Hypersaline Soils Research Articles

Nesterenkonia halotolerans sp. nov. and Nesterenkonia xinjiangensis sp. nov., actinobacteria from saline soils in the west of China.

The taxonomic position of two Gram-positive strains, YIM 70084(T) and YIM 70097(T), isolated from hypersaline soils was determined by a polyphasic approach. Cells of strain YIM 70084(T) are motile cocci, whereas those of strain YIM 70097(T) are non-motile rods. The G+C contents of their DNA are 64.4 and 66.7 mol%. Both strains had chemotaxonomic markers typical of the genus Nesterenkonia and formed a coherent cluster with Nesterenkonia species in a phylogenetic inference based on 16S rDNA sequence analysis, exhibiting less than 97 % similarity to each other and to the other two type strains of the genus. Phylogenetic distinction and differences in the peptidoglycan type, composition of cell-wall sugars, phospholipid patterns, the major menaquinones and other phenotypic characteristics indicate that the strains under study represent two novel species, Nesterenkonia halotolerans sp. nov. (type strain YIM 70084(T)=CCTCC AA 001022(T)=DSM 15474(T)) and Nesterenkonia xinjiangensis sp. nov. (type strain YIM 70097(T)=CCTCC AA 001025(T)=DSM 15475(T)).

First survey of fungi in hypersaline soil and water of Mono Lake area (California)

Mono Lake is a closed lake located in central California, east of the Sierra Nevada mountains. It contains dissolved carbonates, sulfates and chlorides at high concentrations. Due to its high salinity, Mono Lake was sometimes compared to the Dead Sea. However, it appears that Mono Lake water and vicinity abound with life. In this work, the fungal flora living in this extreme ecosystem was studied for the first time. Soil, tufa, water and sediment samples were also analyzed for their mineral and salt composition. Results showed that water was particularly rich in sodium, potassium, phosphorus and boron. Soil and sediments contained very high levels of calcium and magnesium, but also barium, boron and strontium. Sodium, phosphorus and iron levels varied in a large extent from one to another sample. Neutral to very alkaline pH were recorded. Water samples were found sterile in the conditions chosen for fungi isolation, while sediment, soil and tufa samples led to the isolation of a total of 67 fungal species (from 23 samples), belonging to various taxonomic groups. From our results no clear effects of the chemical parameters of the samples were observed on fungal life apart from the pH. The methods chosen did not allow the isolation of extremely halotolerant species. We isolated in this work a series of ubiquitous species, suggesting that a selection of resistant and/or adaptable strains of some common species could have occurred. Depending on the medium and the temperature of isolation, it can be hypothesized that some species were present as dormant structures, while some others, isolated at pH 8 on a medium enriched in Na and Ca, could be in a growing form adapted to alkaline and saline conditions. This work contributes to a better knowledge of the mycobiota present in the Mono Lake's ecosystem.

Characterization of a novel halophilic archaeon, Halobiforma haloterrestris gen. nov., sp. nov., and transfer of Natronobacterium nitratireducens to Halobiforma nitratireducens comb. nov.

Strain 135(T), a novel red-pigmented, aerobic, extremely halophilic member of the Archaea showing rod, coccus and slightly pleomorphic morphology, was isolated from hypersaline soil close to Aswan (Egypt). This organism is neutrophilic, motile and requires at least 2.2 M NaCl, but no MgCl2, for growth and exhibits optimal growth at 42 degrees C. Polar lipid analysis revealed the presence of sulfated triglycosyl diether and triglycosyl diether as the sole glycolipids as well as the absence of the glycerol diether analogue of phosphatidyl glycerosulfate. C20:C20 and C20:C25 core lipids are present in almost equal proportions. The G+C content of the DNA is 66.9 mol%. 16S rDNA analysis revealed that strain 135(T) was a member of the phyletic group defined by the family Halobacteriaceae, but there was a low degree of similarity to other members of this family. Highest similarity values of 96.4 and 93.8-94.3% were obtained to the 16S rDNA of Natronobacterium nitratireducens and Natronobacterium gregoryi, Natronococcus occultus and Natronococcus amylolyticus. Strain 135(T) is able to accumulate polyhydroxybutyrate as intracellular reserve material. On the basis of the data presented, strain 135(T) should be placed in a new genus, Halobiforma gen. nov. as Halobiforma haloterrestris sp. nov. The type strain is strain 135(T) (= DSM 13078(T) = JCM 11627(T)). Moreover, the transfer of Natronobacterium nitratireducens to Halobiforma nitratireducens comb. nov. is proposed.

