Propionate-Degrading Bacterium, Syntrophobacter wolinii sp. nov. gen. nov., from Methanogenic Ecosystems

A new genus and species of a nonmotile gram-negative rod, Syntrophobacter wolinii, is the first bacterium described which degrades propionate only in coculture with an H₂-using organism and in the absence of light or exogenous electron acceptors such as O₂, sulfate, or nitrate. It was isolated from methanogenic enrichments from an anaerobic municipal sewage digestor, using anaerobic roll tubes containing a medium with propionate as the energy source in association with an H₂-using, sulfate-reducing Desulfovibrio sp. which cannot utilize fatty acids other than formate. S. wolinii produced acetate and, presumably, CO₂ and H₂ (or formate) from propionate. In media without sulfate and with Methanospirillum hungatei, a methanogen that uses only H₂-CO₂ or formate as an energy source, acetate, methane, and, presumably, CO₂ were produced from propionate and only small amounts of Desulfovibrio sp. were present. Isolation in coculture with the methanogen was not successful. S. wolinii does not use other saturated fatty acids as energy sources.     

Desulforhabdus amnigenus gen. nov. sp. nov., a sulfate reducer isolated from anaerobic granular sludge

From granular sludge of an upflow anaerobic sludge bed (UASB) reactor treating paper-mill wastewater, a sulfate-reducing bacterium (strain ASRB1) was isolated with acetate as sole carbon and energy source. The bacterium was rod-shaped, (1.4–1.9×2.5–3.4 μm), nonmotile, and gram-negative. Optimum growth with acetate occurred around 37°C in freshwater medium (doubling time: 3.5–5.0 days). The bacterium grew on a range of organic acids, such as acetate, propionate, and butyrate, and on alcohols, and grew autotrophically with H₂, CO₂ and sulfate. Fastest growth occurred with formate, propionate, and ethanol (doubling time: approx. 1.5 days). Strain ASRB1 clusters with the delta subdivision of Proteobacteria and is closely related toSyntrophobacter wolinii a syntrophic propionate oxidizer. Strain ASRB1 was characterized as a new genus and species:Desulforhabdus amnigenus.     

Carbon assimilation pathways in sulfate-reducing bacteria II. Enzymes of a reductive citric acid cycle in the autotrophic Desulfobacter hydrogenophilus

The strict anaerobe Desulfobacter hydrogenophilus is able to grow autotrophically with CO₂, H₂, and sulfate as sole carbon and energy sources. The generation time at 30°C under autotrophic conditions in a pure mineral medium was 15 h, the growth yield was 8 g cell dry mass per mol sulfate reduced to H₂S. Enzymes of the autotrophic CO₂ assimilation pathway were investigated. Key enzymes of the Calvin cycle and of the acetyl CoA pathway could not be found. All enzymes of a reductive citric acid cycle were present at specific activities sufficient to account for the observed growth rate. Notably, an ATP-citrate lyase (1.3 mol · min^-1 · mg cell protein^-1) was present both in autotrophically and in heterotrophically grown cells, which was rapidly inactivated in the absence of ATP. The data indicate that in D. hydrogenophilus a reductive citric acid cycle is operating in autotrophic CO₂ fixation. Since other autotrophic sulfate reducers possess an acetyl CoA pathway for CO₂ fixation, two different autotrophic pathways occur in the same physiological group.Dedicated to Prof. H. G. Wood on the occasion of his 80th birthday     

Syntrophomonas wolfei gen. nov. sp. nov., an Anaerobic, Syntrophic, Fatty Acid-Oxidizing Bacterium

