The new facultatively chemolithoautotrophic, moderately halophilic, sulfate-reducing bacterium Desulfovermiculus halophilus gen. nov., sp. nov., isolated from an oil field

The new mesophilic, chemolithoautotrophic, moderately halophilic, sulfate-reducing bacterium strain 11-6 could grow at a NaCl concentration in the medium of 30-230 g/l, with an optimum at 80-100 g/l. Cells were vibrios motile at the early stages of growth. Lactate, pyruvate, malate, fumarate, succinate, propionate, butyrate, crotonate, ethanol, alanine, formate, and H2 + CO2 were used in sulfate reduction. Butyrate was degraded completely, without acetate accumulation. In butyrate-grown cells, a high activity of CO dehydrogenase was detected. Additional growth factors were not required. Autotrophic growth occurred, in the presence of sulfate, on H2 + CO2 or formate without other electron donors. Fermentation of pyruvate and fumarate was possible in the absence of sulfate. Apart from sulfate, sulfite, thiosulfate, and elemental sulfur were able to serve as electron acceptors. The optimal growth temperature was 37 degrees C; the optimum pH was 7.2. Desulfoviridin was not detected. Menaquinone MK-7 was present. The DNA G+C content was 55.2 mol %. Phylogenetically, the bacterium represented a separate branch within the cluster formed by representatives of the family Desulfohalobiaceae in the subclass Deltaproteobacteria. The bacterium was assigned to a new genus and species, Desulfovermiculus halophilus gen. nov., sp. nov. The type strain is 11-6T (= VKM B-2364), isolated from the highly mineralized formation water of an oil field.     

The new facultatively chemolithoautotrophic, moderately halophilic, sulfate-reducing bacterium Desulfovermiculus halophilus gen. nov., sp. nov., isolated from an oil field

The new mesophilic, chemolithoautotrophic, moderately halophilic, sulfate-reducing bacterium strain 11-6, could grow at a NaCl concentration in the medium of 30–230 g/l, with an optimum at 80–100 g/l. Cells were vibrios motile at the early stages of growth. Lactate, pyruvate, malate, fumarate, succinate, propionate, butyrate, crotonate, ethanol, alanine, formate, and H₂/CO₂ were used in sulfate reduction. Butyrate was degraded completely, without acetate accumulation. In butyrate-grown cells, a high activity of CO dehydrogenase was detected. Additional growth factors were not required. Autotrophic growth occurred, in the presence of sulfate, on H₂/CO₂ or formate without other electron donors. Fermentation of pyruvate and fumarate was possible in the absence of sulfate. Apart from sulfate, sulfite, thiosulfate, and elemental sulfur were able to serve as electron acceptors. The optimal growth temperature was 37°C; the optimum pH was 7.2. Desulfoviridin was not detected. Menaquinone MK-7 was present. The DNA G+C content was 55.2 mol %. Phylogenetically, the bacterium represented a separate branch within the cluster formed by representatives of the family Desulfohalobiaceae in the class Deltaproteobacteria. The bacterium was assigned to a new genus and species, Desulfovermiculus halophilus gen. nov., sp. nov. The type strain is 11-6^T (= VKM B-2364), isolated from the highly mineralized formation water of an oil field.     

Thiorhodococcus minus, gen. nov., sp. nov., a new purple sulfur bacterium isolated from coastal lagoon sediments