Complexation of metal ions in brines: application of electronic spectroscopy in the study of the Cu(II)-LiCl-H2O system between 25 and 90°C

The concentration and transport of metals in hydrothermal solutions depend on how metals ions combine with ligands to form complexes, and experimental methods are necessary to identify the important complexes. UV-Vis-NIR spectrophotometry was used to study the formation of Cu(II)-chloride complexes in LiCl brines up to very high chlorinities (18 m LiCl), at temperatures between 25°C and 90°C. The number of Cu(II)-chloride complexes necessary to account for the variation in spectra with varying chloride molality at each temperature was estimated using principal component analysis. The molar absorptivity coefficients and concentrations of each complex were then determined using a “model-free” analysis, which does not require any assumption about the chemistry of the system, other than the number of absorbing species present. Subsequently, the results from the “model-free” analysis were integrated with independent experimental evidence to develop a thermodynamic speciation model, where the logarithms of the equilibrium constants for Cu(II)-chloride formation reactions were fitted to the data using a non-linear least-squares approach. Maps of the residual function were used to estimate uncertainties in the fitted equilibrium constants.The results of this study are similar to published properties of distorted octahedral [CuCl(OH2)5]+ and [CuCl2(OH2)4]0 at all temperatures, but diverge for [CuCl3(OH2)3]− and distorted tetrahedral [CuCl4]2−. Moreover, the data suggest the presence of [CuCl5]3−, probably with D3h point group, at very high salt concentration. This study demonstrates that it is possible to determine apparent thermodynamic equilibrium constants for the formation of complexes of trace amount of metals in highly concentrated brines, such as those associated with many ore deposits. The results are dependent on the choice of activity coefficients for charged and neutral aqueous complexes, but this influence is relatively small compared with the experimental uncertainty. This study shows that Cu2+ chloro-complexes, predominantly [CuCl2(OH2)4]0 and [CuCl4]2−, will play a dominant role in nature where free oxygen is available (near-surface), and where chloride activities are very high (evaporitic basins; hypersaline soils).

Brines in seepage channels as eluants for subsurface relict biomolecules on Mars?

Water, vital for life, not only maintains the integrity of structural and metabolic biomolecules, it also transports them in solution or colloidal suspension. Any flow of water through a dormant or fossilized microbial community elutes molecules that are potentially recognizable as biomarkers. We hypothesize that the surface seepage channels emanating from crater walls and cliffs in Mars Orbiter Camera images results from fluvial erosion of the regolith as low-temperature hypersaline brines. We propose that, if such flows passed through extensive subsurface catchments containing buried and fossilized remains of microbial communities from the wet Hesperian period of early Mars (approximately 3.5 Ga ago), they would have eluted and concentrated relict biomolecules and delivered them to the surface. Life-supporting low-temperature hypersaline brines in Antarctic desert habitats provide a terrestrial analog for such a scenario. As in the Antarctic, salts would likely have accumulated in water-filled depressions on Mars by seasonal influx and evaporation. Liquid water in the Antarctic cold desert analogs occurs at -80 degrees C in the interstices of shallow hypersaline soils and at -50 degrees C in salt-saturated ponds. Similarly, hypersaline brines on Mars could have freezing points depressed below -50 degrees C. The presence of hypersaline brines on Mars would have extended the amount of time during which life might have evolved. Phototrophic communities are especially important for the search for life because the distinctive structures and longevity of their pigments make excellent biomarkers. The surface seepage channels are therefore not only of geomorphological significance, but also provide potential repositories for biomolecules that could be accessed by landers.

Polymer production by two newly isolated extremely halophilic archaea: application of a novel corrosion-resistant bioreactor

