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Department of Biology, University of Bergen, PO Box 7800, N-5020 Bergen, Norway
Correspondence
Nils-Kåre Birkeland
nils.birkeland{at}bio.uib.no
| ABSTRACT |
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The morphology and growth temperature profile of Thermovirga lienii gen. nov., sp. nov. are shown in supplementary figures available in IJSEM Online.
| MAIN TEXT |
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The family Syntrophomonadaceae is represented by 14 genera. Thermophilic organisms are found in eight of these genera (Anaerobaculum, Anaerobranca, Caldicellulosiruptor, Carboxydocella, Syntrophothermus, Thermaerobacter, Thermosyntropha and Thermanaerovibrio). Here, we describe a novel thermophilic anaerobe, strain Cas60314T, isolated from a Norwegian offshore oil well not injected with seawater. The isolate is proposed as a member of a novel genus and species within the family Syntrophomonadaceae, Thermovirga lienii gen. nov., sp. nov.
The sample used in this study was an oil/water mixture collected at the upper-riser of a Norwegian oil reservoir in the North Sea, the Troll C Reservoir, with the geographical position 60° 53' 10.73'' N 03° 36' 41.41'' E. The concentration of sodium in the production water was 16.4 g l1. The sample was transported from the oil platform at ambient temperature and stored at room temperature prior to being used as an inoculum. The temperature of the water at the sampling site was 68 °C. The pH of the water at 18 °C was 6.8. The Troll C Reservoir has not been injected with seawater.
Enrichment and growth was performed using an anaerobically prepared basal medium containing the following components (l1 distilled water): 20 g NaCl, 0.9 g MgCl2.6H2O, 1.4 g MgSO4.7H2O, 0.33 g KCl, 0.25 g NH4Cl, 0.14 g CaCl2.2H2O, 0.45 g KH2PO4, 1.0 ml trace element solution SL-10 (Widdel et al., 1983
) and 0.5 ml resazurin (0.02 %). After being autoclaved in a dispenser (Lien & Beeder, 1997
) the medium was reduced with 4 ml 0.5 M Na2S under nitrogen gas; 10 ml vitamin solution (Balch et al., 1979
) was added and the pH was adjusted to 6.8 with 1 M NaOH. The medium was dispensed into 50 ml serum bottles. For the enrichment of anaerobic Casamino acid-degrading micro-organisms, Casamino acids (Oxoid) were added from a stock solution to a final concentration of 0.3 % (w/v). Enrichments were carried out at 37, 50, 57, 70 and 80 °C with 10 % inoculum. Positive enrichments were serially diluted in medium solidified by 0.3 % (w/v) Gelrite (Kelco) and incubated anaerobically at the same temperature as that used for the primary enrichment. Colonies from each dilution series were transferred to fresh liquid medium and analysed further. The strain that is characterized here, strain Cas60314T, was obtained after three dilution series in solidified medium.
Morphological studies were performed with a light microscope (Eclipse E400; Nikon) equipped with a digital camera (Nikon). For electron microscopy, exponentially grown cells were fixed in 1.5 % glutaraldehyde in 0.1 M sodium cacodylate buffer at pH 7.4 for 20 min at room temperature. Samples were washed twice with 0.1 M sodium cacodylate buffer, postfixed in 1 % OsO4 for 45 min and rinsed twice with the buffer. Samples were dehydrated in an ethanol series (30, 50, 70, 96 and 100 %). For scanning electron microscopy, samples were dried by critical point drying using a Polaron Range CPD 7501, mounted on scanning electron microscopy stubs, sputter-coated with carbon using a JEOL JFC-2300 HR and then observed with a field-emission scanning electron microscope (FeSEM 7400F) at an accelerating voltage of 1.0 kV. For transmission electron microscopy, samples were treated with propylene oxide as a transitional solvent, prior to infiltration with epoxy resin (Agar). Samples were thin-sectioned on an ultramicrotome (Ultracut S; Reichert) and electron microscopy was performed with a JEM 1230 microscope.
