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1 University of Washington, School of Oceanography, Box 357940, Seattle, WA 98195, USA
2 Departamento de Microbiología y Parasitología, Facultad de Farmacia, Universidad de Sevilla, 41012 Seville, Spain
Correspondence
Jonathan Z. Kaye
jzkaye{at}ocean.washington.edu
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-subclass of the Proteobacteria. Consistent with previously described species, the novel strains were slightly to moderately halophilic and grew in media containing up to 22–27 % total salts. The isolates grew at temperatures as low as -1 to 2 °C and had temperature optima of 30 or 20–35 °C. Both the minimum and optimum temperatures for growth were similar to those of Antarctic and sea-ice Halomonas species and lower than typically observed for the genus as a whole. Phenotypic tests revealed that the isolates were physiologically versatile and tended to have more traits in common with each other than with closely related Halomonas species, presumably a reflection of their common deep-sea, hydrothermal-vent habitat of origin. The G+C content of the DNA for all strains was 56·0–57·6 mol%, and DNA–DNA hybridization experiments revealed that four strains (Eplume1T, Esulfide1T, Althf1T and Slthf2T) represented novel species and that two strains (Eplume2 and Slthf1) were related to Halomonas meridiana. The proposed new species names are Halomonas neptunia (type strain Eplume1T=ATCC BAA-805T=CECT 5815T=DSM 15720T), Halomonas sulfidaeris (type strain Esulfide1T=ATCC BAA-803T=CECT 5817T=DSM 15722T), Halomonas axialensis (type strain Althf1T=ATCC BAA-802T=CECT 5812T=DSM 15723T) and Halomonas hydrothermalis (type strain Slthf2T=ATCC BAA-800T=CECT 5814T=DSM 15725T).
Published online ahead of print on 31 October 2003 as DOI 10.1099/ijs.0.02799-0.
The GenBank accession numbers for the 16S rRNA gene sequences of strains Eplume1T, Eplume2, Esulfide1T, Althf1T, Slthf1 and Slthf2T are respectively AF212202, AF212201, AF212204, AF212206, AF212217 and AF212218.
Details of growth rates of the novel isolates under varying temperatures and salt concentrations, transmission electron micrographs of cells and a 16S rDNA-based maximum-likelihood tree including a wider range of reference species are available as supplementary material in IJSEM Online.
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, 1998; Vreeland et al., 1980; Quesada et al., 1984; Franzmann et al., 1987a; James et al., 1990; Valderrama et al., 1991; Adkins et al., 1993; Duckworth et al., 1996, 2000; Bowman et al., 1997; Satomi et al., 1997; Mormile et al., 1999; Bouchotroch et al., 2001; Yoon et al., 2002; Reddy et al., 2003). They have also recently been found in the very dry environment of the walls and murals of a medieval chapel (Heyrman et al., 2002). This skew in sampling has obscured the observation that halophilic and halotolerant bacteria are easily isolated from marine sediments, the open ocean and low-temperature, sea-water-dominated hydrothermal-vent environments (Forsyth et al., 1971; Baumann et al., 1972, 1983; Ventosa et al., 1984; Takami et al., 1999; Kaye & Baross, 2000; Yoon et al., 2001), where the salinity does not change significantly on the scale of microbial biochemistry. It remains an open question why these halophilic and remarkably halotolerant bacteria inhabit surface sea water and the deep sea distant from coastal hypersaline habitats.
Moderately halophilic bacteria are surprisingly abundant in surface sea water, at mid-ocean depths, in deep water and in low-temperature hydrothermal fluids and plumes, sometimes comprising upwards of 10 % of the total marine microbial assemblage (Kaye & Baross, 2000). Strains of Halomonas and Marinobacter as identified by 16S rRNA gene sequence analysis were consistently found in these water-column and hydrothermal-vent samples (Kaye & Baross, 2000).
