HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Abstract Full Text (PDF) Supplementary Figures Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Wolterink, A. Articles by Kengen, S. W. M. Search for Related Content PubMed PubMed Citation Articles by Wolterink, A. Articles by Kengen, S. W. M. Agricola Articles by Wolterink, A. Articles by Kengen, S. W. M.

Dechloromonas hortensis sp. nov. and strain ASK-1, two novel (per)chlorate-reducing bacteria, and taxonomic description of strain GR-1

¹ Laboratory of Microbiology, Wageningen University, Hesselink van Suchtelenweg 4, 6703 CT Wageningen, The Netherlands
² Department of Environmental Science and Engineering, Kwangju Institute of Science and Technology, Oryong-dong 1, Puk-gu, Gwangju, Korea
³ Laboratory of Toxicology, Pathology and Genetics, National Institute of Public Health and the Environment (RIVM), PO Box 1, 3720 BA Bilthoven, The Netherlands
⁴ Akzo Nobel Central Research, Analytical and Environmental Chemistry Department, PO Box 9300, 6800 SB Arnhem, The Netherlands

Correspondence
Servé W. M. Kengen
serve.kengen{at}wur.nl

	ABSTRACT

TOP ABSTRACT MAIN TEXT REFERENCES

 
Recent studies on the occurrence of (per)chlorate-reducing bacteria have resulted in the characterization of strains capable of dissimilatory (per)chlorate reduction. Phylogenetic analysis has shown that these bacteria are members of the Proteobacteria. Strains have been isolated from polluted and pristine sites, but only strains from polluted sites have been characterized in detail and deposited in culture collections. Herein we describe the isolation and characterization of perchlorate-reducing bacterium strain MA-1^T and chlorate-reducing bacterium strain ASK-1, respectively isolated from a pristine and a chlorate-polluted site. Both isolates are members of the Proteobacteria. The 16S rRNA gene sequence similarity of MA-1^T to Dechloromonas agitata DSM 13637^T is 97·6 %, but the relatedness in DNA–DNA reassociation is only 37 %. Therefore, we propose to classify strain MA-1^T (=DSM 15637^T=ATCC BAA-776^T) as the type strain of a novel species, Dechloromonas hortensis sp. nov. Strain ASK-1 and a previously described strain GR-1 show 100 and 99 % 16S rRNA gene sequence similarity to Pseudomonas chloritidismutans DSM 13592^T and Dechlorosoma suillum DSM 13638^T, respectively. DNA–DNA hybridization studies indicated that strains ASK-1 and GR-1 are related at the species level to P. chloritidismutans DSM 13592^T (79 %) and Dechlorosoma suillum DSM 13638^T (85 %), respectively. As suggested previously, Dechlorosoma suillum appears to be a later heterotypic synonym of Azospira oryzae. Although strain ASK-1 is identified as P. chloritidismutans, its morphology and growth requirements are different from those of the type strain.

The GenBank/EMBL/DDBJ accession numbers of the 16S rRNA gene sequences of strains ASK-1, MA-1 and GR-1 are AY277620, AY277621 and AY277622.

Photographs of colonies and cell extracts of P. chloritidismutans and strain ASK-1 and a transmission electron micrograph of cells of strain GR-1 are available as supplementary material in IJSEM Online.

	MAIN TEXT

TOP ABSTRACT MAIN TEXT REFERENCES

 
The occurrence of perchlorate and chlorate in natural environments is due mainly to human activities. Chlorate is used as a herbicide, as a catalyst in matches and for onsite production of chlorine dioxide (ClO₂), a bleaching agent employed in the paper and pulp industries. Perchlorate is used as rocket propellant in the defence and aerospace industries. In the United States, discharge of perchlorate-containing waste streams has been identified as the major source of perchlorate contamination in drinking water supplies (Renner, 1998; US Environmental Protection Agency, 2000). Chlorate and perchlorate are highly soluble and chemically stable under environmental conditions (Urbansky, 2002). Remediation strategies by chemical reduction or by adsorption to activated carbon are either too slow or incomplete (Urbansky, 1998). Recent research has shown that bioremediation may be the most economically feasible, fastest and easiest means of treating (per)chlorate-contaminated sites and water sources (Coates & Achenbach, 2004). (Per)chlorate-reducing bacteria are able to perform a complete reduction of (per)chlorate to chloride using various carbon compounds or hydrogen as electron donor. (Per)chlorate is reduced to chlorite by a (per)chlorate reductase [EC 1.97.1.1] (Kengen et al., 1999) and subsequently chlorite is converted to chloride and oxygen by a chlorite dismutase [EC 1.13.11.49] (van Ginkel et al., 1996).

