Halostella pelagica sp. nov. and Halostella litorea sp. nov., isolated from salted brown alga Laminaria

Three rod-shaped halophilic archaeal strains, DL-M4T, LYG-109 and DLLS-108T, were isolated from the salted brown alga Laminaria produced in different marine areas of PR China. Cells of strains were motile, formed red-pigmented colonies on agar and lysed in distilled water. The three strains grew optimally with 2.6 M NaCl, with 0.05-0.3 M MgCl2, at 37 °C and at pH 7.0-7.5. The results of phylogenetic analyses based on the 16S rRNA and rpoB' genes differentiated these strains into two clusters belonging to the genus Halostella, which currently contains Halostella salina CBA1114T and Halostella limicola LT12T. Strains DL-M4T and LYG-109 formed a single cluster separate from the current two members of Halostella (94.4-95.7 and 90.0-90.9 % similarities, respectively) while strain DLLS-108T had Hsl. salina CBA1114T as its nearest neighbour (97.7-97.8 and 95.9 % similarities, respectively) and was separated from Hsl. limicola LT12T (94.4-95.8 and 93.4 % similarities, respectively). These clusters represented two distinct novel species as indicated by phenotypic characteristics, polar lipid compositions and whole-genome comparisons. Diverse phenotypic characteristics, morphology and growth characteristics, nutrition and miscellaneous biochemical tests differentiate strains DL-M4T, LYG-109, DLLS-108T from Hsl. limicola LT12T and Hsl. salina CBA1114T. Strains DL-M4T and LYG-109 contained phosphatidylglycerol, phosphatidylglycerol phosphate methyl ester and three unidentified glycolipids, while strain DLLS-108T contained these polar lipids and two unidentified phospholipids. The major respiratory quinones detected in the three isolates were menaquinone MK-8 and MK-8(H2). The average nucleotide identity (ANI) and in silico DNA-DNA hybridization (isDDH) values between the isolated strains and the current two members of Halostella were found to be 79.3-86.6 (ANI) and 22.9-49.8 % (isDDH). All these results showed that the three isolates represent two novel species of the genus Halostella for which the names Halostella pelagica sp. nov. [type strain dl-M4T (=CGMCC 1.13603T=JCM 32954T)] and Halostella litorea sp. nov. [type strain DLLS-108T(=CGMCC 1.13610T=JCM 32955T)] are proposed.

MBSP1: a biosurfactant protein derived from a metagenomic library with activity in oil degradation

Microorganisms represent the most abundant biomass on the planet; however, because of several cultivation technique limitations, most of this genetic patrimony has been inaccessible. Due to the advent of metagenomic methodologies, such limitations have been overcome. Prevailing over these limitations enabled the genetic pool of non-cultivable microorganisms to be exploited for improvements in the development of biotechnological products. By utilising a metagenomic approach, we identified a new gene related to biosurfactant production and hydrocarbon degradation. Environmental DNA was extracted from soil samples collected on the banks of the Jundiaí River (Natal, Brazil), and a metagenomic library was constructed. Functional screening identified the clone 3C6, which was positive for the biosurfactant protein and revealed an open reading frame (ORF) with high similarity to sequences encoding a hypothetical protein from species of the family Halobacteriaceae. This protein was purified and exhibited biosurfactant activity. Due to these properties, this protein was named metagenomic biosurfactant protein 1 (MBSP1). In addition, E. coli RosettaTM (DE3) strain cells transformed with the MBSP1 clone showed an increase in aliphatic hydrocarbon degradation. In this study, we described a single gene encoding a protein with marked tensoactive properties that can be produced in a host cell, such as Escherichia coli, without substrate dependence. Furthermore, MBSP1 has been demonstrated as the first protein with these characteristics described in the Archaea or Bacteria domains.

Halorientalis pallida sp. nov., an extremely halophilic archaeon isolated from a marine saltern

An extremely halophilic archaeon, strain F13-25^T, was isolated from a marine saltern located in Isla Cristina, Huelva, on the south-west coast of Spain. The novel strain had pink-pigmented, non-motile, coccoid cells. Optimal growth was achieved at 25 % (w/v) NaCl, pH 7.5 and 37 °C. Strain F13-25^T possessed two heterogeneous 16S rRNA genes (rrnA and rrnB) most closely related to Halorientalis persicus D108^T (97.6-99.2 % sequence similarity) and Halorientalis regularis TNN28^T (95.9-98.8 %). On the basis of the results of rpoB' gene sequence analysis, strain F13-25^T was also closely related to Halorientalis persicus IBRC-M 10043^T (89.9 %) and Halorientalis regularis TNN28^T (92.3 %). Relatedness values, computed using the Genome-to-Genome Distance Calculator, between strain F13-25^T and Halorientalis persicus IBRC-M 10043^T and Halorientalis regularis IBRC-M 10760^T were 34.6 and 36.2 %, respectively. Average nucleotide identity values based on orthoANI, ANIb and ANIm of strain F13-25^T and Halorientalis persicus IBRC-M 10043^T and Halorientalisregularis IBRC-M 10760^T were 88.0 and 88.8, 87.1 and 87.6 %, and 89.2 and 89.6 %, respectively. All values were far below the threshold accepted for prokaryotic species delineation. The major polar lipids were phosphatidylglycerol, phosphatidylglycerol phosphate methyl ester and one glycolipid chromatographically identical to sulfated diglycosyl diether. The DNA G+C content was 65.7 mol% (genome). The results of phylogenetic, phenotypic and chemotaxonomic analyses indicated that strain F13-25^T represents a novel species of the genus Halorientalis, for which the name Halorientalis pallida sp. nov., with type strain F13-25^T (=CECT 9384^T=IBRC-M 11176^T), is proposed.

Discovery of bacteriorhodopsins in Haloarchaeal species isolated from Indian solar salterns: deciphering the role of the N-terminal residues in protein folding and functional expression

Interesting optical and photochemical properties make microbial rhodopsin a promising biological material suitable for various applications, but the cost-prohibitive nature of production has limited its commercialization. The aim of this study was to explore the natural biodiversity of Indian solar salterns to isolate natural bacteriorhodopsin (BR) variants that can be functionally expressed in Escherichia coli. In this study, we report the isolation, functional expression and purification of BRs from three pigmented haloarchaea, wsp3 (water sample Pondicherry), wsp5 and K1T isolated from two Indian solar salterns. The results of the 16S rRNA data analysis suggest that wsp3, wsp5 and K1T are novel strains belonging to the genera Halogeometricum, Haloferax and Haloarcula respectively. Overall, the results of our study suggest that 17 N-terminal residues, that were not included in the gene annotation of the close sequence homologues, are essential for functional expression of BRs. The primary sequence, secondary structural content, thermal stability and absorbance spectral properties of these recombinant BRs are similar to those of the previously reported Haloarcula marismortui HmBRI. This study demonstrates the cost-effective, functional expression of BRs isolated from haloarchaeal species using E. coli as an expression host and paves the way for feasibility studies for future applications.

Halorussus litoreus sp. nov., isolated from the salted brown alga Laminaria

A halophilic archaeal strain, designated HD8-51T, was isolated from the salted brown alga Laminaria. Cells of strain HD8-51T were motile, pleomorphic coccoid or ovoid, and formed red-pigmented colonies on agar plates. Strain HD8-51T grew optimally at 3.1 M NaCl, 0.03 M MgCl2, 30 °C and pH 7.0. Cells lysed in distilled water and the minimal NaCl concentration to prevent cell lysis was 0.85 M. Based on phylogenetic analyses of the 16S rRNA and rpoB' genes, strain HD8-51T was most closely related to members of the genus Halorussus (92.3-95.6 % and 89.2-91.7% similarities, respectively). The average nucleotide identity values and in silico DNA-DNA hybridization values between strain HD8-51T and Halorussus rarus TBN4T were 81.69 and 24.5 %, respectively. The major polar lipids of strain HD8-51T were phosphatidic acid (PA), phosphatidylglycerol (PG), phosphatidylglycerol phosphate methyl ester (PGP-Me), phosphatidylglycerol sulfate (PGS) and five glycolipids, sulfated galactosyl mannosyl glucosyl diether (S-TGD-1), galactosyl mannosyl glucosyl diether (TGD-1), sulfated mannosyl glucosyl diether (S-DGD-1), mannosyl glucosyl diether (DGD-1) and diglycosyl diether (DGD-2). The DNA G+C content was 65.9 mol%. Based on phenotypic, chemotaxonomic and phylogenetic properties, strain HD8-51T represents a novel species of the genus Halorussus, for which the name Halorussus litoreus sp. nov. is proposed. The type strain is HD8-51T (=CGMCC 1.15333T=JCM 31109T).

