Desulforhopalus vacuolatus gen. nov., sp. nov., a new moderately psychrophilic sulfate-reducing bacterium with gas vacuoles isolated from a temperate estuary

A new type of gas-vacuolated, sulfate-reducing bacterium was isolated at 10° C from reduced mud (E₀ < 0) obtained from a temperate estuary with thiosulfate and lactate as substrates. The strain was moderately psychrophilic with optimum growth at 18–19° C and a maximum growth temperature of 24° C. Propionate, lactate, and alcohols served as electron donors and carbon sources. The organism grew heterotrophically only with hydrogen as electron donor. Propionate and lactate were incompletely oxidized to acetate; traces of lactate were fermented to propionate, CO₂, and possibly acetate in the presence of sulfate. Pyruvate was utilized both with and without an electron acceptor present. The strain did not contain desulfoviridin. The G+C content was 48.4 mol%. The differences in the 16S rRNA sequence of the isolate compared with that of its closest phylogenetic neighbors, bacteria of the genus Desulfobulbus, support the assignment of the isolate to a new genus. The isolate is described as the type strain of the new species and genus, Desulforhopalus vacuolatus. Received: 4 March 1996 / Accepted: 17 June 1996     

Effects of extreme changes of sea water temperature and salinity on the development of the sand dollar <Emphasis Type="Italic">Scaphechinus mirabilis</Emphasis>

The combined effects of temperatures of 14, 17, 20, 22, and 25°C and salinities of 36–12‰ on embryos and larvae of the sand dollar Scaphechinus mirabilis was studied. Embryonic development is the most sensitive stage in the early ontogenesis of S. mirabilis. It is completed at a temperature of 14–20°C in a salinity range of 36–24‰ and at temperature of 22°C to 26‰. The fertilization proceeds in wider ranges of temperature and salinity. Among the swimming larvae, blastulae showed the greatest resistance to variations of these environmental factors. All the larvae survived at a temperature of 14–22°C and a salinity of 36–20‰, and more than 70% of them at 18‰. The pluteus I is the most vulnerable stage; probably this is related to the formation of the larval skeleton and transition to phytoplankton feeding. The survival of larvae at the age of 20 days was 100% at 14–22° C and a salinity of 36–24‰, most of them survived at 14–20°C and a salinity 18‰. The temperature 25 ° C is the most damaging for early development of S. mirabilis. The duration of development of that species lasts 28.5–29 days at 20°C and a salinity of 32.2–32.6‰. At 20 and 22°C, the larvae settled and completed metamorphosis more quickly if sand from the parental habitat was present. The larvae did not settle during the experiment (14 days) at 14 ° C and in the absence of sand.     

<Emphasis Type="Italic">Thermogladius shockii</Emphasis> gen. nov., sp. nov., a hyperthermophilic crenarchaeote from Yellowstone National Park,USA

A hyperthermophilic heterotrophic archaeon (strain WB1) was isolated from a thermal pool in the Washburn hot spring group of Yellowstone National Park, USA. WB1 is a coccus, 0.6–1.2 μm in diameter, with a tetragonal S-layer, vacuoles, and occasional stalk-like protrusions. Growth is optimal at 84°C (range 64–93°C), pH 5–6 (range 3.5–8.5), and <1 g/l NaCl (range 0–4.6 g/l NaCl). Tests of metabolic properties show the isolate to be a strict anaerobe that ferments complex organic substrates. Phylogenetic analysis of the 16S rRNA gene sequence places WB1 in a clade of previously uncultured Desulfurococcaceae and shows it to have ≤96% 16S rRNA sequence identity to Desulfurococcus mobilis, Staphylothermus marinus, Staphylothermus hellenicus, and Sulfophobococcus zilligii. The 16S rRNA gene contains a large insertion similar to homing endonuclease introns reported in Thermoproteus and Pyrobaculum species. Growth is unaffected by the presence of S⁰ or SO₄ ²⁻, thereby differentiating the isolate from its closest relatives. Based on phylogenetic and physiological differences, it is proposed that isolate WB1 represents the type strain of a novel genus and species within the Desulfurococcaceae, Thermogladius shockii gen. nov., sp. nov. (RIKEN = JCM-16579, ATCC = BAA-1607, Genbank 16S rRNA gene = EU183120).     

