Isolation ofBacillus schlegelii,a thermophilic,hydrogen oxidizing,aerobic autotroph,from geothermal and nongeothermal environments

Thermophilic hydrogen-oxidizing strains forming round, terminal endospores were isolated from geothermal areas. They were neutrophilic and facultatively autotrophic. They resembledBacillus schlegelii, a thermophilic hydrogen bacterium found so far only in cold environments. Phenotypic similarities, as well as DNA G+C content and DNA:DNA homologies, clearly revealed that the isolated strains belonged to the taxospeciesB. schlegelii. Hence, the strains ofB. schlegelii found in cold environments are probably allochthonous, their origin being geothermal and volcanic areas.     

Iron Demand by Thermophilic and Mesophilic Bacteria Isolated from an Antarctic Geothermal Soil

The thermophilic bacterial strain MP4 assigned to a new species, likely of the genus Alicyclobacillus, was isolated from geothermal soils on the NW slope of Mount Melbourne, Antarctica. These soils have high iron concentrations and the strain MP4 requires iron additions for growth. Four mesophilic bacterial strains Paenibacillus validus MP5, MP8, and MP10, and P. apiarius MP7, isolated from the same site, need iron supply for growth depending on the medium. Growth temperature of thermophilic strain ranges from 42 to 70 °C, and that one of mesophiles from 25 to 44 °C. Thermophilic and mesophilic strains shared microenvironments with temperature of 42–44 °C and showed optima of pH values ranging from 5.5 to 6.0. The thermophilic strain MP4 reached values of 10⁶ CFU ml⁻¹ in aqueous soil extract from the NW slope of Mt. Melbourne, and 10⁵ CFU ml⁻¹ in water extracts from other geothermal Antarctic areas (Mt. Rittmann and Cryptogam Ridge). Growth of thermophilic bacteria in aqueous extracts of the NW slope of Mount Melbourne soils caused a reduction of 50% of soluble iron content, which was recovered in bacterial biomass. These results suggest a possible involvement of the thermophilic strain MP4 in iron bioavailability in these geothermal soils.     

Production of a novel glycerol-inducible lipase from thermophilic <Emphasis Type="Italic">Geobacillus stearothermophilus</Emphasis> strain-5

In a screening program for isolation of thermophilic lipase-producing bacteria, a number of thermophilic bacteria were isolated from desert soil from Baltim, Egypt. Among 55 isolates, a potent bacterial candidate (starin-5) was characterized and identified by biochemical and PCR techniques, based on 16S rRNA sequencing. Phylogenetic analysis revealed its closeness to geobacilli especially the thermophilic Geobacillus stearothermophilus with optimal growth and lipolytic enzyme activity at 60°C and pH 7.0. An inducible nature of lipolytic enzyme synthesis using glycerol and glucose was demonstrated. Approximately, 94–100% of the original activity was retained due to thermal stability of the crude enzyme after heat treatment for 15 min at 30–60°C. The enzyme retained 84.84% of its original activity during incubation at 70°C (pH 8.0) for 15 min. Lipase enzyme from G. stearothermophilus strain-5 was immobilized on various carriers and the most suitable carrier was chitin that showed 73.03% of activity yield.     

Thermosipho japonicus sp. nov., an extremely thermophilic bacterium isolated from a deep-sea hydrothermal vent in Japan

A novel barophilic, extremely thermophilic bacterium was isolated from a deep-sea hydrothermal vent chimney at the Iheya Basin, in the Okinawa area, Japan. The cells were found to be rod shaped and surrounded by a sheath-like outer structure; the organism did not possess flagella and was not motile. Growth was observed between 45° and 80°C (optimum, 72°C, 45 min doubling time), pH 5.3 and 9.3 (optimum, pH 7.2–7.6), 6.6 and 79 g/l sea salts (optimum, 40 g/l), and 0.1 and 60 MPa (optimum, 20 MPa). Strain IHB1 was found to be a strictly anaerobic chemoorganotroph capable of utilizing yeast extract and proteinaceous substrates such as peptone and tryptone. Elemental sulfur or thiosulfate acted as electron acceptors improving growth. The isolate was able to utilize casein as a sole carbon and energy source in the presence of thiosulfate. The G + C content of the genomic DNA was 31.4 mol%. Phylogenetic analysis based on 16S rDNA sequences and DNA–DNA hybridization analysis indicated that the isolate is closely related to Thermosipho africanus; however, it represents a species distinct from the previously described members of the genus Thermosipho. On the basis of the physiological and molecular properties, we propose that the new isolate represents a new species, which we name Thermosipho japonicus sp. nov. (type strain: IHB1; JCM10495). Received: May 26, 1999 / Accepted: August 7, 1999     

