Growth, natural relationships, cellular fatty acids and metabolic adaptation of sulfate-reducing bacteria that utilize long-chain alkanes under anoxic conditions

Natural relationships, improvement of anaerobic growth on hydrocarbons, and properties that may provide clues to an understanding of oxygen-independent alkane metabolism were studied with two mesophilic sulfate-reducing bacteria, strains Hxd3 and Pnd3. Strain Hxd3 had been formerly isolated from an oil tank; strain Pnd3 was isolated from marine sediment. Strains Hxd3 and Pnd3 grew under strictly anoxic conditions on n-alkanes in the range of C₁₂–C₂₀ and C₁₄–C₁₇, respectively, reducing sulfate to sulfide. Both strains shared 90% 16 S rRNA sequence similarity and clustered with classified species of completely oxidizing, sulfate-reducing bacteria within the δ-subclass of Proteobacteria. Anaerobic growth on alkanes was stimulated by α-cyclodextrin, which served as a non-degradable carrier for the hydrophobic substrate. Cells of strain Hxd3 grown on hydrocarbons and α-cyclodextrin were used to study the composition of cellular fatty acids and in vivo activities. When strain Hxd3 was grown on hexadecane (C₁₆H₃₄), cellular fatty acids with C-odd chains were dominant. Vice versa, cultures grown on heptadecane (C₁₇H₃₆) contained mainly fatty acids with C-even chains. In contrast, during growth on 1-alkenes or fatty acids, a C-even substrate yielded C-even fatty acids, and a C-odd substrate yielded C-odd fatty acids. These results suggest that anaerobic degradation of alkanes by strain Hxd3 does not occur via a desaturation to the corresponding 1-alkenes, a hypothetical reaction formerly discussed in the literature. Rather an alteration of the carbon chain by a C-odd carbon unit is likely to occur during activation; one hypothetical reaction is a terminal addition of a C₁ unit. In contrast, fatty acid analyses of strain Pnd3 after growth on alkanes did not indicate an alteration of the carbon chain by a C-odd carbon unit, suggesting that the initial reaction differed from that in strain Hxd3. When hexadecane-grown cells of strain Hxd3 were resuspended in medium with 1-hexadecene, an adaptation period of 2 days was observed. Also this result is not in favor of an anaerobic alkane degradation via the corresponding 1-alkene. Received: 25 June 1998 / Accepted: 29 July 1998     

Brain Phospholipids as Dietary Source of (n-3) Polyunsaturated Fatty Acids for Nervous Tissue in the Rat

Abstract: In a previous work, we calculated the dietary α-linolenic requirements (from vegetable oil triglycerides) for obtaining and maintaining a physiological level of (n-3) fatty acids in developing animal membranes as determined by the cervonic acid content [22:6(n-3), docosahexaenoic acid]. The aim of the present study was to measure the phospholipid requirement, as these compounds directly provide the very long polyunsaturated fatty acids found in membranes. Two weeks before mating, eight groups of female rats (previously fed peanut oil deficient in α-linolenic acid) were fed different semisynthetic diets containing 6% African peanut oil supplemented with different quantities of phospholipids obtained from bovine brain lipid extract, so as to add (n-3) polyunsaturated fatty acids to the diet. An additional group was fed peanut oil with rapeseed oil, and served as control. Pups were fed the same diet as their respective mothers, and were killed at weaning. Forebrain, sciatic nerve, retina, nerve endings, myelin, and liver were analyzed. We conclude that during the combined maternal and perinatal period, the (n-3) fatty acid requirement for adequate deposition of (n-3) polyunsaturated fatty acids in the nervous tissue (and in liver) of pups is lower if animals are fed (n-3) very long chain polyunsaturated fatty acids found in brain phospholipids [this study, ˜60 mg of (n-3) fatty acids/100 g of diet, i.e., ˜130 mg/1,000 kcal] rather than α-linolenic acid from vegetable oil triglycerides [200 mg of (n-3) fatty acids/100 g of diet, i.e., ˜440 mg/1,000 kcal].     

