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1 Escola Superior de Biotecnologia, Universidade Católica Portuguesa, 4200-072 Porto, Portugal
2 Area de Microbiologia, Universitat de les Illes Balears, 07071 Palma de Mallorca, Spain
3 LEPAEDepartamento de Engenharia Química, Faculdade de Engenharia, Universidade do Porto, 4200-465 Porto, Portugal
Correspondence
Célia M. Manaia
celman{at}esb.ucp.pt
| ABSTRACT |
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-subclass of the Proteobacteria. The highest 16S rDNA sequence similarity of isolate N2-214T was to Azoarcus buckelii (91·9 %), Thauera aromatica (92 %) and Hydrogenophilus thermoluteolus (92·7 %). On the basis of phylogenetic analyses and physiological and chemotaxonomic characteristics, it is proposed that isolate N2-214T (=DSM 15129T=LMG 21637T) represents a new genus and species, Tepidiphilus margaritifer gen. nov., sp. nov.
-hydroxybutyratePublished online ahead of print on 7 February 2003 as DOI 10.1099/ijs.0.02538-0.
The GenBank/EMBL/DDBJ accession number for the 16S rDNA sequence of isolate N2-214T is AJ504663.
| INTRODUCTION |
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-subclass of the Proteobacteria, eight species of thermophilic organisms, included in five genera, have been described to date. The species Thiomonas thermosulfata (Shooner et al., 1996
-Proteobacteria, was described recently (Takeda et al., 2002
Isolation of these organisms has frequently occurred under conditions favouring the recovery of specific metabolic types, namely hydrogen- and sulfur-oxidizing bacteria; this may explain why the majority of thermophilic members of the
-Proteobacteria described to date are chemolithotrophic. Indeed, it is intriguing that, despite the abundance of chemo-organoheterotrophic organisms belonging to the
-Proteobacteria, only a single thermophilic representative of this metabolic group has been described to date.
The present study describes a moderately thermophilic, chemo-organoheterotrophic bacterium, strain N2-214T, isolated from a thermophilic aerobic digester of water-treatment sludge. On the basis of 16S rDNA-based phylogenetic analyses and physiological and chemotaxonomic characteristics, it is proposed that isolate N2-214T represents a new genus and species, for which the name Tepidiphilus margaritifer gen. nov., sp. nov. is proposed.
| METHODS |
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Determination of morphological, growth and biochemical characteristics.
Colony and cell morphology, Gram-staining reaction, production of spores, accumulation of poly-
-hydroxybutyrate (PHB) granules, the number and position of flagella and the temperature range for growth were examined as described by Manaia et al. (2003)
.
Phenotypic tests were carried out as described by Smibert & Krieg (1981)
, using 2-day cultures on LB agar. Unless otherwise stated, all incubations were performed at 50 °C. The pH tolerance range was examined in LB medium, using 10 mM MES (Sigma), for pH 5·06·0 or 10 mM TAPS (Sigma) for pH 6·09·0. Enzymic activities were tested using the API ZYM system by following the instructions of the manufacturer (bioMérieux). Hydrogenase activity was determined on the basis of the descriptions of Aragno & Schlegel (1992)
and Stöhr et al. (2001)
as described by Manaia et al. (2003)
. The nutritional pattern was characterized using the API 50CH system and a defined medium (medium B) as described by Manaia et al. (2003)
. Chemolithoautotrophic growth, the use of H2 as an energy source and the ability to use sulfur or thiosulfate as electrons donors were tested as described by Manaia et al. (2003)
. The ability to grow in the absence of a source of combined nitrogen was tested using medium A without ammonium sulfate, under aerobic conditions or under an N2 atmosphere with nitrate as the electron acceptor.
Determination of genotypic characteristics.
The DNA G+C content was determined as described by Manaia et al. (2003)
.
16S rDNA sequence analysis.