A novel corrosion-resistant bioreactor composed of polyetherether ketone (PEEK), tech glass and silicium nitrite ceramics was constructed and applied for the cultivation of two newly isolated, extremely halophilic archaea producing poly(gamma-glutamic acid) (PGA), or poly(beta-hydroxy butyric acid) (PHB), respectively. These bacteria were isolated from hypersaline soil close to Aswan (Egypt). The isolate strain 40, which is related to the genus Natrialba, produced large amounts of PGA when cultivated on solid medium. Culture conditions were optimised applying the corrosion-resistant bioreactor. PGA production was dependent on NaCl concentration and occurred about at 20% (w/v) NaCl in the medium. A maximum cell density of about 1.6 g cell dry matter/l was obtained when the bioreactor was stirred and aerated in a batch fermentation process using proteose-peptone medium. The supernatant was monitored with respect to PGA formation, and after 90 h a maximum of 470 mg/l culture volume was detected by HPLC analysis. Culture conditions were optimized for the isolate 56, which accumulated PHB as intracellular granules. Batch fermentations in the stirred and aerated bioreactor applying acetate and n-butyric acid as carbon sources led to cell density of 2.28 g cell dry matter/l and a maximum PHB accumulation contributing to about 53% of cellular dry weight. About 4.6 g PHB were isolated from 10.6 g dried cells of strain 56, which exhibited a weight average molar mass of 2.3 x 10(5) g mol(-1) and a polydispersity of about 1.4.

Site Conditions, Not Parental Phenotype, Determine the Height of Spartina foliosa

The effect of parental growth form on ramets introduced to new sites has broad implications for ecological restoration. We asked whether transplants ofSpartina foliosa need to come from tall parents in order to produce tall stands for nesting by the light-footed clapper rail, one of southern California’s many endangered, salt-marsh-dependent species. Tall and shortS. foliosa transplants, collected from local salt marshes, were grown in a common garden and in microcosms, with different results. In the common garden, which had hypersaline soil, offspring of tall versus short clones did not differ, but they did respond to soil variations among blocks. In blocks with less sandy soil, stems were taller and up to 5 times more numerous, and patch sizes were up to 3 times larger. After two years in low-salinity microcosms, transplants receiving nitrogen additions produced more stems and over twice the total stem length of controls, regardless of parental height form. A slight parental effect was seen in this benign environment; the maximum height of tall-form transplants was 15 cm taller than that of short-form transplants, but the effect did not persist through year 2. Results indicate that both height forms ofS. foliosa grew better (taller and more dense) with less environmental stress (lower salinity, more nutrients). We conclude that environmental differences are more important than parental height form in determiningS. foliosa growth. This means that, for restoration purposes,S. foliosa ramets can and should be collected from short clones, rather than from existing, prime nesting habitat.

Fiddler crab–vegetation interactions in hypersaline habitats

Abiotic conditions often change ecological interactions. Studies in areas with low to moderate soil salinities have demonstrated a facultative mutualism between fiddler crabs and salt marsh vegetation. In these habitats, fiddler crab burrowing increases plant growth, and plant roots help support the walls of crab burrows. We looked for these interactions in hypersaline soils bordering unvegetated salt pans in a Georgia salt marsh. Crab burrows and vegetation cover were positively associated. Neither crab removals nor burrow additions demonstrated a positive effect of crabs on vegetation. However, both vegetation removals and the addition of an artificial canopy (suspended shadecloth) demonstrated a strong positive effect of vegetation on crab burrows. In contrast to previous studies, we found no evidence that plants supported burrow walls. Instead, crabs likely associate with vegetation to avoid predators. Our results caution against extrapolating experimental results between habitats with different abiotic conditions.

Salinity effects on the leaf water relations components and ion accumulation patterns in Avicennia germinans (L.) L. seedlings.

Physiological traits involved in leaf water relations were evaluated in Avicennia germinans (L.) L. seedlings growing at different salinities in the field. Analysis of pressure-volume (P-V) curves and sap osmometry were combined to evaluate osmotic adjustment and cell elasticity, and the contribution of accumulated inorganic ions to osmotic potential was estimated. Seedlings growing in soils with interstitial water salinity above that of normal sea water showed a modification of the relationship between water potential and relative water content. Thus, their leaf osmotic potential at maximum turgor (Ψπ(max)) and at zero turgor (Ψπ(0)) was 1.41 and 1.82 MPa lower respectively, than that of the seedlings from the low salinity site. Volumetric moduli of elasticity () were between 17 and 23 MPa. Thus, ɛ was about 6 MPa lower in high-salinity plants indicating that their cells were slightly more elastic. Ionic concentration analysis showed that Σ [anions] and Σ [cations] were higher in the high-salinity site (22-35%) while the water content per unit dry mass was only 12-17% lower. Reduction in water content was insufficient to explain the increase in ion concentration. Ion concentration explained 73 and 66% of the osmotic potential estimated by P-V curves for leaves from low- and high-salinity sites, respectively. In conclusion, this study provided evidence that leaves of A. germinans seedlings adapt to hypersaline soils by increasing solute concentration by 52% and cell elasticity by 26%. Both processes allow leaf water uptake and turgor maintenance over a large range of soil water potential.