Anaerobic bacteria from the digestive tract of North Atlantic fin whales (Balaenoptera physalus)

Abstract Samples were collected from the forestomach and colon of North Atlantic fin whales ( Balaenoptera physalus ) landed at the commercial whaling station at Hvalfjördur, Iceland during three whaling seasons. Techniques were used to enrich for and enumerate anaerobic bacteria, methanogens, and sulfate reducers. Anaerobic bacteria ranged from 10⁸ to 10¹⁰ per ml of digesta in the colon, and from 10⁵ to 10⁹ per ml of digesta in the forestomach. Methanogens and sulfate-reducing bacteria were found in the majority of forestomach and colon samples, with sulfate-reducing bacteria usually occuring at higher concentrations. Enteric bacteria, Vibrio , and Listonella spp. were found in the colon. Volatile fatty acids were detected in significant concentrations in the forestomach of many of the whales. These results support previous findings which suggest that a microbial fermentation occurs in the forestomach of baleen whales.     

Effect of Fish Oil Diet on Fatty Acid Composition of Phospholipids of Brain Membranes and on Kinetic Properties of Na+, K+-ATPase Isoenzymes of Weaned and Adult Rats

Abstract: The influence of dietary (n-3) fatty acids (such as eicosapentaenoic and docosahexaenoic acids) as found in fish oil on Na⁺ sensitivity and ouabain affinity of Na⁺, K⁺-ATPase isoenzymes (α1, α2, α3) was studied in whole brain membranes from weaned and adult rats fed diets for two generations. The long chain (n-3) fatty acids supplied by fish oil decreased the fatty acids of the (n-6) series compared with the standard diet, resulting in a decrease in the (n-6)/(n-3) molar ratio in both 21 - and 60-day- old rats. On the basis of ouabain titration, three inhibitory processes with markedly different affinities were associated with isoenzymes, i.e., low affinity (α1), high affinity (α2), and very high affinity (α3). It appears that the fish oil diet, in part via the modification of membrane fatty acid composition, altered the proportion and ouabain affinity of isoenzymes. Na⁺ sensitivity is the best criterion of physiologic change induced by fish oil diet. We calculated the Na⁺ activation for each isoenzyme and found one Na⁺ sensitivity and two Na⁺ sensitivities per isoenzyme in weanling and adult rats fed different diets, respectively. In contrast to α2 and α3, α1 appears insensitive to membrane change induced by fish oil diet. Fish oil diet, which is known to confer cardioprotection, induced significant modulation of Na⁺, K⁺-ATPase isoenzymes at the brain level.     

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.     

In situ stimulation of bacterial sulfate reduction in sulfate-limited freshwater lake sediments

Abstract By adding sulfate in the form of solid gypsum, it was possible to transform in situ a predominantly methanogenic sediment ecosystem into a sulfate-reducing one. The concentrations of sulfate, sulfide, methane, acetate, propionate, soluble iron, and manganese were determined in the porewater before and after the transition. Although sulfate was no longer limiting, acetate and propionate continued to accumulate and reached much higher concentrations than under sulfate-limited conditions. Metabolic activities of fermenting bacteria and of sulfate reducers, which belong to the group that incompletely oxidizes organic material, might be responsible for the increased production of volatile fatty acids. The elevated concentrations of soluble Fe(II)²⁺ and Mn(II)²⁺ observed in the porewater stem from iron and manganese compounds which may be reduced chemically by hydrogen sulfide and other microbially produced reducing agents or directly through increased activities of the iron and manganese reducing bacteria. In the horizon with high sulfate-reducing activities the methane concentrations in the porewater were lower than in non-stimulated sediment regions. The shape of the concentration depth profile indicates methane consumption through sulfate reducing processes. The in situ experiment demonstrates the response of a natural microbial ecosystem to fluctuations in the environmental conditions.     

Propionate and butyrate dependent bacterial sulfate reduction at extremely haloalkaline conditions and description of Desulfobotulus alkaliphilus sp. nov.

Evidence on the utilization of simple fatty acids by sulfate-reducing bacteria (SRB) at extremely haloalkaline conditions are practically absent, except for a single case of syntrophy by Desulfonatronum on acetate. Our experiments with sediments from soda lakes of Kulunda Steppe (Altai, Russia) showed sulfide production with sulfate as electron acceptor and propionate and butyrate (but not acetate) as an electron donor at a pH 10–10.5 and a salinity 70–180 g l^?1. With propionate as substrate, a highly enriched sulfidogenic culture was obtained in which the main component was identified as a novel representative of the family Syntrophobacteraceae. With butyrate as substrate, a pure SRB culture was isolated which oxidized butyrate and some higher fatty acids incompletely to acetate. The strain represents the first haloalkaliphilic representative of the family Desulfobacteraceae and is described as Desulfobotulus alkaliphilus sp. nov.     