Isolation and identification of two extremely halophilic archaea from sebkhas in the Algerian Sahara

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).

Diversity and bioprospecting of extremely halophilic archaea isolated from Algerian arid and semi-arid wetland ecosystems for halophilic-active hydrolytic enzymes

The diversity of haloarchaea associated with different dry salt lakes in northeastern Algeria was investigated together with their potential of hydrolytic enzyme production. A total of 68 aerobic halophilic archaea were isolated from saline sediments. Based on the 16S rRNA gene sequencing, the isolates were assigned to seven phylotypes within the class Halobacteria, namely Haloarcula, Halococcus, Haloferax, Halogeometricum, Haloterrigena, Natrialba, and Natrinema. The results showed that Haloferax group was found to be dominant in all samples (30 isolates) (44%) with high diversity, followed by Halococcus spp. (13%) (9 isolates). All phylotypes are extreme halophiles and thermotolerant with the ability to grow at temperatures up to 48 °C. In addition, the screening for extracellular halophilic enzymes showed that 89.7% of the isolates were able to produce at least two types of the screened enzymes. The strains producing esterase, gelatinase, inulinase, cellulase and protease activities were the most diverse functional group. These data showed an abundant and diverse haloarchaeal community, detected in Algerian wetland ecosystems, presenting a promising source of molecules with important biotechnological applications.

Halopiger thermotolerans sp. nov., a thermo-tolerant haloarchaeon isolated from commercial salt

Three thermo-tolerant halophilic archaeal strains, SR-441T, SR-412 and SR-188, were isolated from commercial salt samples. Cells were non-motile pleomorphic rod-shaped, and stained Gram-negative. Colonies were pink-pigmented. The three strains were able to grow with 1.7-4.6 M NaCl (optimum, 2.5 M), at pH 6.5-9.0 (optimum, pH 8.0) and at 35-60 °C (optimum, 45 °C). The orthologous 16S rRNA gene sequence similarities amongst the three strains were 98.8-99.3 %, and the level of DNA-DNA relatedness was 71-74 and 72-75 % (reciprocally). The closest relative was Halopiger aswanensis JCM 11628T with 98.6 %-99.1 % similarity in the orthologous 16S rRNA gene sequences, followed by two more Halopiger species, Halopiger xanaduensis JCM 14033T (98.5 %-99.1 %) and Halopiger salifodinae JCM 9578T (95.5 %-95.6 %). DNA-DNA relatednesses between the three strains and H. aswanensis JCM 11628T and H. xanaduensis JCM 14033T were 61 and 54 %, respectively. The polar lipids of the three novel strains were phosphatidylglycerol, phosphatidylglycerol phosphate methyl ester, and bis-sulfated diglycosyl archaeol-1. The most distinctive feature of the three strains was the ability to grow at 60 °C, while the maximum growth temperature of H. aswanensis is 55 °C. Based on phenotypic and phylogenetic analyses, the isolates are considered to represent a novel species of the genus Halopiger, for which the name Halopiger thermotolerans sp. nov. is proposed. The type strain is SR-441T (=JCM 19583T=KCTC 4248T) isolated from solar salt produced in Australia. SR-412 (=JCM 19582) and SR-188 (=JCM 19581) isolated from commercial salt samples are additional strains of the species.

Halobium palmae gen. nov., sp. nov., an extremely halophilic archaeon isolated from a solar saltern

A novel and extremely halophilic archaeon, designated strain 2a_47_2T, was isolated from a solar saltern sample collected in Indonesia. Cells of the strain were Gram-stain-negative, non-motile and pleomorphic and formed orange-red pigmented colonies. Strain 2a_47_2T grew at 20-48 °C (optimum 38-41 °C), pH 6.0-8.5 (optimum pH 7.5), >1.7 M NaCl (optimum 2.6 M) and <0.5 M MgCl2 (optimum 0.3 M). The major polar lipids were phosphatidylglycerol, phosphatidylglycerol phosphate methyl ester, two phospholipids and sulfated diglycosyl diether. The cells mainly contained menaquinone-8. The G+C content in the genomic DNA of the strain was 67.0 mol%. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain 2a_47_2T represents a member of the family Halorubraceae and is different from any other known halophilic archaea. This finding was also demonstrated by phylogenetic analyses based on deduced RpoB' amino acid sequences. Collectively, these results show that strain 2a_47_2T represents a novel genus and species in the family Halorubraceae, and the name Halobium palmae gen. nov., sp. nov. is proposed. The type strain is 2a_47_2T (=NBRC 111368T=InaCC Ar34T).

Halovenus salina sp. nov., an extremely halophilic archaeon isolated from a saltern

An extremely halophilic archaeon was isolated from a water sample of Isla Bacuta saltern in Huelva, Spain. Strain ASP54(T) is a novel red-pigmented, motile, rod-shaped, Gram-stain-negative and strictly aerobic haloarchaeon. Strain ASP54(T) grew in media containing 15-30% (w/v) salts and optimally with 25% (w/v) salts. It grew between pH 5.0 and 9.0 (optimally at pH 7.5) and at 20-40 °C (optimally at 37 °C). Phylogenetic analysis based on multi-locus sequence analysis (MLSA) and the comparison of 16S rRNA gene sequences revealed that strain ASP54(T) is most closely related to the genus Halovenus. The closest relatives were Halovenus aranensis EB27(T) (92.1% 16S rRNA gene sequence similarity), Halorientalis regularis TNN28(T) (92.1%), and Halorientalis persicus D108(T) (92.0%). The polar lipid pattern of strain ASP54(T) consisted of biphosphatidylglycerol, phosphatidylglycerol, phosphatidylglycerol phosphate methyl ester, phosphatidylglycerol sulfate, sulfated mannosyl glucosyl diether and a minor-phospholipid. The predominant respiratory quinone was menaquinone-8 (MK-8) (83%), and a minor amount of MK-8(VIII-H2) (17%) was also detected. The G+C content of the genomic DNA of this strain was 63.1 mol%. Based on the phenotypic, chemotaxonomic and phylogenetic data presented in this study, strain ASP54(T) represents a novel species of the genus Halovenus, for which the name Halovenus salina sp. nov. is proposed. The type strain is ASP54(T) ( = CEC(T) 8749(T) = IBRC-M 10946(T) = JCM 30072(T)).

Halovenus rubra sp. nov., isolated from salted brown alga Laminaria

Halophilic archaeal strain R28(T) was isolated from the brown alga Laminaria produced at Dalian, Liaoning Province, China. The cells of the strain were pleomorphic and lysed in distilled water, stained Gram-negative, and formed red-pigmented colonies. Strain R28(T) was able to grow at 25-50 °C (optimum 42 °C), in the presence of 3.1-5.1 M NaCl (optimum 3.9 M NaCl), with 0.005-1.0 M MgCl(2) (optimum 0.01 M MgCl(2)) and at pH 6.0-9.5 (optimum pH 7.0-7.5). The minimal NaCl concentration to prevent cell lysis was 15 % (w/v). The major polar lipids of the strain were identified as phosphatidic acid, phosphatidylglycerol, phosphatidylglycerol phosphate methyl ester, and two glycolipids chromatographically identical to those of Halovenus aranensis CGMCC 1.11001(T). The 16S rRNA gene and rpoB' gene of strain R28(T) were phylogenetically related to the corresponding genes of Hvn. aranensis CGMCC 1.11001(T) (91.9-97.2 and 82.9 % nucleotide identity, respectively). The DNA G+C content of strain R28(T) was determined to be 56.3 mol%. The phenotypic, chemotaxonomic, and phylogenetic properties suggest that strain R28(T) (=CGMCC 1.10592(T) = JCM 17269(T)) represents a novel species of the genus Halovenus, for which the name Halovenus rubra sp. nov. is proposed.

