Determination of DNA base compositions from melting profiles in dilute buffers

Rhodoblastus sphagnicola sp. nov., a novel acidophilic purple non-sulfur bacterium from Sphagnum peat bog

An isolate of purple non-sulfur bacteria was obtained from an acidicSphagnumpeat bog and designated strain RST. The colour of cell suspensions of this bacterium growing in the light under anaerobic conditions is purplish red. Cells of strain RSTare rod-shaped, 0.8–1.0 μm wide and 2.0–6.0 μm long, motile by means of polar flagella, reproduce by budding and have a tendency to form rosette-like clusters in older cultures. The cells contain lamellar intracytoplasmic membranes underlying, and parallel to, the cytoplasmic membrane. The photosynthetic pigments are bacteriochlorophyllaand carotenoids; the absorption spectrum of living cells shows maxima at 377, 463, 492, 527, 592, 806 and 867 nm. The cells grow photoheterotrophically under anaerobic or microaerobic conditions with various organic carbon sources or grow photolithoautotrophically with H2and CO2. Strain RSTis a moderately acidophilic organism exhibiting growth at pH values between 4.8 and 7.0 (with an optimum at pH 5.2–5.5). The major fatty acids are 16 : 1ω7cand 18 : 1ω7c; the major quinones are Q-10 and Q-9. The DNA G+C content of strain RSTis 62.6 mol%. Analysis of the 16S rRNA gene sequence revealed that the novel isolate is most closely related (97.3 % sequence similarity) to the type strain ATCC 25092Tof the moderately acidophilic purple non-sulfur bacteriumRhodoblastus acidophilus, formerly namedRhodopseudomonas acidophila. However, in contrast toRbl. acidophilus, strain RSTis not capable of aerobic growth in the dark, has no spirilloxanthin among the carotenoids and differs in the pattern of substrate utilization. The value for DNA–DNA hybridization between strain RSTandRbl. acidophilusATCC 25092Tis only 22 %. Thus, strain RSTrepresents a novel species of the genusRhodoblastus, for which the nameRhodoblastus sphagnicolasp. nov. is proposed. Strain RST(=DSM 16996T=VKM B-2361T) is the type strain.

Sulfobacillus thermotolerans sp. nov., a thermotolerant, chemolithotrophic bacterium

A thermotolerant, Gram-positive, aerobic, endospore-forming, acidophilic bacterium (strain Kr1T) was isolated from the pulp of a gold-containing sulfide concentrate processed at 40 °C in a gold-recovery plant (Siberia). Cells of strain Kr1T were straight to slightly curved rods, 0.8–1.2 μm in diameter and 1.5–4.5 μm in length. Strain Kr1T formed spherical and oval, refractile, subterminally located endospores. The temperature range for growth was 20–60 °C, with an optimum at 40 °C. The pH range for growth on medium containing ferrous iron was 1.2–2.4, with an optimum at pH 2.0; the pH range for growth on medium containing S0 was 2.0–5.0, with an optimum at pH 2.5. Strain Kr1T was mixotrophic, oxidizing ferrous iron, S0, tetrathionate or sulfide minerals as energy sources in the presence of 0.02 % yeast extract or other organic substrates. The G+C content of the DNA of strain Kr1T was 48.2±0.5 mol%. Strain Kr1T showed a low level of DNA–DNA reassociation with the known Sulfobacillus species (11–44 %). 16S rRNA gene sequence analysis revealed that Kr1T formed a separate phylogenetic group with a high degree of similarity between the nucleotide sequences (98.3–99.6 %) and 100 % bootstrap support within the phylogenetic Sulfobacillus cluster. On the basis of its physiological properties and the results of phylogenetic analyses, strain Kr1T can be affiliated to a novel species of the genus Sulfobacillus, for which the name Sulfobacillus thermotolerans sp. nov. is proposed. The type strain is Kr1T (=VKM B-2339T=DSM 17362T).

Methanomethylovorans thermophila sp. nov., a thermophilic, methylotrophic methanogen from an anaerobic reactor fed with methanol

A novel thermophilic, obligately methylotrophic, methanogenic archaeon, strain L2FAWT, was isolated from a thermophilic laboratory-scale upflow anaerobic sludge blanket reactor fed with methanol as the carbon and energy source. Cells of strain L2FAWT were non-motile, irregular cocci, 0·7–1·5 μm in diameter and usually occurred singly (sometimes forming clusters of two or four cells). The cells stained Gram-negative and lysed immediately in 0·1 % (w/v) SDS. Growth was inhibited by chloramphenicol and tetracycline, but not by penicillin, bacitracin, spectinomycin, vancomycin or kanamycin. Methanol and mono-, di- and trimethylamine were used as substrates, but H2/CO2, formate, acetate, propanol, dimethyl sulfide and methanethiol were not. The temperature range for growth was 42–58 °C, with an optimum at 50 °C. The fastest growth was observed at a salinity below 100 mM NaCl; no growth occurred above 300 mM NaCl. The optimal pH for growth was 6·5; growth was observed from pH 5 to pH 7·5. The G+C content of the genomic DNA was 37·6 mol%. Analysis of the 16S rRNA gene sequence and the partial methyl-CoM reductase gene sequence revealed that the organism was phylogenetically closely related to Methanomethylovorans hollandica DMS1T (98 % similarity for the 16S rRNA gene sequence and 91 % similarity for the methyl-CoM reductase gene sequence). The DNA–DNA relatedness between L2FAWT and Methanomethylovorans hollandica DMS1T was 46 %. On the basis of these results, strain L2FAWT (=DSM 17232T=ATCC BAA-1173T) represents the type strain of a novel species, for which the name Methanomethylovorans thermophila sp. nov. is proposed.