Spore-forming thermophilic sulfate-reducing bacteria isolated from north sea oil field waters

Thermophilic sulfate-reducing bacteria were isolated from oil field waters from oil production platforms in the Norwegian sector of the North Sea. Spore-forming rods dominated in the enrichments when lactate, propionate, butyrate, or a mixture of aliphatic fatty acids (C(4) through C(6)) was added as a carbon source and electron donor. Representative strains were isolated and characterized. The isolates grew autotrophically on H(2)-CO(2) and heterotrophically on fatty acids such as formate, propionate, butyrate, caproate, valerate, pyruvate, and lactate and on alcohols such as methanol, ethanol, and propanol. Sulfate, sulfite, and thiosulfate but not nitrate could be used as an electron acceptor. The temperature range for growth was 43 to 78 degrees C; the spores were extremely heat resistant and survived 131 degrees C for 20 min. The optimum pH was 7.0. The isolates grew well in salt concentrations ranging from 0 to 800 mmol of NaCl per liter. Sulfite reductase P582 was present, but cytochrome c and desulfoviridin were not found. Electron micrographs revealed a gram-positive cell organization. The isolates were classified as a Desulfotomaculum sp. on the basis of spore formation, general physiological characteristics, and submicroscopic organization. To detect thermophilic spore-forming sulfate-reducing bacteria in oil field water, polyvalent antisera raised against antigens from two isolates were used. These bacteria were shown to be widespread in oil field water from different platforms. The origin of thermophilic sulfate-reducing bacteria in the pore water of oil reservoirs is discussed.     

Effect of sulfate on methanogenic communities that degrade unsaturated and saturated long-chain fatty acids (LCFA)

Anaerobic bacteria involved in the degradation of long-chain fatty acids (LCFA), in the presence of sulfate as electron acceptor, were studied by combined cultivation-dependent and molecular techniques. The bacterial diversity in four mesophilic sulfate-reducing enrichment cultures, growing on oleate (C_18:1, unsaturated LCFA) or palmitate (C_16:0, saturated LCFA), was studied by denaturing gradient gel electrophoresis (DGGE) profiling of polymerase chain reaction (PCR)-amplified 16S rRNA gene fragments. These enrichment cultures were started using methanogenic inocula in order to assess the competition between methanogenic communities and sulfate-reducing bacteria. Phylogenetic affiliation of rRNA gene sequences corresponding to predominant DGGE bands demonstrated that members of the Syntrophomonadaceae , together with sulfate reducers mainly belonging to the Desulfovibrionales and Syntrophobacteraceae groups, were present in the sulfate-reducing enrichment cultures. Subculturing of LCFA-degrading methanogenic cultures in the presence of sulfate resulted in the inhibition of methanogenesis and, after several transfers, archaea could no longer be detected by real-time PCR. Competition for hydrogen and acetate was therefore won by sulfate reducers, but acetogenic syntrophic bacteria were the only known LCFA-degrading organisms present after subculturing with sulfate. Principal component analysis of the DGGE profiles from methanogenic and sulfate-reducing oleate- and palmitate-enrichment cultures showed a greater influence of the substrate than the presence or absence of sulfate, indicating that the bacterial communities degrading LCFA in the absence/presence of sulfate are rather stable.     

Adaptation of anaerobically grown Thauera aromatica,Geobacter sulfurreducens and Desulfococcus multivorans to organic solvents on the level of membrane fatty acid composition