Twenty-four species of Halomonas have been described at the time of writing (Arahal et al., 2002a, b; Heyrman et al., 2002; Yoon et al., 2002; Romanenko et al., 2002; Reddy et al., 2003). The strains analysed here are the first to be characterized from the deep sea and from hydrothermal-vent habitats. Three isolates are also the first enriched using oligotrophic quantities of organic carbon to be characterized. In addition, our results show that four isolates represent novel species of the genus Halomonas. The proposed names are Halomonas neptunia sp. nov., Halomonas sulfidaeris sp. nov., Halomonas axialensis sp. nov. and Halomonas hydrothermalis sp. nov.
Sample collection
In 1991, hydrothermal-plume temperature and particle anomalies above the Main Endeavour Field (MEF; 47°57'N 129°06'W) on the Endeavour Segment of the Juan de Fuca Ridge were detected using a conductivity-temperature-depth-transmissometry package. Plume water was procured with Niskin bottles from 
2000 m depth. In 1995 and 1998, sulfide rock and low-temperature hydrothermal-fluid seafloor emissions were collected with manipulator arms, Niskin bottles or titanium syringe samplers (Von Damm et al., 1985) mounted onto the Deep-Submergence Vehicle Alvin or the Remote-Operated Vehicle ROPOS. These samples were obtained from Axial Seamount (45°56'N 129°59'W), located on the Juan de Fuca Ridge, during ROPOS dive 462 to Cloud vent (27 °C) and from the Southern East Pacific Rise (SEPR; 17°25'S 113°12'W) during Alvin dive 3300 at a 9 °C vent site. The MEF, Axial Seamount and SEPR sites are respectively located at 2200, 1530 and 2580 m sea-water depth.
Enrichment and isolation
For strains Eplume1T, Eplume2 and Esulfide1T, the enrichment medium contained synthetic sea water (SSB), 10 ml trace elements F solution (l-1 SSB) and additional nutrients. SSB contains (l-1 deionized water) 19·6 g NaCl, 3·3 g Na2SO4, 0·5 g KCl, 0·05 g KBr, 0·02 g H3BO3 and 8·8 g MgCl2.6H2O (Baross, 1993). Trace elements F solution consists of (l-1 deionized water) 0·05 g Al2(SO4)3, 0·1 g H3BO3, 0·05 g LiCl, 0·1 g Na2MoO4.2H2O, 0·05 g KBr, 0·05 g KI, 0·05 g NaF, 0·1 g ZnSO4.7H2O, 0·005 g BaCl2, 0·005 g CoCl2.6H2O, 0·01 g CuSO4.5H2O, 0·2 g MnCl2.4H2O, 0·01 g NiCl2.6H2O, 0·005 g Na2SeO4, 0·005 g SrCl2.6H2O, 0·005 g H2WO4 and 0·005 g VOSO4.H2O (Pledger & Baross, 1991; Baross, 1993). For strains Eplume1T and Eplume2, the trace elements solution also contained 0·015 g NiCl2.6H2O, but no NaF. The additional components of the enrichment medium are (l-1 SSB) 1·605 g NaNO3, 5·0 g Na2S2O3.5H2O, 0·02 g yeast extract, 1·0 g PIPES buffer, 0·002 g FeSO4.7H2O, 0·15 g MnSO4.H2O, 0·1 g CaCl2, 0·430 g (NH4)2SO4, 0·036 g KH2PO4 and 13 g purified agar. Trace elements F, FeSO4.7H2O, MnSO4.H2O, CaCl2, (NH4)2SO4, 0·605 g of the NaNO3 and KH2PO4 were added to the medium after autoclaving via filter-sterilization. The pH was adjusted to 7·0.