The 16S rRNA gene sequence was determined after PCR amplification as described by Manaia et al. (2003)
. The nucleotide sequence was compared with reference 16S rDNA sequences in the EMBL database using the FASTA program (Pearson & Lipman, 1988
) and subsequently aligned with reference sequences included in the ARB package (http://www.arb-home.de). Evolutionary distances derived from sequence-pair dissimilarities (Jukes & Cantor, 1969
) were calculated using the PHYLIP package (Felsenstein, 1989
). Calculations were done by using a 50 % conservation filter for the
-Proteobacteria implemented in the ARB package and by using a second filter that excluded only the most variable regions in the 16S rRNA molecule, which corresponded to inserts of different lengths amongst the reference sequences used in the analysis. The tree shown later is the one obtained using the second type of filter, since the topology of the tree for the most closely related genera did not vary regardless of which filter was used, and the bootstrap values were slightly higher. Ambiguously determined nucleotide positions or positions for which no sequence data were available in any of the reference sequences were excluded from the calculations.
Determination of chemotaxonomic characteristics.
Polar lipids, methylated fatty acids and respiratory quinones were extracted and separated as described previously (Manaia et al., 2003
).
| RESULTS AND DISCUSSION |
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Cells of strain N2-214T were Gram-negative, non-spore-forming rods, 2·0 µm long and 0·7 µm wide, with a single polar flagellum. The isolate tested positive for oxidase and catalase and for the presence of intracellular PHB granules. Strain N2-214T reduced nitrate to a compound more reduced than nitrite, since nitrite was not detected in the supernatant of cultures. The isolate could grow under anaerobic conditions (N2-saturated atmosphere) using nitrate as an electron acceptor, both in complex media and in mineral medium supplemented with acetate, ethanol or benzoate. Isolate N2-214T could reduce triphenyltetrazolium in the presence of hydrogen but not in its absence, suggesting the presence of hydrogenase activity. However, since this organism could grow in a N2-saturated atmosphere in the absence of H2 gas, it is possible to conclude that this organism is not a strictly hydrogen-oxidizing chemolithoheterotroph. The optimal temperature for growth of strain N2-214T in LB medium was around 50 °C, with a maximal growth temperature of 61 °C. The nutritional pattern of strain N2-214T revealed an inability to use the sugars that were tested and a preference for organic acids, e.g. malate, acetate or benzoate, as carbon sources; other substrates, such as ethanol and the amino acids glutamic acid and asparagine, could also be used as single carbon sources (Table 1
). The strain could not grow autotrophically in mineral medium supplemented with sodium hydrogen carbonate in the presence of hydrogen, S0 or thiosulfate; in the presence of acetate as a carbon source, these potential electron donors did not enhance growth.
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The G+C content of the genomic DNA of strain N2-214T was 64·8 mol%.
Nearly the complete 16S rDNA sequence of strain N2-214T was determined (1456 nucleotides). Phylogenetic analysis of the 16S rDNA sequence of strain N2-214T showed its affiliation to the
-Proteobacteria, a result that is in agreement with the polar lipid and respiratory quinone composition (see below). The 16S rDNA sequence was then compared with all species with validly published names of the most closely related genera, Azoarcus, Thauera and Hydrogenophilus (Springer et al., 1998
; Hayashi et al., 1999
; Song et al., 1998
, 1999
, 2000
, 2001
; Reinhold-Hurek & Hurek, 2000
; Stöhr et al., 2001
; Mechichi et al., 2002
), and several other genera in the
-Proteobacteria. The 16S rDNA sequence of strain N2-214T was not closely related to those of other genera within this subclass, the highest similarities (approx. 9293 %) being to the sequences of Azoarcus buckelii (Mechichi et al., 2002
), Thauera aromatica (Anders et al., 1995
) and H. thermoluteolus (Hayashi et al., 1999
). Comparative evolutionary distance analyses of the 16S rDNA sequence of strain N2-214T demonstrated that it branched from the lineage leading to the genus Hydrogenophilus (Fig. 1
), a result that was also supported by parsimony, maximum-likelihood and bootstrapping methods. The polar lipid pattern of strain N2-214T, obtained by TLC, revealed the presence of phosphatidylethanolamine (PE) and phosphatidylglycerol (PG) as the major phospholipids. A similar polar lipid pattern, characterized by the predominance of PE and PG, is described for other members of the
-Proteobacteria (Wilkinson, 1988
). The only respiratory quinone detected for isolate N2-214T was ubiquinone 8, which is also characteristic of micro-organisms belonging to the
-Proteobacteria (Suzuki et al., 1993
).