The effect of different solvents and pollutants on the cellular fatty acid composition of three bacterial strains: Thauera aromatica, Geobacter sulfurreducens and Desulfococcus multivorans, representatives of diverse predominant anaerobic metabolisms was investigated. As the prevailing adaptive mechanism in cells of T. aromatica and G. sulfurreducens whose cellular fatty acids patterns were dominated by palmitic acid (C16:0) and palmitoleic acid (C16:1cis), the cells reacted by an increase in the degree of saturation of their membrane fatty acids when grown in the presence of sublethal concentrations of the chemicals. Next to palmitic acid C16:0, the fatty acid pattern of D. multivorans was dominated by anteiso-branched fatty acids which are characteristic for several sulfate-reducing bacteria. The cells responded to the solvents with an increase in the ratio of straight-chain saturated (C14:0, C16:0, C18:0) to anteiso-branched fatty acids (C15:0anteiso, C17:0anteiso, C17:1anteisoΔ9cis). The results show that anaerobic bacteria react with similar mechanisms like aerobic bacteria in order to adapt their membrane to toxic organic solvents. The observed adaptive modifications on the level of membrane fatty acid composition can only be carried out with de novo synthesis of the fatty acids which is strictly related to cell growth. As the growth rates of anaerobic bacteria are generally much lower than in the so far investigated aerobic bacteria, this adaptive response needs more time in anaerobic bacteria. This might be one explanation for the previously observed higher sensitivity of anaerobic bacteria when compared with aerobic ones.     

Cellular fatty acid patterns inPseudomonas sp. CF600 during catechol and phenol degradation in media supplemented with glucose as an additional carbon source

Fatty acid composition inPseudomonas sp. CF600 during degradation of catechol and phenol individually and their mixture was investigated. Moreover, the influence of glucose as an additional, easily degradable carbon source on fatty acid profiling in bacteria grown on these aromatic substrates was studied. Both catechol and phenol treatments caused in bacterial cells crucial changes in the distribution of tested groups of fatty acids. The major changes included the increase of fatty acid saturation, decrease in the percentage of cyclopropane fatty acid 17:0cy and the appearance of branched and hydroxy fatty acids. Under catechol, phenol and their mixture exposure saturated/unsaturated ratio showed the value 6.5, 5.68 and 6.38 whereas in control cells this ratio reached the value 3.05. As a response to aromatic compounds bacteria formed fatty acids that were not detected in control cells growing on glucose. It has been demonstrated that the supplementation of cultured media containing single aromatic substrates or/and their mixture with glucose resulted in changes in degradation rates of catechol and phenol. It seemed that glucose influenced some metabolic pathways responsible for the assimilation of aromatic compounds. The incubation of cells in the presence of aromatic compounds and glucose rapidly led to alterations of whole-cell derived fatty acid composition. The most important changes were associated with saturation level of fatty acids and cyclopropane fatty acid contents.     

A genomic view on syntrophic versus non-syntrophic lifestyle in anaerobic fatty acid degrading communities

In sulfate-reducing and methanogenic environments complex biopolymers are hydrolyzed and degraded by fermentative micro-organisms that produce hydrogen, carbon dioxide and short chain fatty acids. Degradation of short chain fatty acids can be coupled to methanogenesis or to sulfate-reduction. Here we study from a genome perspective why some of these micro-organisms are able to grow in syntrophy with methanogens and others are not. Bacterial strains were selected based on genome availability and upon their ability to grow on short chain fatty acids alone or in syntrophic association with methanogens. Systematic functional domain profiling allowed us to shed light on this fundamental and ecologically important question. Extra-cytoplasmic formate dehydrogenases (InterPro domain number; IPR006443), including their maturation protein FdhE (IPR024064 and IPR006452) is a typical difference between syntrophic and non-syntrophic butyrate and propionate degraders. Furthermore, two domains with a currently unknown function seem to be associated with the ability of syntrophic growth. One is putatively involved in capsule or biofilm production (IPR019079) and a second in cell division, shape-determination or sporulation (IPR018365). The sulfate-reducing bacteria Desulfobacterium autotrophicum HRM2, Desulfomonile tiedjei and Desulfosporosinus meridiei were never tested for syntrophic growth, but all crucial domains were found in their genomes, which suggests their possible ability to grow in syntrophic association with methanogens. In addition, profiling domains involved in electron transfer mechanisms revealed the important role of the Rnf-complex and the formate transporter in syntrophy, and indicate that DUF224 may have a role in electron transfer in bacteria other than Syntrophomonas wolfei as well. This article is a part of a Special Issue entitled: 18th European Bioenergetics Conference (Biochim. Biophys. Acta, Volume 1837, Issue 7, July 2014).     