Halophilic archaea cultivated from surface sterilized middle-late eocene rock salt are polyploid

Live bacteria and archaea have been isolated from several rock salt deposits of up to hundreds of millions of years of age from all around the world. A key factor affecting their longevity is the ability to keep their genomic DNA intact, for which efficient repair mechanisms are needed. Polyploid microbes are known to have an increased resistance towards mutations and DNA damage, and it has been suggested that microbes from deeply buried rock salt would carry several copies of their genomes. Here, cultivable halophilic microbes were isolated from a surface sterilized middle-late Eocene (38–41 million years ago) rock salt sample, drilled from the depth of 800 m at Yunying salt mine, China. Eight unique isolates were obtained, which represented two haloarchaeal genera, Halobacterium and Halolamina. We used real-time PCR to show that our isolates are polyploid, with genome copy numbers of 11–14 genomes per cell in exponential growth phase. The ploidy level was slightly downregulated in stationary growth phase, but the cells still had an average genome copy number of 6–8. The polyploidy of halophilic archaea living in ancient rock salt might be a factor explaining how these organisms are able to overcome the challenge of prolonged survival during their entombment.

Salinigranum rubrum gen. nov., sp. nov., a member of the family Halobacteriaceae isolated from a marine solar saltern

Halophilic archaeal strain GX10(T) was isolated from the Gangxi marine solar saltern in China. Strain GX10(T) was observed to have pleomorphic cells that lysed in distilled water, stained Gram-negative and produced red-pigmented colonies. Strain GX10(T) was able to grow at 20-50 °C (optimum 37 °C), with 1.4-4.8 M NaCl (optimum 3.1 M NaCl), with 0-0.7 M MgCl2 (optimum 0.05 M MgCl2) and at pH 5.0-9.0 (optimum pH 7.0). The major polar lipids of strain GX10(T) were identified as phosphatidylglycerol, phosphatidylglycerol phosphate methyl ester, two major glycolipids chromatographically identical to sulfated mannosyl glucosyl diether and mannosyl glucosyl diether, and five unidentified glycolipids. Phylogenetic tree reconstructions based on 16S rRNA gene and rpoB' sequences revealed that strain GX10(T) was distinct from the related genera, Halogranum, Haloferax, Halopelagius, Halogeometricum, Halobellus, Haloplanus and Halorubrum. The DNA G+C content of strain GX10(T) was 62.9 mol%. The phenotypic, chemotaxonomic and phylogenetic properties suggested that strain GX10(T) represents a novel species of a new genus within the family Halobacteriaceae, for which the name Salinigranum rubrum gen. nov., sp. nov. is proposed. The type strain of the type species is GX10(T) ( = CGMCC 1.10385(T) = JCM 17116(T)).

Halosimplex pelagicum sp. nov. and Halosimplex rubrum sp. nov., isolated from salted brown alga Laminaria, and emended description of the genus Halosimplex

Two halophilic archaeal strains, R2(T) and R27(T), were isolated from the brown alga Laminaria produced at Dalian, Liaoning Province, China. Both had pleomorphic cells that lysed in distilled water, stained Gram-negative and formed red-pigmented colonies. They grew optimally at 42 °C, pH 7.0 and in the presence of 3.1-3.4 M NaCl and 0.03-0.5 M Mg(2+). The major polar lipids of the two strains were phosphatidylglycerol (PG), phosphatidylglycerol phosphate methyl ester (PGP-Me) and four major glycolipids chromatographically identical to those of Halosimplex carlsbadense JCM 11222(T). 16S rRNA gene analysis revealed that each strain had two dissimilar 16S rRNA genes and both strains were phylogenetically related to Halosimplex carlsbadense JCM 11222(T) (92.7-98.8 % similarities). The rpoB' gene similarities between strains R2(T) and R27(T) and between these strains and Halosimplex carlsbadense JCM 11222(T) were 95.7 %, 96.1 % and 95.8 %, respectively. The DNA G+C contents of strains R2(T) and R27(T) were 62.5 mol% and 64.0 mol%, respectively. The DNA-DNA hybridization values between strains R2(T) and R27(T) and between the two strains and Halosimplex carlsbadense JCM 11222(T) were 43 %, 52 % and 47 %, respectively. It was concluded that strain R2(T) ( = CGMCC 1.10586(T) = JCM 17263(T)) and strain R27(T) ( = CGMCC 1.10591(T) = JCM 17268(T)) represent two novel species of the genus Halosimplex, for which the names Halosimplex pelagicum sp. nov. and Halosimplex rubrum sp. nov. are proposed. An emended description of the genus Halosimplex is also presented.

Halobellus rarus sp. nov., a halophilic archaeon from an inland salt lake of China

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)).

Pulp mill wastewater sediment reveals novel methanogenic and cellulolytic populations

Pulp mill wastewater generated from wheat straw is characterized as high alkalinity and very high COD pollution load. A naturally developed microbial community in a pulp mill wastewater storage pool that had been disused were investigated in this study. Owing to natural evaporation and a huge amount of lignocellulose's deposition, the wastewater sediment contains high concentrations of organic matters and sodium ions, but low concentrations of chloride and carbonate. The microbiota inhabiting especially anaerobic community, including methanogenic arhcaea and cellulolytic species, was studied. All archaeal sequences fall into 2 clusters of family Halobacteriaceae and methanogenic archaeon in the phylum Euryarchaeota. In the methanogenic community, phylogenetic analysis of methyl coenzyme M reductase A (mcrA) genes targeted to novel species in genus Methanoculleus or novel genus of order Methanomicrobiales. The predominance of Methanomicrobiales suggests that methanogenesis in this system might be driven by the hydrogenotrophic pathway. As the important primary fermenter for methane production, the cellulolytic community of enzyme GHF48 was found to be dominated by narrower breadth of novel clostridial cellulase genes. Novel anoxic functional members in such extreme sediment provide the possibility of enhancing the efficiency of anoxic treatment of saline and alkaline wastewaters, as well as benefiting to the biomass transformation and biofuel production processes.

[Diversity and enzyme-producing activity of culturable halophilic bacteria in Daishan Saltern of East China]

Soil and saline water samples were collected from the Daishan Saltern of East China, and the halophilic bacteria were isolated and cultured by using selective media, aimed to investigate the diversity and enzyme-producing activity of culturable halophilic bacteria in saltern environment. A total of 181 strains were isolated by culture-dependent method. Specific primers were used to amplify the 16S rRNA gene of bacteria and archaea. The operation taxonomy units (OTUs) were determined by ARDRA method, and the representative strain of each OTU was sequenced. The phylogenetic position of all the isolated strains was determined by 16S rRNA sequencing. The results showed that the isolated 181 strains displayed 21 operational taxonomic units (OTUs), of which, 12 OTUs belonged to halophilic bacteria, and the others belonged to halophilic archaea. Phylogenetic analysis indicated that there were 7 genera presented among the halophilic bacteria group, and 4 genera presented among the halophilic archaea group. The dominant halophilic strains were of Halomonas and Haloarcula, with 46.8% in halophilic bacteria and 49.1% in halophilic archaea group, respectively. Enzyme-producing analysis indicated that most strains displayed enzyme-producing activity, including the activities of producing amylase, proteinase and lipase, and the dominant strains capable of enzyme-producing were of Haloarcula. Our results showed that in the environment of Daishan Saltern, there existed a higher diversity of halophilic bacteria, being a source sink for screening enzyme-producing bacterial strains.

