we propose that the seven isolates from the soda lakes are placed into a novel species, Natronolimnobiussulfurireducens sp. nov. (type strain AArc1 T =JCM 30663 T =UNIQEM U932 T ), and the Searles Lake isolate, AArc-Sl T , into a new genus and species Halalkaliarchaeum desulfuricum (=JCM 30664 T =UNIQEM U999 T ).

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).

Keke Salt Lake is located in the Qaidamu Basin of China. It is a unique magnesium sulfate-subtype hypersaline lake that exhibits a halite domain ecosystem, yet its microbial diversity has remained unstudied. Here, the microbial community structure and diversity was investigated via high-throughput sequencing of the V3-V5 regions of 16S rRNA genes. A high diversity of operational taxonomic units was detected for Bacteria and Archaea (734 and 747, respectively), comprising 21 phyla, 43 classes, and 201 genera of Bacteria and 4 phyla, 4 classes, and 39 genera of Archaea. Salt-saturated samples were dominated by the bacterial genera Bacillus (51.52%-58.35% relative abundance), Lactococcus (9.52%-10.51%), and Oceanobacillus (8.82%-9.88%) within the Firmicutes phylum (74.81%-80.99%), contrasting with other hypersaline lakes. The dominant Archaea belonged to the Halobacteriaceae family, and in particular, the genera (with an abundance of >10% of communities) Halonotius, Halorubellus, Halapricum, Halorubrum, and Natronomonas. Additionally, we report the presence of Nanohaloarchaeota and Woesearchaeota in Qinghai-Tibet Plateau lakes, which has not been previously documented. Total salinity (especially Mg 2+ , Cl - , Na + , and K + ) mostly correlated with taxonomic distribution across samples. These results expand our understanding of microbial resource utilization within hypersaline lakes and the potential adaptations of dominant microorganisms that allow them to inhabit such environments.

A halophilic archaeal strain, YC93T, was isolated from Yuncheng salt lake in Shanxi Province, China. Cells were pleomorphic rods, stained Gram-negative and formed light-red-pigmented colonies on agar plates. Strain YC93T was able to grow at 25–50 °C (optimum 37 °C), with 1.4–4.8 M NaCl (optimum 2.0 M), with 0–1.0 M MgCl2 (optimum 0.05 M) and at pH 6.0–9.5 (optimum pH 7.0). Cells lysed in distilled water and the minimal NaCl concentration to prevent cell lysis was 8 % (w/v). 16S rRNA gene sequence analysis revealed that strain YC93T had two dissimilar 16S rRNA genes both of which were phylogenetically related to those of the two recognized members of the genus Halorussus (93.0–95.3 % similarity). The rpoB′ gene of strain YC93T was phylogenetically related to the corresponding gene of Halorussus rarus TBN4T (91.3 % similarity) and Halorussus ruber YC25T (90.5 %). The major polar lipids were phosphatidylglycerol, phosphatidylglycerol phosphate methyl ester, phosphatidylglycerol sulfate and five glycolipids chromatographically identical to those of Halorussus rarus CGMCC 1.10122T. The DNA G+C content of strain YC93T was 64.6 mol%. The phenotypic, chemotaxonomic and phylogenetic properties suggested that strain YC93T represents a novel species of the genus Halorussus, for which the name Halorussus amylolyticus sp. nov. is proposed. The type strain is YC93T ( = CGMCC 1.12126T = JCM 18367T).