Chemical composition of <Emphasis Type="Italic">Desulfovibrio desulfuricans</Emphasis> lipid A

Lipopolysaccharides also called endotoxins are an integral component of the outer membrane of Gram-negative bacteria. When released from the bacterial surface, they interact with a host immune system, triggering excessive inflammatory response. Lipid A is the biologically most active part of endotoxin, and its activity is modulated by the quantity, quality and arrangement of its fatty acids. Desulfovibrio desulfuricans is sulfate-reducing, Gram-negative bacterium that is supposed to be opportunistic pathogens of humans and animals. In the present study, chemical composition of lipid A from various strains of D. desulfuricans was analyzed by gas chromatography/mass spectrometry. It was found that the fatty acid component of the lipid A contains dodecanoic, tetradecanoic, 3-hydroxytetradecanoic and hexadecanoic acids, and its carbohydrate core is composed of glucosamine. The analysis of 3-acyloxyacyl residue of the lipid A revealed the presence of amide-bound 3-(dodecanoyloxy)tetradecanoic and 3-(hexadecanoyloxy)tetradecanoic acids and ester-bound 3-(tetradecanoyloxy)tetradecanoic acid. It was concluded that both fatty acid and 3-acyloxyacyl residue profiles of the lipid A from the studied bacteria were similar to those of E. coli and S.enterica.     

Investigation of the sulfate-reducing bacterial community in the aerobic water and chemocline zone of the Black Sea by the fish technique

Fluorescent in situ hybridization (FISH) was used to analyze the abundance and phylogenetic composition of sulfate-reducing bacteria in the aerobic waters and in the oxic/anoxic transitional zone (chemocline) of the Black Sea, where biogenic formation of reduced sulfur compounds was detected by radioisotope techniques. Numerous sulfate-reducing bacteria of the genera Desulfotomaculum (30.5% of detected bacterial cells), Desulfovibrio (29.6%), and Desulfobacter (6.7%) were revealed in the aerobic zone at a depth of 30 m, while Desulfomicrobium-related bacteria (33.5%) were prevalent in the upper chemocline waters at 150-m depth. Active cells of sulfate-reducing bacteria were much more abundant in the samples collected in summer than in the winter samples from the deep-sea zone. The presence of physiologically active sulfate reducers in oxic and chemocline waters of the Black Sea correlates with the hydrochemical data on the presence of reduced sulfur compounds in the aerobic water column.     

Identification of crude-oil components and microorganisms that cause souring under anaerobic conditions

Oil souring has important implications with respect to energy resources. Understanding the physiology of the microorganisms that play a role and the biological mechanisms are both important for the maintenance of infrastructure and mitigation of corrosion processes. The objective of this study was to identify crude-oil components and microorganisms in oil-field water that contribute to crude-oil souring. To identify the crude-oil components and microorganisms that are responsible for anaerobic souring in oil reservoirs, biological conversion of crude-oil components under anaerobic conditions was investigated. Microorganisms in oil field water in Akita, Japan degraded alkanes and aromatics to volatile fatty acids (VFAs) under anaerobic conditions, and fermenting bacteria such as Fusibacter sp. were involved in VFA production. Aromatics such as toluene and ethylbenzene were degraded by sulfate-reducing bacteria (Desulfotignum sp.) via the fumarate-addition pathway and not only degradation of VFA but also degradation of aromatics by sulfate-reducing bacteria was the cause of souring. Naphthenic acid and 2,4-xylenol were not converted.     

Extractable and lipopolysaccharide fatty acid and hydroxy acid profiles from Desulfovibrio species

An analysis of the phospholipid ester-linked and the lipopolysaccharide (LPS) fatty acids and hydroxy fatty acids of six lactate-utilizing Desulfovibrio-type sulfate-reducing bacteria (SRB) has been performed using capillary gas-liquid chromatography-mass spectrometry (GLC-MS). The concentrations of normal fatty acids were essentially similar, with the possible exception of a high content of normal fatty acids in the LPS of Desulfovibrio gigas. Determination of monounsaturated acid double bond configuration was performed by GLC-MS analysis of the derivatized fatty acids. A total of nine branched chain and eight straight chain monounsaturated fatty acids was detected in the Desulfovibrio species analyzed. The major component detected in five Desulfovibrio was the 17-carbon iso-branched monoenoic acid which showed cis unsaturation [i17:1(n-7)c] seven carbons from the terminal methyl group of the fatty acid chain. D. gigas, in contrast, contained almost no unsaturated fatty acids and was greatly enriched in iso-branched 15:0. Major differences between strains were found in the phospholipid and LPS hydroxy fatty acids. These components, in addition to the i17:1(n-7)c and other characteristic branched chain unsaturated acids, can possibly be utilized as signatures of the lactate-utilizing SRB.     