Halobellus limi sp. nov. and Halobellus salinus sp. nov., isolated from two marine solar salterns

Two halophilic archaea, strains TBN53(T) and CSW2.24.4(T), were characterized to elucidate their taxonomic status. Strain TBN53(T) was isolated from the Taibei marine solar saltern near Lianyungang city, Jiangsu province, China, whereas strain CSW2.24.4(T) was isolated from a saltern crystallizer in Victoria, Australia. Cells of the two strains were pleomorphic, stained Gram-negative and produced red-pigmented colonies. Strain TBN53(T) was able to grow at 25-55 °C (optimum 45 °C), with 1.4-5.1 M NaCl (optimum 2.6-3.9 M NaCl), with 0-1.0 M MgCl(2) (optimum 0-0.1 M MgCl(2)) and at pH 5.5-9.5 (optimum pH 7.0), whereas strain CSW2.24.4(T) was able to grow at 25-45 °C (optimum 37 °C), with 2.6-5.1 M NaCl (optimum 3.4 M NaCl), with 0.01-0.7 M MgCl(2) (optimum 0.05 M MgCl(2)) and at pH 5.5-9.5 (optimum pH 7.0-7.5). Cells of the two isolates lysed in distilled water. The minimum NaCl concentrations that prevented cell lysis were 8 % (w/v) for strain TBN53(T) and 12 % (w/v) for strain CSW2.24.4(T). The major polar lipids of the two strains were phosphatidylglycerol, phosphatidylglycerol phosphate methyl ester and phosphatidylglycerol sulfate, with two glycolipids chromatographically identical to sulfated mannosyl glucosyl diether and mannosyl glucosyl diether, respectively. Trace amounts of other unidentified lipids were also detected. On the basis of 16S rRNA gene sequence analysis, strains TBN53(T) and CSW2.24.4(T) showed 94.1 % similarity to each other and were closely related to Halobellus clavatus TNN18(T) (95.0 and 94.7 % similarity, respectively). Levels of rpoB' gene sequence similarity between strains TBN53(T) and CSW2.24.4(T), and between these strains and Halobellus clavatus TNN18(T) were 88.5, 88.5 and 88.1 %, respectively. The DNA G+C contents of strains TBN53(T) and CSW2.24.4(T) were 69.2 and 67.0 mol%, respectively. The level of DNA-DNA relatedness between strain TBN53(T) and strain CSW2.24.4(T) was 25 %, and these two strains showed low levels of DNA-DNA relatedness with Halobellus clavatus TNN18(T) (30 and 29 % relatedness, respectively). Based on these phenotypic, chemotaxonomic and phylogenetic properties, two novel species of the genus Halobellus are proposed to accommodate these two strains, Halobellus limi sp. nov. (type strain TBN53(T) = CGMCC 1.10331(T) = JCM 16811(T)) and Halobellus salinus sp. nov. (type strain CSW2.24.4(T) = DSM 18730(T) = CGMCC 1.10710(T) = JCM 14359(T)).

Salinarchaeum laminariae gen. nov., sp. nov.: a new member of the family Halobacteriaceae isolated from salted brown alga Laminaria

Halophilic archaeal strains R26(T) and R22 were isolated from the brown alga Laminaria produced at Dalian, Liaoning Province, China. Cells from the two strains were pleomorphic rods and Gram negative, and colonies were red pigmented. Strains R26(T) and R22 were able to grow at 20-50°C (optimum 37°C) in 1.4-5.1 M NaCl (optimum 3.1-4.3 M) at pH 5.5-9.5 (optimum pH 8.0-8.5) and neither strain required Mg(2+) for growth. Cells lyse in distilled water and the minimum NaCl concentration required to prevent cell lysis was 8% (w/v) for strain R26(T) and 12% (w/v) for strain R22. The major polar lipids of the two strains were phosphatidylglycerol, phosphatidylglycerol phosphate methyl ester and minor phosphatidylglycerol sulfate; glycolipids were not detected. Phylogenetic analyses based on 16S rRNA genes and rpoB' genes revealed that strains R26(T) and R22 formed a distinct clade with the closest relative, Natronoarchaeum mannanilyticum. The DNA G+C content of strains R26(T) and R22 was 65.8 and 66.4 mol%, respectively. The DNA-DNA hybridization value between strains R26(T) and R22 was 89%. The phenotypic, chemotaxonomic and phylogenetic properties suggest that the strains R26(T) and R22 represent a novel species in a new genus within the family Halobacteriaceae, for which the name Salinarchaeum laminariae gen. nov., sp. nov. is proposed. The type strain is R26(T) (type strain R26(T) = CGMCC 1.10590(T) = JCM 17267(T), reference strain R22 = CGMCC 1.10589).

Haloquadratum walsbyi: limited diversity in a global pond

Background

Haloquadratum walsbyi commonly dominates the microbial flora of hypersaline waters. Its cells are extremely fragile squares requiring >14%(w/v) salt for growth, properties that should limit its dispersal and promote geographical isolation and divergence. To assess this, the genome sequences of two isolates recovered from sites at near maximum distance on Earth, were compared.

Principal Findings

Both chromosomes are 3.1 MB in size, and 84% of each sequence was highly similar to the other (98.6% identity), comprising the core sequence. ORFs of this shared sequence were completely synteneic (conserved in genomic orientation and order), without inversion or rearrangement. Strain-specific insertions/deletions could be precisely mapped, often allowing the genetic events to be inferred. Many inferred deletions were associated with short direct repeats (4–20 bp). Deletion-coupled insertions are frequent, producing different sequences at identical positions. In cases where the inserted and deleted sequences are homologous, this leads to variant genes in a common synteneic background (as already described by others). Cas/CRISPR systems are present in C23^T but have been lost in HBSQ001 except for a few spacer remnants. Numerous types of mobile genetic elements occur in both strains, most of which appear to be active, and with some specifically targetting others. Strain C23^T carries two ∼6 kb plasmids that show similarity to halovirus His1 and to sequences nearby halovirus/plasmid gene clusters commonly found in haloarchaea.

Conclusions

Deletion-coupled insertions show that Hqr. walsbyi evolves by uptake and precise integration of foreign DNA, probably originating from close relatives. Change is also driven by mobile genetic elements but these do not by themselves explain the atypically low gene coding density found in this species. The remarkable genome conservation despite the presence of active systems for genome rearrangement implies both an efficient global dispersal system, and a high selective fitness for this species.

Halogranum salarium sp. nov., a halophilic archaeon isolated from sea salt

Three halophilic archaea, strains B-1(T), B-3 and B-4, were isolated from evaporitic salt crystals from Namhae, Korea. Cells of the strains were Gram-stain-negative, motile and pleomorphic, and colonies were red-pigmented. The three isolates had identical 16S rRNA gene sequences and formed a tight phylogenetic clade with Halogranum rubrum RO2-11(T) in the genus Halogranum, showing 99.5% sequence similarity. The next most closely related species were Halogranum amylolyticum and Halogranum gelatinilyticum (97.4 and 96.3% similarity to the respective type strains). The phylogeny based on the full-length RNA polymerase subunit B' gene (rpoB') was in agreement with the 16S rRNA gene sequence analysis, but allowed better discrimination. DNA-DNA hybridization between a representative strain (B-1(T)) and the type strains of Hgn. rubrum, Hgn. amylolyticum and Hgn. gelatinilyticum revealed less than 40% relatedness. Polar lipid analysis showed that the three isolates contained phosphatidylglycerol, phosphatidylglycerol phosphate methyl ester and three glycolipids. Combined genotypic and phenotypic data supported the conclusion that strains B-1(T), B-3 and B-4 represent a novel species of the genus Halogranum, for which the name Halogranum salarium sp. nov. is proposed. The type strain is B-1(T) (=KCTC 4066(T)=DSM 23171(T)).

Novel insights into the diversity of catabolic metabolism from ten haloarchaeal genomes

BACKGROUND

The extremely halophilic archaea are present worldwide in saline environments and have important biotechnological applications. Ten complete genomes of haloarchaea are now available, providing an opportunity for comparative analysis.

METHODOLOGY/PRINCIPAL FINDINGS

We report here the comparative analysis of five newly sequenced haloarchaeal genomes with five previously published ones. Whole genome trees based on protein sequences provide strong support for deep relationships between the ten organisms. Using a soft clustering approach, we identified 887 protein clusters present in all halophiles. Of these core clusters, 112 are not found in any other archaea and therefore constitute the haloarchaeal signature. Four of the halophiles were isolated from water, and four were isolated from soil or sediment. Although there are few habitat-specific clusters, the soil/sediment halophiles tend to have greater capacity for polysaccharide degradation, siderophore synthesis, and cell wall modification. Halorhabdus utahensis and Haloterrigena turkmenica encode over forty glycosyl hydrolases each, and may be capable of breaking down naturally occurring complex carbohydrates. H. utahensis is specialized for growth on carbohydrates and has few amino acid degradation pathways. It uses the non-oxidative pentose phosphate pathway instead of the oxidative pathway, giving it more flexibility in the metabolism of pentoses.