New species of mole crickets of the Gryllotalpa gryllotalpa group (Orthoptera: Gryllotalpidae) from Israel, based on morphology, song recordings, chromosomes and cuticular hydrocarbons, with comments on the distribution of the group in Europe and the Mediterranean region

Two sibling species of mole crickets of the Gryllotalpa gryllotalpa group inhabit Israel. Both are described as new species based on differences in their morphology, acoustic behaviour, chromosome number, cuticular hydrocarbon pattern and habitats. The species with males having 2n = 23 chromosomes, described in the past as the ‘Dead Sea race’, is designated as G. marismortui sp.n. It is an endangered species. In morphology and chromosome number it is similar to G. cossyrensis Bacetti & Capra from Italy, but differs in the composition of cuticular hydrocarbons. Gryllotalpa marismortui occurs in a limited geographical area along the shore of the Dead Sea. Another species, with 2n = 19 chromosomes, is described as G. tali sp.n. and is found throughout Israel. The calling songs of the males of the new species differ markedly. Females of the respective chromosomal numbers discriminate in favour of the homospecific call. Their habitats are strikingly different: G. marismortui lives in hypersaline soil along the Dead Sea shore (total chloride 187.25 meq %), G. tali inhabits freshwater soil (9.31 meq %). The distribution of the twelve known sibling species and one chromosomal race (not yet described) of the G. gryllotalpa group from Europe and the eastern Mediterranean is summarized. The zoogeography and phylogeny of the group are discussed.

Plasmids from Halomonas eurihalina, a microorganism which produces an exopolysaccharide of biotechnological interest

The moderately halophilic bacterium Halomonas eurihalina strain F2-7, able to produce an exopolysaccharide, was found to contain two plasmids named pVE1 and pVE2, of 8.1 and 5.8 kb respectively. We found no evidence for the involvement of these plasmids in the expression of the mucoid phenotype. Restriction maps of both plasmids were constructed. Southern hybridization revealed similarities between them but excluded the existence of sequences homologous to other plasmids isolated from the Halomonas species. Neither pVE1 nor pVE2 displayed any homology with other plasmids isolated from moderate halophiles. The occurrence of similar plasmids in other strains of Halomonas eurihalina, isolated from hypersaline soils, has been detected. These small plasmids may be useful for the development of cloning vectors for moderately halophilic bacteria.

Bacillus salexigens sp. nov., a new moderately halophilic Bacillus species.

Bacillus salexigens sp. nov. is proposed based on the characteristics of six moderately halophilic, grampositive, rod-shaped strains isolated from salterns and hypersaline soils located in different geographical areas of Spain. These strains were motile, formed endospores, were strictly aerobic, were catalase and oxidase positive, and contained peptidoglycan of the meso-diamlnopimelic acid type in their vegetative cell walls. The DNA base compositions of these strains ranged from 36.3 to 39.5 mol%, and these organisms constitute a homology group with levels of DNA-DNA homology ranging from 73 to 100%. The 16S rRNA sequence of strain C-20MoT, which was used as the representative strain of these isolates, groups with the 16S rRNA sequences of members of the genus Bacillus, and the highest level of similarity is 95.4%. The type strain is strain C-20Mo (= ATCC 700290 = DSM 11483 = CCM 4646).

Disturbance and Intraspecific Variation in the Clonal Morphology of Salt Marsh Perennials

While considerable interest has focused on interspecific differences in dispersal and colonizing ability, the relationship between disturbance and intraspecific differences in colonizing ability has received less study. Here, we examined the relationship between wrack-burial disturbance and intraspecific variation in clonal morphology of a fugitive clonal species, Distichlis spicata, and a competitively dominant species, Spartina patens. We tested three hypotheses : 1) clones invading gaps exhibit greater mobility (i.e., displacement) than clones within dense swards, 2) clones invading gaps within infrequently disturbed marshes exhibit greater mobility than clones invading gaps within frequently disturbed marshes, and 3) rhizome connections to ramets of D. spicata inside gaps enable the ramets to tolerate hypersaline and highly-reduced soils within lower-lying gaps. Clones of D. spicata from gaps had greater growth rates, produced longer rhizomes, and exhibited greater mobility than clones from dense swards. The magnitude of this difference in mobility was greatest in an infrequently disturbed marsh and lowest in a frequently disturbed marsh. In contrast, we did not observe significant differences in clonal dispersal between clones of S. patens from gaps and swards. The effect of severing rhizomes initiating D. spicata ramets within gaps in the Juncus gerardi zone was more detrimental to survival at lower elevations, where salinity was highest and redox was lowest. Our results suggest that intraspecific variation in clonal morphology of marsh perennials can be strongly affected by disturbances but also show that disturbance effects can be species- and site-specific. Our results also suggest that invasion of hypersaline and highly reduced soils within gaps by ramets of D. spicata may be facilitated by physiological integration with ramets located outside gaps.