Pseudomonas pachastrellae sp. nov., isolated from a marine sponge

Two Gram-negative, non-fermentative, non-denitrifying, non-pigmented, rod-shaped bacteria that were motile by means of polar flagella, designated strains KMM 330(T) and KMM 331, were isolated from a deep-sea sponge specimen and subjected to a polyphasic taxonomic study. The new isolates exhibited 16S rRNA gene sequence similarity of 99.9 %, and their mean level of DNA-DNA relatedness was 82 %. Phylogenetic analysis based on their 16S rRNA gene sequences placed the strains within the genus Pseudomonas as an independent deep clade. Strain KMM 330(T) shared highest sequence similarity (96.3 %) with each of Pseudomonas fulva NRIC 0180(T), Pseudomonas parafulva AJ 2129(T) and Pseudomonas luteola IAM 13000(T); sequence similarity to other recognized species of the genus Pseudomonas was below 95.7 %. The marine sponge isolates KMM 330(T) and KMM 331 could be distinguished from the other recognized Pseudomonas species based on a unique combination of their phenotypic characteristics, including growth in 8 or 10 % NaCl, the absence of pigments, the inability to denitrify and lack of carbohydrate utilization. On the basis of phylogenetic analysis, physiological and biochemical characterization, strains KMM 330(T) and KMM 331 should be classified as a novel species of the genus Pseudomonas, for which the name Pseudomonas pachastrellae sp. nov. is proposed. The type strain is KMM 330(T) (=JCM 12285(T)=NRIC 0583(T)=CCUG 46540(T)).

Reclassification of 'Sulfobacillus thermosulfidooxidans subsp. thermotolerans' strain K1 as Alicyclobacillus tolerans sp. nov. and Sulfobacillus disulfidooxidans Dufresne et al. 1996 as Alicyclobacillus disulfidooxidans comb. nov., and emended description of the genus Alicyclobacillus

Comparative analysis of 16S rRNA gene sequences, DNA-DNA hybridization data and phenotypic properties revealed that 'Sulfobacillus thermosulfidooxidans subsp. thermotolerans' strain K1 is not a member of the genus Sulfobacillus. Phylogenetically, strain K1 is closely related to unclassified strains of the genus Alicyclobacillus: the 16S rRNA gene sequence of strain K1 is similar to that of Alicyclobacillus sp. AGC-2 (99.6 %), Alicyclobacillus sp. 5C (98.9 %) and Alicyclobacillus sp. CLG (98.6 %) and bacterium GSM (99.1 %). The 16S rRNA gene sequence similarity values for strain K1 and species of the genus Alicyclobacillus with validly published names were in the range 92.1-94.6 %, and for S. thermosulfidooxidans VKM B-1269(T) the value was 87.7 %. Sulfobacillus disulfidooxidans SD-11(T) was also phylogenetically related to strain K1 (92.6 % sequence similarity) and thus belonged to the genus Alicyclobacillus. Chemotaxonomic data, such as the major cell-membrane lipid components of strains K1 and SD-11(T) (omega-alicyclic fatty acids) and the major isoprenoid quinone (menaquinone MK-7) of strain K1, supported the affiliation of strains K1 and SD-11(T) to the genus Alicyclobacillus. Physiological and molecular biological tests allowed genotypic and phenotypic differentiation of strains K1 and SD-11(T) from the nine Alicyclobacillus species with validly published names. The G+C content of the DNA of strain K1 was 48.7+/-0.6 mol%; that of strain SD-11(T) was 53+/-1 mol%. DNA-DNA reassociation studies showed low relatedness (22 %) between strains K1 and SD-11(T), and even lower relatedness (3-5 %) between these strains and Alicyclobacillus acidocaldarius subsp. acidocaldarius ATCC 27009(T), DSM 446(T). DNA reassociation of strains K1 and SD-11(T) with Alicyclobacillus cycloheptanicus DSM 4006(T) gave values of 15 and 21, respectively. Based on the phenotypic and phylogenetic characteristics of strains K1 and SD-11(T), Alicyclobacillus tolerans sp. nov. (type strain, K1(T)=VKM B-2304(T)=DSM 16297(T)) and Alicyclobacillus disulfidooxidans comb. nov. (type strain, SD-11(T)=ATCC 51911(T)=DSM 12064(T)) are proposed.