An anaerobic, nonphototrophic bacterium that β-oxidizes saturated fatty acids (butyrate through octanoate) to acetate or acetate and propionate using protons as the electron acceptor (H₂ as electron sink product) was isolated in coculture with either a non-fatty acid-degrading, H₂-utilizing Desulfovibrio sp. or methanogens. Three strains of the bacterium were characterized and are described as a new genus and species, Syntrophomonas wolfei. S. wolfei is a gram-negative, slightly helical rod with round ends that possesses between two to eight flagella laterally inserted along the concave side of the cell. It has a multilayered cell wall of the gram-negative type. The presence of muramic acid, inhibition of growth by penicillin, and increased sensitivity of the cells to lysis after treatment with lysozyme indicate that peptidoglycan is present in the cell wall. Cells of S. wolfei contain poly-β-hydroxybutyrate. Isoheptanoate was degraded to acetate, isovalerate, and H₂. Carbohydrates, proteinaceous materials, alcohols, or other tested organic compounds do not support growth. Common electron acceptors are not utilized with butyrate as the electron donor. Growth and degradation of fatty acids occur only in syntrophic association with H₂-using bacteria. The most rapid generation time obtained by cocultures of S. wolfei with Desulfovibrio and Methanospirillum hungatei is 54 and 84 h, respectively. The addition of Casamino Acids but neither Trypticase nor yeast extract stimulated growth and resulted in a slight decrease in the generation time of S. wolfei cocultured with M. hungatei. The addition of H₂ to the medium stopped growth and butyrate degradation by S. wolfei.     

Desulfosporomusa polytropa gen. nov., sp. nov., a novel sulfate-reducing bacterium from sediments of an oligotrophic lake

Five strains of sulfate-reducing bacteria were isolated from the highest positive dilutions of a most probable number (MPN) series supplemented with lactate and inoculated with sediments from the oligotrophic Lake Stechlin. The isolates were endospore-forming and were motile by means of laterally inserted flagella. They stained Gram-negative and contained b-type cytochromes. CO difference spectra indicated the presence of P582 as a sulfite reductase. Phylogenetic analyses of the 16S rDNA sequences revealed that the isolates were very closely affiliated with the genus Sporomusa. However, sulfate and amorphous Fe(OH)₃, but not sulfite, elemental sulfur, MnO₂, or nitrate were used as terminal electron acceptors. Homoacetogenic growth was found with H₂/CO₂ gas mixture, formate, methanol, ethanol, and methoxylated aromatic compounds. The strains grew autotrophically with H₂ plus CO₂ in the presence or absence of sulfate. Formate, butyrate, several alcohols, organic acids, carbohydrates, some amino acids, choline, and betaine were also utilized as substrates. The growth yield with lactate and sulfate as substrate was 7.0 g dry mass/mol lactate and thus two times higher than in sulfate-free fermenting cultures. All isolates were able to grow in a temperature range of 4–37°C. Physiologically and by the presence of a Gram-negative cell wall, the new isolates resemble known Desulfosporosinus species. However, phylogenetically they are affiliated with the Gram-negative genus Sporomusa belonging to the Selenomonas subgroup of the Firmicutes. Therefore, the new isolates reveal a new phylogenetic lineage of sulfate-reducing bacteria. A new genus and species, Desulfosporomusa polytropa gen. nov., sp. nov. is proposed.Dedicated to Prof. H. G. Schlegel on the occasion of his 80th birthday.     

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.     

<Emphasis Type="Italic">Desulfovibrio legallis</Emphasis> sp. nov.: A Moderately Halophilic,Sulfate-Reducing Bacterium Isolated from a Wastewater Digestor in Tunisia

A new moderately halophilic sulfate-reducing bacterium (strain H₁^T) was enriched and isolated from a wastewater digestor in Tunisia. Cells were curved, motile rods (2–3 x 0.5 μm). Strain H₁^T grew at temperatures between 22 and 43°C (optimum 35°C), and at pH between 5.0 and 9.2 (optimum 7.3–7.5). Strain H₁^T required salt for growth (1–45 g of NaCl/l), with an optimum at 20–30 g/l. Sulfate, sulfite, thiosulfate, and elemental sulfur were used as terminal electron acceptors but not nitrate and nitrite. Strain H₁^T utilized lactate, pyruvate, succinate, fumarate, ethanol, and hydrogen (in the presence of acetate and CO₂) as electron donors in the presence of sulfate as electron acceptor. The main end-products from lactate oxidation were acetate with H₂ and CO₂. The G + C content of the genomic DNA was 55%. The predominant fatty acids of strain H₁^T were C_15:0 iso (38.8%), C_16:0 (19%), and C_14:0 iso 3OH (12.2%), and menaquinone MK-6 was the major respiratory quinone. Phylogenetic analysis of the small-subunit (SSU) ribosomal RNA (rRNA) gene sequence indicated that strain H₁^T was affiliated to the genus Desulfovibrio. On the basis of SSU rRNA gene sequence comparisons and physiological characteristics, strain H₁^T is proposed to be assigned to a novel species of sulfate reducers of the genus Desulfovibrio, Desulfovibrio legallis sp. nov. (= DSM 19129^T = CCUG 54389^T).     