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-Proteobacteria. However, this may be due to the difficulty in cultivating these organisms under laboratory conditions, since bacteria belonging to the
-Proteobacteria have been detected in studies employing culture-independent molecular methods to describe the biological diversity of high-temperature natural (e.g. Ward et al., 1998
-proteobacterium HMD 444 (accession number AB015328) in both meso- and thermophilic bioreactors. In this respect, is interesting to note that strains HMD 444 and N2-214T share 16S rRNA sequence identity above 99 % (according to FASTA analysis), suggesting that they might eventually represent the same species. However, such a conclusion would only be possible on the basis of a DNADNA hybridization study (Stackebrandt & Goebel, 1994
Description of Tepidiphilus gen. nov.
Tepidiphilus (Te.pi.di'phi.lus. L. adj. tepidus lukewarm; Gr. adj. philos friendly to; N.L. masc. n. Tepidiphilus liker of lukewarm conditions).
Forms rod-shaped cells that stain Gram-negative. Endospores are not formed. Slightly thermophilic. PHB granules are accumulated. Grows anaerobically in the presence of nitrate. Oxidase- and catalase-positive. Major phospholipids are PE and PG; ubiquinone 8 is the major respiratory quinone. Major fatty acids are C16 : 0 and cyclo-C19 : 0. Chemo-organotrophic. Organic acids and amino acids, but no sugars, are used as single carbon sources. The type species is Tepidiphilus margaritifer.
Description of Tepidiphilus margaritifer sp. nov.
Tepidiphilus margaritifer (mar.ga.ri'ti.fer. L. n. margarita pearl; L. masc. suffix -fer carrying; N.L. masc. adj. margaritifer pearl-carrying, referring to the nacre-like appearance of the colonies).
Shows the following properties in addition to those in the genus description. Forms rod-shaped cells, 2·0 µm long and 0·7 µm wide. Cells are motile by a single polar flagellum. Colonies grown on LB agar are nacre-like and 12 mm in diameter after 3648 h growth. Growth occurs above 25 °C and below 61 °C; the optimal growth temperature is approximately 50 °C. Growth occurs between pH 6 and 8. Hydrogenase-positive. The major fatty acids at the optimal temperature for growth are C16 : 0, C18 : 1 and cyclo-C19 : 0; C10 : 0 3-OH is also present. The DNA G+C content of the type strain is 64·8 mol%.
The type strain, strain N2-214T (=DSM 15129T=LMG 21637T), was isolated from a thermophilic digester of wastewater-treatment sludge.
| ACKNOWLEDGEMENTS |
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| REFERENCES |
|---|
|
|
|---|
Aragno, M. & Schlegel, H. G. (1992). The mesophilic hydrogen oxidizing (Knallgas) bacteria. In The Prokaryotes, 2nd edn, pp. 39173933. Edited by A. Balows, H. G. Trüper, M. Dworkin, W. Harder & K. H. Schleifer. New York: Springer.
Caldwell, D. E., Caldwell, S. J. & Laycock, J. P. (1976). Thermothrix thiopara gen. et sp. nov. a facultatively anaerobic facultative chemolithotroph living at neutral pH and high temperature. Can J Microbiol 22, 15091517.[Medline]
Carlton, B. C. & Brown, B. J. (1981). Gene mutation. In Manual Methods for General Microbiology, pp. 409443. Edited by P. Gerhardt, R. G. E. Murray, R. N. Costilow, E. W. Nester, W. A. Wood, N. R. Krieg & G. H. Phillips. Washington, DC: American Society for Microbiology.