Seasonal plant water uptake patterns in the saline southeast Everglades ecotone

The purpose of this study was to determine the seasonal water use patterns of dominant macrophytes coexisting in the coastal Everglades ecotone. We measured the stable isotope signatures in plant xylem water of Rhizophora mangle, Cladium jamaicense, and Sesuvium portulacastrum during the dry (DS) and wet (WS) seasons in the estuarine ecotone along Taylor River in Everglades National Park, FL, USA. Shallow soilwater and deeper groundwater salinity was also measured to extrapolate the salinity encountered by plants at their rooting zone. Average soil water oxygen isotope ratios (δ ¹⁸O) was enriched (4.8 ± 0.2‰) in the DS relative to the WS (0.0 ± 0.1‰), but groundwater δ ¹⁸O remained constant between seasons (DS: 2.2 ± 0.4‰; WS: 2.1 ± 0.1‰). There was an inversion in interstitial salinity patterns across the soil profile between seasons. In the DS, shallow water was euhaline [i.e., 43 practical salinity units (PSU)] while groundwater was less saline (18 PSU). In the WS, however, shallow water was fresh (i.e., 0 PSU) but groundwater remained brackish (14 PSU). All plants utilized 100% (shallow) freshwater during the WS, but in the DS R. mangle switched to a soil–groundwater mix (δ 55% groundwater) while C. jamaicense and S. portulacastrum continued to use euhaline shallow water. In the DS, based on δ ¹⁸O data, the roots of R. mangle roots were exposed to salinities of 25.4 ± 1.4 PSU, less saline than either C. jamaicense (39.1 ± 2.2 PSU) or S. portulacastrum (38.6 ± 2.5 PSU). Although the salinity tolerance of C. jamaicense is not known, it is unlikely that long-term exposure to high salinity is conducive to the persistence of this freshwater marsh sedge. This study increases our ecological understanding of how water uptake patterns of individual plants can contribute to ecosystem levels changes, not only in the southeast saline Everglades, but also in estuaries in general in response to global sea level rise and human-induced changes in freshwater flows.     

A New Halophilic Heterolobosean Flagellate,Aurem hypersalina gen. n. et sp. n., Closely Related to the Pleurostomum‐Tulamoeba Clade: Implications for Adaptive Radiation of Halophilic Eukaryotes

Halophilic protozoa are independently scattered across the molecular phylogeny of eukaryotes; most of which are assigned to Heterolobosea. Here, we isolated a biflagellate from a hypersaline water of 342‰ salinity. This isolate shared several morphological features with typical halophilic heterolobosean flagellates. In addition, molecular phylogenetic trees of the 18S rRNA gene sequences clearly indicated flagellate is a heterolobosean species closely related to the halophilic Tulamoebidae. However, the flagellate was not accommodated to any described genus. Cells were ovoid‐shaped, and no amoebae were observed. The two unequal flagella beat heterodynamically. An ear‐like bulge at the margin of a cytostomal groove was observed. Flagellates could grow at 100–200‰ salinity, suggesting an obligately halophilic species. Currently, it appears that the new halophilic Aurem hypersalina forms a strong clade with Tulamoebidae, and is sister to the Tulamoebidae, indicating that this new clade is composed almost entirely of obligate halophilic taxa. Thus, A. hypersalina and the Tulamoebidae clade currently represent a unique adaptive radiation of halophilic eukaryotes.     