A new marine phototrophic purple sulfur bacterium (strain CE2203) was isolated in pure culture from a man-made coastal lagoon located on the Atlantic coast (Arcachon Bay, France). Single cells were coccus-shaped, did not contain gas vesicles, and were highly motile. Intracellular photosynthetic membranes were of the vesicular type. Bacteriochlorophyll a and carotenoids of the normal spirilloxanthin series were present as photosynthetic pigments. Hydrogen sulfide, thiosulfate, elemental sulfur, and molecular hydrogen were used as electron donors during photolithotrophic growth under anoxic conditions, while carbon dioxide was utilized as carbon source. Acetate, propionate, lactate, glycolate, pyruvate, fumarate, succinate, fructose, sucrose, ethanol, and propanol were photoassimilated in the presence of hydrogen sulfide. During growth on sulfide, elemental sulfur globules were stored inside the cells. Chemotrophic growth under microoxic conditions in the dark was possible. The DNA base composition was 66.9 mol% G+C. Comparative sequence analysis of the 16S rRNA gene confirmed the membership of strain CE2203 in the family Chromatiaceae. Morphological characteristics of strain CE2203 indicated a close affiliation to the genera Thiocystis and Thiocapsa. However, the phylogenetic treeing revealed no closer relationship to Thiocystis spp. than to Thiocapsa roseopersicina or other known members of the Chromatiaceae. Consequently, strain CE2203 is proposed as the type strain of a new genus and species, Thiorhodococcus minus gen. nov., sp. nov. Received: 23 December 1996 / Accepted: 27 March 1997     

A new 3-hydroxybutyrate fermenting anaerobe,Ilyobacter polytropus,gen. nov. sp. nov., possessing various fermentation pathways

From marine anoxic mud, a new strictly anaerobic, Gram-negative, non-sporeforming bacterium was isolated with 3-hydroxybutyrate as substrate. 3-Hydroxybutyrate and crotonate were fermented to acetate and butyrate. Glycerol was fermented to 1,3-propanediol and 3-hydroxypropionate. Acetate and formate were the only products of pyruvate or citrate fermentation. Glucose and fructose were fermented to acetate, formate and ethanol. Malate and fumarate were fermented to acetate, formate and propionate. Neither sulfate, sulfur, nor nitrate was reduced. The DNA base ratio was 32.2±0.5 mol% guanine plus cytosine. Strain CuHbu1 is described as type strain of a new genus and species, Ilyobacter polytropus gen. nov. sp. nov., in the family Bacteroidaceae.     

Ectothiorhodospira marismortui sp. nov., an obligately anaerobic,moderately halophilic purple sulfur bacterium from a hypersaline sulfur spring on the shore of the Dead Sea

A novel type of purple sulfur bacterium was isolated from a hypersaline sulfur spring on the shore of the Dead Sea. The cells of the isolate are irregularly rod-shaped or curved, and motile by means of a tuft of polar flagella. The photosynthetic system, containing bacteriochlorophyll a and carotenoids of the spirilloxanthin series, is located on stacks of lamellar membranes in the cell cytoplasm. The organism can grow either photoautotrophically with sulfide as electron donor, which is oxidized via extracellular sulfur to sulfate, or photoheterotrophically, using acetate, succinate, fumarate, malate or pyruvate as carbon sources. The bacterium is obligately anaerobic, and requires a source of reduced sulfur for growth. The isolate is moderately halophilic, and grows optimally at NaCl concentrations between 3 and 8%, temperatures between 30 and 45°C, and neutral pH. 16S ribosomal RNA oligonucleotide cataloging suggests a close relationship to purple sulfur bacteria of the genus Ectothiorhodospira. As the isolate differs greatly from the described members of the genus Ectothiorhodospira, we describe the isolate as a new species, and propose the name Ectothiorhodospira marismortui sp. nov.     

Characterization of a new platelet-forming purple sulfur bacterium,Amoebobacter pedioformis sp. nov.

The dominant purple sulfur bacterium of a reddish-colored waste water pond near Taichung, Taiwan, was isolated in pure culture, strain CML2. Individual cells were nearly spherical, nonmotile, and contained in their peripheral parts was vacuoles that appeared like elongated, curved tubes. Four to sixteen cells formed platelet-like aggregates reminiscent of Thiopedia rosea. The intracellular photosynthetic membrane system of the cells was of vesicular type; the photosynthetic pigments consisted of bacteriochlorophyll a and spirilloxanthin as the major carotenoid. The color of cell suspensions was pink to rosered. Under anaerobic conditions photolithoautotrophic growth occurred with sulfide, elemental sulfur or thiosulfate; sulfur globules were stored as an intermediary oxidation product. In the presence of sulfide, acetate, lactate and pyruvate were photoassimilated; strain CML2 lacked assimilatory sulfate reduction. Fastest photoautotrophic growth (11 h doubling time) was obtained at pH 7.5, 35°C and a light intensity of about 1000 lux (tungsten lamp). Chemolithoautotrophic growth in the dark was possible under reduced oxygen partial pressure with reduced sulfur compounds as respiratory substrates. The DNA base composition of strain CML2 was 65.5 mol% G+C. Strain CML2 is described as type strain of a new species, Amoebobacter pedioformis sp. nov., in the family Chromatiaceae.     