Desulfacinum subterraneumsp. 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 m), nonmotile, non-spore-forming, and gram-negative. Growth occurs at 45 to 65°C (with an optimum at 60°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 101^T) and Desulfacinum infernum(strain BG1^T) is as low as 34%. Analysis of the nucleotide sequence of 16S rDNA places strain 101^Tin the phylogenetic cluster of the Desulfacinumspecies 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 subterraneumsp. nov., with strain 101 as the type strain.     

Carbon assimilation pathways in sulfate reducing bacteria. Formate,carbon dioxide,carbon monoxide,and acetate assimilation by Desulfovibrio baarsii

Desulfovibrio baarsii is a sulfate reducing bacterium, which can grown on formate plus sulfate as sole energy source and formate and CO₂ as sole carbon sources. It is shown by ¹⁴C labelling studies that more than 60% of the cell carbon is derived from CO₂ and the rest from formate. The cells thus grow autotrophically. Labelling studies with [¹⁴C]acetate, ¹⁴CO and [¹⁴C]formate indicate that CO₂ fixation does not proceed via the Calvin cycle. The labelling patterns of alanine, aspartate, glutamate, and glucosamine indicate that acetate (or activated acetic acid) is an early intermediate in formate and CO₂ assimilation; the methyl group of acetate is derived from formate, and the carboxyl group from CO₂ via CO; pyruvate is formed from acetyl-CoA by reductive carboxylation. The capacity to synthesize an acetate unit from two C₁-compounds obviously distinguishes D. baarsii from those Desulfovibrio species, which require acetate as a carbon source in addition to CO₂.     

Anaerobic degradation of phenol and phenol derivatives by Desulfobacterium phenolicum sp. nov.

A new sulfate-reducing bacterium was enriched and isolated from marine sediment with phenol as sole electron donor and carbon source. Strain Ph01 grew well in defined media without growth factors. Further aromatic compounds oxidized by strain Ph01 were benzoate, phenylacetate, 2-hydroxybenzoate, 4-hydroxybenzoate, 4-hydroxyphenylacetate, p-cresol, indole, anthranilic acid, and phenylalanine. Various fatty acids, alcohols and dicarboxylic acids were also utilized by strain Ph01. Sulfate and thiosulfate served as electron acceptors and were reduced to H₂S. Stoichiometric measurements with strain Ph01 showed complete oxidation of phenol to CO₂. Cytochromes and menaquinone MK-7(H₂) were present; desulfoviridin could not be detected. Strain Ph01 is described as type strain of the new species Desulfobacterium phenolicum.In further marine enrichments with 4-hydroxybenzoate, 4-hydroxyphenylacetate, p-cresol or o-cresol as substrates and sulfate as electron acceptor a variety of morphologically different sulfate-reducing bacteria developed. However, since the new isolate strain Ph01 was able to degrade all these aromatic compounds (except o-cresol) no further studies with the enrichment cultures were carried out.     