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     

Thermococcus peptonophilus sp. nov., a fast-growing,extremely thermophilic archaebacterium isolated from deep-sea hydrothermal vents

Two extremely thermophilic archaebacteria, strains OG-1 and SM-2, were isolated from newly discovered deep-sea hydrothermal vent areas in the western Pacific ocean. These strains were cocci, obligately anaerobic Archaea about 0.7–2 μm in diameter. Optimum growth conditions for OG-1 and SM-2 were at 85–90°C (range 60–100°C), pH 6 (range pH 4–8), a NaCl concentration of 3% (range 1–5%), and a nutrient concentration (tryptone plus yeast extract) of 0.2% (range 0.005–5%). Elemental sulfur stimulated the growth rate fourfold. Ammonium slightly stimulated growth. Both tryptone and yeast extract allowed growth as sole carbon sources; these isolates were not able to utilize or grow exclusively on sucrose, glucose, maltose, succinate, pyruvate, propionate, acetate, or free amino acids. OG-1 showed the fastest growth rate within the genus Thermococcus. Growth was inhibited by rifampicin. The DNA G+C content was 52 mol%. Sequencing of their 16S rDNA gene fragment indicated that these isolates belonged to the genus Thermococcus. OG-1 and SM-2 were different than the described Thermococcus species. We propose that OG-1 belongs to a new species: Thermococcus peptonophilus. Received: 8 March 1995 / Accepted: 24 May 1995     

The isolation and initial characterization of mercury resistant chemolithotrophic thermophilic bacteria from mercury rich geothermal springs

Mercury rich geothermal springs are likely environments where mercury resistance is critical to microbial life and where microbe-mercury interactions may have evolved. Eleven facultative thermophilic and chemolithoautotrophic, thiosulfate oxidizing bacteria were isolated from thiosulfate enrichments of biofilms from mercury rich hot sulfidic springs in Mount Amiata, Italy. Some strains were highly resistant to mercury (≥200 μM HgCl₂) regardless of its presence or absence during primary enrichments, and three reduced ionic mercury to its elemental form. The gene encoding for the mercuric reductase enzyme (MerA), was amplified by PCR from seven strains. However, one highly resistant strain did not reduce mercury nor carried merA, suggesting an alternative resistance mechanism. All strains were members of the order Bacillales and were most closely related to previously described thermophiles belonging to the Firmicutes. Phylogenetic analyses clustered the MerA of the isolates in two supported novel nodes within the Firmicutes lineage and a comparison with the 16S rRNA gene tree suggested at least one case of horizontal gene transfer. Overall, the results show that the thermophilic thiosulfate oxidizing isolates were adapted to life in presence of mercury mostly, but not exclusively, by possessing MerA. These findings suggest that reduction of mercury by chemolithotrophic thermophilic bacteria may mobilize mercury from sulfur and iron deposits in geothermal environments.     

Isolation of Thermus strains from hot composts (60 to 80 degrees C).

High numbers (10(7) to 10(10) cells per g [dry weight]) of heterotrophic, gram-negative, rod-shaped, non-sporeforming, aerobic, thermophilic bacteria related to the genus Thermus were isolated from thermogenic composts at temperatures between 65 and 82 degrees C. These bacteria were present in different types of wastes (garden and kitchen wastes and sewage sludge) and in all the industrial composting systems studied (open-air windows, boxes with automated turning and aeration, and closed bioreactors with aeration). Isolates grew fast on a rich complex medium at temperatures between 40 and 80 degrees C, with optimum growth between 65 and 75 degrees C. Nutritional characteristics, total protein profiles, DNA-DNA hybridization (except strain JT4), and restriction fragment length polymorphism profiles of the DNAs coding for the 16S rRNAs (16S rDNAs) showed that Thermus strains isolated from hot composts were closely related to Thermus thermophilus HB8. These newly isolated T. thermophilus strains have probably adapted to the conditions in the hot-compost ecosystem. Heterotrophic, ovalspore-forming, thermophilic bacilli were also isolated from hot composts, but none of the isolates was able to grow at temperatures above 70 degrees C. This is the first report of hot composts as habitats for a high number of thermophilic bacteria related to the genus Thermus. Our study suggests that Thermus strains play an important role in organic-matter degradation during the thermogenic phase (65 to 80 degrees C) of the composting process.     