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     

<Emphasis Type="Italic">Desulfurispirillum alkaliphilum</Emphasis> gen. nov. sp. nov., a novel obligately anaerobic sulfur- and dissimilatory nitrate-reducing bacterium from a full-scale sulfide-removing bioreactor

Strain SR 1^T was isolated under anaerobic conditions using elemental sulfur as electron acceptor and acetate as carbon and energy source from the Thiopaq bioreactor in Eerbeek (The Netherlands), which is removing H₂S from biogas by oxidation to elemental sulfur under oxygen-limiting and moderately haloalkaline conditions. The bacterium is obligately anaerobic, using elemental sulfur, nitrate and fumarate as electron acceptors. Elemental sulfur is reduced to sulfide through intermediate polysulfide, while nitrate is dissimilatory reduced to ammonium. Furthermore, in the presence of nitrate, strain SR 1^T was able to oxidize limited amounts of sulfide to elemental sulfur during anaerobic growth with acetate. The new isolate is mesophilic and belongs to moderate haloalkaliphiles, with a pH range for growth (on acetate and nitrate) from 7.5 to 10.25 (optimum 9.0), and a salt range from 0.1 to 2.5 M Na⁺ (optimum 0.4 M). According to phylogenetic analysis, SR 1^T is a member of a deep bacterial lineage, distantly related to Chrysiogenes arsenatis (Macy et al. 1996). On the basis of the phenotypic and genetic data, the novel isolate is placed into a new genus and species, Desulfurispirillum alkaliphilum (type strain SR^T = DSM 18275 = UNIQEM U250). Nucleotide sequence accession number: the GenBank/EMBL accession number of the 16S rRNA gene sequence of strain SR 1^T is DQ666683.     

Disproportionation of inorganic sulfur compounds by the sulfate-reducing bacterium Desulfocapsa thiozymogenes gen. nov., sp. nov.

A new strictly anaerobic, gram-negative bacterium was isolated from the sediment of a freshwater lake after enrichment with thiosulfate as the energy source. The strain, named Bra2 (DSM 7269), is able to grow by disproportionation of thiosulfate or sulfite to sulfate plus sulfide. Elemental sulfur is also disproportionated to sulfate and sulfide, but this only supports growth if free sulfide is chemically removed from the culture, e.g., by precipitation with amorphous ferric hydroxide. Growth is also possible by coupling the reduction of sulfate to sulfide with the oxidation of ethanol, propanol, or butanol to the corresponding fatty acid. The cells are rod-shaped, motile, and have genomic DNA with a mol% G+C content of 50.7. Cytochromes are present, but desulfoviridin is not. The new strain was shown to be related to, but distinct from members of the genus Desulfobulbus on the basis of physiological characteristics and by comparative sequence analysis of its 16S rDNA. Strain Bra2 is described as the type strain of a new taxon, Desulfocapsa thiozymogenes gen. nov., sp. nov. Received: 29 January 1996 / Accepted: 31 May 1996     

A new purple sulfur bacterium from saline littoral sediments,Thiorhodovibrio winogradskyi gen. nov. and sp. nov.