Characterization of Two Subsurface H2-Utilizing Bacteria, Desulfomicrobium hypogeium sp. nov. and Acetobacterium psammolithicum sp. nov., and Their Ecological Roles

We examined the relative roles of acetogenic and sulfate-reducing bacteria in H₂ consumption in a previously characterized subsurface sandstone ecosystem. Enrichment cultures originally inoculated with ground sandstone material obtained from a Cretaceous formation in central New Mexico were grown with hydrogen in a mineral medium supplemented with 0.02% yeast extract. Sulfate reduction and acetogenesis occurred in these cultures, and the two most abundant organisms carrying out the reactions were isolated. Based on 16S rRNA analysis data and on substrate utilization patterns, these organisms were named Desulfomicrobium hypogeium sp. nov. and Acetobacterium psammolithicum sp. nov. The steady-state H₂ concentrations measured in sandstone-sediment slurries (threshold concentration, 5 nM), in pure cultures of sulfate reducers (threshold concentration, 2 nM), and in pure cultures of acetogens (threshold concentrations 195 to 414 nM) suggest that sulfate reduction is the dominant terminal electron-accepting process in the ecosystem examined. In an experiment in which direct competition for H₂ between D. hypogeium and A. psammolithicum was examined, sulfate reduction was the dominant process.     

New types of acetate-oxidizing,sulfate-reducing Desulfobacter species,D. hydrogenophilus sp. nov., D. latus sp. nov., and D. curvatus sp. nov.

Sulfate-reducing bacteria with oval to rod-shaped cells (strains AcRS1, AcRS2) and vibrio-shaped cells (strains AcRM3, AcRM4, AcRM5) differing by size were isolated from anaerobic marine sediment with acetate as the only electron donor. A vibrio-shaped type (strain AcKo) was also isolated from freshwater sediment. Two strains (AcRS1, AcRM3) used ethanol and pyruvate in addition to acetate, and one strain (AcRS1) grew autotrophically with H₂, sulfate and CO₂. Higher fatty acids or lactate were never utilized. All isolates were able to grow in ammonia-free medium in the presence of N₂. Nitrogenase activity under such conditions was demonstrated by the acetylene reduction test. The facultatively lithoautotrophic strain (AcRS1), a strain (AcRS2) with unusually large cells (2×5 m), and a vibrio-shaped strain (AcRM3) are described as new Desulfobacter species, D. hydrogenophilus, D. latus, and D. curvatus, respectively.     

Novel Processes for Anaerobic Sulfate Production from Elemental Sulfur by Sulfate-Reducing Bacteria

Sulfate reducers and related organisms which had previously been found to reduce Fe(III) with H₂ or organic electron donors oxidized S⁰ to sulfate when Mn(IV) was provided as an electron acceptor. Organisms catalyzing this reaction in washed cell suspensions included Desulfovibrio desulfuricans, Desulfomicrobium baculatum, Desulfobacterium autotrophicum, Desulfuromonas acetoxidans, and Geobacter metallireducens. These organisms produced little or no sulfate from S⁰ with Fe(III) as a potential electron acceptor or in the absence of an electron acceptor. In detailed studies with Desulfovibrio desulfuricans, the stoichiometry of sulfate and Mn(II) production was consistent with the reaction S⁰ + 3 MnO₂ + 4H⁺→SO₄^2- + 3Mn(II) + 2H₂O. None of the organisms evaluated could be grown with S⁰ as the sole electron donor and Mn(IV) as the electron acceptor. In contrast to the other sulfate reducers evaluated, Desulfobulbus propionicus produced sulfate from S⁰ in the absence of an electron acceptor and Fe(III) oxide stimulated sulfate production. Sulfide also accumulated in the absence of Mn(IV) or Fe(III). The stoichiometry of sulfate and sulfide production indicated that Desulfobulbus propionicus disproportionates S⁰ as follows: 4S⁰ + 4H₂O→SO₄^2- + 3HS^- + 5 H⁺. Growth of Desulfobulbus propionicus with S⁰ as the electron donor and Fe(III) as a sulfide sink and/or electron acceptor was very slow. The S⁰ oxidation coupled to Mn(IV) reduction described here provides a potential explanation for the Mn(IV)-dependent sulfate production that previous studies have observed in anoxic marine sediments. Desulfobulbus propionicus is the first example of a pure culture known to disproportionate S⁰.     