Perennially stratified salt lakes situated in the Transylvanian Basin (Central Romania) were surveyed for the diversity of culturable halophilic archaea (Fam. Halobacteriaceae). The physical and chemical characteristics of the waters indicated that all the investigated lakes were meromictic and neutral hypersaline. Samples collected from upper, intermediate, and deeper water layers and sediments were used for the isolation of halophilic strains followed by 16S rRNA gene-based identification and phenotypic characterization. The phylogenetic analysis of the 16S rRNA gene sequences revealed that all 191 isolates reported in this study and 43 strains previously isolated were affiliated with the family Halobacteriaceae and classified to 18 genera. Haloferax was the most frequently isolated genus (~47 %), followed by Halobacterium spp. (~12 %), and Halorubrum spp. (~11 %). Highest culturable diversity was detected in Brâncoveanu Lake, the oldest and saltiest of all studied lakes, while the opposite was observed in the most stable and least human-impacted Fără Fund Lake. One strain from Ursu Lake might possibly constitute a novel Halorubrum species as shown by phylogenetic analysis. Several haloarchaeal taxa recently described in Asian (i.e., Iran, China) saline systems were also identified as inhabiting the Transylvanian salt lakes thus expanding our knowledege on the geographic distribution of Halobacteriaceae.

The halophilic archaeal strain, YC82(T), was isolated from Yuncheng salt lake in Shanxi, PR China. Cells from strain YC82(T) were Gram-stain negative, pleomorphic rods, which lysed in distilled water and formed light-red colonies on solid media. Strain YC82(T) grew at 25-50 °C (optimum 37 °C), in 1.4-4.8 M NaCl (optimum 2.0 M), in 0-1.0 M MgCl2 (optimum 0.05 M) and at pH 6.0-9.5 (optimum pH 7.5). The major polar lipids of strain YC82(T) were phosphatidic acid, phosphatidylglycerol, phosphatidylglycerol phosphate methyl ester, phosphatidylglycerol sulfate and three glycolipids, which were chromatographically identical to those of Haloarchaeobius iranensis IBRC-M 10013(T) and Haloarchaeobius litoreus CGMCC 1.10390(T). 16S rRNA gene analysis revealed that strain YC82(T) had two dissimilar 16S rRNA genes and that it was phylogenetically related to Hab. iranensis IBRC-M 10013(T) (94.3-99.0 % nucleotide identity) and Hab. litoreus CGMCC 1.10390(T) (94.1-98.8 % nucleotide identity). The rpoB' gene similarities between strain YC82(T) and Hab. iranensis IBRC-M 10013(T) and Hab. litoreus CGMCC 1.10390(T) were 96.5 % and 95.7 %, respectively. The DNA G+C content of strain YC82(T) was 63.7 mol%. Strain YC82(T) showed low DNA-DNA relatedness with Hab. iranensis IBRC-M 10013(T) and Hab. litoreus CGMCC 1.10390(T). The phenotypic, chemotaxonomic and phylogenetic properties of strain YC82(T) ( = CGMCC 1.12232(T) = JCM 18644(T)) suggest that it represents a novel species of the genus Haloarchaeobius, for which the name Haloarchaeobius salinus sp. nov. is proposed. An emended description of the genus Haloarchaeobius is also presented., (© 2015 IUMS.)

Halophilic archaeal strain YC25(T) was isolated from Yuncheng salt lake in Shanxi, China. Cells of strain YC25(T) were observed to be pleomorphic rods, stained Gram-negative, and formed red-pigmented colonies on solid media. Strain YC25(T) was found to be able to grow at 25-50 °C (optimum 37 °C), at 1.4-4.8 M NaCl (optimum 1.7 M), at 0-1.0 M MgCl2 (optimum 0.01 M), and at pH 5.5-9.0 (optimum pH 6.5). The cells lysed in distilled water, and the minimal NaCl concentration to prevent cell lysis was found to be 8 % (w/v). The major polar lipids of the strain were phosphatidylglycerol (PG), phosphatidylglycerol phosphate methyl ester (PGP-Me), phosphatidylglycerol sulfate (PGS), sulfated galactosyl mannosyl glucosyl diether (S-TGD-1), sulfated mannosyl glucosyl diether (S-DGD-1), galactosyl mannosyl glucosyl diether (TGD-1), mannosyl glucosyl diether (DGD-1), and an unknown diglycosyl diether (DGD-2) chromatographically identical to those of Halorussus rarus CGMCC 1.10122(T). The 16S rRNA gene and rpoB' gene of strain YC25(T) were phylogenetically related to the corresponding genes of Halorussus rarus CGMCC 1.10122(T) (94.3-95.4 and 91.5 % nucleotide identity, respectively). The DNA G+C content of strain YC25(T) was determined to be 63.3 mol%. The phenotypic, chemotaxonomic, and phylogenetic properties suggested that strain YC25(T) (=CGMCC 1.12122(T) = JCM 18363(T)) represents a new species of Halorussus, for which the name Halorussus ruber sp. nov. is proposed.