Two strains of a new purple sulfur bacterium were isolated in pure culture from the littoral sediment of a saline lake (Mahoney Lake, Canada) and a marine microbial mat from the North Sea island of Mellum, respectively. Single cells were vibrioid-to spirilloid-shaped and motile by means of single polar flagella. Intracellular photosynthetic membranes were of the vesicular type. As photosynthetic pigments, bacteriochlorophyll a and the carotenoids lycopene, rhodopin, anhydrorhodovibrin, rhodovibrin and spirilloxanthin were present.Hydrogen sulfide and elemental sulfur were used under anoxic conditions for phototrophic growth. In addition one strain (06511) used thiosulfate. Carbon dioxide, acetate and pyruvate were utilized by both strains as carbon sources. Depending on the strain propionate, succinate, fumarate, malate, tartrate, malonate, glycerol or peptone may additionally serve as carbon sources in the light. Optimum growth rates were obtained at pH 7.2, 33 °C, 50 mol m^-2 s^-1 intensity of daylight fluorescent tubes and a salinity of 2.2–3.2% NaCl. During growth on sulfide, up to ten small sulfur globules were formed inside the cells. The strains grew microaerophilic in the dark and exhibited high specific respiration rates. No vitamins were required for growth. The DNA base composition was 61.0–62.4 mol% G+C.The newly isolated bacterium belongs to the family chromatiaceae and is described as a member of a new genus and species, Thiorhodovibrio winogradskyi gen. nov. and sp. nov. with the type strain SSP1, DSM No. 6702.     

Beneckea gazogenes sp. nov., a red,facultatively anaerobic,marine bacterium

A red, facultatively anaerobic marine bacterium was isolated from samples of saltwater marsh mud. The Gram-negative microorganism was rod-shaped and possessed a single sheathed polar flagellum. The red pigment that the cells produced was identified as prodigiosin. THe bacteria grew readily on synthetic seawater media containing carbohydrates, amino acids, organic acids, or tricarboxylic acid cycle intermediates as sole sources of carbon and energy. Na⁺ was required for growth. Cells fermented glucose to CO₂, H₂, ethanol, acetate, succinate, and pyruvate. The guanine-plus-cytosine content of the strain’s DNA was 47.1 mole%. The morphological and physiological characteristics of this bacterium, together with the mole % G+C of its DNA, place it in the genusBeneckea. The main features of this strain are sufficiently different from previously described members of the genus to place it in a new species for which the nameBeneckea gazogenes is proposed.     

Fermentation of cinnamate by a mesophilic strict anaerobe,Acetivibrio multivorans sp. nov.

A cinnamate-fermenting bacterium (strain PeC1) was isolated in pure culture from anoxic sludge of an oil refinery wastewater treatment facility. It was a mesophilic gram-negative non-sporing actively motile rod. It did not reduce nitrate, sulfte, or other sulfur compounds as electron acceptors. It fermented cinnamate to 3-phenylpropionate, benzoate, and acetate; crotonate to butyrate and acetate; pyruvate to lactate and acetate; acetoin to ethanol and acetate; and carbohydrates to ethanol, formate, and acetate. The DNA base ratio of the strain was 44 mol% guanine plus cytosine. It is described as a new species of the genus Acetivibrio, A. multivorans sp. nov.     

Ectothiorhodosinus mongolicum gen. nov., sp. nov., a New Purple Bacterium from a Soda Lake in Mongolia

A new nonmotile purple sulfur bacterium (strain M9) was isolated from the steppe soda lake Lake Dzun Uldziin Nur (pH 9.4; mineralization, 3.3%) situated in southeastern Mongolia. Individual cells appear as vibrios 0.3–0.5 × 0.7–1 m in size. The dividing cells often do not separate from each other, forming an almost closed ring. The internal photosynthetic membranes are represented by concentric lamellae lining the cell wall. Photosynthetic pigments are bacteriochlorophyll a and carotenoids of the spirilloxanthin series. The main carotenoid (>96%) is spirilloxanthin. Two typical light-harvesting complexes (LH1 and LH2) are present in the membranes in a 1 : 1 ratio. The bacterium is an anaerobe and facultative photoorganoheterotroph. Photolithoautotrophic growth on sulfide is scarce. Thiosulfate is utilized as an electron donor only in the presence of organic matter. Globules of elemental sulfur are formed as an intermediary product of sulfide and thiosulfate oxidation and are deposited outside the cells. The end product of oxidation is sulfate. In the presence of sulfide and carbonates, acetate, lactate, malate, pyruvate, propionate, succinate, and fumarate are used as additional sources of carbon in anoxygenic photosynthesis. Vitamins are not required. The bacterium is an alkaliphile, the pH optimum is at 8.3–9.1, the pH range is 7.6–10.1. The optimum NaCl concentration in the medium is 1 to 7%; the range is 0.5 to 0.9%. The optimum carbonate content in the medium is 2%; the range is 1 to 10%. The best growth occurs at 30–35°C. The DNA G+C content is 57.5 mol %. According to the results of analysis of the 16S rRNA gene sequences, the new isolate M9 belongs to the phylogenetic cluster containing representatives of the family Ectothiorhodospiraceae within the class Gammaproteobacteria. In this class, the new isolate forms a new branch, which occupies an intermediate position between the representatives of the genera Ectothiorhodospira and Thiorhodospira. Based on the phenotypic and genetic characteristics, the new purple sulfur bacterium was assigned to a new species of a new genus of the family Ectothiorhodospiraceae, Ectothiorhodosinus mongolicum gen. nov., sp. nov.     