Ruminococcus hydrogenotrophicus sp. nov., a new H2/CO2-utilizing acetogenic bacterium isolated from human feces

A new H₂/CO₂-utilizing acetogenic bacterium was isolated from the feces of a non-methane-excreting human subject. The two strains S5a33 and S5a36 were strictly anaerobic, gram-positive, non-sporulating coccobacilli. The isolates grew autotrophically by metabolizing H₂/CO₂ to form acetate as sole metabolite and were also able to grow heterotrophically on a variety of organic compounds. The major end product of glucose and fructose fermentation was acetate; the strains also formed ethanol, lactate and, to a lesser extent, isobutyrate and isovalerate. The G+C content of DNA of strain S5a33 was 45.2 mol%. 16S rRNA gene sequencing demonstrated that the two acetogenic isolates were phylogenetically identical and represent a new subline within Clostridium cluster XIVa. Based on phenotypic and phylogenetic considerations, a new species, Ruminococcus hydrogenotrophicus, is proposed. The type strain of R. hydrogenotrophicus is S5a33 (DSM 10507). Furthermore, H₂/CO₂ acetogenesis appeared to be a common property of most of the species phylogenetically closely related to strain S5a33 (Clostridium coccoides, Ruminococcus hansenii, and Ruminococcus productus). Received: 11 April 1996 / Accepted: 11 June 1996     

Anaerobic degradation of aniline and dihydroxybenzenes by newly isolated sulfate-reducing bacteria and description of Desulfobacterium anilini

A new, rod-shaped, Gram-negative, non-sporing sulfate reducer (strain Ani1) was enriched and isolated from marine sediment with aniline as sole electron donor and carbon source. The strain degraded aniline completely to CO2 and NH3 with stoichiometric reduction of sulfate to sulfide. Strain Ani1 also degraded aminobenzoates and further aromatic and aliphatic compounds. The strain grew in sulfide-reduced mineral medium supplemented only with vitamin B12 and thiamine. Cells contained cytochromes, carbon monoxide dehydrogenase, and sulfite reductase P582, but no desulfoviridin. Strain Ani1 is described as a new species of the genus Desulfobacterium D. anilini. Marine enrichments with the three dihydroxybenzene isomers led to three different strains of sulfate-reducing bacteria; each of them could grow only with the isomer used for enrichment. Two strains isolated with catechol (strain Cat2) or resorcinol (strain Re10) were studied in detail. Both strains oxidized their substrates completely to CO2, and contained cytochromes, carbon monoxide dehydrogenase, and sulfite reductase P 582. Desulfoviridin was not present. Whereas the rod-shaped catechol oxidizer (strain Cat2) was able to grow on 18 aromatic compounds and several aliphatic substrates, the coccoid resorcinol-degrading bacterium (strain Re10) utilized only resorcinol, 2,4-dihydroxybenzoate and 1,3-cyclohexanedion. These strains could not be affiliated with existing species of sulfate-reducing bacteria. A further coccoid sulfate-reducing bacterium (strain Hy5) was isolated with hydroquinone and identified as a subspecies of Desulfococcus multivorans. Most-probable-number enumerations with catechol, phenol, and resorcinol showed relatively large numbers (10(4)-10(6) per ml) of aryl compound-degrading sulfate reducers in marine sediment samples.     

Fructose degradation byDesulfovibrio sp. in pure culture and in coculture withMethanospirillum hungatei

In a mineral medium containing sulfate, the sulfate-reducing bacteriumDesulfovibrio sp. strain JJ degraded 1 mol of fructose stoichiometrically to 1 mol of H₂S, 2 mol of acetate, and presumably 2 mol of CO₂. The doubling time was 10 h, and the yield was 41.6 g dry weight/mol fructose degraded. In the absence of sulfate, the hydrogenophilic methanogenMethanospirillum hungatei replaced sulfate as hydrogen sink. In such cocultures, 1 mol of fructose was converted to acetate, methane, succinate, and presumably CO₂ in varying concentrations. The growth yield of the H₂-transferring association was 33 g dry weight/mol fructose. In the absence of sulfate,Desulfovibrio strain JJ slowly fermented 1 mol of fructose to 1 mol of succinate, 0.5 mol of acetate, and 0.5 mol of ethanol. The results are compared with those of other anaerobic hexose-degrading bacteria.     