<Emphasis Type="Italic">Acinetobacter brisouii</Emphasis> sp. nov., isolated from a wetland in Korea

A bacterial strain 5YN5-8^T was isolated from peat layer on Yongneup in Korea. Cells of strain 5YN5-8^T were strictly aerobic, Gram-negative, coccobacilli, non-spore forming, and non-motile. The isolate exhibited optimal growth at 28°C, pH 7.0, and 0–1% NaCl. Results of 16S rRNA gene sequence analyses indicated a close relationship of this isolate to Acinetobacter calcoaceticus (97.8% similarity for strain DSM 30006^T). It also exhibited 94.4–97.8% 16S rRNA gene sequence similarities to the validly published Acinetobacter species. The value for DNA-DNA hybridization between strain 5YN5-8^T and other members of the genus Acinetobacter ranged from 16 to 28%. Predominant cellular fatty acids were C_18:1 ω9c, summed feature 4 containing C_15:0 iso 2-OH and/or C_16:1 ω7c, and C_16:0. The DNA G+C content was 43.9 mol%. Phylogenetic, phenotypic, and chemotaxonomic data accumulated in this study revealed that the isolate could be classified in a novel species of the genus Acinetobacter. The name Acinetobacter brisouii sp. nov. is proposed for the novel species, with 5YN5-8^T (=KACC 11602^T = DSM 18516^T) as the type strain.     

Lysinibacillus mangiferahumi sp. nov., a new bacterium producing nematicidal volatiles

A Gram-positive bacterium, designated M-GX18^T, was isolated from the rhizosphere soil of mango (Guangxi Province, China). The isolate produced nematicidal volatile compounds with activities against the root-knot nematode Meloidogyne incognita. The organism was motile, catalase- and oxidase-positive, spore-forming and rod shaped. The predominant menaquinone was MK-7 and the major cellular fatty acid profiles were iso-C_15:0, anteiso-C_15:0 and iso-C_16:0. The DNA G+C content was 38.9%. A phylogenetic analysis based on 16S rRNA gene sequences showed that this organism represented a new species of the genus Lysinibacillus. Strain M-GX18^T exhibited high 16S rRNA gene sequence similarity with its closest neighbors Lysinibacillus sphaericus (98.5%), Lysinibacillus fusiformis (98.1%) and Lysinibacillus xylanilyticus (98.6%). The physiological, biochemical and chemotaxonomic data, including DNA–DNA hybridization relatedness data, indicate that strain M-GX18^T can be distinguished from all the related species of the genus Lysinibacillus. Therefore, on the basis of the polyphasic taxonomic data presented, a new species of the genus Lysinibacillus, Lysinibacillus mangiferahumi, with the type strain M-GX18^T (=DSM 24076^T = CCTCC AB 2010389^T) is proposed.     

Influence of changes in sea water salinity on the growth,photosynthetic pigment content,and cell size of the benthic alga <Emphasis Type="Italic">Attheya ussurensis</Emphasis> Stonik,Orlova et Crawford, 2006 (Bacillariophyta)

The study deals with the effect of changes in salinity from 32 to 4‰ (at an interval of 4‰) on the growth, chlorophyll a and carotenoid contents, and cell size of the benthic alga Attheya ussurensis (Bacillariophyta). A. ussurensis showed high tolerance to reduced salinity and ability to adapt to salinity changes from 16 to 12‰. In this salinity range, the cells restored their shapes, sizes, and physiological functions. The number of cells and photosynthetic pigment content were highest at a salinity reduction to 24‰. At 8‰, algal cells remained alive, but the process of cell division was inhibited; as a result, the number of cells was significantly lower than in the control, the cells did not restore their sizes and shapes and remained deformed until the end of the experiment. A drop in salinity to 4‰ caused a complete loss of cell viability of A. ussurensis within a day of exposure to this factor.     

Caldimonas hydrothermale sp. nov., a novel thermophilic bacterium isolated from roman hot bath in south Tunisia

A polyphasic approach was used to characterize a bacterium, HAN-85^T, isolated from thermal water in natural thermal spring at Tozeur, an oasis in southwest Tunisia. The novel isolate was thermophilic, strictly aerobic and amylolytic bacterium, which stained Gram negative. Cells were short rods motile by means of a single polar flagellum. Their optimum temperature and pH required for growth were 55°C and pH 7, respectively. Comparative 16S rRNA gene sequence analyses showed that strain HAN-85^T belonged to the genus Caldimonas, with highest sequence similarity to the type strains Caldimonas manganoxidans and Caldimonas taiwanensis. DNA–DNA hybridization measurements revealed low DNA relatedness (35.2–44.5%) between the novel isolate and its closest relative, C. manganoxidans. The major cellular fatty acid components were 16:0, 17:0 cyclo and summed feature 3. The DNA G+C content was 68.3 mol%. Taken together, the results of DNA–DNA hybridization, fatty acids profile, physiological tests and biochemical analyses have allowed the genotypic and phenotypic differentiation of the isolate from currently recognized Caldimonas species. Therefore, we suggest that this isolate is a novel species within the genus Caldimonas and propose that it should be named Caldimonas hydrothermale sp. nov. The type strain is HAN-85^T (=DSM 18497^T =LMG 23755^T). The Gen Bank/Embl/DDBJ accession number for the 16S rRNA gene sequence of strain DSM 18497^T is AM283038.     