Desulfonatronum cooperativum sp. nov., a novel hydrogenotrophic, alkaliphilic, sulfate-reducing bacterium, from a syntrophic culture growing on acetate

A novel alkaliphilic, sulfate-reducing bacterium was isolated from a syntrophic acetate-decomposing community enriched from samples of the soda lake Khadin, Tuva, Russia; the isolate was designated strain Z-7999T. Cells of strain Z-7999T were vibrioid, Gram-negative, 0·4–0·5×1·0–2·5 μm and motile by means of a polar flagellum. The temperature range for growth was 15–40 °C, with an optimum of 35–38 °C. The pH range for growth was 6·7–10·3, with an optimum of pH 8·0–9·0. The NaCl concentration range for growth was 1–80 g l−1. The novel isolate was obligately anaerobic, was alkaliphilic with a broad pH range and had an obligate requirement for carbonate ions in the growth medium. In the presence of sulfate as electron acceptor, it grew with hydrogen, formate and lactate. It was not able to ferment sugars, organic acids, amino acids or peptides. During growth on formate, strain Z-7999T reduced sulfite and thiosulfate to sulfide. It was able to grow lithoheterotrophically with sulfate and formate when acetate was added as a carbon source for biosynthesis of biomass. The G+C content of the genomic DNA of strain Z-7999T was 56·5 mol%. Results of comparative 16S rRNA gene sequence analyses revealed that strain Z-7999T was part of the δ-Proteobacteria and clustered with other members of the genus Desulfonatronum (similarity values of 95·2 and 95·3 % to Desulfonatronum lacustre and Desulfonatronum thiodismutans, respectively). DNA–DNA hybridization with D. lacustre was 37 %. On the basis of physiological and phylogenetic data, it is proposed that strain Z-7999T (=DSM 16749T=VKM B-2329T) should be placed in the genus Desulfonatronum as a representative of a novel species, Desulfonatronum cooperativum sp. nov.

Pseudomonas xanthomarina sp. nov., a novel bacterium isolated from marine ascidian

Two Pseudomonas-like yellow-orange-pigmented non-fluorescent denitrifying strains KMM 235 and KMM 1447T were isolated from marine ascidian specimens and investigated by a polyphasic approach to clarify their taxonomic status. On the basis of 16S rDNA gene sequence data the new isolates clustered with the Pseudomonas stutzeri species group with sequence similarities of >98%. The results of DNA-DNA hybridization and biochemical characterization showed genetic and phenotypic distinction between strains KMM 235 and KMM 1447T and from the other validly described Pseudomonas species. Strain KMM 235 was found to be closely related to the type strain of Pseudomonas stutzeri in their phenotypic and genetic characteristics and represented, probably, a new P. stutzeri genomovar. It is proposed that strain KMM 1447T be classified as a new species of the genus Pseudomonas, Pseudomonas xanthomarina sp. nov., with the type strain KMM 1447T (=JCM 12468T=NRIC 0617T=CCUG 46543T).

Marinobacter bryozoorum sp. nov. and Marinobacter sediminum sp. nov., novel bacteria from the marine environment

Two marine, Gram-negative, aerobic, halophilic strains, designated KMM 3657T and KMM 3840T, were isolated and found to be phylogenetically closely related to each other, showing 96·6 % 16S rRNA gene sequence similarity. Both strains are members of the genus Marinobacter in the γ-Proteobacteria (94·7–98·0 % 16S rRNA gene sequence similarity). Strain KMM 3657T and Marinobacter lipolyticus SM19T were closely related, with 98·0 % sequence similarity. The novel strains shared generic physiological and chemotaxonomic properties with Marinobacter species, but differed in their temperature range for growth, inability to grow in 20 % NaCl and at >43 °C, metabolic properties and fatty acid composition. On the basis of phenotypic and phylogenetic analysis data, it is proposed that the strains represent two novel species, Marinobacter bryozoorum sp. nov., with the type strain KMM 3840T (=50-11T=DSM 15401T), and Marinobacter sediminum sp. nov., with the type strain KMM 3657T (=R65T=DSM 15400T).

Psychrobacter maritimus sp. nov. and Psychrobacter arenosus sp. nov., isolated from coastal sea ice and sediments of the Sea of Japan

Four strains of Gram-negative, aerobic, psychrotolerant, non-motile, non-pigmented bacteria were isolated from coastal sea-ice and sediment samples. These strains displayed the general chemotaxonomic and phenotypic features of members of the genus Psychrobacter. 16S rRNA gene sequencing positioned the three isolates KMM 3646T, KMM 3643 and KMM 3645 and isolate KMM 3659T in two distinct lineages within the genus Psychrobacter, displaying less than 98·5 % sequence similarity to the type strains of other Psychrobacter species. Genomic distinctness was supported by phenotypic differences in growth temperatures, salinity range for growth and metabolic properties. Based on a combination of phenotypic and biochemical characteristics and phylogenetic position, it is proposed that the members of these two distinct lineages represent two novel species, for which the names Psychrobacter maritimus sp. nov. (type strain Pi2-20T=KMM 3646T=DSM 15387T) and Psychrobacter arenosus sp. nov. (type strain R7T=KMM 3659T=DSM 15389T) are proposed.