Felsenstein, J. (1989). PHYLIP phylogeny inference package. Cladistics 5, 164166.
Goto, E., Kodama, T. & Minoda, Y. (1978). Growth and taxonomy of thermophilic hydrogen bacteria. Agr Biol Chem 42, 13051308.
Hayashi, N. R., Ishida, T., Yokota, A., Kodama, T. & Igarashi, Y. (1999). Hydrogenophilus thermoluteolus gen. nov., sp. nov., a thermophilic, facultatively chemolithoautotrophic, hydrogen-oxidizing bacterium. Int J Syst Bacteriol 49, 783786.
Hugenholtz, P., Pitulle, C., Hershberger, K. L. & Pace, N. R. (1998). Novel division level bacterial diversity in a Yellowstone hot spring. J Bacteriol 180, 366376.
Jukes, T. H. & Cantor, C. R. (1969). Evolution of protein molecules. In Mammalian Protein Metabolism, pp. 21132. Edited by H. N. Munro. New York: Academic Press.
LaPara, T. M., Nakatsu, C. H., Pantea, L. & Alleman, J. E. (2000). Phylogenetic analysis of bacterial communities in mesophilic and thermophilic bioreactors treating pharmaceutical wastewater. Appl Environ Microbiol 66, 39513959.
Macy, J. M., Rech, S., Auling, G., Dorsch, M., Stackebrandt, E. & Sly, L. I. (1993). Thauera selenatis gen. nov., sp. nov., a member of the beta subclass of Proteobacteria with a novel type of anaerobic respiration. Int J Syst Bacteriol 43, 135142.
Manaia, C. M. & Moore, E. R. B. (2002). Pseudomonas thermotolerans sp. nov., a thermotolerant species of the genus Pseudomonas sensu stricto. Int J Syst Evol Microbiol 52, 22032209.[Abstract]
Manaia, C. M., Nunes, O. C. & Nogales, B. (2003). Caenibacterium thermophilum gen. nov., sp. nov., isolated from a thermophilic aerobic digester of municipal sludge. Int J Syst Evol Microbiol 53, 13751382.
Mechichi, T., Stackebrandt, E., Gad'on, N. & Fuchs, G. (2002). Phylogenetic and metabolic diversity of bacteria degrading aromatic compounds under denitrifying conditions, and description of Thauera phenylacetica sp. nov., Thauera aminoaromatica sp. nov., and Azoarcus buckelii sp. nov. Arch Microbiol 178, 2635.[CrossRef][Medline]
Moreira, C., Rainey, F. A., Nobre, M. F., da Silva, M. T. & da Costa, M. S. (2000). Tepidimonas ignava gen. nov., sp. nov., a new chemolithoheterotrophic and slightly thermophilic member of the
-Proteobacteria. Int J Syst Evol Microbiol 50, 735742.[Abstract]
Odintsova, E. V., Jannasch, H. W., Mamone, J. A. & Langworthy, T. A. (1996). Thermothrix azorensis sp. nov., an obligately chemolithoautotrophic, sulfur-oxidizing, thermophilic bacterium. Int J Syst Bacteriol 46, 422428.
Pearson, W. R. & Lipman, D. J. (1988). Improved tools for biological sequence comparison. Proc Natl Acad Sci U S A 85, 24442448.
Reinhold-Hurek, B. & Hurek, T. (2000). Reassessment of the taxonomic structure of the diazotrophic genus Azoarcus sensu lato and description of three new genera and new species, Azovibrio restrictus gen. nov., sp. nov., Azospira oryzae gen. nov., sp. nov. and Azonexus fungiphilus gen. nov., sp. nov. Int J Syst Evol Microbiol 50, 649659.[Abstract]
Reinhold-Hurek, B., Hurek, T., Gillis, M., Hoste, B., Vancanneyt, M., Kersters, K. & De Ley, J. (1993). Azoarcus gen. nov., nitrogen-fixing proteobacteria associated with roots of Kallar grass (Leptochloa fusca (L.) Kunth), and description of two species, Azoarcus indigens sp. nov. and Azoarcus communis sp. nov. Int J Syst Bacteriol 43, 574584.