(Per)chlorate-reducing bacteria are widespread in nature (van Ginkel et al., 1995; Coates et al., 1999; Wu et al., 2001) and have been isolated from chlorate- and perchlorate-contaminated sites. For example, ‘Acinetobacter thermotoleranticus’ was isolated from a match-factory waste stream (Stepanyuk et al., 1992). Previous studies on the ubiquity and diversity of (per)chlorate-reducing bacteria resulted in the description of Dechloromonas and Dechlorosoma species; to date, these appear to be the dominant (per)chlorate-reducing bacteria in the environment (Coates et al., 1999). (Per)chlorate-reducing activity has been observed not only in chlorate- or perchlorate-polluted samples, but also in pristine sediments and soils (van Ginkel et al., 1995; Coates et al., 1999; Wu et al., 2001). However, no isolate from a pristine setting has been characterized or deposited in culture collections. Here, we describe two novel strains, MA-1^T and ASK-1, isolated, respectively, from garden soil and the sludge of a bioreactor treating a bromate-/chlorate-polluted waste stream. We also performed phylogenetic analysis on a third, previously described strain, strain GR-1 (Rikken et al., 1996). Strain GR-1 was included here because it represents one of the best studied (per)chlorate-reducing bacteria, especially concerning the biochemistry of the reduction process. However, a taxonomic description was as yet lacking.

Enrichment and cultivation of strains MA-1^T and ASK-1 were performed in anoxic medium as described previously for Pseudomonas chloritidismutans DSM 13592^T (Wolterink et al., 2002) with the following modifications: The gas phase used was N₂/CO₂ (80 : 20) and, instead of 0·5 g Na₂S, 0·2 g Na₂SO₄ was used as a sulfur source (Wolterink et al., 2002). For the isolation of both strains, chlorate (10 mM) and acetate (10 mM) were used as electron acceptor and electron donor, respectively. Batch cultures were incubated in the dark at 30 °C, pH 7·2, on an orbital shaker set at 100 r.p.m. For enrichment and isolation of strain ASK-1, sludge was taken from an anaerobic bioreactor treating chlorate-/bromate-polluted wastewater. Samples from this sludge were also used to isolate P. chloritidismutans DSM 13592^T (Wolterink et al., 2002). Pure cultures of strain ASK-1 were obtained following repeated application of the roll-tube dilution method (Hungate, 1969). To isolate strain MA-1^T, approximately 2 g garden soil was added to 40 ml of the medium described above. Strain MA-1^T was isolated to purity on aerobically incubated nutrient agar plates. Enrichment cultures were monitored for chlorate reduction by analysing the growth medium by HPLC as described previously (Scholten & Stams, 1995). Oxygen levels were measured by GC as described by Stams et al. (1993). Substrates were added from 0·8 M stock solutions to give final concentrations of 10 mM. Use of the following electron donors (10 mM) was evaluated with chlorate (10 mM) as electron acceptor: acetate, propionate, glucose, maltose, mannitol, malate, lactate, arabinose, hydrogen, glycine, glycerol, formate, gluconate, ethanol, starch, citrate and succinate. The following electron acceptors (10 mM) were tested with acetate (10 mM) as electron donor: perchlorate, chlorate, chlorite, nitrate, bromate, sulfate and oxygen. All anions were supplied as sodium salts. For strain MA-1^T, Fe³⁺ reduction to Fe²⁺ [Fe³⁺ applied as iron(III) citrate] was monitored spectrophotometrically at 562 nm using the ferrozine assay described by Lovley & Phillips (1987). Different medium pH values were obtained by changing the CO₂ concentration appropriately in the gas phase, calculated using the Henderson–Hasselbach equation (Wolterink et al., 2002). Growth was followed at the following temperatures: 10, 20, 30, 37 and 50 °C. Strain GR-1 (=DSM 11199) was grown in a medium described before (Rikken et al., 1996) with modifications described by Kengen et al. (1999), P. chloritidismutans DSM 13592^T was grown in the medium described by Wolterink et al. (2002) and Pseudomonas stutzeri DSM 50227 was grown in the medium described by Matsubara et al. (1982) as modified by Coyle et al. (1985). Gram-type was determined by Gram staining using the protocol described by Plugge et al. (2000).