Thiocapsa marina sp. nov., a novel, okenone-containing, purple sulfur bacterium isolated from brackish coastal and marine environments

Four marine, phototrophic, purple sulfur bacteria (strains 5811T, 5812, BM-3 and BS-1) were isolated in pure culture from different brackish to marine sediments in the Mediterranean Sea, the White Sea and the Black Sea. Single cells of these strains were coccus-shaped, non-motile and did not contain gas vesicles. The colour of cell suspensions that were grown in the light was purple–red. Bacteriochlorophyll a and carotenoids of the okenone series were present as photosynthetic pigments. Photosynthetic membrane systems were of the vesicular type. Hydrogen sulfide, thiosulfate, elemental sulfur and molecular hydrogen were used as electron donors during photolithotrophic growth under anoxic conditions; carbon dioxide was utilized as the carbon source. During growth on sulfide, elemental sulfur globules were stored inside the cells. In the presence of hydrogen sulfide, several organic substances could be photoassimilated. Comparative 16S rDNA sequence analysis revealed an affiliation of these four strains to the genus Thiocapsa. Both phylogenetic analysis and the results of DNA–DNA hybridization studies revealed that these strains formed a separate cluster within the genus Thiocapsa. Thus, according to phenotypic characteristics and mainly the carotenoid composition, 16S rDNA sequence analysis and DNA–DNA hybridization data, it is proposed that these strains should be classified as a novel species, Thiocapsa marina sp. nov., with strain 5811T (=DSM 5653T=ATCC 43172T) as the type strain.

Newly isolated Bacillus clausii GMBAE 42: an alkaline protease producer capable to grow under higly alkaline conditions

AIMS

The isolation and identification of new Bacillus sp. capable of growing under highly alkaline conditions as alkaline protease producers.

METHODS AND RESULTS

A Bacillus strain capable of growing under highly alkaline conditions was isolated from compost. The strain is a Gram-positive, spore-forming, motile, aerobic, catalase- and oxidase-positive, alkaliphilic bacterium and designated as GMBAE 42. Good growth of the strain was observed at pH 10. The strain was identified as Bacillus clausii according to the physiological properties, cellular fatty acid composition, G + C content of genomic DNA and 16S rRNA gene sequence analyses. The result of 16S rRNA sequence analyses placed this bacterium in a cluster with B. clausii. The G + C content of the genomic DNA of the isolate GMBAE 42 was found to be 49 mol%. The crude extracellular alkaline protease produced by the isolate showed maximal activity at pH 11.0 and 60 degrees C.

CONCLUSIONS

The results suggest that isolated strain GMBAE 42 is a new type of B. clausii capable of growing at pH 10.0 and produce extracellular alkaline protease very active at pH 11.0.

SIGNIFICANCE AND IMPACT OF THE STUDY

Isolated strain could be used in commercial alkaline protease production and its enzyme can be considered as a candidate as an additive for commercial detergents.

Methylocella tundrae sp. nov., a novel methanotrophic bacterium from acidic tundra peatlands

A novel species, Methylocella tundrae, is proposed for three methanotrophic strains (T4T, TCh1 and TY1) isolated from acidic Sphagnum tundra peatlands. These strains are aerobic, Gram-negative, non-motile, dinitrogen-fixing rods that possess a soluble methane monooxygenase and utilize the serine pathway for carbon assimilation. Strains T4T, TCh1 and TY1 are moderately acidophilic organisms capable of growth between pH 4·2 and 7·5 (optimum 5·5–6·0) and between 5 and 30 °C (optimum 15 °C). The major phospholipid fatty acid is 18 : 1ω7c. The DNA G+C content of strain T4T is 63·3 mol%. The three strains possess almost identical 16S rRNA gene sequences and are most closely related to two previously identified species of Methylocella, Methylocella palustris (97 % similarity) and Methylocella silvestris (97·5 % similarity). DNA–DNA hybridization values of strain T4T with Methylocella palustris KT and Methylocella silvestris BL2T were respectively 27 and 36 %. Thus, the tundra strains represent a novel species, for which the name Methylocella tundrae sp. nov. is proposed. Strain T4T (=DSM 15673T=NCIMB 13949T) is the type strain.