CONCLUSIONS

These new genomes expand our understanding of haloarchaeal catabolic pathways, providing a basis for further experimental analysis, especially with regard to carbohydrate metabolism. Halophilic glycosyl hydrolases for use in biofuel production are more likely to be found in halophiles isolated from soil or sediment.

Halostagnicola kamekurae sp. nov., an extremely halophilic archaeon from solar salt

A novel extremely halophilic archaeon, strain 194-10(T), was isolated from a solar salt sample imported into Japan from the Philippines. Strain 194-10(T) was pleomorphic, neutrophilic and mesophilic and required at least 10 % (w/v) NaCl but no MgSO(4) . 7H(2)O for growth; it exhibited optimal growth at 15 % (w/v) NaCl and 60 mM MgSO(4) . 7H(2)O. Strain 194-10(T) grew at 20-45°C (optimum, 30°C) and pH 6.0-9.0 (optimum, pH 6.5-7.0). The G+C content of its DNA was 59.8 mol%. 16S rRNA gene sequence analysis revealed closest proximity to Halostagnicola larsenii XH-48(T) (98.5 % similarity), the sole representative of the genus Halostagnicola. Polar lipid analysis revealed that strain 194-10(T) contained phosphatidylglycerol and phosphatidylglycerol phosphate methyl ester (the latter derived from both C(20)C(20) and C(20)C(25) archaeol) and several unidentified glycolipids. The results of DNA-DNA hybridization (20.7 % relatedness between Hst. larsenii JCM 13463(T) and strain 194-10(T)) and physiological and biochemical characteristics allowed differentiation of strain 194-10(T) from Hst. larsenii XH-48(T). Therefore, strain 194-10(T) represents a novel species of the genus Halostagnicola, for which the name Halostagnicola kamekurae sp. nov. is proposed, with the type strain 194-10(T) (=DSM 22427(T) =JCM 16110(T) =CECT 7536(T)).

Further refinement of the phylogeny of the Halobacteriaceae based on the full-length RNA polymerase subunit B' (rpoB') gene

A considerable number of species of the Halobacteriaceae possess multiple copies of the 16S rRNA gene that exhibit more than 5 % divergence, complicating phylogenetic interpretations. Two additional problems have been pointed out: (i) the genera Haloterrigena and Natrinema show a very close relationship, with some species being shown to overlap in phylogenetic trees reconstructed by the neighbour-joining method, and (ii) alkaliphilic and neutrophilic species of the genus Natrialba form definitely separate clusters in neighbour-joining trees, suggesting that these two clusters could be separated into two genera. In an attempt to solve these problems, the RNA polymerase B' subunit has been used as an additional target molecule for phylogenetic analysis, using partial sequences of 1305 bp. In this work, a primer set was designed that consistently amplified the full-length RNA polymerase B' subunit gene (rpoB') (1827-1842 bp) from 85 strains in 27 genera of the Halobacteriaceae. Differences in sequence length were found within the first 15 to 31 nt, and their downstream sequences (1812 bp) were aligned unambiguously without any gaps or deletions. Phylogenetic trees reconstructed from nucleotide sequences and deduced amino acid sequences by the maximum-likelihood method demonstrated that multiple species/strains in most genera individually formed cohesive clusters. Two discrepancies were observed: (i) the two species of Natronolimnobius were placed in definitely different positions, in that Natronolimnobius innermongolicus was placed in the Haloterrigena/Natrinema cluster, while Natronolimnobius baerhuensis was closely related to Halostagnicola larsenii, and (ii) Natronorubrum tibetense was segregated from the three other Natronorubrum species in the protein tree, while all four species formed a cluster in the gene tree, although supported by a bootstrap value of less than 50 %. The six Haloterrigena species/strains and the five species of Natrinema formed a large cluster in both trees, with Halopiger xanaduensis and Nln. innermongolicus located in the cluster in the protein tree and Nln. innermongolicus in the gene tree. Hpg. xanaduensis broke into the cluster of the genus Halobiforma, instead of the Haloterrigena/Natrinema cluster, in the gene tree. The six Natrialba species formed a tight cluster with two subclusters, of neutrophilic species and alkaliphilic species, in both trees. Overall, our data strongly suggest that (i) Nln. innermongolicus is a member of Haloterrigena/Natrinema, (ii) Nrr. tibetense might represent a new genus and (iii) the two genera Haloterrigena and Natrinema might constitute a single genus. As more and more novel species and genera are proposed in the family Halobacteriaceae, the full sequence of the rpoB' gene may provide a supplementary tool for determining the phylogenetic position of new isolates.

Archaeal diversity at the great salt plains of Oklahoma described by cultivation and molecular analyses

The Great Salt Plains of Oklahoma is a natural inland terrestrial hypersaline environment that forms evaporite crusts of mainly NaCl. Previous work described the bacterial community through the characterization of 105 isolates from 46 phylotypes. The current report describes the archaeal community through both microbial isolation and culture-independent techniques. Nineteen distinct archaea were isolated, and ten were characterized phenetically. Included were isolates phylogenetically related to Haloarcula, Haloferax, Halorubrum, Haloterrigena, and Natrinema. The isolates were aerobic, non-motile, Gram-negative organisms and exhibited little capacity for fermentation. All of the isolates were halophilic, with most requiring at least 15% salinity for growth, and all grew at 30% salinity. The isolates were mainly mesothermic and could grow at alkaline pH (8.5). A 16S rRNA gene library was generated by polymerase chain reaction amplification of direct soil DNA extracts, and 200 clones were sequenced and analyzed. At 99% and 94% sequence identity, 36 and 19 operational taxonomic units (OTUs) were detected, respectively, while 53 and 22 OTUs were estimated by Chao1, respectively. Coverage was relatively high (100% and 59% at 89% and 99% sequence identity, respectively), and the Shannon Index was 3.01 at 99% sequence identity, comparable to or somewhat lower than hypersaline habitats previously studied. Only sequences from Euryarchaeota in the Halobacteriales were detected, and the strength of matches to known sequences was generally low, most near 90% sequence identity. Large clusters were observed that are related to Haloarcula and Halorubrum. More than two-thirds of the sequences were in clusters that did not have close relatives reported in public databases.

Natronorubrum sediminis sp. nov., an archaeon isolated from a saline lake

Two novel haloalkaliphilic archaea, strains CG-6T and CG-4, were isolated from sediment of the hypersaline Lake Chagannor in Inner Mongolia, China. Cells of the two strains were pleomorphic, non-motile and strictly aerobic. They required at least 2.5 M NaCl for growth, with optimum growth at 3.4 M NaCl. They grew at pH 8.0-11.0, with optimum growth at pH 9.0. Hypotonic treatment with less than 1.5 M NaCl caused cell lysis. The two strains had similar polar lipid compositions, possessing C20C20 and C20C25 derivatives of phosphatidylglycerol and phosphatidylglycerol phosphate methyl ester. No glycolipids were detected. Comparison of 16S rRNA gene sequences and morphological features placed them in the genus Natronorubrum. 16S rRNA gene sequence similarities to strains of recognized species of the genus Natronorubrum were 96.2-93.8%. Detailed phenotypic characterization and DNA-DNA hybridization studies revealed that the two strains belong to a novel species in the genus Natronorubrum, for which the name Natronorubrum sediminis sp. nov. is proposed; the type strain is CG-6T (=CECT 7487T =CGMCC 1.8981T =JCM 15982T).

Halorubrum luteum sp. nov., isolated from Lake Chagannor, Inner Mongolia, China

A novel halophilic archaeon, strain CGSA15(T), was isolated from water of Lake Chagannor in China. The strain grew optimally at 33-37 degrees C, pH 9.5-10.0 and 4.0-4.3 M NaCl. The major polar lipids were phosphatidylglycerol and phosphatidylglycerol phosphate methyl ester. The genomic DNA G+C content of strain CGSA15(T) was 60.2 mol%. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain CGSA15(T) was a member of the genus Halorubrum and was related most closely to Halorubrum alkaliphilum AS 1.3528(T) (96.1 % similarity) and Halorubrum tibetense AS 1.3239(T) (96.9 %). Levels of DNA-DNA relatedness between strain CGSA15(T) and Hrr. alkaliphilum AS 1.3528(T) and Hrr. tibetense AS 1.3239(T) were 36.7 and 28.9 %, respectively. According to the phenotypic and genotypic data presented, strain CGSA15(T) is considered to represent a novel species of the genus Halorubrum, for which the name Halorubrum luteum sp. nov. is proposed. The type strain is CGSA15(T) (=CGMCC 1.6783(T) =CECT 7303(T)).