Genetic Diversity among Thermophilic Bacteria Isolated from Geothermal Sites by Using Two PCR Typing Methods

Microbial communities thriving at two hot springs, Hammam Pharaon (Pharaoh's Bath) and Oyoun Mossa (Moses springs), in Egypt was studied by cultural and molecular methods. Thirteen morphologically distinct strains of facultative anaerobic thermophilic bacterial isolates have been characterized and identified using phenotypic and genotypic characters including RAPD-PCR, ERIC-PCR typing, plasmid analysis and 16S rRNA sequencing. All isolates produced plasmid DNA with various sizes ranging from 0.7 kb to a larger plasmid 7.2 kb. The bacterial strains could tolerate a temperature range between 45 to 85°C and a pH between 4–11. Also, sulphate-reducing bacteria (SRB) in the thermal springs were investigated with combined biochemical and molecular approaches. A sulphate-reducing bacteria medium containing lactate was used for enrichment and isolation, which yielded Gram negative, rod shaped, anaerobic, non-spore-forming and motile bacteria capable of reducing sulphate to sulphide. These grew at temperatures ranging from 30 to 50°C and could use pyruvate, lactate and ethanol as electron donors. The dissimilatory sulphite reductase (DSR) gene sequences of eleven representative isolates revealed that the strains belonged to the sulphur reducing bacterial species Desulfovibrio vulgaris. 16S rRNA gene partial sequence results indicated the presence of novel or existing species of Bacillus (one species), Anoxybacillus (four species) and Geobacillus (eight species). In this study phenotypic and genotypic diversity were applied for the first time to differentiate thermophilic bacteria of such geothermal sites in Sinai, Egypt.     

Isolation and characterization of two novel ethanol-tolerant facultative-anaerobic thermophilic bacteria strains from waste compost

In a search for potential ethanologens, waste compost was screened for ethanol-tolerant thermophilic microorganisms. Two thermophilic bacterial strains, M5EXG and M10EXG, with tolerance of 5 and 10% (v/v) ethanol, respectively, were isolated. Both isolates are facultative anaerobic, non-spore forming, non-motile, catalase-positive, oxidase-negative, Gram-negative rods that are capable of utilizing a range of carbon sources including arabinose, galactose, mannose, glucose and xylose and produce low amounts of ethanol, acetate and lactate. Growth of both isolates was observed in fully defined minimal media within the temperature range 50–80°C and pH 6.0–8.0. Phylogenetic analysis of the 16S rDNA sequences revealed that both isolates clustered with members of subgroup 5 of the genus Bacillus. G+C contents and DNA–DNA relatedness of M5EXG and M10EXG revealed that they are strains belonging to Geobacillus thermoglucosidasius. However, physiological and biochemical differences were evident when isolates M5EXG and M10EXG were compared with G. thermoglucosidasius type strain (DSM 2542^T). The new thermophilic, ethanol-tolerant strains of G. thermoglucosidasius may be candidates for ethanol production at elevated temperatures.     

Isolation and characterization of a new CO-utilizing strain, Thermoanaerobacter thermohydrosulfuricus subsp. carboxydovorans, isolated from a geothermal spring in Turkey