Physiological Integration among Clonal Ramets during Invasion of Disturbance Patches in a New England Salt Marsh

Resource sharing between ramets growing across environmental resource gradients may have important consequences for clonal plant populations and community dynamics. As the clonal salt marsh grasses, Spartina patens and Distichlis spicata, vegetatively colonize disturbance-generated bare patches, they span steep gradients in soil salinity and available sunlight. Examination of water relations and carbon translocation in the field and greenhouse revealed that connected ramets of these marsh grasses share water and carbon in response to gradients in resource availability. Ramets colonizing disturbance patches rely upon physiological integration with connected parent ramets to overcome water stress associated with hypersaline patch environments. In addition, upon establishment inside a bare patch, daughter ramets may translocate carbon back to shaded parent ramets in the surrounding vegetation outside of patches. Physiological integration of ramets colonizing disturbance-generated bare patches and parent ramets outside of patches may explain the predominance of vegetative invasion over sexual recruitment in marsh succession. Hypersaline soil conditions, which inhibit seedling recruitment into patches, have little effect on the success of clonal colonizers that can import water from parent ramets. This success appears to be due to the ability of clonal marsh grasses to translocate water and carbon products between ramets growing across opposing gradients in resource availability.

Plant invasion of newly exposed hypersaline Dead Sea shores

THE level of the Dead Sea, the lowest (about –400 m) and one of the most salty (salinity about 340 g l−1) lakes on earth, is lowering at a rate of approximately 0.5m annually owing to extensive exploitation of its main perennial tributary (the Jordan River) and the extreme aridity of the region (annual precipitation is about 60 mm)1. Consequently, new hypersaline sea shores are exposed, forming a unique, originally sterile ecosystem. The first plants invade these newly exposed shores after several years while soil water salinity is still extremely high. Here we use stable isotopes of oxygen and hydrogen to show that a variety of such perennial pioneer plants are able to make use of occasional floodwater which is distinct from the bulk of the hypersaline soil water found in their root zone. Our results provide new insight into the ways in which plants can invade extremely hostile environments and extend their ecological limits of distribution.

Cooperative and Competitive Interactions in the Recruitment of Marsh Elders

While most studies of plant recruitment focus on competitive interactions, recruitment can be influenced by both positive and negative interactions. We studied recruitment in the marsh elder, Iva frutescens, to examine the relationship between positive and negative forces in recruitment. Marsh elder seedling establishment was competitively precluded in undisturbed habitats by the dense perennial turfs that dominate marsh habitats. Adult marsh elders, however, passively trapped tidally transported plant debris that kills underlying vegetation. As a result, adult Iva created bare space and positively influenced seedling recruitment by facilitating the formation of seedling safe sites. Within bare patches, Iva seedling survivorship was high under adult conspecifics and at high seedling densities. In contrast, solitary Iva seedlings without adult neighbors suffered extremely high mortality. These positive associations among neighbors were experimentally shown to result from neighbor buffering of hypersaline soil conditions. Salinities in unshaded bare patches were elevated due to increased exposure to radiation and surface evaporation. Both adult nurse plants and high seedling densities shaded the soil, ameliorated high soil salinities, and thus had positive effects on seedling performance. Under adult canopies or when soil salinities were experimentally reduced by shading or watering, positive associations did not occur and all interactions among seedlings or between seedlings and adults were competitive. Our results indicate that marsh plant recruitment is dictated by a balance between positive and negative forces. Moreover, since positive interactions were only seen once densities and physical forces had been experimentally manipulated, our results when that positive interactions may be important forces in assemblages even where they are not conspicuous. These findings contribute to growing evidence that positive interactions, particularly those mediated by neighbor amelioration of harsh physical conditions, are important community level processes in a wide range of plant and animal assemblages.