<Emphasis Type="Italic">Marinobacterium marisflavi</Emphasis> sp. nov., Isolated from a Costal Seawater

A marine bacterium designated strain IMCC4074^T was isolated from surface seawater collected off Incheon Port, the Yellow Sea, and subjected to a polyphasic taxonomy. The strain was Gram-negative, chemoheterotrophic, slightly halophilic, strictly aerobic, and motile rods. Based on 16S rRNA gene sequence comparisons, the strain was most closely related to Marinobacterium litorale KCTC 12756^T (93.9%) and shared low 16S rRNA gene sequence similarities with members of the genus Marinobacterium (91.8–93.9%) and the genus Neptunomonas (93.4%) in the order Oceanospirillales. Phylogenetic analyses showed that this marine isolate formed an independent phyletic line within the genus Marinobacterium clade. The DNA G+C composition of the strain was 56.0 mol% and the predominant constituents of the cellular fatty acids were C_16:0 (28.0%), C_16:1 ω7c and/or iso-C_15:0 2-OH (19.3%), C_18:1 ω7c (17.8%), and C_17:1 cyclo (12.5%), which differentiated the strain from other Marinobacterium species. Based on the taxonomic data collected in this study, only a distant relationship could be found between strain IMCC4074^T and other members of the genus Marinobacterium, thus the strain represents a novel species of the genus Marinobacterium, for which the name Marinobacterium marisflavi sp. nov. is proposed. The type strain of Marinobacterium marisflavi is IMCC4074^T (= KCTC 12757^T = LMG 23873^T). The GenBank/EMBL/DDBJ accession number for the 16S rRNA gene sequence of strain IMCC4074^T is EF468717. An erratum to this article can be found at     

Anoxybacillus thermarum sp. nov., a novel thermophilic bacterium isolated from thermal mud in Euganean hot springs, Abano Terme, Italy

A novel aerobe thermophilic endospore-forming bacterium designated strain AF/04^T was isolated from thermal mud located in Euganean hot springs, Abano Terme, Padova, Italy. Strain AF/04^T was Gram-positive, motile, rod-shaped, occurring in pairs, or filamentous. The isolate grew between 55 and 67°C (optimum 65°C) and at pH 6.0–7.5 (optimum pH 7.2). The strain was aerobic and grew on maltose, trehalose, and sodium acetate as sole carbon sources. The G + C content of DNA was 53.5 mol%. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain AF/04^T falls within the genus Anoxybacillus. Levels of 16S rRNA gene sequence similarity between strain AF/04^T and the type strains of recognized Anoxybacillus species ranged from 95 to 99%. Chemotaxonomic data (major isoprenoid quinone–menaquinone-7; major fatty acid iso-C15:0 and anteiso-C17:0) supported the affiliation of strain AF/04^T to the genus Anoxybacillus. Based on phenotypic and chemotaxonomic characteristics, 16S rRNA gene sequence analysis and DNA–DNA hybridization data, it was proposed that strain AF/04^T (=DSM 17141^T = ATCC BAA 1156^T) should be placed in the genus Anoxybacillus as the type strain of a novel species, Anoxybacillus thermarum sp. nov.     