A novel anaerobic, thermophilic, Gram-positive, spore-forming, and sugar-fermenting bacterium (strain TLO) was isolated from a geothermal spring in Ayaş, Turkey. The cells were straight to curved rods, 0.4–0.6 μm in diameter and 3.5–10 μm in length. Spores were terminal and round. The temperature range for growth was 40–80°C, with an optimum at 70°C. The pH optimum was between 6.3 and 6.8. Strain TLO has the capability to ferment a wide variety of mono-, di-, and polysaccharides and proteinaceous substrates, producing mainly lactate, next to acetate, ethanol, alanine, H₂, and CO₂. Remarkably, the bacterium was able to grow in an atmosphere of up to 25% of CO as sole electron donor. CO oxidation was coupled to H₂ and CO₂ formation. The G + C content of the genomic DNA was 35.1 mol%. Based on 16S rRNA gene sequence analysis and the DNA–DNA hybridization data, this bacterium is most closely related to Thermoanaerobacter thermohydrosulfuricus and Thermoanaerobacter siderophilus (99% similarity for both). However, strain TLO differs from Thermoanaerobacter thermohydrosulfuricus in important aspects, such as CO-utilization and lipid composition. These differences led us to propose that strain TLO represents a subspecies of Thermoanaerobacter thermohydrosulfuricus, and we therefore name it Thermoanaerobacter thermohydrosulfuricus subsp. carboxydovorans.     

“Bacillus thermoantarcticus” sp. nov., from Mount Melbourne,Antarctica: a novel thermophilic species

 A novel thermophilic Gram-positive bacillus, “Bacillus thermoantarcticus”, isolated from geothermal soil near the crater of Mount Melbourne, is described. The organism grows at an optimal temperature of 63^°C at pH 6.0, is oxidase-positive, catalase-negative and produces an exopolysaccharide, an exocellular xylanase, an intracellular alcohol dehydrogenase and exo- and endocellular α-glucosidase(s). The sequence of 16S rDNA is very similar to that of “Bacillus thermoglucosidasius”; however, the guanine-plus-cytosine (G+C) content is 8 mol% higher. The type strain is “Bacillus thermoantarcticus” (DSM 9572). Received : 3 February 1995/Accepted : 12 May 1995     

Selective enrichment and characterization of Roseospirillum parvum, gen. nov. and sp. nov., a new purple nonsulfur bacterium with unusual light absorption properties

A new type of phototrophic purple bacterium, strain 930I, was isolated from a microbial mat covering intertidal sandy sediments of Great Sippewissett Salt Marsh (Woods Hole, Mass., USA). The bacterium could only be enriched at a wavelength of 932 (± 10) nm. Cells were vibrioid- to spirilloid-shaped and motile by means of bipolar monotrichous flagellation. The intracytoplasmic membranes were of the lamellar type. Photosynthetic pigments comprised bacteriochlorophyll a and the carotenoids spirilloxanthin and lycopenal. The isolated strain exhibited an unusual, long-wavelength absorption maximum at 911 nm. Sulfide or thiosulfate served as electron donor for anoxygenic phototrophic growth. During growth on sulfide, elemental sulfur globules formed outside the cells. Elemental sulfur could not be further oxidized to sulfate. In the presence of sulfide plus bicarbonate, fructose, acetate, propionate, butyrate, valerate, 2-oxoglutarate, pyruvate, lactate, malate, succinate, fumarate, malonate, casamino acids, yeast extract, L(+)-alanine, and L(+)-glutamate were assimilated. Sulfide, thiosulfate, or elemental sulfur served as a reduced sulfur source for photosynthetic growth. Maximum growth rates were obtained at pH 7.9, 30 °C, 50 μmol quanta m^–2 s^–1 of daylight fluorescent tubes, and a salinity of 1–2% NaCl. The strain grew microaerophilically in the dark at a partial pressure of 1 kPa O₂. The DNA base composition was 71.2 mol% G + C. Sequence comparison of 16S rRNA genes indicated that the isolate is a member of the α-Proteobacteria and is most closely related to Rhodobium orientis at a similarity level of 93.5%. Because of the large phylogenetic distance to known phototrophic species of the α-Proteobacteria and of its unique absorption spectrum, strain 930I is described as a new genus and species, Roseospirillum parvum gen. nov. and sp. nov. Received: 29 December 1998 / Accepted: 17 March 1999     

Diversity and distribution of alkaliphilic psychrotolerant bacteria in the Qinghai–Tibet Plateau permafrost region