An extremely halophilic archaeon, strain IC35(T), was isolated from a mud sample of the Aran-Bidgol salt lake in Iran. The novel strain was cream, non-motile, rod-shaped and required at least 2.5 M NaCl, but not MgCl2, for growth. Optimal growth was achieved with 3.4 M NaCl and 0.1 M MgCl2. The optimum pH and temperature for growth were pH 7.0 (grew over a pH range of 6.5-9.0) and 40 °C (grew over a temperature range of 30-50 °C), respectively. Analysis of 16S rRNA gene sequences revealed that strain IC35(T) clustered with species of the genus Halovivax, with sequence similarities of 97.3%, 96.6% and 96.3%, respectively, to Halovivax limisalsi IC38(T), Halovivax asiaticus EJ-46(T) and Halovivax ruber XH-70(T). The rpoB' gene similarities between the novel strain and Halovivax limisalsi IBRC-M 10022(T), Halovivax ruber JCM 13892(T) and Halovivax asiaticus JCM 14624(T) were 90.2 %, 90.2% and 89.9%, respectively. The polar lipid pattern of strain IC35(T) consisted of phosphatidylglycerol and phosphatidylglycerol phosphate methyl ester; six unknown glycolipids and two minor phospholipids were also observed. The only quinone present was MK-8 (II-H2). The G+C content of the genomic DNA was 63.2 mol%. DNA-DNA hybridization studies (29% hybridization with Halovivax limisalsi IBRC-M 10022(T)), as well as biochemical and physiological characterization, allowed strain IC35(T) to be differentiated from other species of the genus Halovivax. A novel species, Halovivax cerinus sp. nov., is therefore proposed to accommodate this strain. The type strain is IC35(T) ( = IBRC-M 10256(T) = KCTC 4050(T))., (© 2015 IUMS.)

A Gram-stain-negative, cream-pigmented, motile, extremely halophilic archaeon, designated strain IC38(T), was isolated from a saline mud sample taken from a hypersaline lake, Aran-Bidgol, in Iran. The strain required at least 2.5 M NaCl for growth. However, MgCl2 was not required. Optimal growth occurred with 4.3 M NaCl and 0.2 M MgCl2. The optimum pH and temperature for growth were pH 7.0 and 35 °C, respectively, and strain IC38(T) was able to grow over a pH range of 6.5-9.0, and a temperature range of 25-45 °C. Analysis of the 16S rRNA gene sequence revealed that strain IC38(T) clustered with the two species of the genus Halovivax, Halovivax asiaticus EJ-46(T) and Halovivax ruber XH-70(T), with sequence similarities of 96.4% and 96.1%, respectively. The similarities between the rpoB' gene of the novel strain and Halovivax asiaticus and Halovivax ruber were 90.7% and 90.3%, respectively. The polar lipid pattern of strain IC38(T) consisted of phosphatidylglycerol and phosphatidylglycerol phosphate methyl ester. Three unidentified glycolipids and two minor phospholipids were also observed. The DNA G+C content of strain IC38(T) was 62.6 mol%. On the basis of the phylogenetic analysis, as well as the biochemical and physiological characteristics, the new isolate is suggested to be a representative of a novel species of the genus Halovivax, for which the name Halovivax limisalsi sp. nov. is proposed. The type strain of Halovivax limisalsi is IC38(T) ( = IBRC-M 10022(T) = KCTC 4051(T))., (© 2014 IUMS.)