Strains Eplume1T and Eplume2 were obtained from primary enrichment colonies that grew after plume water was passed through 0·2 µm polycarbonate filters, placed onto agar slants in stoppered serum bottles and incubated at 2 °C with an air headspace into which CH4 was injected. Strain Esulfide1T was isolated from a colony that grew after a sulfide rock sample was smeared onto an agar surface and incubated under an air headspace at 20 °C. Strains Althf1T, Slthf1 and Slthf2T were enriched with the medium described above except that it contained 160 g NaCl and 1·0 g trisodium citrate l-1 but no agar. Broth tubes were incubated with an air headspace at 20 °C onboard ship as part of quantitative enrichments using the most probable number (MPN) technique (Greenberg et al., 1992), and 100 µl aliquots from three different most-dilute MPN tubes (1 : 50–1 : 500 dilutions) were subsequently spread onto agar surfaces of the same medium. All strains were purified by triplicate streaking.
Growth experiments
The growth medium used to determine the temperature and pH ranges was a broth containing SSB (3·2 % total salts; 0·45 M Na+), 10 ml of trace elements F, the additional components listed above (except for PIPES) and 1·0 g trisodium citrate l-1. The pH range was determined at 20 °C. For the temperature and salt growth curves, Tris buffer (2·4 g l-1) was added and the pH was adjusted to 8·0 (results available as Supplementary Fig. I in IJSEM Online). Cells were tested for growth at -5 °C in this medium with 160 g NaCl l-1 (18 % total salts; 2·9 M Na+). For the salt growth curves (performed at 30 °C), the amount of NaCl was varied from 0 to 250 g l-1, whereby the total amount of salt in the medium ranged from 21 to 270 g l-1 (0·12–4·4 M Na+). Growth was also tested with 0·5 % total salts and without any salt. Cd2+ tolerance (0·05, 0·5, 1·0, 2·0, 3·0, 4·0 and 5·0 mM) was assayed (20 °C, SSB, pH 7·0) by adding a filter-sterilized solution of CdCl2.2·5H2O dissolved in SSB, and the lowest concentration that completely inhibited growth is reported. Anaerobic growth and anaerobic nitrate reduction were tested (20 °C, SSB, pH 7·0) by dispensing the growth medium into Balch tubes, purging and filling the tubes with argon four times while vortexing (Balch & Wolfe, 1976), reducing with Na2S.9H2O (0·05 % final concentration), monitoring oxygen removal with resazurin (0·0002 % final concentration) and assaying nitrite production colorimetrically (Smibert & Krieg, 1994). Anaerobic growth was also checked at 20 °C with stabs of modified Hugh and Leifson medium with SSB and glucose as the only carbon source (Smibert & Krieg, 1994). Under certain growth conditions when cell yield was low, growth was noted as positive if the number of cells exceeded >107 ml-1 from an initial concentration of <105 ml-1, as monitored by phase-contrast microscopy.
For growth rate calculations, 40 ml medium was dispensed into autoclaved 125 ml flasks with foam stoppers or aluminium foil covers and inoculated. Growth rates were determined by monitoring OD600 using a Lambda2S UV/Vis spectrophotometer (Perkin Elmer). The slope of the exponential-growth portion of the logarithmic growth curve was averaged from triplicate runs. In order to convert optical density to cell number, growth rates were determined simultaneously in triplicate by monitoring the increase in cell concentration obtained by direct counts with DAPI (4',6-diamidino-2-phenylindole) (Porter & Feig, 1980) at pH 7·0, 20 °C and SSB salt concentration and the appropriate ratios were calculated.
Phenotypic characteristics
Tests for 121 characteristics were performed, including morphological, cultural, physiological, biochemical and nutritional features (Table 1). Test procedures were described previously (García et al., 1987; Quesada et al., 1984; Ventosa et al., 1982). All strains were motile rods with peritrichous flagella, 2–3 µm in length and 1 µm in width (1·5 µm wide for strain Slthf2T). The cells maintained their shape under all growth conditions at different temperatures and salinities, except for strains Eplume2 and Slthf1, which formed chains of incompletely divided cells at 
2 °C. Colonies were round, smooth and cream-coloured. Endospores were not observed for any strain under any condition. The strains were psychrotolerant and slightly to moderately halophilic.