Isolation of thermophilic Desulfotomaculum strains with methanol and sulfite from solfataric mud pools, and characterization of Desulfotomaculum solfataricum sp. nov

Four strains of thermophilic, endospore-forming, sulfate-reducing bacteria were enriched and isolated from hot solfataric fields in the Krafla area of north-east Iceland, using methanol and sulfite as substrates. Morphologically, these strains resembled thermophilic Desulfotomaculum species. The strains grew with alcohols, including methanol, with glucose and fructose as electron donors, and with sulfate, sulfite or thiosulfate as electron acceptors. For all four strains, the optimum temperature and pH for growth were 60 degrees C and pH 7.3, respectively; no added NaCl was required. Phylogenetic analysis based on partial 16S rRNA gene sequence comparisons showed high levels of similarity of the novel strains (>92 %) with Desulfotomaculum kuznetsovii and Desulfotomaculum luciae. However, DNA-DNA hybridization studies with D. kuznetsovii revealed that the four strains belonged to one novel species. A representative of this group of isolates, strain V21(T), is proposed as the type strain of a novel species of the spore-forming, sulfate-reducing genus Desulfotomaculum, namely Desulfotomaculum solfataricum (type strain V21(T)=DSM 14956(T)=CIP 107984(T)).

Metschnikowia vanudenii sp. nov. and Metschnikowia lachancei sp. nov., from flowers and associated insects in North America

Two new species of the ascosporic yeast genus Metschnikowia were isolated from nectaries and associated muscoid flies of flowers from the common milkweed (Asclepias syriaca) in North America, and are described as Metschnikowia vanudenii [type strain=PYCC 4650(T)=CBS 9134(T)=NRRL Y-27243(T)=UWO(PS) 86A4.1(T)] and Metschnikowia lachancei [type strain=PYCC 4605(T)=CBS 9131(T)=NRRL Y-27242(T)=UWO(PS) 7ASB2.3(T)]. As with the previously described Metschnikowia gruessii, M. vanudenii has vegetative cells with an 'aeroplane' or cross-like configuration, produces ovoid chlamydospores and forms ellipsoidopedunculate asci with two acicular ascospores. Metschnikowia lachancei is distinguished from other Metschnikowia species by formation of club-shaped asci with 1-2 thick clavate ascospores. The phylogenetic positions of the proposed new species within Metschnikowia were determined from sequence analysis of the D1/D2 domain of 26S rDNA. The new species show low nuclear DNA relatedness with neighbouring taxa.

Assignment of 'Alteromonas marinoglutinosa' NCIMB 1770 to Pseudoalteromonas mariniglutinosa sp. nov., nom. rev., comb. nov

The taxonomic position of the marine bacterium 'Alteromonas marinoglutinosa' NCIMB 1770 was investigated in a polyphasic study. Analysis of 16S rDNA sequence and DNA-DNA reassociation values confirmed the phylogenetic position of strain NCIMB 1770 within the genus Pseudoalteromonas as a separate species, distinct from all Pseudoalteromonas species with validly described names. On the basis of physiological and molecular properties, it is proposed that strain NCIMB 1770 is classified as Pseudoalteromonas mariniglutinosa sp. nov., nom. rev., comb. nov., with the type strain NCIMB 1770T (=KMM 3635T).

Methanol utilization by a novel thermophilic homoacetogenic bacterium, Moorella mulderi sp. nov., isolated from a bioreactor

A thermophilic, anaerobic, spore-forming bacterium (strain TMS) was isolated from a thermophilic bioreactor operated at 65 degrees C with methanol as the energy source. Cells were gram-positive straight rods, 0.4-0.6 microm x 2-8 microm, growing as single cells or in pairs. The temperature range for growth was 40-70 degrees C with an optimum at 65 degrees C. Growth was observed from pH 5.5 to 8.5, and the optimum pH was around 7. The salinity range for growth was 0-45 g NaCl l(-1 )with an optimum at 10 g l(-1). The isolate was able to grow on methanol, H(2)-CO(2 )(80/20%, v/v), formate, lactate, pyruvate, glucose, fructose, cellobiose and pectin. The bacterium reduced thiosulfate to sulfide. The G+C content of the DNA was 53 mol%. Comparison of 16S rRNA genes revealed that strain TMS is related to Moorella glycerini (96%, sequence similarity), Moorella thermoacetica (92%) and Moorella thermoautotrophica (92%). On the basis of physiological and phylogenetic differences, strain TMS is proposed as a new species within the genus Moorella, Moorella mulderi sp. nov. (=DSM 14980, =ATCC BAA-608).

Marinomonas primoryensis sp. nov., a novel psychrophile isolated from coastal sea-ice in the Sea of Japan

Two bacterial strains (KMM 3633(T) and KMM 3634) were isolated from marine coastal sea-ice and characterized by using phenotypic and molecular methods. The isolates were aerobic, Gram-negative, psychrophilic, halophilic and motile by means of a single polar flagellum. The DNA G + C content was 45.3-45.6 mol%. The major cellular fatty acids were C(16 :0), C(16 : 1)omega9c and C(18 : 1)omega7c. Comparison of almost-complete 16S rDNA sequences demonstrated that the strains were phylogenetically closely related to each other (99.5% sequence identity), and related to Marinomonas species (94.4-96.4% identity). DNA-DNA reassociation between KMM 3633(T) and KMM 3634 occurred at a level of 92%. Based on phenotypic, chemotaxonomic and phylogenetic properties, the name Marinomonas primoryensis sp. nov. is proposed for strains KMM 3633(T) and KMM 3634; the type strain is KMM 3633(T) (= JCM 11775(T) = NRIC 523(T)).