Description of Desulfotomaculum nigrificans subsp. salinus as a new species, Desulfotomaculum salinum sp. nov

This study focused on the physiological, chemotaxonomic, and genotypic characteristics of two thermophilic spore-forming sulfate-reducing bacterial strains, 435T and 781, of which the former has previously been assigned to the subspecies Desulfotomaculum nigrificans subsp. salinus. Both strains reduced sulfate with the resulting production of H2S on media supplemented with H2 + CO2, formate, lactate, pyruvate, malate, fumarate, succinate, methanol, ethanol, propanol, butanol, butyrate, valerate, or palmitate. Lactate oxidation resulted in acetate accumulation; butyrate was oxidized completely, with acetate as an intermediate product. Growth on acetate was slow and weak. Sulfate, sulfite, thiosulfate, and elemental sulfur, but not nitrate, served as electron acceptors for growth with lactate. The bacteria performed dismutation of thiosulfate to sulfate and hydrogen sulfide. In the absence of sulfate, pyruvate but not lactate was fermented. Cytochromes of b and c types were present. The temperature and pH optima for both strains were 60-65 degrees C and pH 7.0. Bacteria grew at 0 to 4.5-6.0% NaCl in the medium, with the optimum being at 0.5-1.0%. Phylogenetic analysis based on a comparison of incomplete 16S rRNA sequences revealed that both strains belonged to the C cluster of the genus Desulfotomaculum, exhibiting 95.5-98.3% homology with the previously described species. The level of DNA-DNA hybridization of strains 435T and 781 with each other was 97%, while that with closely related species D. kuznetsovii 17T was 51-52%. Based on the phenotypic and genotypic properties of strains 435T and 781, it is suggested that they be assigned to a new species: Desulfotomaculum salinum sp. nov., comb. nov. (type strain 435T = VKM B 1492T).     

Desulfacinum subterraneum sp.nov.--a new thermophilic sulfate-reducing bacterium isolated from a high temperature oil field

A new thermophilic sulfate-reducing bacterium isolated from the high-temperature White Tiger oil field (Vietnam) is described. Cells of the bacterium are oval (0.4-0.6 by 0.6-1.8 microns), nonmotile, non-spore-forming, and gram-negative. Growth occurs at 45 to 65 degrees C (with an optimum at 60 degrees C) at NaCl concentrations of 0 to 50 g/l. In the course of sulfate reduction, the organism can utilize lactate, pyruvate, malate, fumarate, ethanol, salts of fatty acids (formate, acetate, propionate, butyrate, caproate, palmitate), yeast extract, alanine, serine, cysteine, and H2 + CO2 (autotrophically). In addition to sulfate, the bacterium can use sulfite, thiosulfate, and elemental sulfur as electron acceptors. In the absence of electron acceptors, the bacterium can ferment pyruvate and yeast extract (a yet unrecognized capacity of sulfate reducers) with the formation of acetate and H2. The G + C content of DNA is 60.8 mol %. The level of DNA-DNA hybridization of the isolate (strain 101T) and Desulfacinum infernum (strain B alpha G1T) is as low as 34%. Analysis of the nucleotide sequence of 16S rDNA places strain 101T in the phylogenetic cluster of the Desulfacinum species within the sulfate reducer subdivision of the delta subclass of Proteobacteria. All these results allowed the bacterium studied to be described as a new species, Desulfacinum subterraneum sp. nov., with strain 101 as the type strain.     