Haloplanus natans gen. nov., sp. nov., an extremely halophilic, gas-vacuolate archaeon isolated from Dead Sea-Red Sea water mixtures in experimental outdoor ponds

To study biological phenomena in the Dead Sea and to simulate the effects of mixing Dead Sea water with Red Sea water, experimental mesocosms were operated at the Dead Sea Works at Sedom, Israel. Dense communities of red halophilic archaea developed in mesocosms filled with 80 % Dead Sea water and 20 % Red Sea water after enrichment with phosphate. The most common type of colonies isolated from these brines belonged to the genus Halorubrum. A few white-pinkish opaque colonies contained pleomorphic flat cells with gas vesicles. Three strains isolated from the latter colonies were characterized in depth. Their 16S rRNA gene sequences showed only 91 % similarity to the closest cultured relative (Haloferax mediterranei), indicating that the new strains represent a novel species of a new genus. The name Haloplanus natans gen. nov., sp. nov. is proposed for this novel organism. The type strain of Haloplanus natans is RE-101(T) (=DSM 17983(T)=JCM 14081(T)).

Halalkalicoccus jeotgali sp. nov., a halophilic archaeon from shrimp jeotgal, a traditional Korean fermented seafood

A novel, extremely halophilic archaeon B3T was isolated from shrimp-salted seafood. Its morphology, physiology, biochemical features and 16S rRNA gene sequence were characterized. Strain B3T is non-motile, Gram-variable, requires at least 10 % (w/v) NaCl for growth and grows in the ranges of 21–50 °C and pH 6.5–9.0. The DNA G+C content of strain B3T was 63.2 mol%. Phylogenetic analysis based on the 16S rRNA gene sequences indicated that strain B3T belonged to the genus Halalkalicoccus and was phylogenetically closely related to the type strain Halalkalicoccus tibetensis (98.64 %). However, DNA–DNA hybridization experiments showed 7.0 % relatedness between strain B3T and a strain of a reference species of the genus Halalkalicoccus. Combined analysis of 16S rRNA gene sequences, DNA–DNA relatedness data, physiological and biochemical tests indicated that the genotypic and phenotypic characteristics differentiate strain B3T from other Halalkalicoccus species. On the basis of the evidence presented in this report, strain B3T represents a novel species of the genus Halalkalicoccus, for which the name Halalkalicoccus jeotgali. sp. nov. is proposed. The type strain is B3T (=KCTC 4019T=DSM 18796T=JCM 14584T=CECT 7217T).

Halorubrum litoreum sp. nov., an extremely halophilic archaeon from a solar saltern

An extremely halophilic archaeon, strain Fa-1T, was isolated from a marine solar saltern in Fujian, China. Strain Fa-1T required Mg2+ and at least 2.0 M NaCl for growth. It was able to grow at pH 6.5–9.0 (optimally at pH 7.0–7.5) and at 20–55 °C (optimally at 37–42 °C). The major polar lipids of strain Fa-1T were phosphatidylglycerol, phosphatidylglycerol phosphate methyl ester, phosphatidylglycerol sulfate and a sulfated diglycosyl diether. On the basis of a 16S rRNA gene sequence analysis, strain Fa-1T was closely related to nine species of the genus Halorubrum, showing sequence similarities of 97.4–98.4 %. The G+C content of the DNA of strain Fa-1T is 64.9 mol% (T m). DNA–DNA hybridization values between strain Fa-1T and the most closely related members of the genus Halorubrum were below 51 %. On the basis of the data from this study, strain Fa-1T represents a novel species of the genus Halorubrum, for which the name Halorubrum litoreum sp. nov. is proposed. The type strain is Fa-1T (=CGMCC 1.5336T =JCM 13561T).

Phylogenetic relationships within the family Halobacteriaceae inferred from rpoB′ gene and protein sequences

In order to clarify the current phylogeny of the haloarchaea, particularly the closely related genera that have been difficult to sort out using 16S rRNA gene sequences, the DNA-dependent RNA polymerase subunit B′ gene (rpoB′) was used as a complementary molecular marker. Partial sequences of the gene were determined from 16 strains of the family Halobacteriaceae. Comparisons of phylogenetic trees inferred from the gene and protein sequences as well as from corresponding 16S rRNA gene sequences suggested that species of the genera Natrialba, Natronococcus, Halobiforma, Natronobacterium, Natronorubrum, Natrinema/Haloterrigena and Natronolimnobius formed a monophyletic group in all trees. In the RpoB′ protein tree, the alkaliphilic species Natrialba chahannaoensis, Natrialba hulunbeirensis and Natrialba magadii formed a tight group, while the neutrophilic species Natrialba asiatica formed a separate group with species of the genera Natronorubrum and Natronolimnobius. Species of the genus Natronorubrum were split into two groups in both the rpoB′ gene and protein trees. The most important advantage of the use of the rpoB′ gene over the 16S rRNA gene is that sequences of the former are highly conserved amongst species of the family Halobacteriaceae. All sequences determined so far can be aligned unambiguously without any gaps. On the other hand, gaps are necessary at 49 positions in the inner part of the alignment of 16S rRNA gene sequences. The rpoB′ gene and protein sequences can be used as an excellent alternative molecular marker in phylogenetic analysis of the Halobacteriaceae.

Halopiger xanaduensis gen. nov., sp. nov., an extremely halophilic archaeon isolated from saline Lake Shangmatala in Inner Mongolia, China

Strain SH-6(T) was isolated from the sediment of Lake Shangmatala, a saline lake in Inner Mongolia (China). Cells were pleomorphic. The organism was neutrophilic and required at least 2.5 M (15 %) NaCl, but not MgCl(2), for growth; optimal growth occurred at 4.3 M (25 %) NaCl. The G+C content of its DNA was 63.1 mol%. 16S rRNA gene sequence analysis revealed that strain SH-6(T) is a member of the family Halobacteriaceae, but there was a low level of similarity with other members of this family. Highest sequence similarity (94.6 %) was obtained with the 16S rRNA genes of the type strains of Natronolimnobius innermongolicus and Natronolimnobius baerhuensis. Polar lipid analyses revealed that strain SH-6(T) contains phosphatidylglycerol and phosphatidylglyceromethylphosphate, derived from both C(20)C(20) and C(20)C(25) glycerol diethers together with the glycolipid S(2)-DGD-1. On the basis of the data obtained, the new isolate could not be classified in any recognized genus. Strain SH-6(T) is thus considered to represent a novel species in a new genus within the family Halobacteriaceae, order Halobacteriales, for which the name Halopiger xanaduensis gen. nov., sp. nov. is proposed. The type strain of Halopiger xanaduensis is SH-6(T) (=CECT 7173(T)=CGMCC 1.6379(T)=JCM 14033(T)).

Haloquadratum walsbyi gen. nov., sp. nov., the square haloarchaeon of Walsby, isolated from saltern crystallizers in Australia and Spain

Strains C23T and HBSQ001 were isolated from solar salterns and are novel square-shaped, aerobic, extremely halophilic members of the domain Archaea and family Halobacteriaceae. Cells stained Gram-negative and grew optimally in media containing 18 % salts at around neutral pH. Mg2+ is not required. The DNA G+C content of both isolates was 46.9 mol% and DNA-DNA cross-hybridization showed a relatedness of 80 %. Their 16S rRNA gene sequences showed only 2 nucleotide differences (99.9 % identity) and phylogenetic tree reconstructions with other recognized members of the Halobacteriaceae indicated that they formed a distinct clade, with the closest relative being Halogeometricum borinquense PR 3T (91.2 % sequence identity). The major polar glycolipid of both isolates was the sulfated diglycosyl diether lipid S-DGD-1. Electron cryomicrosopy of whole cells revealed similar internal structures, such as gas vesicles and polyhydroxyalkanoate granules, but the cell wall of isolate HBSQ001 displayed a more complex S-layer compared with that of isolate C23T. The phenotypic characterization and phylogenetic data support the placement of isolates C23T and HBSQ001 in a novel species in a new genus within the Halobacteriaceae, for which we propose the name Haloquadratum walsbyi gen. nov., sp. nov. The type strain of Haloquadratum walsbyi is C23T (=JCM 12705T=DSM 16854T).