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DNA extraction and purification
Cells from the strains included in Table 2 were harvested, washed, suspended in 0·15 M NaCl/0·1 M EDTA buffer (pH 8·0) (5 g wet weight in 50 ml buffer) and lysed with lysozyme (10 mg) at 37 °C and with SDS (2 % final concentration) at 60 °C. The DNA was extracted and purified by the method of Marmur (1961). Purity was assessed from the A260/A280 and A230/A260 ratios (Johnson, 1994).
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) obtained with a model UV/Vis Lambda 20 spectrophotometer (Perkin Elmer) at 260 nm; this instrument was programmed for a temperature increase of 1·0 °C min-1. The G+C content was calculated from the thermal denaturation temperature by using the equation of Owen & Hill (1979). The G+C content of reference DNA from Escherichia coli NCTC 9001T was taken to be 51 mol% (Owen & Pitcher, 1985). The G+C content of the DNA of the six strains ranged between 56·0 and 57·6 mol% (Table 2
). These values are similar to those described for members of the genus Halomonas (Dobson et al., 1993; Arahal et al., 2002b).
Preparation of 3H-labelled DNA and DNA–DNA hybridization experiments
DNA was radioactively labelled by the multiprime system with a commercial kit (RPN 1601Y; Amersham), using [1',2',5'-3H]dCTP (Amersham). The mean specific activity obtained with this procedure was 8·8x106 c.p.m. (µg DNA)-1. The labelled DNA was denatured before hybridization by being heated at 100 °C for 5 min and then placed on ice. DNA–DNA hybridization was studied by the competition procedure described by Johnson (1994). Competitor DNA was sonicated (Braun Melsungen) at 50 W for two 15 s intervals. Membrane filters (HAHY; Millipore) containing reference DNA (25 µg cm-2) were placed in 5 ml screw-cap vials that contained the labelled, sheared, denatured DNA and the denatured, sheared competitor DNA. The ratio of the concentration of competitor DNA to the concentration of labelled DNA was at least 150 : 1. The final reaction concentrations were 2xSSC (0·15 M NaCl, 0·015 M trisodium citrate, pH 7±0·2) and 30 % formamide and the final volume was 140 µl. Hybridization experiments were carried out under optimal conditions with temperatures ranging between 55·0 and 55·5 °C, which is within the limits of validity for the filter method (De Ley & Tijtgat, 1970). The vials were shaken slightly for 18 h in a water bath (Grant Instruments); these procedures were done in triplicate. After hybridization, the filters were measured with a liquid scintillation counter (Beckman Instruments) and the percentage of hybridization was calculated as described by Johnson (1994). At least two independent determinations were carried out for each experiment and mean values are reported (Table 2). The overall standard deviation was 6 %; in the case of high DNA relatedness values (
70 %), it was 2 %. The percentage of DNA hybridization obtained between strains Eplume1T, Esulfide1T, Althf1T and Slthf2T and with previously characterized Halomonas species was very low (1–53 %). Strains Eplume2 and Slthf1 had >70 % DNA hybridization with each other and with Halomonas meridiana DSM 5425T, indicating that they are members of this species.
Comparative analysis of 16S rRNA gene sequences
Cultures were grown in 500 ml flasks and pelleted by centrifuging at 10 000 g for 20–40 min at 4 °C. Genomic DNA was extracted using the IsoQuick kit (Orca Research). Almost complete 16S rRNA gene sequences were obtained by using the PCR with the bacterial primers 8F (5'-AGAGTTTGATCCTGGCTCAG), 519R (5'-GWATTACCGCGGCKGCTG), 515F (5'-GTGCCAAGCMGCCGCGGTAA), 907R (5'-CCGTCAATTCMTTTRAGTTT), 926F (5'-AAACTYAAAKGAATTGACGG) and 1492R (5'-GGTTACCTTGTTACGACTT) (Lane, 1991). Gene fragments were sequenced with an Applied Biosystems sequencer (ABI) model 373A or a MegaBACE 1000 (Molecular Dynamics) at the University of Washington Marine Molecular Biotechnology Laboratory or an ABI100 at the Molecular Genetics Instrumentation Facility at the University of Georgia, Athens, USA. Sequences of approximately 1300 bp (bases 95–1406; E. coli numbering) were aligned with other sequences acquired from the GenBank database after excising variable stem–loops (bases 201–216 and 1135–1139; E. coli numbering). A maximum-likelihood phylogenetic tree including other members of the family Halomonadaceae was constructed with TREE-PUZZLE version 5.0 (Strimmer & von Haeseler, 1996; Schmidt et al., 2002) and visualized with TreeView version 1.5 (Page, 1996) (Fig. 1). All six novel strains were phylogenetically closely related to species in group 2 (Arahal et al., 2002b) of the genus Halomonas. DNA–DNA hybridization data were consistent with the 16S rRNA gene phylogeny.