Growth was determined by direct cell counting with a light microscope (Labophot; Nikon) and a counting chamber (Thoma). All growth experiments were performed using Belco tubes with 10 ml medium. For physiological characterization with regard to pH, temperature, NaCl concentration and possible use of alternative electron acceptors, 0.3 % peptone (Oxoid) and 0.02 % yeast extract (Difco) were used as substrates. Gradients of pH and NaCl were obtained by mixing media with different pH or NaCl concentrations, respectively. The pH was measured at room temperature. Amorphous Fe(III) oxide was synthesized by neutralizing a solution of FeCl3 as described previously (Lovley & Phillips, 1986
). The production of magnetite was tested for by holding a magnet close to the culture tube. The production of sulfide was measured as described by Cline (1969)
.
Substrates were tested with the following concentrations: 10 mM for glutamate, alanine, leucine, isoleucine, valine, arginine, serine, threonine, glycine and 2-oxoglutarate; 20 mM for pyruvate, methanol, ethanol, phenol, lactate, acetate, propionate, malate, succinate, citrate and formate; 25 mM for glucose, maltose, xylose, ribose, sucrose, arabinose, fructose, lactose, mannose and maltodextrin; and 0.3 % (w/v) for xylane, cellulose, starch and chitin, peptone, meat extract, casein, tryptone and Casamino acids. The utilization of H2 was tested with a gas phase comprising N2/H2 (1 : 1). The utilization of various substrates was tested in medium with or without 0.05 % (w/v) yeast extract and 0.1 % (w/v) cystine.
The effect of various concentrations of oxygen on growth was investigated in medium that was not reduced with sulfide and by exchanging portions of the gas phase with air.
GC was used to determine the production of ethanol and fatty acids (HP 5890; Hewlett Packard) and of hydrogen and CO2 (HP 6890; Hewlett Packard). The HP 5890 was equipped with an HPLC column (ZB-WAX; Phenomenex) and a flame-ionization detector. The oven temperature was programmed to remain at 65 °C for 1 min before rising to 150 °C in increments of 8 °C min1. Helium (60 ml min1) was used as the carrier gas. The HP 6890 apparatus was equipped with a HayeSep R (Hewlett Packard) packed column and a thermal conductivity detector (Hewlett Packard). The oven temperature was 125 °C. Argon (30 ml min1) was used as the carrier gas. Genomic DNA was isolated using the cetyltrimethylammonium bromide method as modified by Lien et al. (1998)
. The 16S rRNA gene sequence was selectively amplified using a PCR with universal primers 5'-GAG TTT GAT CCT GGC TCA G-3' and 5'-GAA AGG AGG TGA TCC AGC C-3', as modified by Loffler et al. (2000)
. The PCR was performed with an initial denaturation at 94 °C for 3 min, followed by 30 cycles of annealing at 50 °C for 30 s, extension at 72 °C for 1.5 min and denaturation at 94 °C for 50 s and, finally, an extension cycle at 72 °C for 10 min. After purification with a PCR purification kit (Stratagene), the PCR products were sequenced according to the protocol of the ABI Prism BigDye Terminator kit (Perkin Elmer). The 16S rRNA gene sequence obtained from strain Cas60314T was compared with other sequences in the GenBank database (Benson et al., 2005
), using BLAST (Altschul et al., 1997
) to identify its closest relatives. Alignments for phylogenetic analysis were made by using CLUSTAL X (Thompson et al., 1997
). A phylogenetic reconstruction was produced using PHYLIP software (version 3.63) with the JukesCantor distance matrix (Jukes & Cantor, 1969
) and the neighbour-joining algorithm (Saitou & Nei, 1987
). Confidence in the tree topology was determined by using 100 bootstrapped trees (Felsenstein, 1985
).
Determination of the G+C content (mol%) was performed at the Deutsche Sammlung von Mikroorganismen und Zellkulturen (Braunschweig, Germany), using HPLC as described by Mesbah et al. (1989)
.
Growth occurred in enrichments with Casamino acids at 37, 50 and 57 °C after 37 days. No growth was observed in enrichments at 70 or 80 °C after 3 weeks incubation. Each enrichment was serially diluted in medium solidified with Gelrite, and round, white colonies 0.51 mm in diameter developed after 25 days. Single colonies were obtained from all positive enrichments, and all strains analysed had identical 16S rRNA gene sequences. One of the isolates, originating from the enrichment at 57 °C, was studied further. After two additional dilutions in solidified medium, the strain, now designated Cas60314T, was considered pure.