Rhabdochromatium marinum gen. nom. rev., sp. nov., a purple sulfur bacterium from a salt marsh microbial mat

A new purple sulfur bacterium was isolated in pure culture (strain 8315) from a laminated microbial mat at Great Sippewissett Salt Marsh, Cape Cod, Mass., USA. Single cells were large rods, 10–20 times longer than wide, and predominantly strainght with slightly conical ends. Cells were motile by polarly inserted flagellar tufts. Intracellular photosynthetic membranes were of the vesicular-type. Photosynthetic pigments were bacteriochlorophylla and the carotenoids lycopene, rhodovibrin, anhydrorhodovibrin, and rhodopin. The new bacterium was strictly anaerobic and obligately phototrophic. Hydrogen, hydrogen sulfide, elemental sulfur, and thiosulfate were used as electron donors for photoautotrophic growth. In sulfide-reduced, bicarbonate-containing media, acetate, propionate, and pyruvate were photoassimilated. Growth factors were not required. Optimum growth rates were obtained at pH 7.3, 30°C, a salinity of 1.5–5.0% NaCl, and a light intensity of about 500 lx (tungsten lamp). The DNA base composition of strain 8315 was 60.4 mol% G+C. Comparison of 16S rDNA oligonucleotide catalogue data showed that the new bacterium must be considered a new genus of the Chromatiaceae. The nameRhabdochromatium is revived, and the new speciesRhabdochromatium marinum sp. nov. is described.     

Anaerobic degradation of indolic compounds by sulfate-reducing enrichment cultures,and description of Desulfobacterium indolicum gen. nov., sp. nov.

Indole (1.5 mmol/l) added to suflate-rich marine mud or sulfate-free sewage digestor sludge was anaerobically degraded within one week. Enrichments from sludge samples in defined indole-containing media with or without sulfate were selective for sulfate-reducing bacteria or mixed methanogenic associations, respectively. Other enrichments of sulfate-reducing bacteria were obtained with skatole, indoleacetate, indolepropionate, quinoline, and pyridine. From a marine enrichment with indole as sole electron donor and carbon source, an oval to rod-shaped, Gram-negative, nonsporing sulfate-reducing bacterium (strain In04) was isolated. Growth occurred in defined bicarbonate-buffered, sulfide-reduced media supplemented with vitamin B₁₂. Furthen aromatic compounds utilized as electron donors and carbon sources were anthranilic acid and quinoline. Nonaromatic compounds used as substrates were formate, acetate, propionate, ethanol, propanol, butanol, pyruvate, malate, fumarate, and succinate. However, growth with substrates other than indole was rather slow. Thiosulfate served as an alternative electron acceptor. Complete oxidation of indole to CO₂ was shown by stoichiometric measurements in batch culture with sulfate as electron acceptor. An average growth yield of 31.3 g cell dry weight was obtained per mol of indole oxidized. Pigment analysis revealed that cytochromes and menaquinone MK-7 (H₂) were present. Desulfoviridin could not be detected. Strain In04 is described as new species of the new genus Desulfobacterium indolicum.     

Desulfurispira natronophila gen. nov. sp. nov.: an obligately anaerobic dissimilatory sulfur-reducing bacterium from soda lakes