The Qinghai–Tibet Plateau represents a unique permafrost environment, being a result of high elevation caused by land uplift. And the urgency was that plateau permafrost was degrading rapidly under the current predicted climatic warming scenarios. Hence, the permafrost there was sampled to recover alkaliphilic bacteria populations. The viable bacteria on modified PYGV agar were varied between 10² and 10⁵ CFU/g of dry soil. Forty-eight strains were gained from 18 samples. Through amplified ribosomal DNA restriction analysis (ARDRA) and phylogenetic analyses, these isolates fell into three categories: high G + C gram positive bacteria (82.3%), low G + C gram positive bacteria (7.2%), and gram negative α-proteobacteria (10.5%). The strains could grow at pH values ranging from 6.5 to 10.5 with optimum pH in the range of 9–9.5. Their growth temperatures were below 37°C and the optima ranging from 10 to 15°C. All strains grew well when NaCl concentration was below 15%. These results indicate that there are populations of nonhalophilic alkaliphilic psychrotolerant bacteria within the permafrost of the Qinhai-Tibet plateau. The abilities of many of the strains to produce extracellular protease, amylase and cellulase suggest that they might be of potential value for biotechnological exploitation.     

Thermophilic protease-producing Geobacillus from Buranga hot springs in Western Uganda

Two proteolytic thermophilic aerobic bacterial strains, PA-9 and PA-5, were isolated from Buranga hot springs in western Uganda. The cells were rods, approximately 10–12 μm in length and 3 μm in width. Isolate PA-9 grew at between 38°C and 68°C (optimum, 62°C), and PA-5 grew at between 37°C and 72°C (optimum, 60°C). Both isolates grew optimally at pH 7.5–8.5. Their 16S rRNA gene sequences indicated that they belong to the newly described genus Geobacillus. Zymogram analysis of the crude enzyme extracts revealed the presence of two extracellular proteases for isolate PA-5, and at least eight for isolate PA-9. The optimum temperature and pH for casein-degrading activity were 70°C, pH 6.5 for isolate PA-9, but caseinolytic activity could also be observed at 2°C. In the case of isolate PA-5, optimal activity was observed over a temperature and pH range of 50–70°C and pH 5–10, respectively. Received: 26 November 2001 / Accepted: 12 December 2001     

Thermodesulforhabdus norvegicus gen. nov., sp. nov., a novel thermophilic sulfate-reducing bacterium from oil field water

A novel gram-negative, thermophilic, acetate-oxidizing, sulfate-reducing bacterium, strain A8444, isolated from hot North Sea oil field water, is described. The rod-shaped cells averaged 1 μm in width and 2.5 μm in length. They were motile by means of a single polar flagellum. Growth was observed between 44 and 74°C, with an optimum at 60°C. Spores were not produced. Sulfate and sulfite were used as electron acceptors. Sulfur, thiosulfate, nitrate, fumarate, and pyruvate were not reduced. In the presence of sulfate, growth was observed with acetate, lactate, pyruvate, butyrate, succinate, malate, fumarate, valerate, caproate, heptanoate, octanoate, nonadecanoate, decanoate, tridecanoate, pentadecanoate, palmitate, heptadecanoate, stearate, and ethanol. Pyruvate, lactate, and fumarate did not support fermentative growth. Cytochromes of the c-type were present. Desulfoviridin, desulforubidin, P582, and desulfofuscidin were not present. The G+C content of the DNA was 51 mol%. Sequence analysis of 16S rDNA showed that phylogenetically strain A8444 belongs to the delta subdivision of the Proteobacteria. The closest relatives are Desulfacinum infernum and Syntrophobacter wolinii. Strain A8444 is described as the type strain of the new taxon Thermodesulforhabdus norvegicus gen. nov., sp. nov. Received: 4 May 1995 / Accepted: 11 July 1995     

A thermophilic green sulfur bacterium from New Zealand hot springs,Chlorobium tepidum sp. nov.