Almost full-length (approx. 95 %) 16S rRNA gene sequences for strains ASK-1, MA-1^T and GR-1 were determined at the DSMZ by direct sequencing of PCR-amplified 16S rRNA genes as described by Rainey et al. (1996). 16S rRNA gene sequences were analysed using ARB software (Ludwig & Strunk, 1996). 16S rRNA gene sequences of the three strains were compared to the following type strains: P. chloritidismutans DSM 13592^T (GenBank accession no. AY017341), Dechloromonas agitata DSM 13637^T (AF047462) and Azospira oryzae LMG 9096^T (AF011347). Also, P. stutzeri DSM 50227 (GenBank accession no. U26415), closely related to P. chloritidismutans DSM 13592^T (Wolterink et al., 2002), and Dechlorosoma suillum DSM 13638^T (AF170348), closely related to Azospira oryzae LMG 9096^T, were used for 16S rRNA gene sequence comparison. Genomic DNA was isolated by chromatography on hydroxyapatite after the method of Cashion et al. (1977). DNA–DNA hybridization between strain GR-1 and Dechlorosoma suillum DSM 13638^T, strain MA-1^T and Dechloromonas agitata DSM 13637^T and strain ASK-1 and P. chloritidismutans DSM 13592^T was carried out as described by De Ley et al. (1970), as modified by Huß et al. (1983) and Escara & Hutton (1980). Renaturation rates were computed with the TRANSFER.BAS program (Jahnke, 1992). The G+C content of strain MA-1^T was determined using the HPLC method described by Mesbah et al. (1989); unmethylated lambda DNA (Sigma) was used as the standard. DNA–DNA hybridization studies as well as G+C analyses were conducted at the DSMZ.

Cell extracts were prepared in an anaerobic glovebox containing H₂/N₂ (4 : 96) gas (Wolterink et al., 2002). Oxyanion reductase activities were determined spectrophotometrically, as described previously by Kengen et al. (1999), by monitoring the oxidation of reduced methyl viologen at 578 nm and 30 °C. Chlorite dismutase activity was determined as described by Wolterink et al. (2002), by measuring O₂ production with a Clark-type oxygen electrode (Yellow Springs Instruments). We define 1 U activity as the amount of enzyme required to convert 1 µmol chlorite (or chlorate, bromate, nitrate) min^–1. The protein content of the cell extracts was determined according to the method of Bradford (1976) with BSA as the standard.

Cells of strain GR-1 were prepared for electron microscopy by fixation in 4 % formaldehyde in 0·01 M PBS (pH 7·6). Cells were subsequently washed, dispersed in PBS and adsorbed to glow-discharged, carbon-stabilized, Formvar-coated nickel grids, negatively stained using 2·0 % ammonium molybdate (pH 5·1) or 2·0 % potassium phosphotungstate (pH 6·0), and analysed in a Philips TECNAI 12 electron microscope at an operating voltage of 80 kV. Images were digitally stored and analysed using analySIS (Soft-imaging software). Images were printed after grey-value modification.