Microbial community succession was examined over a two-year period using spatially and temporally coordinated water chemistry measurements, metagenomic sequencing, phylogenetic binning and de novo metagenomic assembly in the extreme hypersaline habitat of Lake Tyrrell, Victoria, Australia. Relative abundances of Haloquadratum-related sequences were positively correlated with co-varying concentrations of potassium, magnesium and sulfate, but not sodium, chloride or calcium ions, while relative abundances of Halorubrum, Haloarcula, Halonotius, Halobaculum and Salinibacter-related sequences correlated negatively with Haloquadratum and these same ionic factors. Nanohaloarchaea and Halorhabdus-related sequence abundances were inversely correlated with each other, but not other taxonomic groups. These data, along with predicted gene functions from nearly-complete assembled population metagenomes, suggest different ecological phenotypes for Nanohaloarchaea and Halorhabdus-related strains versus other community members. Nucleotide percent G+C compositions were consistently lower in community metagenomic reads from summer versus winter samples. The same seasonal G+C trends were observed within taxonomically binned read subsets from each of seven different genus-level archaeal groups. Relative seasonal abundances were also linked to percent G+C for assembled population genomes. Together, these data suggest that extreme ionic conditions may exert selective pressure on archaeal populations at the level of genomic nucleotide composition, thus contributing to seasonal successional processes. Despite the unavailability of cultured representatives for most of the organisms identified in this study, effective coordination of physical and biological measurements has enabled discovery and quantification of unexpected taxon-specific, environmentally mediated factors influencing microbial community structure.

Saline, meromictic lakes with significant depth are usually formed as a result of salt mining activity. Ocnei Lake is one of the largest Transylvanian (Central Romania) neutral, hypersaline lake of man-made origin. We aimed to survey the seasonal dynamics of archaeal diversity in the water column of Ocnei Lake by employing microbiological methods as well as molecular techniques based on the sequence analysis of the 16S rRNA gene. We found that archaeal diversity in the water column increased with depth and salinity, with 8 OTUs being detected in the epilimnion compared to 21 found in the chemocline, and 32 OTUs in the monimolimnion. Down to 3.5 m depth, the archaeal community was markedly dominated by the presence of an unclassified archaeon sharing 93% sequence identity to Halogeometricum spp. At the chemocline, the shift in archaeal community composition was associated with an increase in salinity, the main factor affecting the vertical distribution of archaeal assemblages. It appears that the microoxic and hypersaline monimolimnion is populated by several major haloarchaeal taxa, with minor fluctuations in their relative abundances throughout all seasons. The culturable diversity was reasonably correlated to the dominant OTUs obtained by molecular methods. Our results indicate that Ocnei Lake represents a relatively stable extreme habitat, accommodating a diverse and putatively novel archaeal community, as 30% of OTUs could not be classified at the genus level.

An extremely halophilic archaeon, strain D108(T), was isolated from a brine sample of Aran-Bidgol salt lake in Iran. The novel strain was cream-pigmented, motile, pleomorphic rod-shaped and required at least 2.5 M NaCl but not MgCl2 for growth. Optimal growth was achieved with 4.3 M NaCl and 0.1 M MgCl2. The optimum pH and temperature for growth were pH 7.5 and 40 °C, respectively, and the strain was able to grow over a pH range of 6.5 to 9.0, and a temperature range of 30 to 50 °C. Phylogenetic analysis based on 16S rRNA gene sequence comparisons revealed that strain D108(T) clustered with the type strain of the sole species of the genus Halorientalis, Halorientalis regularis TNN28(T), with a sequence similarity of 98.8 %. The polar lipid pattern of strain D108(T) consisted of phosphatidylglycerol, phosphatidylglycerol phosphate methyl ester, one phosphoglycolipid and two glycolipids. The only quinone present was MK-8(II-H2). The DNA G+C content of strain D108(T) was 62.8 mol%. DNA-DNA hybridization studies (45 % with Halorientalis regularis IBRC-M 10760(T)), as well as biochemical and physiological characterization, allowed strain D108(T) to be differentiated from Halorientalis regularis. A novel species of the genus Halorientalis, Halorientalis persicus sp. nov., is therefore proposed to accommodate this strain. The type strain is D108(T) ( = IBRC-M 10043(T) = CECT 8375(T)). An emended description of the genus Halorientalis is also proposed.