Glaciecola mesophila sp. nov., a novel marine agar-digesting bacterium

Alteromonas-like strains KMM 241(T) and KMM 642, isolated from marine invertebrate specimens, were investigated to clarify their taxonomic position. The novel isolates were aerobic, Gram-negative, motile, slightly halophilic and heterotrophic and hydrolysed polysaccharides. They did not hydrolyse urea, gelatin or casein and produced acid weakly from carbohydrates. The DNA G + C content ranged between 44.6 and 44.8 mol%. DNA-DNA similarity between the two strains was 71%. Comparison of the 16S rRNA gene sequence of strain KMM 241(T) revealed 94.5-94.8% similarity to Glaciecola species. The novel strains shared several phenotypic and physiological properties with members of Glaciecola, but they differed in their lack of pigment production, their minimal and maximal growth temperatures and their ability to hydrolyse agar and carrageenan and in the utilization of organic compounds. On the basis of phenotypic and physiological characteristics as well as phylogenetic analysis, the isolates should be assigned to a novel species, Glaciecola mesophila sp. nov. The type strain is strain KMM 241(T) (=DSM 15026(T)).

Pseudoalteromonas agarivorans sp. nov., a novel marine agarolytic bacterium

The phenotypic, genomic and phylogenetic characteristics of four aerobic, Gram-negative, non-fermentative, motile, non-pigmented, agarolytic Pseudoalteromonas-like bacteria, isolated from marine environments, have been investigated. These bacteria share DNA-DNA similarities above 86%. Comparative 16S rDNA sequence analysis of strain KMM 255T revealed its membership of the genus Pseudoalteromonas; it shares 99.9% sequence similarity with Pseudoalteromonas distincta, Pseudoalteromonas elyakovii, Pseudoalteromonas atlantica and Pseudoalteromonas espejiana. DNA-DNA reassociation levels obtained for strain KMM 255T and type strains of these four species and other Pseudoalteromonas species were below 45%. The marine isolates differed from known species of the genus by the fact that the cells are motile by means of a single flagellum or two to four polar unsheathed flagella and by an inability to utilize most organic compounds. On the basis of phenotypic, DNA-DNA hybridization and phylogenetic data, it is concluded that the isolates represent a novel species within the genus Pseudoalteromonas, for which the name Pseudoalteromonas agarivorans sp. nov. is proposed. The type strain is strain KMM 255T (= DSM 14585T).

Oligonucleotide Melting Temperatures under PCR Conditions: Nearest-Neighbor Corrections for Mg2+, Deoxynucleotide Triphosphate, and Dimethyl Sulfoxide Concentrations with Comparison to Alternative Empirical Formulas

Background: Many techniques in molecular biology depend on the oligonucleotide melting temperature (Tm), and several formulas have been developed to estimate Tm. Nearest-neighbor (N-N) models provide the highest accuracy for Tm prediction, but it is not clear how to adjust these models for the effects of reagents commonly used in PCR, such as Mg2+, deoxynucleotide triphosphates (dNTPs), and dimethyl sulfoxide (DMSO).

Methods: The experimental Tms of 475 matched or mismatched target/probe duplexes were obtained in our laboratories or were compiled from the literature based on studies using the same real-time PCR platform. This data set was used to evaluate the contributions of [Mg2+], [dNTPs], and [DMSO] in N-N calculations. In addition, best-fit coefficients for common empirical formulas based on GC content, length, and the equivalent sodium ion concentration of cations [Na+eq] were obtained by multiple regression.

Results: When we used [Na+eq] = [Monovalent cations] + 120($\batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(\sqrt{{[}Mg^{2{+}}{]}\ {-}\ {[}dNTPs{]}}\) \end{document}$) (the concentrations in this formula are mmol/L) to correct ΔS0 and a DMSO term of 0.75 °C (%DMSO), the SE of the N-N Tm estimate was 1.76 °C for perfectly matched duplexes (n = 217). Alternatively, the empirical formula Tm (°C) = 77.1 °C + 11.7 × log[Na+eq] + 0.41(%GC) − 528/bp − 0.75 °C(%DMSO) gave a slightly higher SE of 1.87 °C. When all duplexes (matched and mismatched; n = 475) were included in N-N calculations, the SE was 2.06 °C.

Conclusions: This robust model, accounting for the effects of Mg2+, DMSO, and dNTPs on oligonucleotide Tm in PCR, gives reliable Tm predictions using thermodynamic N-N calculations or empirical formulas.