Metabolism of 2,4,6-trinitrotoluene (TNT) by Desulfovibrio sp. (B strain)

A sulfate-reducing bacterium, Desulfovibrio sp. (B strain) isolated from an anaerobic reactor treating furfural-containing waste-water was studied for its ability to metabolize trinitrotoluene (TNT). The result showed that this isolate could transform 100 ppm TNT within 7 to 10 days of incubation at 37°C, when grown with 30 mm pyruvate as the primary carbon source and 20 mm sulfate as electron acceptor. Under these conditions, the main intermediate produced was 2,4-diamino-6-nitrotoluene. Under culture conditions where TNT served as the sole source of nitrogen for growth with pyruvate as electron donor and sulfate as electron acceptor, TNT was first converted to 2,4-diamino-6-nitrotoluene within 10 days of incubation. This intermediate was further converted to toluene by a reductive deamination process via triaminotoluene. Apart from pyruvate, various other carbon sources such as ethanol, lactate, formate and H₂ + CO₂ were also studied as potential electron donors for TNT metabolism. The rate of TNT biotransformation by Desulfovibrio sp. (B strain) was compared with other sulfate-reducing bacteria and the results were evaluated. This new strain may be useful in decontaminating TNT-contaminated soil and water under anaerobic conditions in conjunction with toluene-degrading denitrifiers (Pseudomonas spp.) or toluene-degrading sulfate reducers in a mixed culture system. Correspondence to: R. Boopathy     

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     

Immunological Cross-Reactivities of Adenosine-5′-Phosphosulfate Reductases from Sulfate-Reducing and Sulfide-Oxidizing Bacteria

Crude extracts from 14 species of sulfate-reducing bacteria comprising the genera Desulfovibrio, Desulfotomaculum, Desulfobulbus, and Desulfosarcina and from three species of sulfide-oxidizing bacteria were tested in an enzyme-linked immunosorbent assay with polyclonal antisera to adenosine 5′-phosphosulfate reductase from Desulfovibrio desulfuricans G100A. The results showed that extracts from Desulfovibrio species were all highly cross-reactive, whereas extracts from the other sulfate-reducing genera showed significantly less cross-reaction. An exception was Desulfotomaculum orientis, which responded more like Desulfovibrio species than the other Desulfotomaculum strains tested. Extracts from colorless or photosynthetic sulfur bacteria were either unreactive or exhibited very low levels of reactivity with the antibodies to the enzyme from sulfate reducers. These results were confirmed by using partially purified enzymes from sulfate reducers and the most cross-reactive sulfide oxidizer, Thiobacillus denitrificans. Two types of monoclonal antibodies to adenosine 5′-phosphosulfate reductase were also isolated. One type reacted more variably with the enzymes of the sulfate reducers and poorly with the Thiobacillus enzyme, whereas the second reacted strongly with Desulfovibrio, Desulfotomaculum orientis, and Thiobacillus enzymes.     

Fermentation of trihydroxybenzenes by Pelobacter acidigallici gen. nov. sp. nov., a new strictly anaerobic,non-sporeforming bacterium

Five strains of rod-shaped, Gram-negative, non-sporing, strictly anaerobic bacteria were isolated from limnic and marine mud samples with gallic acid or phloroglucinol as sole substrate. All strains grew in defined mineral media without any growth factors; marine isolates required salt concentrations higher than 1% for growth, two freshwater strains only thrived in freshwater medium. Gallic acid, pyrogallol, 2,4,6-trihydroxybenzoic acid, and phloroglucinol were the only substrates utilized and were fermented stoichiometrically to 3 mol acetate (and 1 mol CO₂) per mol with a growth yield of 10g cell dry weight per mol of substrate. Neither sulfate, sulfur, nor nitrate were reduced. The DNA base ratio was 51.8% guanine plus cytosine. A marine isolate, Ma Gal 2, is described as type strain of a new genus and species, Pelobacter acidigallici gen. nov. sp. nov., in the family Bacteroidaceae. In coculture with Acetobacterium woodii, the new isolates converted also syringic acid completely to acetate. Cocultures with Methanosarcina barkeri converted the respective substrates completely to methane and carbon dioxide.