Two halophilic archaeal strains, YC20(T) and XD15, were isolated from a marine solar saltern and an inland salt lake in China. Both had pleomorphic cells that lysed in distilled water, stained Gram-negative and formed red-pigmented colonies. They were neutrophilic, requiring at least 100 g NaCl l(-1) and 0.5-95 g MgCl2 l(-1) for growth at the optimum growth temperature of 37 °C. The major polar lipids of the two strains were phosphatidylglycerol (PG), phosphatidylglycerol phosphate methyl ester (PGP-Me), phosphatidylglycerol sulfate (PGS) and two major glycolipids chromatographically identical to sulfated mannosyl glucosyl diether (S-DGD-1) and mannosyl glucosyl diether (DGD-1), respectively. Trace amounts of two unidentified glycolipids were also detected. The 16S rRNA gene sequences of the two strains were 99.5 % identical and showed 94.0-95.9 % similarity to the most closely related members of the genus Halobellus of the family Halobacteriaceae. The rpoB' gene sequence similarity between strains YC20(T) and XD15 was 98.2 % and these sequences showed 89.6-92.8 % similarity to those of the most closely related members of the genus Halobellus. The DNA G+C contents of strains YC20(T) and XD15 were 65.8 mol% and 65.4 mol%, respectively. The DNA-DNA hybridization value between strain YC20(T) and strain XD15 was 92 %, and the two strains showed low DNA-DNA relatedness to members of the genus Halobellus. The phenotypic, chemotaxonomic and phylogenetic properties suggest that strains YC20(T) and XD15 represent a novel species of the genus Halobellus, for which the name Halobellus inordinatus sp. nov. is proposed. The type strain is YC20(T) ( = CGMCC 1.12120(T) = JCM 18361(T)) and the other strain is XD15 ( = CGMCC 1.12236 = JCM 18648).

Two halophilic archaeal strains, YC21(T) and YC77, were isolated from an inland salt lake of China. Both have pleomorphic rod-shaped cells that lyse in distilled water, stain Gram-negative and form red-pigmented colonies. They are neutrophilic, require at least 2.1 M NaCl for growth under the optimum growth temperature of 37 °C. The major polar lipids of the two strains were phosphatidylglycerol (PG), phosphatidylglycerol phosphate methyl ester (PGP-Me), phosphatidylglycerol sulfate (PGS), two major glycolipids (GL1 and GL2) chromatographically identical to sulfated mannosyl glucosyl diether (S-DGD-1) and mannosyl glucosyl diether (DGD-1), respectively. Trace amounts of two unidentified lipids (GL0-1 and GL0-2) were also detected. The 16S rRNA gene sequences of the two strains are 99.9 % identical, show 94.0-98.9 % similarity to the closest relative members of Halobellus of the family Halobacteriaceae. The rpoB' gene similarity between strains YC21(T) and YC77 is 99.8 % and show 90.3-95.3 % similarity to the closest relative members of Halobellus. The DNA G+C content of strains YC21(T) and YC77 were 66.1 and 66.2 mol%, respectively. The DNA-DNA hybridization value between strain YC20(T) and strain YC77 was 89 %, and the two strains showed low DNA-DNA relatedness with Halobellus limi TBN53(T), the most related member of Halobellus. The phenotypic, chemotaxonomic and phylogenetic properties suggest that strains YC21(T) and YC77 represent a novel species of the genus Halobellus, for which the name Halobellus rarus sp. nov. is proposed. The type strain is YC21(T) (=CGMCC 1.12121(T) = JCM 18362(T)).