Oceanobacillus kimchii sp. nov. Isolated from a traditional Korean fermented food

A moderate halophile, strain X50^T, was isolated from mustard kimchi, a traditional Korean fermented food. The organism grew under conditions ranging from 0–15.0% (w/v) NaCl (optimum: 3.0%), pH 7.0–10.0 (optimum: pH 9.0) and 15–45°C (optimum: 37°C). The morphological, physiological, and biochemical features and the 16S rRNA gene sequences of strain X50^T were characterized. Colonies of the isolate were creamcolored and the cells were rod-shaped. Phylogenetic analysis based on the 16S rRNA gene sequence indicated that strain X50^T belongs to the genus Oceanobacillus and is closely related phylogenetically to the type strain O. iheyensis HTE831^T (98.9%) and O. oncorhynchi subsp. oncorhynchi R-2^T (97.0%). The cellular fatty acid profiles predominately included anteiso-C_15:0 and iso-C_15:0. The G+C content of the genomic DNA of the isolate was 37.9 mol% and the major isoprenoid quinone was MK-7. Analysis of the 16S rRNA gene sequences, DNA-DNA relatedness and physiological and biochemical tests indicated genotypic and phenotypic differences among strain X50^T and reference species in the genus Oceanobacillus. Therefore, strain X50^T was proposed as a novel species and named Oceanobacillus kimchii. The type strain of the new species is X50^T (=JCM 16803^T =KACC 14914^T =DSM 23341^T).     

Evidence for Local Ciliate Endemism in an Alpine Anoxic Lake

Despite its long history, biogeography has received relatively little attention within the field of microbial ecology. Consequently, a fierce debate rages whether protists inhabit restricted geographic areas (endemism hypothesis) or are globally dispersed (ubiquitous dispersal hypothesis). The data presented in this article support the endemism hypothesis. We succeeded in isolating an oligohymenophorean ciliate from a microbial mat in a meromictic anoxic alpine lake (Alatsee) in Germany. The ciliary pattern and the morphometry of this isolate are remarkably similar to Urocentrum turbo (Mueller, 1786) Nitzsch, 1827. However, the organism does not possess trichocysts, a conspicuous and characteristic feature of U. turbo. Instead, the U. turbo-like isolate from lake Alatsee displays merely trichocyst anlagen (“ghosts”) in the cytoplasm that are only visible after protargol impregnation and which become never attached to the cell’s cortex. Despite the distinctness of this difference, such a morphospecies has not been described from any other environment. Thus, we suggest that the U. turbo-like isolate from lake Alatsee is a local endemic ecotype, although the sequences of the 18S rRNA, ITS1, 5.8S rRNA, and ITS2 genes are nearly identical to those of U. turbo (Mueller, 1786) Nitzsch, 1827. This indicates that neither 18S rDNA nor ITS1, ITS2, and 5.8S rDNA sequences are reliable means to conclusively resolve different morphospecies or ecotypes of ciliates. As a consequence, we argue that protist species richness can only be reliably accounted for by considering both molecular and morphological data.     

<Emphasis Type="Italic">Chromocurvus halotolerans</Emphasis> gen. nov., sp. nov., a gammaproteobacterial obligately aerobic anoxygenic phototroph,isolated from a Canadian hypersaline spring

A strain EG19^T of aerobic bacteria able to form pleomorphic cells was isolated from a brine spring runoff stream in the west central region of the province of Manitoba, Canada. The pale pinkish purple strain contained bacteriochlorophyll a incorporated into light-harvesting I and reaction center complexes. Its inability to grow under anaerobic illuminated conditions prompted designation as a member of the functional group known as aerobic anoxygenic phototrophic bacteria. Phylogenetic analysis of the 16S rRNA gene sequence revealed that it belonged to the Gammaproteobacteria, forming a distinct branch of phototrophs distantly related to most described aerobic anoxygenic phototrophs, quite marginally related (95.6%) both to the only other described gammaproteobacterial aerobic phototroph, Congregibacter litoralis, and also to nonphototrophs in the genus Haliea (95.1–96.1%). Physiological tests demonstrated tolerance profiles to salinity (0–18% NaCl), pH (7–12), and temperature (7–40°C) consistent with survival in a shallow hypersaline stream on the exposed, vegetation-depleted salt playa of its native East German Creek. Phylogenetic data and phenotypic properties such as pigment composition, morphology, and physiology support the proposal of the novel genus and species Chromocurvus halotolerans gen. nov., sp. nov., with EG19^T (=DSM 23344^T, =VKM B-2659^T) as the type strain.     