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; Mormile et al., 1999; Takami et al., 1999; Kaye & Baross, 2000; Bouchotroch et al., 2001; Okamoto et al., 2001; Takai et al., 2001; Yoon et al., 2001, 2002; Heyrman et al., 2002; Reddy et al., 2003). The numerical significance of members of this group in hydrothermal-vent and pelagic environments (Kaye & Baross, 2000) underscores why it is important to understand their physiology, growth rates and metabolic capabilities. Their success in diverse marine microbial ecosystems may be attributed to their metabolic and physiological versatility. The Halomonas isolates described here and previously can oxidize an extensive variety of organic compounds (Baumann et al., 1972, 1983; Ventosa et al., 1998; Kaye & Baross, 2000; Mata et al., 2002), which may contribute directly to their survival in the marine environment by enabling them to take advantage of many forms of transiently available nutrients. In addition, three of the novel strains were isolated on oligotrophic quantities of organic carbon. This study augments previous reports of members of the genus Halomonas able to grow on the low levels of (albeit high-quality) carbon relevant to most of the marine ecosystem.
The phenotypic data presented in Table 1 reveal the enzymological and metabolic variability among members of Halomonas rRNA group 2 (Arahal et al., 2002b). The percentage of characteristics shared between the six novel isolates and their closest phylogenetic relatives varied between 51 and 70 % for strains Eplume2, Slthf1 and Althf1T with H. meridiana, Halomonas aquamarina and Halomonas magadiensis, 51 and 78 % for strains Eplume1T and Esulfide1T with Halomonas variabilis and Halomonas glaciei and 69 % for strain Slthf2T with Halomonas venusta. Strains Eplume2 and Slthf1 each only shared 51 % of traits with the type strain of H. meridiana, consistent with the phenotypic variability observed in this species (James et al., 1990). One caveat of phenotypic comparisons is that the conditions and media used to determine these traits vary between studies, and this may explain in part why the phenotypic data mirror the phylogeny poorly. Yet, when contrasting the phylogeny based on 16S or 23S rRNA gene sequences (Arahal et al., 2002b) with phenotypic dendrograms (Mata et al., 2002) for which data were generated under identical conditions among the species examined, the incongruity between hypothesized evolutionary history and present-day phenotype is immediately apparent.
It is interesting to note that the novel strains were often more similar to one another than to previously described species. For example, strains Eplume2, Slthf1 and Althf1T had 66–83 % of traits in common and strains Eplume1T and Esulfide1T gave 70 % of the same responses to physiological tests. Of particular note is that the novel strains tolerated 0·05–4·0 mM Cd2+ (inhibited by 0·5–5·0 mM Cd2+), reduced nitrate to nitrite (strains Slthf1 and Slthf2T also reduced nitrite) and grew weakly anaerobically. Four strains also reduced nitrate anaerobically. These abilities are hypothesized to be key adaptations for living in warm, heavy-metal-enriched subseafloor habitats associated with hydrothermal vents, where oxygen may become limiting at temperatures as low as 10 °C and nitrate and nitrite may become limiting at 30 °C (Butterfield et al., 1997; Huber et al., 2003; Mehta et al., 2003). The higher phenotypic similarity values amongst the hydrothermal-vent isolates may indeed reflect their common (yet geographically disparate) habitat of origin.