Enterobacter kobei sp. nov., a new species of the family Enterobacteriaceae resembling Enterobacter cloacae

The name Enterobacter kobei sp. nov. is proposed for a group of organisms referred to as NIH Group 21 at the National Institute of Health, Tokyo. The members of this species are Gram-negative, motile rods conforming to the definition of the family Enterobacteriaceae. The DNA relatedness of 23 strains of NIH Group 21 to the representative proposed as the type strain of this species averaged 82% at 70 degrees C, whereas the relatedness to other species within the family Enterobacteriaceae was less than 42%. Because the phenotypic resemblance to Enterobacter cloacae is very close and the DNA relatedness (12-42%) is closer to species of the genus Enterobacter than to other species of the family, the members of NIH Group 21 were placed in the genus Enterobacter. Close phenotypic and genetic relationships were also found between NIH Group 21 and a member of a group of organisms referred to as Enteric Group 69 at the Centers for Disease Control and Prevention (CDC), Atlanta, Georgia, USA. It is suggested that the latter could be regarded as a subspecific rank of E. kobei, though this is subject to study of further strains. The majority of strains of E. kobei were isolated from clinical specimens. A culture of the type strain (NIH 1485-79) has been deposited in the Japan Collection of Microorganisms as JCM 8580.

A short autocomplementary sequence in the 5' leader region is responsible for dimerization of MoMuLV genomic RNA

Previous work has shown that a region of Moloney murine leukemia virus (MoMuLV) RNA located between nucleotides 280 and 330 in the PSI region (nt 215-565) is implicated in the dimerization process. We show with a deletion from nucleotides 290-299 in PSI RNA transcripts and through an antisense oligonucleotide complementary to nucleotides 275-291 that the 283-298 region is involved in RNA dimer formation in vitro. In an attempt to further characterize the mechanism of dimer formation, a series of short RNA transcripts was synthesized which overlapps the PSI region of MoMuLV RNA. The dimerization of these RNAs is temperature dependent. The predicted secondary structure of the 278-303 region, as a function of temperature, reveals that this sequence is able to adopt two conformations: (1) the U288 AGCUA293 sequence in a loop; (2) part of the same nucleotides implicated in a stem. These results, together with thermodynamic analysis, strongly suggest that (1) the loop conformation of the UAGCUA sequence modulates the relative amount of RNA dimer and (2) a 16 bp long Watson-Crick base pairing is involved in RNA dimer formation. We propose that loop-loop recognition via the U288 AGCUA293 sequence leads to a stable structure induced by a stem-loop opening. Furthermore, our results do not support purine quartet formation as necessary for the dimerization of the 5' leader MoMuLV RNA.

Thermal denaturation of double-stranded nucleic acids: prediction of temperatures critical for gradient gel electrophoresis and polymerase chain reaction

A program is described which calculates the thermal stability and the denaturation behaviour of double-stranded DNAs and RNAs up to a length of 1000 base pairs. The algorithm is based on recursive generation of conditional and a priori probabilities for base stacking. Output of the program may be compared directly to experimental results; thus the program may be used to optimize the nucleic acid fragments, the primers and the experimental conditions prior to experiments like polymerase chain reactions, temperature-gradient gel electrophoresis, denaturing-gradient gel electrophoresis and hybridizations. The program is available in three versions; the first version runs interactively on VAXstations producing graphics output directly, the second is implemented as part of the HUSAR package at GENIUSnet, the third runs on any computer producing text output which serves as input to available graphics programs.

Myxozyma vanderwaltii sp. nov. (Candidaceae), a new yeast species isolated from a flower of Protea repens (L.) L

Three strains of an undescribed species of the genus Myxozyma were recovered. The new species differs from other accepted species of the genus in its assimilation pattern of carbon sources, mol% G + C and low DNA-DNA homology. A description of the new species, Myxozyma vanderwaltii, and a key to the species accepted in the genus are given.

Identification of Oklahoma isolate as a strain of Pseudomonas pseudomallei

Based on the morphological, physiological, biochemical and nutritional characteristics, cellular fatty acid and lipid composition, ubiquinone-8 as the major respiratory quinone, guanine-plus-cytosine content of DNA, DNA-DNA homology value, and sequence alignment of 16S rRNA nucleotides, Oklahoma isolate was reidentified as a strain of Pseudomonas pseudomallei.

Myxozyma neotropica sp. nov. (Candidaceae)--a new yeast species from Costa Rica

Two strains of an undescribed, soil-borne species of the genus Myxozyma were recovered. They differ from other accepted species of this genus in their carbon assimilation pattern, mol% G+C and low extent of DNA complementary. A description of the new species, Myxozyma neotropica, and a key to the species accepted in the genus are given.

Kluyveromyces piceae sp. nov., a new yeast species isolated from the rhizosphere of Picea abies (L.) Karst

Two strains of an undescribed species of the genus Kluyveromyces were recovered from the rhizosphere of spruce. A description of the new species, Kluyveromyces piceae, is given and its classification on basis of ascospore shape, substrate utilization, G+C-content, DNA-DNA-reassociation data and habitat specificity is discussed.

Fellomyces horovitziae sp. nov., a new basidiomycetous yeast species isolated from a Xenasmatella basidiocarp

A new species of the genus Fellomyces, F. horovitziae, was isolated from a Xenasmatella basidiocarp. It differs from other accepted species in its carbon assimilation pattern, mol% G + C and low DNA-DNA homology. The delimiting characters are discussed and a key to the genus is provided.