Thermophilic green sulfur bacteria of the genus Chlorobium were isolated from certain acidic high sulfide New Zealand hot springs. Cells were Gram-negative nonmotile rods of variable length and contained bacteriochlorophyll c and chlorosomes. Cultures of thermophilic chlorobia grew only under anaerobic, phototrophic conditions, either photoautotrophically or photoheterotrophically. The optimum growth temperature for the strains of thermophilic green sulfur bacteria isolated was 47–48°C with generation times of about 2 h being observed. The upper temperature limit for growth was about 52°C. Thiosulfate was a major electron donor for photoautotrophic growth while sulfide alone was only poorly used. N₂ fixation was observed at 48°C and cell suspensions readily reduced acetylene to ethylene. The G+C content of DNA from strains of thermophilic chlorobia was 56.5–58.2 mol% and the organisms positioned phylogenetically within the green sulfur bacterial branch of the domain Bacteria. The new phototrophs are described as a new species of the genus Chlorobium, Chlorobium tepidum.This paper is dedicated to Professor Norbert Pfennig on the occasion of his 65th birthday     

Thermoanaerobacterium thermostercus sp. nov., a new anaerobic thermophilic hydrogen-producing bacterium from buffalo-dung

A novel thermophilic, anaerobic, rod-shaped bacterium strain, designated Buff, was isolated from buffalo-dung samples collected from a buffalo-farm located in Caserta (Campania, south of Italy). Strain Buff was Gram-positive, motile and no spore-forming. The growth temperature range was 40–65°C with an optimum at 60°C, while pH growth range at 60°C was 5.5–8.0 with an optimum at about pH 6.5. NaCl growth concentration ranged from 0 to 2.0% with an optimum at 0.5% (w/v); no growth was observed with the presence of NaCl 3.0% (w/v). The strain produced ethanol, acetate, lactate, H₂, H₂S and CO₂ by glucose fermentation. The DNA G + C content was 34.4 mol%. As determined by 16S rRNA sequence analysis, this organism belonged to the genus Thermoanaerobacterium. On the basis of the physiological and molecular properties, we propose for strain Buff the new species designation Thermoanaerobacterium thermostercus sp. nov. This novel organism represents the first species of the genus Thermoanaerobacterium isolated from buffalo-dung. The type strain is Buff (=DSM 22141 = ATCC BAA-1776).     

Gene cloning,purification, and characterization of recombinant DNA ligases of the thermophilic archaea <Emphasis Type="Italic">Pyrococcus abyssi</Emphasis> and <Emphasis Type="Italic">Methanobacterium thermoautotrophicum</Emphasis>

DNA ligase genes of the thermophilic archaeae Pyrococcus abyssi (Pab DNA ligase) and Methanobacterium thermoautotrophicum (Mth DNA ligase) were cloned in Escherichia coli. The resulting recombinant enzymes were tested for activity in a ligation mixture with two oligonucleotides, one containing a preformed hairpin structure. The yield of the reaction products was maximal at temperatures close to 70°C for either enzyme; their accumulation reached a plateau at 70–75% of the theoretical yield at a stoichiometric enzyme-to-substrate ratio. The enzymes differed in thermal stability. The half-life of Pab DNA ligase was approximately 60 min at 90°C. Mth DNA ligase was completely inactivated within 10 min at this temperature. The recombinant DNA ligases from P. abyssi and M. thermoautotrophicum remained stabile during long-term storage at 4°C.     

Isolation and characterization of Desulfovibrio senezii sp. nov., a halotolerant sulfate reducer from a solar saltern and phylogenetic confirmation of Desulfovibrio fructosovorans as a new species

A new halotolerant Desulfovibrio, strain CVL^T (T = type strain), was isolated from a solar saltern in California. The curved, gram-negative, nonsporeforming cells (0.3 × 1.0–1.3 μm) occurred singly, in pairs, or in chains, were motile by a single polar flagellum and tolerated up to 12.5% NaCl. Strain CVL^T had a generation time of 60 min when grown in lactate-yeast extract medium under optimal conditions (37°C, pH 7.6, 2.5% NaCl). It used lactate, pyruvate, cysteine, or H₂/CO₂ + acetate as electron donors, and sulfate, sulfite, thiosulfate, or fumarate as electron acceptors. Elemental sulfur, nitrate, or oxygen were not used. Sulfite and thiosulfate were disproportionated to sulfate and sulfide. The G+C content of the DNA was 62 mol%. Phylogenetic analysis revealed that Desulfovibrio fructosovorans was the nearest relative. Strain CVL^T is clearly different from other Desulfovibrio species, and is designated Desulfovibrio senezii sp. nov. (DSM 8436). Received: 27 February 1998 / Accepted: 15 June 1998