Cultural and morphological characteristics are given in the description of the novel genus and species. The cells of strain Cas60314T were motile only in the early exponential growth phase. The cells were straight rods 0.40.8 µm in diameter and 23 µm in length (see Supplementary Fig. S1a available in IJSEM Online). They appeared as single cells or in chains of two to five cells. During growth, strain Cas60314T formed aggregates of up to several hundred cells (see Supplementary Fig. S1b in IJSEM Online). Scanning electron microscopy revealed the presence of flagella (Fig. 1a
). The Gram reaction was negative and a two-layered cell-wall structure typical of Gram-negative cells was observed in ultrathin sections (Fig. 1b
). Spore formation was not observed.
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Strain Cas60314T was able to grow with 100 % H2 in the headspace, with peptone as the substrate.
Table 1
shows the end products from some of the substrates utilized by strain Cas60314T. In addition, propionate was formed when succinate was used as substrate and cystine as an electron acceptor. In this case, however, no growth could be detected.
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Because of the various possibilities for contamination in the sampling procedure, and the possibility of contamination of an entire reservoir in the drilling or oil-recovery processes, it is not straightforward to determine whether organisms isolated from oil-reservoir samples are natural inhabitants of these habitats. In some cases, as in the case of Desulfovibrio longus, an indigenous nature can even be excluded (Magot et al., 1992
). Strain Cas60314T was isolated from a reservoir that is not injected with seawater. This eliminates one common source of contamination of oil wells, and strengthens the view that strain Cas60314T is indigenous to the oil reservoir.
On the basis of its phenotypic characteristics as well as its distinct phylogenetic position, strain Cas60314T is considered to represent a novel genus and species, for which the name Thermovirga lienii gen. nov., sp. nov. is proposed.
Description of Thermovirga gen. nov.
Thermovirga (Ther.mo.vir'ga. Gr. fem. n. therme heat; L. fem. n. virga rod; N.L. fem. n. Thermovirga the hot rod).
Cells occur singly or in chains and have the ability to form aggregates. Motile. Gram-negative. No spores are formed. Growth is anaerobic. Cells are thermophilic and slightly halophilic. Able to ferment proteinous substrates, some single amino acids and a limited number of organic acids, but not sugars, fatty acids or alcohols. Able to reduce cystine and elemental sulfur to hydrogen sulfide. The type species is Thermovirga lienii.
Description of Thermovirga lienii sp. nov.
Thermovirga lienii (li.en.i'i. N.L. gen. n. lienii named in honour of the Norwegian microbiologist Professor Torleiv Lien, for his important contribution in the study of anaerobes from petroleum reservoirs).
Cells are motile and typically 23 µm in length and 0.40.8 µm wide. Cells occur singly or in chains and can form aggregates of up to several hundred cells. The temperature range for growth is 3768 °C (optimum, 58 °C; see Supplementary Fig. S2 available in IJSEM Online). The pH range for growth is 6.28.0 (optimum, pH 6.57.0). The NaCl range for growth is 580 g l1 (optimum, 2030 g l1). Substrates that can be utilized by strain Cas60314T in medium not supplied with yeast extract are as follows: peptone, Casamino acids, meat extract, tryptone and casein. Yeast extract is required for fermentation of pyruvate, serine and 2-oxoglutarate. Substrates that can be utilized only in medium supplied with yeast extract and cystine are as follows: glutamate, alanine, leucine, isoleucine, valine and arginine. The following substrates are not fermented in the presence of yeast extract, but were not tested in medium supplied with cystine: xylose, ribose, sucrose, arabinose, fructose, lactose, mannose, maltodextrin, xylane, cellulose, starch and chitin. Substrates that cannot be utilized in the presence of yeast extract and in the presence or absence of cystine are as follows: H2, glucose, maltose, threonine, glycine, methanol, ethanol, phenol, lactate, acetate, propionate, malate, succinate, citrate and formate. Strain Cas60314T does not perform the Stickland reaction when alanine is provided as electron donor and serine or arginine is provided as electron acceptor. Cystine stimulates growth. Cystine and elemental sulfur, but not thiosulfate, are reduced to hydrogen sulfide. Amorphous Fe(III) does not stimulate growth, and, in its presence, magnetite is not formed. The G+C content of the genomic DNA is 46.6 mol% (HPLC).