Shooner, F., Bousquet, J. & Tyagi, R. D. (1996). Isolation, phenotypic characterization, and phylogenetic position of a novel, facultatively autotrophic, moderately thermophilic bacterium, Thiobacillus thermosulfatus sp. nov. Int J Syst Bacteriol 46, 409415.
Smibert, R. M. & Krieg, N. R. (1981). General characterization. In Manual of Methods for General Microbiology, pp. 409443. Edited by P. Gerhardt, R. G. E. Murray, R. N. Costilow, E. W. Nester, W. A. Wood, N. R. Krieg & G. H. Phillips. Washington, DC: American Society for Microbiology.
Song, B., Young, L. Y. & Palleroni, N. J. (1998). Identification of denitrifier strain T1 as Thauera aromatica and proposal for emendation of the genus Thauera definition. Int J Syst Bacteriol 48, 889894.
Song, B., Häggblom, M. M., Zhou, J., Tiedje, J. M. & Palleroni, N. J. (1999). Taxonomic characterization of denitrifying bacteria that degrade aromatic compounds and description of Azoarcus toluvorans sp. nov. and Azoarcus toluclasticus sp. nov. Int J Syst Bacteriol 49, 11291140.
Song, B., Palleroni, N. J. & Häggblom, M. M. (2000). Description of strain 3CB-1, a genomovar of Thauera aromatica, capable of degrading 3-chlorobenzoate coupled to nitrate reduction. Int J Syst Evol Microbiol 50, 551558.[Abstract]
Song, B., Palleroni, N. J., Kerkhof, L. J. & Häggblom, M. M. (2001). Characterization of halobenzoate-degrading, denitrifying Azoarcus and Thauera isolates and description of Thauera chlorobenzoica sp. nov. Int J Syst Evol Microbiol 51, 589602.[Abstract]
Springer, N., Ludwig, W., Philipp, B. & Schink, B. (1998). Azoarcus anaerobius sp. nov., a resorcinol-degrading, strictly anaerobic, denitrifying bacterium. Int J Syst Bacteriol 48, 953956.
Stackebrandt, E. & Goebel, B. M. (1994). Taxonomic note: a place for DNA-DNA reassociation and 16S rRNA sequence analysis in the present species definition in bacteriology. Int J Syst Bacteriol 44, 846849.
Stöhr, R., Waberski, A., Liesack, W., Völker, H., Wehmeyer, U. & Thomm, M. (2001). Hydrogenophilus hirschii sp. nov., a novel thermophilic hydrogen-oxidizing
-proteobacterium isolated from Yellowstone National Park. Int J Syst Evol Microbiol 51, 481488.[Abstract]
Suzuki, K., Goodfellow, M. & O'Donnell, A. G. (1993). Cell envelopes and classification. In Handbook of New Bacterial Systematics, pp. 195250. Edited by M. Goodfellow & A. G. O'Donnell. London: Academic Press.
Takeda, M., Kamagata, Y., Ghiorse, W. C., Hanada, S. & Koizumi, J. (2002). Caldimonas manganoxidans gen. nov., sp nov., a poly(3-hydroxybutyrate)-degrading, manganese-oxidizing thermophile. Int J Syst Evol Microbiol 52, 895900.[Abstract]
Ward, D. M., Ferris, M. J., Nold, S. C. & Bateson, M. M. (1998). A natural view of microbial biodiversity within hot spring cyanobacterial mat communities. Microbiol Mol Biol Rev 62, 13531370.
Wilkinson, S. G. (1988). Gram-negative bacteria. In Microbial Lipids, vol. I, p. 299488. Edited by C. Ratledge & S. G. Wilkinson. London: Academic Press.
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