Another consistent difference from previously characterized Halomonas species was that the cardinal temperatures for growth were more similar to those of Antarctic and sea-ice Halomonas isolates (Franzmann et al., 1987a; Bowman et al., 1997; Reddy et al., 2003), shifted cooler by 5–10 °C, than to those of Halomonas strains isolated at higher incubation temperatures and/or from higher temperature and surface-pressure environments (Ventosa et al., 1998). This is not surprising, given that low temperatures can be analogous to high hydrostatic pressures with respect to their effects on proteins and lipids (Bartlett, 2002). Strains Eplume1T, Eplume2, Esulfide1T and Slthf2T were obtained from hydrothermal-vent samples at 10 °C, and the downshift in temperature growth characteristics is presumed to reflect an adaptation to cold, pressurized deep-sea habitats. In addition, the isolation of cold-shifted strain Althf1T from a warm (27 °C) deep-sea hydrothermal vent indicates that the cold-shifted phenotype observed at 1 atm may in fact reflect an overarching hydrostatic pressure adaptation.
The cold-shifted temperature growth characteristics were also reflected in the phylogeny. Isolates Eplume2, Slthf1 and Althf1T showed a close phylogenetic relationship with H. meridiana, which was isolated from a seasonally subzero Antarctic hypersaline lake (James et al., 1990). H. glaciei, isolated from Antarctic fast ice, was a close relative of strains Eplume1T and Esulfide1T as well (the depth and temperature of the environment from which H. aquamarina was isolated is not known; ZoBell & Upham, 1944). The phylogenetic link between Antarctic and deep-sea hydrothermal-vent bacteria has been observed previously among numerous Halomonas isolates (Okamoto et al., 2001). However, given that strain Slthf2T was closely related to H. venusta (isolated from tropical surface sea water; Baumann et al., 1972) and given that H. variabilis (isolated from the Great Salt Lake at 22 °C; Fendrich, 1988) was as close a cousin as H. glaciei to Eplume1T and Esulfide1T, the phylogenetic clustering of cold-shifted Halomonas was not as robust as the psychropiezophilic monophyly observed among other -Proteobacteria such as Colwellia and Shewanella (DeLong et al., 1997; Kato & Nogi, 2001).
It is interesting to find bacteria in the deep sea with optimal growth at a salt concentration greater than sea-water salinity and with the ability to tolerate up to 22–27 % total salts. Low-temperature hydrothermal-vent fluids (<100 °C) are a mixture of sea water and hot hydrothermal or crustal fluid (Butterfield et al., 1997), the salinity of which can vary between one-tenth and twice that of sea water (Von Damm, 1995). Typically, sea water is the dominant component of low-temperature hydrothermal fluids, and its proportion varies inversely with temperature (Butterfield & Massoth, 1994; Cooper et al., 2000; Koschinsky et al., 2002). The fluids from which strains Althf1T, Slthf1 and Slthf2T were obtained were composed of >90 % sea water and had salt contents (measured as chlorinity) slightly less than the ambient deep-sea concentrations (D. Butterfield and K. L. Von Damm, personal communications). Hydrothermal plumes, from which strains Eplume1T and Eplume2 were isolated, are even more dilute in hydrothermal component than low-temperature fluids and are >99·9 % sea water (Lilley et al., 1995). The pore-water salinity within sulfide structures, such as where strain Esulfide1T was isolated, is poorly constrained, however. Takai et al. (2001) found evidence of archaeal obligate halophiles within a sulfide structure based on an environmental 16S rRNA gene sequence phylogeny, suggestive of a stable brine environment, but, without direct measurements, the salinity of the interstitial fluids in this dynamic habitat remains unknown. Hot subseafloor brines have also been proposed as a proximal hypersaline habitat (Kaye & Baross, 2000), but there is no known mechanism by which these brines might be cooled sufficiently without diluting out the salt.