The type strain, Cas60314T (=DSM 17291T=ATCC BAA-1197T), was isolated from production-water samples from an oil reservoir in the North Sea.
| ACKNOWLEDGEMENTS |
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| REFERENCES |
|---|
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Baena, S., Fardeau, M. L., Labat, M., Ollivier, B., Thomas, P., Garcia, J. L. & Patel, B. K. C. (1998). Aminobacterium colombiense gen. nov. sp. nov., an amino acid-degrading anaerobe isolated from anaerobic sludge. Anaerobe 4, 241250.
Baena, S., Fardeau, M. L., Ollivier, B., Labat, M., Thomas, P., Garcia, J. L. & Patel, B. K. C. (1999). Aminomonas paucivorans gen. nov., sp. nov., a mesophilic anaerobic, amino-acid-utilizing bacterium. Int J Syst Bacteriol 49, 975982.
Baena, S., Fardeau, M. L., Labat, M., Ollivier, B., Garcia, J. L. & Patel, B. K. C. (2000). Aminobacterium mobile sp. nov., a new anaerobic amino-acid-degrading bacterium. Int J Syst Evol Microbiol 50, 259264.[Abstract]
Balch, W. E., Fox, G. E., Magrum, L. J., Woese, C. R. & Wolfe, R. S. (1979). Methanogens: re-evaluation of a unique biological group. Microbiol Rev 43, 260296.
Benson, D. A., Karsch-Mizrachi, I., Lipman, D. J., Ostell, J. & Wheeler, D. L. (2005). GenBank. Nucleic Acids Res 33, D34D38.
Birkeland, N. K. (2004). The microbial diversity of deep subsurface oil reservoirs. In Petroleum Biotechnology: Developments and Perspectives, pp. 385403. Edited by R. Vazquez-Duhalt & R. Quintero-Ramirez. Amsterdam: Elsevier.
Cheng, G. S., Plugge, C. M., Roelofsen, W., Houwen, F. P. & Stams, A. J. M. (1992). Selenomonas acidaminovorans sp. nov., a versatile thermophilic proton-reducing anaerobe able to grow by decarboxylation of succinate to propionate. Arch Microbiol 157, 169175.
Cline, J. D. (1969). Spectrophotometric determination of hydrogen sulfide in natural waters. Limnol Oceanogr 14, 454458.
Felsenstein, J. (1985). Confidence limits on phylogenies: an approach using the bootstrap. Evolution 39, 783791.[CrossRef]
Jukes, T. H. & Cantor, C. R. (1969). Evolution of protein molecules. In Mammalian Protein Metabolism, pp. 211232. Edited by H. N. Munro. New York: Academic Press.
Lien, T. & Beeder, J. (1997). Desulfobacter vibrioformis sp. nov., a sulfate reducer from a wateroil separation system. Int J Syst Bacteriol 47, 11241128.
Lien, T., Madsen, M., Rainey, F. A. & Birkeland, N. K. (1998). Petrotoga mobilis sp. nov., from a North Sea oil-production well. Int J Syst Bacteriol 48, 10071013.
Loffler, F. E., Sun, Q., Li, J. R. & Tiedje, J. M. (2000). 16S rRNA gene-based detection of tetrachloroethene-dechlorinating Desulfuromonas and Dehalococcoides species. Appl Environ Microbiol 66, 13691374.
Lovley, D. R. & Phillips, E. J. P. (1986). Organic matter mineralization with the reduction of ferric iron in anaerobic sediments. Appl Environ Microbiol 51, 683689.
Magot, M., Caumette, P., Desperrier, J. M., Matheron, R., Dauga, C., Grimont, F. & Carreau, L. (1992). Desulfovibrio longus sp. nov., a sulfate-reducing bacterium isolated from an oil-producing well. Int J Syst Bacteriol 42, 398403.
Magot, M., Ravot, G., Campaignolle, X., Ollivier, B., Patel, B. K. C., Fardeau, M. L., Thomas, P., Crolet, J. L. & Garcia, J. L. (1997). Dethiosulfovibrio peptidovorans gen. nov., sp. nov., a new anaerobic, slightly halophilic, thiosulfate-reducing bacterium from corroding offshore oil wells. Int J Syst Bacteriol 47, 818824.