Halovivax ruber sp. nov., an extremely halophilic archaeon isolated from Lake Xilinhot, Inner Mongolia, China

A Gram-negative, pleomorphic, extremely halophilic archaeon, designated strain XH-70(T), was isolated from the saline Lake Xilinhot, in Inner Mongolia, China. It formed small (0.9-1.5 mm), red-pigmented, elevated colonies on agar medium. The strain required at least 2.5 M NaCl and 5 mM Mg(2+) for growth. The 16S rRNA gene sequence analysis indicated that strain XH-70(T) belongs to the family Halobacteriaceae, showing 99.5 % similarity to the type strain of Halovivax asiaticus and 94.7 and 94.6 % similarity, respectively, to the type strains of Natronococcus amylolyticus and Natronococcus occultus. Polar lipid analysis supported the placement of strain XH-70(T) in the genus Halovivax. DNA-DNA hybridization studies (32 % with Halovivax asiaticus CGMCC 1.4248(T)), as well as biochemical and physiological characterization, allowed strain XH-70(T) to be differentiated from Halovivax asiaticus. A novel species, Halovivax ruber sp. nov., is therefore proposed to accommodate this strain. The type strain is XH-70(T) (=CGMCC 1.6204(T)=DSM 18193(T)=JCM 13892(T)).

Haloterrigena hispanica sp. nov., an extremely halophilic archaeon from Fuente de Piedra, southern Spain

An extremely halophilic archaeon belonging to the order Halobacteriales was isolated from Fuente de Piedra salt lake, Spain. This strain, designated FP1T, was a pleomorphic coccoid, neutrophilic and required at least 15 % (w/v) NaCl for growth. Strain FP1T grew at 37–60 °C, with optimal growth at 50 °C. Mg2+ was not required, but growth was observed with up to 10 % (w/v) MgSO4. Polar lipid analysis revealed the presence of mannose-6-sulfate(1-2)-glucose glycerol diether as a major glycolipid. Both C20C20 and C20C25 core lipids were present. The genomic DNA G+C content was 62.0 mol%. Phylogenetic analysis based on comparison of 16S rRNA gene sequences demonstrated that the isolate was most closely related to species of the genus Haloterrigena. DNA–DNA reassociation values between strain FP1T and the most closely related species of the genus Haloterrigena (Haloterrigena thermotolerans, Haloterrigena saccharevitans and Haloterrigena limicola) were lower than 29 %. It is therefore considered that strain FP1T represents a novel species of the genus Haloterrigena, for which the name Haloterrigena hispanica sp. nov. is proposed. The type strain is FP1T (=DSM 18328T=ATCC BAA-1310T).

Diversity of halophilic archaea from six hypersaline environments in Turkey

The diversity of archaeal strains from six hypersaline environments in Turkey was analyzed by comparing their phenotypic characteristics and 16S rDNA sequences. Thirty-three isolates were characterized in terms of their phenotypic properties including morphological and biochemical characteristics, susceptibility to different antibiotics, and total lipid and plasmid contents, and finally compared by 16S rDNA gene sequences. The results showed that all isolates belong to the family Halobacteriaceae. Phylogenetic analyses using approximately 1,388 bp comparisions of 16S rDNA sequences demonstrated that all isolates clustered closely to species belonging to 9 genera, namely Halorubrum (8 isolates), Natrinema (5 isolates), Haloarcula (4 isolates), Natronococcus (4 isolates), Natrialba (4 isolates), Haloferax (3 isolates), Haloterrigena (3 isolates), Halalkalicoccus (1 isolate), and Halomicrobium (1 isolate). The results revealed a high diversity among the isolated halophilic strains and indicated that some of these strains constitute new taxa of extremely halophilic archaea.

Halorubrum arcis sp. nov., an extremely halophilic archaeon isolated from a saline lake on the Qinghai–Tibet Plateau, China

A Gram-negative, aerobic, neutrophilic and extremely halophilic archaeon (strain AJ201T), isolated from Ayakekum salt lake on the Qinghai–Tibet Plateau, was investigated by a polyphasic approach. The DNA G+C content of strain AJ201Twas 65.7 mol%. The major polar lipid profile and phylogenetic analysis based on 16S rRNA gene sequences supported the allocation of the strain to the genusHalorubrum. The results of DNA–DNA hybridizations and physiological and biochemical tests allowed genotypic and phenotypic differentiation of strain AJ201Tfrom closely related species. Therefore, strain AJ201Trepresents a novel species of the genusHalorubrum, for which the nameHalorubrum arcissp. nov. is proposed. The type strain is strain AJ201T(=CGMCC 1.5343T=JCM 13916T).

Natronorubrum sulfidifaciens sp. nov., an extremely haloalkaliphilic archaeon isolated from Aiding salt lake in Xin-Jiang, China

An extremely haloalkaliphilic archaeon, strain AD2T, was isolated from Aiding salt lake in Xin-Jiang, China. Strain AD2T required at least 12 % NaCl for growth. MgCl2 was not required. The isolate was able to grow over a pH range of 8.0–10.0 and temperature range of 20–55 °C, with optimal growth at pH 8.7–9.2 and 44–47 °C. The major polar lipids of strain AD2T were phosphatidylglycerol and phosphatidylglycerol phosphate methyl ester; glycolipids were not detected. Analysis of its 16S rRNA gene sequence indicated that strain AD2T was phylogenetically related to members of the genus Natronorubrum, with sequence similarities to the type strains of Natronorubrum bangense, Natronorubrum tibetense and Natronorubrum aibiense of 97.1, 95.9 and 96.1 %, respectively. The G+C content of its DNA was 60.9 mol% (T m). Levels of DNA–DNA relatedness between strain AD2T and the type strains of Nrr. bangense, Nrr. tibetense and Nrr. aibiense were 49, 38 and 41 %, respectively. It was concluded that strain AD2T represents a novel species of the genus Natronorubrum, for which the name Natronorubrum sulfidifaciens sp. nov. is proposed. The type strain is AD2T (=CGMCC 1.6307T=JCM 14089T).

[Studies on bacteriorhodopsin gene and sequence of 16S rRNA encoding genes of halophilic archaea of Xingjiang Aibi Lake]

One hundred and forty-eight strains of halophilic archaea were isolated from 40 samples of soil, lake water, and silt. To study and analyze the species and bacteriorhodopsin(BR) protein resource, partial DNA fragments encoding BR protein from helix C to helix G andl6S rRNA encoding genes from 6 strains of halophilic archaea were amplified by polymerase chain(PCR) , and their DNA sequences were determined. The results indicate that the reduced amino acid sequences of BR protein from helix C to helix G of ABDH11 is obviously different from those of other existing proteins. The results of homology analysis on BR gene andl6S rRNA and phylogenetic analysis on 16S rRNA show that strains ABDH10 and ABDH40 are novel members of genus Natronorubrum and Natrinema, respectively; the sequence of ABDH40 was obtained from GenBank and the number of sequence is AY989910. The protein from helix C to helix G of ABDH11 is significantly different from that of other strains.