Phenotypic and Chemotaxonomic Characterization of Marinococcus halophilus

Summary A phenotypic and chemotaxonomic study has been carried out on 55 moderately halophilic Gram-positive motile cocci isolated from hypersaline soils and solar salterns located near Alicante and Cadiz (Spain) and six reference strains. All the strains were examined for 158 morphological, physiological, biochemical, nutritional and antibiotic susceptibility tests, showing phenotypic characteristics similar to Marinococcus halophilus; however, a different range of nutritional features was observed. Nine strains were chosen as representative isolates and were studied in more detail. All these strains had mesodiaminopimelic acid in the cell wall, DNA base composition ranging between 46.6 to 48.8 mol%, and menaquinone systems with seven isoprene units. The DNA-DNA hybridization experiments showed a high degree of homology (60–98%) between the representative strains examined and the type strain M. halophilus CCM 2706, and low levels (1–40%) with the other Gram positive moderately halophilic cocci studied, indicating that the fresh isolates and the species M. halophilus constitute a genospecies.

Isolation of phages HM5 and HM15 from hypersaline soil

Two phages, HM‐15 and HM‐5, active on halotoleranl strains, were isolated from hypersaline soil samples. Both phages showed an isometric head and a flexible non‐contractile tail. No difference was detected between 5 and 10% (w/v) salt concentration on phages adsorption. In contrast, variations in salt concentration modified growth curves. Survival experiments with HM‐15 phage showed an optimal survival at 10% (w/v) while 20% was the most advantageous for HM‐5 survival. In general, behaviour of these phages resembled that of moderately halophilic microorganisms.

Nitrogen Assessments in a Constructed and a Natural Salt Marsh of San Diego Bay.

Soil nitrogen pools were lower in a 4-yr-old constructed salt marsh than in an adjacent natural marsh of San Diego Bay. Aboveground biomass and foliar nitrogen content of Spartina foliosa were both lower for the constructed marsh. Soil organic carbon, which was highly positively correlated with total nitrogen, was also lower in the constructed marsh. Rates of nitrogen fixation were higher for the natural marsh in surface soils (1 cm depth) but not in the rhizosphere (10 cm depth). Experimental additions of organic matter increased rates of nitrogen fixation substantially for both the constructed and natural marsh soils, with glucose stimulating greater increases than Spartina foliosa detritus (roots and rhizomes). In comparison with natural marshes studied elsewhere, the San Diego Bay sites have low nitrogen pools and little soil organic carbon. Nitrogen mineralization rates (in situ incubations) were high in both marshes studied. The low nitrogen pools reflect low tidal import and infrequent streamflow influxes and, possibly, high nitrogen demands of vegetation stressed by hypersaline soils.

A Taxonomic Study of Heterotrophic Halophilic and Non-halophilic Bacteria from a Solar Saltern

SUMMARY: A total of 564 strains of heterotrophic non-halophilic, marine, moderately halophilic and extremely halophilic bacteria was isolated from a saltern located near Huelva, SW Spain, facing the Atlantic Ocean. With the exception of the extremely halophilic bacteria, these were analysed by numerical techniques using the simple matching (SSM ) coefficient and clustering was achieved using the unweighted pair group method with averages (UPGMA) algorithm. At the 72.5% similarity level, a different number of phenons was found for each salinity group of bacteria. Of the 154 non-halophilic strains, the majority were recovered in 10 phenons, representing members of the genera Staphylococcus, Bacillus and Micrococcus. The 138 marine strains, with the exception of 24 strains, clustered into 12 phenons; seven phenons were assigned to the suprageneric grouping Pseudomonas-Alteromonas-Deleya, and the other phenons to Micrococcus, Staphylococcus, Bacillus and Vibrio. The 140 moderately halophilic strains grouped into eight phenons, with only 11 strains left unassigned. The majority of these isolates were assigned to the genus Deleya (two phenons) and they showed great similarity with the recently described species D. halophila, isolated from hypersaline soils. Four phenons comprised microorganisms with phenotypic characteristics very similar to the moderately halophilic Vibrio costicola. Two phenons were assigned to the genera Flavobacterium and Acinetobacter but these strains were not similar to previously described species. Of the 145 extremely halophilic isolates studied, the most important group was identified as belonging to the species Halobacterium salinarium (86 strains), followed by H. saccharovorum (20 strains), H. vallismortis (19 strains), Haloarcula hispanica (12 strains) and Halobacterium mediterranei (7 strains). Only one coccus was isolated, with characteristics very similar to those of Halococcus morrhuae.