An analytical study of the dimerization of in vitro generated RNA of Moloney murine leukemia virus MoMuLV

The genome of Moloney murine leukemia virus(MoMuLV) is composed of two identical RNA molecules joined at their 5' ends by the dimer linkage structure (DLS). Recently it was shown that in vitro generated MuLV RNA formed dimeric molecules and that dimerization sequences are located within the Psi encapsidation domain between positions 215 and 420. Conditions for the spontaneous dimerization of a MuLV RNA fragment encompassing the Psi domain have been investigated. The rate of spontaneous MuLV RNA dimer formation is dependent upon RNA, NaCl and MgCl2 concentrations as well as temperature. Thermal denaturation of in vitro generated dimer RNA of 350 nt, from positions 215 to 565, gave a Tm of about 58 degrees C in 100 mM NaCl. This Tm value is very close to that found for RNA corresponding to the 5' 755 nt and to the genomic 70 S RNA isolated from virions. According to thrermodynamic parameters derived from denaturation curves of MuLV dimer RNA generated in vitro, the dimer linkage structure probably involves short sequences.

Zygozyma smithiae sp.n. (Lipomycetaceae), a new ambrosia yeast from southern Africa

A new species of the genus Zygozyma, Z. smithiae, was recovered from frass of the ambrosia beetle, Crossotarsus externedentatus in Northern Natal. A description of the new species and key to the genus are given.

Azospirillum irakense sp. nov., a nitrogen-fixing bacterium associated with rice roots and rhizosphere soil

A new species of nitrogen-fixing bacteria, Azospirillum irakense, was found associated with roots and the rhizosphere of rice in the region of Diwaniyah (Qadisya), Iraq. The seven isolates, on which the species description is based, have vibrioid to S-shaped cells with one polar flagellum in liquid medium. Additional lateral flagella are seen on cells grown on nutrient agar. Poly-beta-hydroxybutyrate granules are present in cells. Nitrogen fixation occurs in microaerobic conditions. The phenotypic characters were found to be very close to those of A. amazonense with the following differences: growth occurred in the presence of 3% NaCl, and at pH 5.5 and 8.5, myo-inositol was not utilized as sole source of carbon and energy and pectin was slowly (6 to 9 days) hydrolysed. The seven studied strains formed a DNA-relatedness group distinct from other Azospirillum and Herbaspirillum species. The G + C content of the DNA was 64 to 67 mol %. The type strain is KBC1 (CIP 103311).

Debaryomyces udenii, sp. nov. (Saccharomycetaceae), a new species from soil

A new, soil-associated species of the genus Debaryomyces, D. udenii, is described. The species is characterized by pusticulate rather than verrucate ascospores, and slowly lytic asci.

Determination of G + C content of DNA using high-performance liquid chromatography for the identification of staphylococci and micrococci

The guanine-plus-cytosine (G + C) content of different species of Staphylococcus and Micrococcus was determined by high-performance liquid chromatography. Purified bacterial DNA was hydrolysed by nuclease P1. The nucleotides were separated by chromatography and quantified by measurement of the optical density at 260 nm. The G + C content of staphylococci ranged from 31.5 to 37.9 moles %, and that of micrococci from 68.7 to 75.2. Most of our results were comparable to those obtained with the thermal method.

Phenotypic and genomic studies of "Cytophaga psychrophila" isolated from diseased rainbow trout (Oncorhynchus mykiss) in France

Five strains of gliding bacteria were isolated in France from farmed diseased rainbow trouts reared at low water temperature. The resemblance of these bacteria to the known fish pathogen "Cytophaga psychrophila" led to their comparative study with reference strain NCMB 1947 and with an American isolate. Morphological, physiological, and biochemical characteristics of the seven strains proved to be similar. Comparison of their DNA by the S1 nuclease DNA-DNA hybridization method showed that the seven strains formed a tight genomic species with DNA relatedness above 90%. This is the first identification of this fish pathogen in a European country. The main phenotypic characteristics differentiating this bacterium from other nonpathogenic gliding bacteria of fish origin include a poor gliding movement, yellow compact or weakly rhizoid colonies on solid media, and the presence of flexirubin-type pigments. The inability to metabolize any carbohydrates, the strong proteolytic activity, the absence of growth in more than 0.5% NaCl, and the tolerance to a maximum temperature of 25 degrees C are also useful characteristics of this group of bacteria.

Species delineation in the genus Nadsonia Sydow

The genus Nadsonia Sydow is revised on the basis of morphology, physiology, amino acid and fatty acid composition, electrophoretic patterns of some enzymes and DNA relatedness. Two species, N. commutata (type CBS 6640) and N. fulvescens, with two varieties, N. fulvescens var. fulvescens (type CBS 2596) and N. fulvescens var. elongata (type CBS 2594) nov. comb. are recognized. A modified diagnosis of the genus and a key are given.