Two extremely halophilic archaea, designated YIM 94188(T) and YIM 94189, were isolated from Qijiaojing lake in Xinjiang province, north-west China and subjected to taxonomic characterization using a polyphasic approach. The cells of the two strains were coccoid, non-motile and Gram-stain-negative. Colonies were pink-white-pigmented and aerobic. Growth occurred at 10-30% (w/v) NaCl, 20-55 °C and pH 6.0-8.0 (optimum: 20-25% NaCl, 37-42 °C, pH 6.5-7.0). Magnesium was necessary for growth in the range of 0.2-1.2 M. Phylogenetic analysis based on the 16S rRNA gene sequences indicated that the two strains belonged to the genus Halopelagius showing 98.5% sequence similarity to the closest phylogenetic neighbour, Halopelagius inordinatus RO5-2(T). In addition, the DNA-DNA hybridization values of strains YIM 94188(T) and YIM 94189 to Halopelagius inordinatus RO5-2(T) were 35.7% and 37.7%, respectively. Polar lipid analyses revealed that the two strains contained phosphatidylglycerol (PG), phosphatidylglycerol phosphate methyl ester (PGP-Me), sulfated mannosyl glucosyl diether (S-DGD-1) and mannosyl glucosyl diether (DGD-1). The DNA G+C contents of strains YIM 94188(T) and YIM 94189 were 66.3 mol% and 64.6 mol%, respectively. On the basis of physiological and chemotaxonomic data, and phylogenetic analysis, strains YIM 94188(T) and YIM 94189 were classified as representing a novel species in the genus Halopelagius. The name Halopelagius fulvigenes sp. nov. is proposed, with YIM 94188(T) (=CCTCC AB 2010456(T)=JCM 17506(T)) as the type strain.

A new haloalkaliphilic archaeon, strain B4(T), was isolated from the former lake Texcoco in Mexico. The cells were Gram-negative, pleomorphic-shaped, pink to red pigmented and aerobic. Strain B4(T) required at least 2.5 M NaCl for growth, with optimum growth at 3.4 M NaCl. It was able to grow over a pH range of 7.5-10.0 and temperature of 25-50 °C, with optimal growth at pH 9 and 37 °C. Cells are lysed in hypotonic treatment with less than 1.3 M NaCl. The major polar lipids of strain B4(T) were phosphatidylglycerol and methyl-phosphatidylglycerophosphate. Phospholipids were detected, but not glycolipids. The nucleotide sequence of the 16S rRNA gene revealed that the strain B4(T) was phylogenetically related to members of the genus Natronorubrum. Sequence similarity with Natronorubrum tibetense was 96.28 %, with Natronorubrum sulfidifaciens 95.06 % and Natronorubrum sediminis 94.98 %. The G+C content of the DNA was 63.3 mol%. The name of Natronorubrum texcoconense sp. nov. is proposed. The type strain is B4(T) (=CECT 8067(T) = JCM 17497(T)).

Two halophilic archaea, strains MDB25(T) and MDB20, were isolated from a sample of the brine from Lake Medee, at a depth of 3050 m, in the Mediterranean Sea. Cells of the organisms were Gram-negative, non-motile and pleomorphic, and colonies were red pigmented. Strains MDB25(T) and MDB20 showed optimum growth at 45°C, in 2.6-3.4M NaCl and at pH 7.0-8.0. The major polar lipids of the two strains were phosphatidylglycerol (PG1 and PG2), phosphatidylglycerol phosphate methyl ester (PGP-Me) and mannose-2,6-dissulfate (1→2)-glucose glycerol diether (S(2)-DGD). Menaquinone MK-8 and MK-8(H(2)) were the major respiratory quinones. The DNA G+C content of strain MDB25(T) was 63.0%. The strains were facultatively anaerobic but grew better under aerobic conditions, nitrate served as electron acceptor. Analysis of the almost complete 16S rRNA gene sequence indicated that the strains MDB25(T) and MDB20 represented a member of the genus Natrinema in the family Halobacteriaceae. Both strains formed a distinct cluster and were most closely related to Natrinema ejinorense JCM 13890(T) and Haloterrigena longa JCM 13562(T) (98.0% and 97.9% sequence similarity, respectively). Based on 16S rRNA gene sequence analysis, DNA-DNA hybridization results, physiological and biochemical characteristics we describe a new species represented by strain MDB25(T) (=DSM 25055(T) =JCM 17869(T)) for which we propose the name Natrinema salaciae sp. nov., (Copyright © 2012 Elsevier GmbH. All rights reserved.)