Variation in Microbial Community Structure in Two Boreal Peatlands as Determined by Analysis of Phospholipid Fatty Acid Profiles

Analyses of phospholipid fatty acids (PLFAs) were used to assess variation in community structure and total microbial biomass in two boreal peatlands in Sweden. The total PLFA concentration in peat ranged from 0.16 to 7.0 nmol g of wet peat(sup-1) (median, 0.70 nmol g of wet peat(sup-1)). Principal-component analysis of PLFA data revealed that the degree of depth-related variation in PLFA composition was high among peatland habitats, with general differences between wet sites, with water tables within a few centimeters of the moss surface, and dry sites, with water tables >10 cm below the moss surface. However, variation in PLFA composition over the growing season was negligible. In the principal-component analyses, most PLFAs were determined to be parts of clusters of covarying fatty acids, suggesting that they originated in the same functional groups of microorganisms. Major clusters were formed by monounsaturated (typical of gram-negative eubacteria), terminally branched (gram-positive or anaerobic gram-negative eubacteria), methyl-branched and branched unsaturated (sulfate-reducing bacteria and/or actinomycetes), (omega)8 monounsaturated (methane-oxidizing bacteria), and polyunsaturated (eucaryotes) PLFAs. Within the clusters, PLFAs had rather distinct concentration-depth distributions. For example, PLFAs from sulfate-reducing bacteria and/or actinomycetes and those from methane-oxidizing bacteria had maximum concentrations slightly below and at the average water table depth, respectively.     

Mineralization of monofluorobenzoate by a diculture under sulfate-reducing conditions

Abstract A mesophilic, dehalogenating, sulfate-reducing diculture was isolated from an anaerobic lake sediment. One strain of the diculture is proposed to be an endospore-forming Desulfotomaculum species, the second strain was a vibrioid, motile and non-sporeforming species which is tentatively assigned to the genus Desulfovibrio . The diculture was able to mineralize 4- and 2-fluorobenzoate both isomers being incompletely oxidized with the release of acetate, which was subsequently used by both sulfate-reducing strains. Other electron donors used for growth included benzoate, 3- and 4-hydroxybenzoate, protocatechuate, catechol, phenol, 2,5-dimethoxyphenol, fatty acids up to C₈, malate and pyruvate. The culture obtained from a freshwater habitat grew optimally at NaCl concentrations of 0.3–0.5 g 1⁻¹, 33–37°C, and pH 7.4. Our experiments showed that certain fluorinated aromatic hydrocarbons could serve as sole sources of carbon and energy for sulfate-reducing bacteria.     

Phylogenetic analysis of Syntrophobacter wolinii reveals a relationship with sulfate-reducing bacteria

A 16S rRNA sequence analysis of Syntrophobacter wolinii was done by using PCR amplification of the 16S rRNA-genes from DNA isolated from the S. wolinii-Desulfovibrio sp. coculture. Phylogenetic analysis using the obtained sequence revealed that S. wolinii was not related to bacteria growing syntrophically on other fatty acids than propionate, but was related to sulfate-reducing bacteria. The closest related bacteria are Desulfomonile tiedjei and Desulfoarculus baarsii.     

Isolation and characterization of an anaerobic benzoate-degrading spore-forming sulfate-reducing bacterium, Desulfotomaculum sapomandens sp. nov.

Abstract Spore-forming sulfate-reducing bacteria (SRB) were enriched selectively from various kinds of aerobic soils with fatty acids as the sole carbon and energy source. A Gram-negative motile rod-shaped bacterium, which produced gas vacuoles during sporulation was isolated. It degraded alcohols, aromatic and n-fatty acids (up to C₁₈) except for propionate, completely to CO₂. Sulfate, sulfite, thiosulfate or elemental sulfur served as electron acceptors. Because of its sensitivity to H₂S, the isolate never produced more than 8 mM dissolved sulfide at pH 7.0. G + C-content of the DNA was 48.0 mol %. The isolated strain Pato is described as a new species Desulfotomaculum sapomandens .