Habitats such as sea ice, Antarctic hypersaline lakes and saline alkaline waters confront micro-organisms with multiple physiological stresses. These environments also contain Halomonas species, and it was therefore not surprising to culture novel Halomonas isolates from deep-sea hydrothermal-vent habitats, where micro-organisms are typically responding to dynamic nutrient regimes and fluctuating temperatures and heavy-metal concentrations, all while under moderate hydrostatic pressures (Karl, 1995). The novel micro-organisms described here comprise the first complete characterizations of Halomonas strains isolated from deep-sea and hydrothermal-vent habitats, some of which are also the first to be enriched with oligotrophic concentrations of organic carbon. Based on the phylogeny, levels of DNA–DNA hybridization and phenotypic differences among the novel and previously described taxa, we conclude that four of the strains represent novel species within the genus Halomonas.
Description of Halomonas neptunia sp. nov.
Halomonas neptunia (nep.tu'ni.a. L. fem. adj. neptunia Neptunian, pertaining to Neptunus, Roman god of the sea).
Cells are rods with rounded ends and are found primarily as single cells and doublets. Psychrotolerant and halophilic growth. No growth at -5 °C (with 18 % total salts) or 40 °C. No growth at pH 4·0 or 13·0. No growth without salt. Other characteristics provided in Tables 1 and 2.
The type strain, Eplume1T (=ATCC BAA-805T=CECT 5815T=DSM 15720T), was isolated from a hydrothermal plume at 2000 m depth above the Main Endeavour Field of the Endeavour Segment of the Juan de Fuca Ridge, north-east Pacific Ocean.
Description of Halomonas sulfidaeris sp. nov.
Halomonas sulfidaeris (sul.fid.ae'ris. N.L. neut. n. sulfidum sulfide; L. neut. gen. n. aeris of ore; N.L. neut. gen. n. sulfidaeris from sulfide ore).
Cells are rods with rounded ends and are found primarily as single cells and doublets. Psychrotolerant and halophilic growth. No growth at -5 °C (with 18 % total salts) or 40 °C. No growth at pH 4·0 or 11·0. No growth without salt. Other characteristics provided in Tables 1 and 2.
The type strain, Esulfide1T (=ATCC BAA-803T=CECT 5817T=DSM 15722T), was isolated from metal sulfide rock at 2200 m depth in the Main Endeavour Field of the Endeavour Segment of the Juan de Fuca Ridge, north-east Pacific Ocean.
Description of Halomonas axialensis sp. nov.
Halomonas axialensis (a.xi.a.len'sis. N.L. fem. adj. axialensis pertaining to Axial Seamount, Juan de Fuca Ridge, north-east Pacific Ocean).
Cells are rods with rounded ends and are found primarily as single cells and doublets. Psychrotolerant and moderately halophilic growth. No growth at -5 °C (with 18 % total salts) or 40 °C. No growth at pH 4·0 or 13·0. No growth without salt. Other characteristics provided in Tables 1 and 2.
The type strain, Althf1T (=ATCC BAA-802T=CECT 5812T=DSM 15723T), was isolated from low-temperature hydrothermal fluid (Cloud Vent) at 1530 m depth on Axial Seamount on the Juan de Fuca Ridge, north-east Pacific Ocean.
Description of Halomonas hydrothermalis sp. nov.
Halomonas hydrothermalis (hy.dro.ther.ma'lis. N.L. fem. adj. hydrothermalis pertaining to hydrothermal vents).
Cells are squat rods with rounded ends and are found primarily as single cells and doublets. Psychrotolerant and moderately halophilic growth. No growth at -1 °C or 50 °C. No growth at pH 4·0 or 13·0. No growth without salt. Other characteristics provided in Tables 1 and 2.
The type strain, Slthf2T (=ATCC BAA-800T=CECT 5814T=DSM 15725T), was isolated from low-temperature hydrothermal fluid at 2580 m depth at 17·5°S on the SEPR, South Pacific Ocean near Easter Island.
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ACKNOWLEDGEMENTS |
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