<Emphasis Type="Italic">Aliihoeflea aestuarii</Emphasis> gen. nov., sp. nov., a novel bacterium isolated from tidal flat sediment

A novel Gram-negative and rod-shaped bacterium, designated N8^T, was isolated from tidal flat sediment. Phylogenetic analysis based on 16S rRNA gene sequences showed that N8^T strain is associated with the family Phyllobacteriaceae: two uncultured clones (98.4 and 99.8% 16S rRNA gene sequence similarity) and the genus Mesorhizobium (≤97.0%). The novel strain formed a separate clade with uncultured clones in the phylogenetic tree based on 16S rRNA gene sequences. Cellular fatty acid profiles predominately comprised C_18:1 ω7c and C_19:0 cyclo ω8c. The major isoprenoid quinone is ubiquinone-10 and genomic DNA G+C content is 53.4 mol%. The polyphasic taxonomic study indicates that the novel strain N8^T represents a novel species of the new genus in the family Phyllobacteriaceae, named Aliihoeflea aestuarii. The type strain is N8^T (= KCTC 22052^T= JCM 15118^T= DSM 19536^T).     

Thermococcus acidaminovorans sp. nov., a new hyperthermophilic alkalophilic archaeon growing on amino acids

From a shallow marine hydrothermal system at Vulcano (Italy), a new hyperthermophilic member of the Archaea was isolated. The cells are coccoid – shaped and possess up to five flagella. They grow between 56° and 93°C (optimum 85°C) and pH 5.0–9.5 (optimum 9.0). The organism is strictly anaerobic and grows heterotrophically on defined amino acids and complex organic substrates such as casamino acids, yeast extract, peptone, meat extract, tryptone, and casein. Polysulfide and elemental sulfur are reduced to H₂S. In the absence of polysulfide or elemental sulfur, the isolate grows at a significantly reduced rate. Growth is not influenced by the presence of H₂. DNA–DNA hybridization and 16S rRNA partial sequences indicated that the new isolate belongs to the genus Thermococcus, and represents a new species, Thermococcus acidaminovorans. The type strain is isolate AEDII10 (DSM 11906). Received: September 24, 1997 / Accepted: January 1, 1998     

Silicibacter lacuscaerulensis gen. nov., sp. nov., a mesophilic moderately halophilic bacterium characteristic of the Blue Lagoon geothermal lake in Iceland

Mesophilic, moderately halophilic bacteria were isolated from a silica-rich geothermal lake, the Blue Lagoon in Iceland. The isolates are strictly aerobic, but reduce nitrate to nitrite, and are oxidase- and catalase-positive. The nonsporeforming and nonmotile Gram negative rods are 0.6–0.8 μm in diameter and variable in length (9–18 μm), and contain gas vacuoles. The GC content in their DNA is 66.15%. The minimum, optimum, and maximum temperatures for growth are 22°C, 45°:C, and 50°C, respectively. The isolates do not grow without added salt in the medium and can grow at up to 7% NaCl (w/v). The optimal salinity for growth is 3.5%–4% NaCl. The pH range for growth is 6.5–8.5, with the optimal pH at 7.0. At optimal conditions the bacterium has a doubling time of 80 min. The main cytochrome is a membrane-bound cytochrome c with an α-peak at 549 nm. Sequencing of 16S rRNA from the type strain ITI-1157 revealed it to be a proteobacterium of the α-subclass with the closest relatives being Roseobacter litoralis and Paracoccus kocurii. The new isolates do not contain bacteriochlorophyll a and are considered to represent a new genus and a new species, Silicibacter lacuscaerulensis. Received: September 17, 1996 / Accepted: December 10, 1996     

<Emphasis Type="Italic">Natronoflexus pectinivorans</Emphasis> gen. nov. sp. nov., an obligately anaerobic and alkaliphilic fermentative member of <Emphasis Type="Italic">Bacteroidetes</Emphasis> from soda lakes