Halorubrum orientale sp. nov., a halophilic archaeon isolated from Lake Ejinor, Inner Mongolia, China

A motile, pleomorphic, red-pigmented archaeon, strain EJ-52T, was isolated from water from Lake Ejinor, a saline lake in Inner Mongolia, China. Analysis of the almost-complete 16S rRNA gene sequence showed that the isolate was phylogenetically related to species of the genus Halorubrum, being most closely related to Halorubrum saccharovorum ATCC 29252T (96.1% sequence similarity), Halorubrum lacusprofundi JCM 8891T (95.9%), Halorubrum tibetense AS 1.3239T (95.2%), Halorubrum alcaliphilum AS 1.3528T (95.2%) and Halorubrum vacuolatum JCM 9060T (95.1%). The polar lipids of strain EJ-52T were C20C20 derivatives of phosphatidylglycerol phosphate and phosphatidylglycerol phosphate methyl ester and a sulfated diglycosyl diether. Strain EJ-52T requires at least 2.5 M NaCl for growth and grows optimally at 3.4 M NaCl. The strain grows at 25-50 degrees C, with optimal growth occurring at 35-45 degrees C. Mg2+ is not required. The DNA G+C content is 64.2 mol%. On the basis of the data obtained in this study, strain EJ52T represents a novel species, for which the name Halorubrum orientale sp. nov. is proposed. The type strain is EJ-52T (=CECT 7145T=JCM 13889T=CGMCC 1.6295T).

Genetic analysis of the br gene in halophilic archaea isolated from Xinjiang region

Some novel members of extremely halophilic Archaea, strain AJ11, AJ12 and AJ13, were isolated from Aularz Lake located in Altun Mountain National Nature Reserve of Xinjiang Uygur Autonomous Region in China. Partial DNA fragments encoding a bacteriorhodopsin (BR) as well as for 16S rRNA of isolated strains were amplified by PCR and their DNA sequences were determined subsequently. On the basis of homology and phylogenetic analysis about 16S rDNA, it was considered that the isolated strains formed a microbiological population are the members of genus Natrinema. The results of genetic analysis, such as GC content, transition/transversion (Ti/Tv) rate ratios, synonymous substitution rates (Ks), indicated that the br fragments with high level of genetic divergence are faced with both purifying selection and bias mutation pressure. The study provides the base for using of species and BR proteins resources.

Haladaptatus paucihalophilus gen. nov., sp. nov., a halophilic archaeon isolated from a low-salt, sulfide-rich spring

Two novel strains of halophilic archaea, DX253Tand GY252, were isolated from Zodletone Spring, a low-salt, sulfide- and sulfur-rich spring in south-western Oklahoma, USA. The cells were cocci or coccobacilli and occurred singly or in pairs. The two strains grew in a wide range of salt concentrations (0.8–5.1 M) and required at least 5 mM Mg2+for growth. The pH range for growth was 5–7.5 and the temperature range was 25–45 °C. In addition to having the capacity to grow at relatively low salt concentrations, cells remained viable in distilled water after prolonged incubation. The two diether phospholipids that are typical of members of the orderHalobacteriales, phosphatidylglycerol and phosphatidylglycerol phosphate methyl ester, were present. Phosphatidylglycerol sulfate and two unidentified glycolipids were also detected. Each strain had two distinct 16S rRNA gene sequences that were only 89.5–90.8 % similar to sequences from the most closely related cultured and recognized species within the orderHalobacteriales. The DNA G+C content of the type strain was found to be 60.5 mol%. The closest relatives were clones and uncharacterized isolates obtained from coastal salt-marsh sediments with salinities equivalent to that of seawater. The physiological, biochemical and phylogenetic differences between strains DX253Tand GY252 and other previously described genera of extremely halophilic archaea suggest that these novel strains represent a novel species and genus within the familyHalobacteriaceae, for which the nameHaladaptatus paucihalophilusgen. nov., sp. nov. is proposed. The type strain is DX253T(=JCM 13897T=DSM 18195T=ATCC BAA-1313T=KCTC 4006T).

Halovivax asiaticus gen. nov., sp. nov., a novel extremely halophilic archaeon isolated from Inner Mongolia, China

Strain EJ-46T, a novel pleomorphic, aerobic, extremely halophilic member of the Archaea was isolated from sediment of the saline Lake Ejinor, in Inner Mongolia, China. This organism was neutrophilic and required at least 15 % (2.5 M) NaCl for growth. MgCl2 was not required. The isolate was able to grow at pH 6.0-9.0. Optimum growth occurred in media containing 20 % (3.4 M) NaCl at pH 7.0-7.5. Polar lipid analysis revealed the presence of phosphatidylglycerol and phosphatidylglycerol phosphate methyl ester, derived from both C20C20 and C20C25 glycerol diethers. Four glycolipids were detected, one of which may be novel. The DNA G+C content was 60.3 mol%. 16S rRNA gene analysis revealed that strain EJ-46T was a member of the phylogenetic group defined by the family Halobacteriaceae, and the highest 16S rRNA gene similarity values of 94.9 and 94.8 % were obtained with the haloalkaliphilic species of the genus Natronococcus, Natronococcus occultus and Natronococcus amylolyticus, respectively. Based on the phenotypic, genotypic and phylogenetic analyses, it is proposed that the novel isolate should be classified as representing a new genus and species, for which the name Halovivax asiaticus gen. nov., sp. nov. is proposed. The type strain is EJ-46T (=CGMCC 1.4248T = CECT 7098T).

Natrinema ejinorense sp. nov., isolated from a saline lake in Inner Mongolia, China

A Gram-negative, non-motile, neutrophilic, pleomorphic and extremely halophilic archaeon, strain EJ-57T, was isolated from saline Lake Ejinor in Inner Mongolia, China. Strain EJ-57T was able to grow at 25–50 °C, required at least 1.8 M NaCl for growth (optimum at 3.4 M NaCl) and grew over a pH range from 6.0 to 8.5 (optimum at pH 7.0). Hypotonic treatment with less than 1.5 M NaCl caused cell lysis. Analysis of the almost complete 16S rRNA gene sequence indicated that the isolate represented a member of the genus Natrinema in the family Halobacteriaceae. Strain EJ-57T was most closely related to Natrinema versiforme JCM 10478T (96.2 % sequence similarity), Natrinema pallidum NCIMB 777T (95.9 % sequence similarity), Natrinema altunense JCM 12890T (95.8 % sequence similarity) and Natrinema pellirubrum NCIMB 786T (95.5 % sequence similarity). However, DNA–DNA hybridization experiments showed that strain EJ-57T was not related to these species, with levels of DNA–DNA relatedness equal to or below 39 %. The major polar lipids of the isolate were C20C20 and C20C25 derivatives of phosphatidylglycerol, phosphatidylglycerol phosphate methyl ester and the disulfated glycolipid S2-DGA-1. The G+C content of the genomic DNA was 64.7 mol%. Comparative analysis of phenotypic characteristics between strain EJ-57T and recognized Natrinema species supported the conclusion that EJ-57T represents a novel species within this genus, for which the name Natrinema ejinorense sp. nov. is proposed. The type strain is EJ-57T (=CECT 7144T=JCM 13890T=CGMCC 1.6202T).

Halorubrum lipolyticum sp. nov. and Halorubrum aidingense sp. nov., isolated from two salt lakes in Xin-Jiang, China

Two extremely halophilic archaea, strains 9-3(T) and 31-hong(T), were isolated from Aibi salt lake and Aiding salt lake in Xin-Jiang, China. Their morphology, physiology, biochemical features, polar lipid compositions and 16S rRNA gene sequences were characterized in order to elucidate their taxonomic status. The results from this study indicated that strains 9-3(T) and 31-hong(T) are members of the genus Halorubrum. Their physiological properties and polar lipid compositions are clearly different from those of the currently described species of Halorubrum. DNA-DNA relatedness values for strain 9-3(T) with respect to its closely related neighbours Halorubrum saccharovorum JCM 8865(T) and Halorubrum lacusprofundi JCM 8891(T) were 51.6 and 25.1 %, respectively, DNA-DNA relatedness values for strain 31-hong(T) with respect to its closely related neighbours Hrr. saccharovorum JCM 8865(T) and Hrr. lacusprofundi JCM 8891(T) were 29.4 and 44.9 %, respectively, and DNA-DNA relatedness between strains 9-3(T) and 31-hong(T) was 54 %. Thus, two novel species of the genus Halorubrum are proposed, Halorubrum lipolyticum sp. nov. (type strain 9-3(T)=CGMCC 1.5332(T)=JCM 13559(T)) and Halorubrum aidingense sp. nov. (type strain 31-hong(T)=CGMCC 1.2670(T)=JCM 13560(T)).

Halorubrum ezzemoulense sp. nov., a halophilic archaeon isolated from Ezzemoul sabkha, Algeria

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.