Magot, M., Ollivier, B. & Patel, B. K. C. (2000). Microbiology of petroleum reservoirs. Antonie van Leeuwenhoek 77, 103116.[CrossRef][Medline]
Menes, R. J. & Muxi, L. (2002). Anaerobaculum mobile sp. nov., a novel anaerobic, moderately thermophilic, peptide-fermenting bacterium that uses crotonate as an electron acceptor, and emended description of the genus Anaerobaculum. Int J Syst Evol Microbiol 52, 157164.[Abstract]
Mesbah, M., Premachandran, U. & Whitman, W. (1989). Precise measurement of the G+C content of deoxyribonucelic acid by high-performance liquid chromatography. Int J Syst Bacteriol 39, 159167.
Miranda-Tello, E., Fardeau, M. L., Sepulveda, J., Fernandez, L., Cayol, J. L., Thomas, P. & Ollivier, B. (2003). Garciella nitratireducens gen. nov., sp nov., an anaerobic, thermophilic, nitrate- and thiosulfate-reducing bacterium isolated from an oilfield separator in the Gulf of Mexico. Int J Syst Evol Microbiol 53, 15091514.
Nazina, T. N., Ivanova, A. E., Kanchaveli, L. P. & Rozanova, E. P. (1988). A new spore-forming thermophilic methylotrophic sulfate-reducing bacterium, Desulfotomaculum kuznetsovii sp. nov. Microbiology (English translation of Mikrobiologiia)57, 659663.
Nilsen, R. K., Torsvik, T. & Lien, T. (1996). Desulfotomaculum thermocisternum sp. nov., a sulfate reducer isolated from a hot North Sea oil reservoir. Int J Syst Bacteriol 46, 397402.
Orphan, V. J., Taylor, L. T., Hafenbradl, D. & Delong, E. F. (2000). Culture-dependent and culture-independent characterization of microbial assemblages associated with high-temperature petroleum reservoirs. Appl Environ Microbiol 66, 700711.
Ravot, G., Magot, M., Fardeau, M. L., Patel, B. K. C., Thomas, P., Garcia, J. L. & Ollivier, B. (1999). Fusibacter paucivorans gen. nov., sp. nov., an anaerobic, thiosulfate-reducing bacterium from an oil-producing well. Int J Syst Bacteriol 49, 11411147.
Rees, G. N., Patel, B. K. C., Grassia, G. S. & Sheehy, A. J. (1997). Anaerobaculum thermoterrenum gen. nov., sp nov., a novel, thermophilic bacterium which ferments citrate. Int J Syst Bacteriol 47, 150154.
Saitou, N. & Nei, M. (1987). The neighbor-joining method: a new method for reconstructing phylogenetic trees. Mol Biol Evol 4, 406425.[Abstract]
Surkov, A. V., Dubinina, G. A., Lysenko, A. M., Glockner, F. O. & Kuever, J. (2001). Dethiosulfovibrio russensis sp. nov., Dethiosulfovibrio marinus sp. nov. and Dethiosulfovibrio acidaminovorans sp. nov., novel anaerobic, thiosulfate- and sulfur-reducing bacteria isolated from Thiodendron sulfur mats in different saline environments. Int J Syst Evol Microbiol 51, 327337.[Abstract]
Thompson, J. D., Gibson, T. J., Plewniak, F., Jeanmougin, F. & Higgins, D. G. (1997). The CLUSTAL_X windows interface: flexible strategies for multiple sequence alignment aided by quality analysis tools. Nucleic Acids Res 25, 48764882.
Widdel, F., Kohring, G. W. & Mayer, F. (1983). Studies on dissimilatory sulfate-reducing bacteria that decompose fatty-acids. III. Characterization of the filamentous gliding Desulfonema limicola gen. nov., sp. nov., and Desulfonema magnum sp. nov. Arch Microbiol 134, 286294.[CrossRef]
Zavarzina, D. G., Zhilina, T. N., Tourova, T. P., Kuznetsov, B. B., Kostrikina, N. A. & Bonch-Osmolovskaya, E. A. (2000). Thermanaerovibrio velox sp. nov., a new anaerobic, thermophilic, organotrophic bacterium that reduces elemental sulfur, and emended description of the genus Thermanaerovibrio. Int J Syst Evol Microbiol 50, 12871295.[Abstract]
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