Anaerobic enrichment with pectin at pH 10 and moderate salinity inoculated with sediments from soda lakes of the Kulunda Steppe (Altai, Russia) resulted in the isolation of a novel member of the Bacteroidetes, strain AP1^T. The cells are long, flexible, Gram-negative rods forming pink carotenoids. The isolate is an obligate anaerobe, fermenting various carbohydrates to acetate and succinate. It can hydrolyze and utilize pectin, xylan, starch, laminarin and pullulan as growth substrates. Growth is possible in a pH range from 8 to 10.5, with an optimum at pH 9.5, and at a salinity range from 0.1 to 2 M Na⁺. Phylogenetic analysis based on 16S rRNA sequences placed the isolate into the phylum Bacteroidetes as a separate lineage within the family Marinilabilaceae. On the basis of distinct phenotype and phylogeny, the soda lake isolate AP1^T is proposed to be assigned in a new genus and species Natronoflexus pectinivorans (=DSM24179^T = UNIQEM U807^T).     

<Emphasis Type="Italic">Halomonas sediminis</Emphasis> sp. nov., a new halophilic bacterium isolated from salt-lake sediment in China

A novel Gram-negative, slightly halophilic, catalase- and oxidase-positive, obligately aerobic bacterium, strain YIM-C248^T, was isolated from a sediment sample collected from a salt-lake in the Qaidam Basin in Qinghai, north-west China. Cells were non-sporulating short rods, occurring singly or as doublets, motile with peritrichous flagella. Growth occurred with 1–15% (w/v) NaCl [optimum 2–4% (w/v) NaCl], at pH 6.0–10.0 (optimum pH 7.5) and at 4–35°C (optimum 25–30°C). The major cellular fatty acids were C_18:1 ω7c, C_12:0 3-OH, cyclo C_19:0 ω8c, C_16:0 and C_16:1. The predominant respiratory quinone was Q-9 and the genomic DNA G + C content was 58.6 mol%. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain YIM-C248^T should be assigned to the genus Halomonas. The sequence similarities between the isolate and the type strains of members of the genus Halomonas were in the range of 92.5–97.5%. The combination of phylogenetic analysis, DNA–DNA hybridization data, phenotypic characteristics and chemotaxonomic differences supported the view that strain YIM-C248^T represents a new species of the genus Halomonas, for which the name Halomonas sediminis sp. nov. is proposed, with YIM-C248^T (=CCTCC AA 207031 = KCTC 22167) as the type strain. The GenBank/EMBL/DBBJ accession number for the 16S rRNA gene sequence of strain YIM-C248^T is EU135707.     

Phylogenetic analysis of Methanobrevibacter isolated from feces of humans and other animals

Comparative 16S rRNA gene sequence and genomic DNA reassociation analyses were used to assess the phylogenetic relationships of Methanobrevibacter fecal isolates. The 16S rRNA gene sequences of Methanobrevibacter smithii strain PS and the human fecal isolates B181 and ALI were essentially identical, and their genomic DNA reassociated at values greater than 94%. The analysis of 16S rRNA sequences of the horse, pig, cow, rat, and goose fecal isolates confirm that they are members of the genus Methanobrevibacter. They had a high degree of sequence similarity (97–98%) with the 16S rRNA gene of M. smithii, indicating that they share a common line of descent. The 16S rRNA genes of the horse and pig isolates had 99.3% sequence similarity. Sequence analysis of the 16S rRNA gene of the sheep fecal isolate showed that it formed a separate line of descent in the genus Methanobrevibacter. Genomic DNA reassociation studies indicate that the horse, pig, cow, and goose fecal isolates represent at least three new species. The horse and pig isolates were the only animal isolates that had > 70% genomic DNA reassociation and represent strains of a single species. The cow, goose, and sheep isolates had little or no genomic DNA reassociation with M. smithii or with each other. The relationship of the rat isolate to the other animal isolates was not determined. An evaluation of the relationship of 16S rRNA gene sequence similarity and genomic DNA reassociation of Methanobrevibacter and other methanogenic archaea indicated that genomic DNA reassociation studies are necessary to establish that two methanogenic organisms belong to the same species. Received: 17 November 1997 / Accepted: 16 January 1998