A novel pale pink-pigmented halophilic archaeon, strain DC30(T), was isolated from Aran-Bidgol salt lake, a hypersaline playa in Iran. Cells of strain DC30(T) were non-motile and pleomorphic, from rods to triangular or disc-shaped. Strain DC30(T) required at least 1.7 M NaCl and 0.05 M MgCl(2) for growth (optimum, 3 M NaCl and 0.1 M MgCl(2)). The optimum pH and temperature for growth of strain DC30(T) were pH 7.5 and 40 °C, respectively, although it was capable of growth over pH and temperature ranges of 6.5-8.5 and 25-50 °C, respectively. Analysis of the 16S rRNA gene sequence showed that strain DC30(T) was a member of the family Halobacteriaceae. However, it had low 16S rRNA gene sequence similarities of 92.4%, 89.4% and 89.1% to the most closely related haloarchaeal taxa, the type species of the genera Halorubrum, Halogranum and Haloplanus, respectively. The DNA G+C content was 66.0 mol%. Phosphatidylglycerol and phosphatidylglycerol phosphate methyl ester, common phospholipids found in haloarchaea, were present. Three minor phospholipids and one unidentified glycolipid were also observed. The only quinone present was MK-8(II-H(2)). The physiological, biochemical and phylogenetic differences between strain DC30(T) and other previously described genera of extremely halophilic archaea suggest that strain DC30(T) represents a novel species in a new genus within the family Halobacteriaceae, for which the name Halopenitus persicus gen. nov., sp. nov. is proposed. The type strain of Halopenitus persicus is DC30(T) ( = IBRC 10041(T) = KCTC 4046(T)).

A novel red-pigmented halophilic archaeon, strain EB27(T), was isolated from Aran-Bidgol salt lake, a hypersaline playa in Iran. Cells of strain EB27(T) were non-motile and pleomorphic (rods to triangular or disc-shaped). Strain EB27(T) required at least 2.5 M NaCl and 0.1 M MgCl(2) for growth. Optimal growth was achieved at 4 M NaCl and 0.5 M MgCl(2). The optimum pH and temperature for growth were pH 7.5 and 40 °C; it was able to grow at pH 6.0-8.0 and 25-50 °C. 16S rRNA gene sequence analysis showed that strain EB27(T) is a member of the family Halobacteriaceae; however, levels of 16S rRNA gene sequence similarity were as low as 90.0, 89.3 and 89.1 % to the most closely related haloarchaeal taxa, namely Halalkalicoccus tibetensis DS12(T), Halosimplex carlsbadense 2-9-1(T) and Halorhabdus utahensis AX-2(T), respectively. The DNA G+C content of strain EB27(T) was 61 mol%. Strain EB27(T) contained phosphatidylglycerol and phosphatidylglycerol phosphate methyl ester, common phospholipids found in haloarchaea, together with two minor phospholipids. The only quinone present was MK-8(II-H(2)). Physiological, biochemical and phylogenetic differences between strain EB27(T) and recognized genera of extremely halophilic archaea suggest that this strain represents a novel species in a new genus within the family Halobacteriaceae, for which the name Halovenus aranensis gen. nov., sp. nov. is proposed. The type strain of Halovenus aranensis, the type species of the new genus, is strain EB27(T) ( = IBRC-M 10015(T) = CGMCC 1.11001(T)).

The draft genome sequence (4,398,155 bp, with 65.35% G+C content) of Halobiforma lacisalsi AJ5, an extremely halophilic archaeon isolated from a salt lake, is reported here. This is the first genome report for a species of the Halobiforma genus.