Tepidimicrobium ferriphilum gen. nov., sp. nov., a novel moderately thermophilic, Fe(III)-reducing bacterium of the order Clostridiales.

A moderately thermophilic, anaerobic bacterium (strain SB91T) was isolated from a freshwater hot spring at Barguzin Valley, Buryatiya, Russia. Cells of strain SB91T were straight to slightly curved rods, 0.5-0.6 microm in diameter and 3.0-7.0 mum in length. Formation of endospores was not observed. The temperature range for growth was 26-62 degrees C, with an optimum at 50 degrees C. The pH range for growth was 5.5-9.5, with an optimum at pH 7.5-8.0. The substrates utilized by strain SB91T in the presence of 9,10-anthraquinone 2,6-disulfonate included peptone, tryptone, Casamino acids, yeast extract, beef extract, casein hydrolysate, alanine plus glycine, alanine plus proline, L-valine and n-propanol. Carbohydrates were not utilized. Strain SB91T reduced amorphous Fe(III) oxide, Fe(III) citrate, Fe(III) EDTA or Fe(III) nitrilotriacetate with peptone, L-valine or n-propanol as an electron donor. Strain SB91T reduced 9,10-anthraquinone 2,6-disulfonate, thiosulfate, elemental sulfur, fumarate and selenite. Strain SB91T survived after exposure to gamma-radiation at a dose of 5.4 kGy. The G+C content of the DNA of strain SB91T was 33 mol%. Analysis of the 16S rRNA gene sequence revealed that the isolated organism belonged to cluster XII of the clostridia. On the basis of its physiological properties and the results of phylogenetic analyses, it is proposed that strain SB91T represents the sole species of a novel genus, Tepidimicrobium; the name Tepidimicrobium ferriphilum gen. nov., sp. nov. is proposed, with strain SB91T (=DSM 16624T=VKM B-2348T) as the type strain.

Leucobacter luti sp. nov., and Leucobacter alluvii sp. nov., two new species of the genus Leucobacter isolated under chromium stress.

Two strains designated RF6(T) and RB10(T) were isolated, from activated sludge and from river sediments, respectively, both systems receiving chromium contaminated water. Phylogenetic analysis showed that strain RF6(T)and strain RB10(T) represented two new species of the genus Leucobacter. Strain RB10(T) can be distinguished from RF6(T) by its ability to grow at 37 degrees C, by showing a different optimum pH, by cell wall amino acids different relative amount and by having the fatty acid strait C16:0 as the third most abundant fatty acid. On the basis of the distinct peptidoglycan composition, 16S ribosomal DNA sequence analysis, DNA-DNA reassociation values, and phenotypic characteristics we are of the opinion that strain RF6(T) represents a new species of the genus Leucobacter for which we propose the name Leucobacter luti (CIP 108818(T)=LMG 23118) and that strain RB10(T) represents an additional new species of the same genus for which we propose the name Leucobacter alluvii (CIP 108819(T)=LMG 23117).

Characterization of Carnobacterium divergens strain 6251 isolated from intestine of Arctic charr (Salvelinus alpinus L.).

An atypical strain of Carnobacterium divergens, strain 6251, was isolated from the small intestine of Arctic charr (Salvelinus alpinus L.), fed high dietary carbohydrate. This strain showed marked growth inhibitory effects in vitro against the fish pathogens Aeromonas salmonicida subsp. salmonicida (furunculosis), Vibrio anguillarum (vibriosis) and Vibrio viscocus (winter ulcer). The strain is a non-motile Gram-positive psychrotrophic rod that lacks both catalase and oxidase, grows at pH 9.1 (CTAS agar), but not on acetate containing media (pH < or = 5.4), on TCBS or at < or =6% sodium chloride content. Strain 6251 is facultatively anaerobic and utilises tryptone as a sole source of nutrient. Further characterisation showed the most abundant cellular fatty acid of strain 6251 to be oleic acid (18:1) (n-9) (36.0%). Sequencing of a 16S rDNA region of 578 nucleotides and AFLP microbial fingerprinting suggested that strain 6251 is not closely related to any carnobacteria known, however, DNA-DNA similarity determinations showed high similarity (96.2%) with the type strain of Carnobacterium divergens. The unique phenotypic attributes of this strain represent new information on the biodiversity and ecology of carnobacteria and especially of the species C. divergens.

Coryneform bacteria in throat cultures of healthy individuals.

Throat swabs from 113 healthy individuals from Hamburg, Germany, and Zurich, Switzerland, were investigated for coryneform bacteria with nonselective and selective media. Ninety specimens contained 123 strains. Surprisingly, 76% of them were strains of Corynebacterium durum (47%) and Rothia dentocariosa (29%). Only two were strains of Corynebacterium pseudodiphtheriticum, and none were strains of C. striatum, C. amycolatum, or C. diphtheriae.

Clostridium thermocellum JW20 (ATCC 31549) is a coculture with Thermoanaerobacter ethanolicus.

A PCR assay based on 16S rRNA sequence differences among four thermophilic anaerobic bacterial strains was used to demonstrate contamination of Clostridium thermocellum JW20 (ATCC 31549) with a Thermoanaerobacter ethanolicus strain. Therefore, we suggest that interpretation of experimental results with C. thermocellum JW20 be viewed with caution.

A novel thermostable dextranase from a Thermoanaerobacter species cultured from the geothermal waters of the Great Artesian Basin of Australia.

A Gram-negative sporulating thermophilic anaerobe, designated AB11Ad, was isolated from the heated waters of the Great Artesian Basin of Australia. It grew on a variety of carbohydrates including glucose, starch, and dextran and produced a thermostable and thermoactive extracellular endo-dextranase. The enzyme was produced more actively under pH controlled continuous culture conditions than under batch conditions. Ammonium sulfate precipitated crude dextranase exhibited a temperature optimum of 70 degrees C and a pH optimum between 5 and 6. The half life was approximately 6.5 h at 75 degrees C and 2 h at 80 degrees C at pH 5.0 and in the absence of added dextran. 16S rRNA sequence analysis indicated that isolate AB11Ad was a member of the genus Thermoanaerobacter.

Characterization of a new obligately anaerobic thermophile, Thermoanaerobacter wiegelii sp. nov.

An obligately anaerobic, extremely thermophilic Thermoanaerobacter species was isolated from a freshwater pool formed from a geothermally heated (56 to 69 degrees C) water outlet in Government Gardens, Rotorua, New Zealand. This organism was a spore-forming, gram-negative, rod-shaped bacterium. Strain Rt8.B1T (= DSM 10319T) (T = type strain) fermented a wide variety of mono-, di-, and polysaccharides and produced ethanol, acetate, lactate, propionate, and hydrogen. Sugar alcohols were also fermented, but organic acids and amino acids were not utilized. On the basis of its morphological characteristics, DNA G + C content, obligately anaerobic, thermophilic, polysaccharolytic nature, and levels of 16S rRNA sequence homology, we propose that strain Rt8.B1T should be classified in the genus Thermoanaerobacter as a new species, Thermoanaerobacter wiegelii.