Anaerobic enrichment cultures with elemental sulfur as electron acceptor and either acetate or propionate as electron donor and carbon source at pH 10 and moderate salinity inoculated with sediments from soda lakes in Kulunda Steppe (Altai, Russia) resulted in the isolation of two novel members of the bacterial phylum Chrysiogenetes. The isolates, AHT11 and AHT19, represent the first specialized obligate anaerobic dissimilatory sulfur respirers from soda lakes. They use either elemental sulfur/polysulfide or arsenate as electron acceptor and a few simple organic compounds as electron donor and carbon source. Elemental sulfur is reduced to sulfide through intermediate polysulfide, while arsenate is reduced to arsenite. The bacteria belong to the obligate haloalkaliphiles, with a pH growth optimum from 10 to 10.2 and a salt range from 0.2 to 3.0 M Na⁺ (optimum 0.4–0.6 M). According to the phylogenetic analysis, the two strains were close to each other, but distinct from the nearest relative, the haloalkaliphilic sulfur-reducing bacterium Desulfurispirillum alkaliphilum, which was isolated from a bioreactor. On the basis of distinct phenotype and phylogeny, the soda lake isolates are proposed as a new genus and species, Desulfurispira natronophila (type strain AHT11^T = DSM22071^T = UNIQEM U758^T).     

Complete oxidation of catechol by the strictly anaerobic sulfate-reducing Desulfobacterium catecholicum sp. nov.

From an anaerobic enrichment culture with vanillate as substrate, a catechol-degrading lemon-shaped nonsporing sulfate-reducing bacterium, strain NZva20, was isolated in pure culture. Growth occurred in defined, bicarbonate-buffered, sulfide-reduced freshwater medium with catechol as sole electron donor and carbon source. Catechol was completely oxidized to CO₂ with an average growth yield of 31 g cell dry mass per mol of catechol, corresponding to 9.5 g cell dry mass per mol of sulfate reduced. Further substrates utilized as electron donors and carbon sources were resorcinol, hydroquinone, benzoate and several other aromatic compounds, hydrogen plus carbon dioxide, formate, lactate, pyruvate, alcohols including methanol, dicarboxylic acids, acetate, propionate and higher fatty acids up to 18 carbon atoms. Instead of sulfate, sulfite, thiosulfate, dithionite or nitrate served as electron acceptors. Nitrate was reduced to ammonium. Strain NZva20 is the first bacterium in which the complete oxidation of organic substrates is linked to the ammonification of nitrate. Elemental sulfur was not utilized as electron acceptor. In the absence of an electron acceptor slow growth occurred on pyruvate or fumarate. The G+C content of the DNA of strain NZva20 was 52.4 mol%. Cytochromes were present. Desulfoviridin could not be detected. Strain NZva20 is described as type strain of a new species, Desulfobacterium catecholicum sp. nov.Affectionately dedicated to Professor Ralph S. Wolfe on the occassion of his 65th birthday     

Fermentation of 2,3-butanediol by Pelobacter carbinolicus sp. nov. and Pelobacter propionicus sp. nov., and evidence for propionate formation from C2 compounds

From anaerobic enrichments with 2,3-butanediol as sole substrate pure cultures of new Gram-negative, strictly anaerobic, non-sporeforming bacteria were isolated. Similar isolates were obtained with acetoin as substrate. From marine muds in saltwater medium a short rod (strain Gra Bd 1) was isolated which fermented butanediol, acetoin and ethylene glycol to acetate and ethanol. The DNA base ratio of this strain was 52.3 mol% guanine plus cytosine.From freshwater sediments and sewage sludge, a different type of short rod (strain Ott Bd 1) was isolated in freshwater medium, which fermented butanediol, acetoin, ethanol, lactate and pyruvate stoichiometrically to acetate and propionate. Propanol and butanol were oxidized to the respective fatty acids with concomitant reduction of acetate and bicarbonate to propionate. The DNA base ratio of strain Ott Bd 1 was 57.4 mol% guanine plus cytosine. No other substrates were used by the isolates, and no other products could be detected. In cocultures with Acetobacterium woodii or Methanospirillum hungatei, strain Gra Bd 1 also grew on ethanol, propanol, and butanol by fermenting these alcohols to the respective fatty acids and molecular hydrogen. Cytochromes could not be detected in any of the new isolates. Since both types of bacteria can not be affiliated to any of the existing genera and species, the new species Pelobacter carbinolicus and Pelobacter propionicus are proposed. The mechanism of butanediol degradation and propionate formation from acetate as well as the ecological importance of both processes are discussed.