Strain ASK-1
The 16S rRNA gene sequence of strain ASK-1 was 100 % similar to those of P. chloritidismutans DSM 13592^T and P. stutzeri DSM 50227 (Wolterink et al., 2002). DNA–DNA hybridization between strain ASK-1 and P. chloritidismutans DSM 13592^T showed 79 % relatedness. To differentiate two species, DNA–DNA similarity should be less than 60–70 % (Stackebrandt & Goebel, 1994). Therefore, strain ASK-1 is identified as a strain of P. chloritidismutans. Both bacteria are chlorate-reducing bacteria that can only grow with oxygen and chlorate as electron acceptors. Details of utilization of electron donors and acceptors are available in Table 1. Apparently, respiration with chlorate is the only energy-yielding process under anaerobic conditions. The observed doubling times for P. chloritidismutans DSM 13592^T and strain ASK-1 were respectively 1·5 and 10·6 h when chlorate and acetate were used as electron acceptor and electron donor. Respiration with chlorate is reflected in the observed chlorate reductase activity in cell-free extracts of ASK-1 (6·1 U mg^–1). Bromate reductase activity (4·5 U mg^–1) was also found, although no growth was observed on this compound. No reductase activity was found for , or . Similar results have been obtained for P. chloritidismutans DSM 13592^T, with chlorate and bromate reductase activities of 9·0 and 8·6 U mg^–1, respectively (Wolterink et al., 2002). Despite the phylogenetic and physiological similarities, a morphological difference was seen when chlorate-grown cells were plated under aerobic conditions on nutrient agar plates. P. chloritidismutans DSM 13592^T formed yellow–brown circular colonies and strain ASK-1 formed white circular colonies. Remarkably, a cell extract of chlorate-grown cells of P. chloritidismutans DSM 13592^T (grown in strictly anaerobic medium) had a red–brownish colour, whereas a cell extract of chlorate-grown cells of strain ASK-1 (grown in anoxic medium) was white. This colour difference of chlorate-grown cells is most likely a result of the level of haem-containing chlorite dismutase in cell extracts, which was found to be respectively 134 and 6·3 U mg^–1 for P. chloritidismutans and strain ASK-1. Pictures of these colonies and cell extracts are available as Supplementary Fig. S1 in IJSEM Online. The strain has been deposited as P. chloritidismutans strain ASK-1 (=DSM 15671=ATCC BAA-775).

A. oryzae LMG 9096^T and Dechlorosoma suillum DSM 13638^T share many phenotypic characteristics, including carbon source utilization preferences. Both bacteria are able to fix N₂, which is a distinguishing feature of A. oryzae LMG 9096^T. A nifH homologue has been detected in both strains, and Tan & Reinhold-Hurek (2003) observed that both can reduce acetylene (C₂H₂) to ethylene (C₂H₄), which confirms that the nifH gene is functional and nitrogenase is present. However, there is a key difference between these strains, the inability of A. oryzae LMG 9096^T to perform dissimilatory perchlorate reduction.

Details of electron donor and acceptor usage of strain GR-1 are available in Table 1. Supplementary Fig. S2 depicts an electron micrograph of cells of strain GR-1. The cells possess a single polar flagellum and are rod-shaped with dimensions of 1·8±0·2x0·60±0·05 µm. The micrograph reveals electron-transparent globules that vary in size and number among cells. These globules possibly contain poly--hydroxybutyrate or other kinds of poly--hydroxyalkanoates (Thalen et al., 1999). We also found strain GR-1 to have fimbriae, by which it can presumably attach itself to surfaces (data not shown).

Strain MA-1^T
Strain MA-1^T showed 99·9 and 97·6 % 16S rRNA gene sequence similarity to Dechloromonas sp. strain SIUL and Dechloromonas agitata DSM 13637^T, respectively. The 16S rRNA gene sequence similarity between strain MA-1^T and Ferribacterium limneticum CdA-1^T was 97·5 %. Unfortunately, this strain is not available in culture collections and therefore could not be included in further studies. DNA–DNA hybridization between Dechloromonas agitata DSM 13637^T and strain MA-1^T showed only 37 % relatedness, indicating that strain MA-1^T represents a distinct species. The G+C content for strain MA-1^T is 63·6 mol%, which is similar to that of Dechloromonas agitata (63·6 mol%). Based on the 16S rRNA gene sequence data, strain MA-1^T resides in the Dechloromonas group (Achenbach et al., 2001), which also contains the genera Rhodocyclus and Ferribacterium. However, representatives of the latter two genera are not capable of chlorate reduction nor do they dismutate chlorite to chloride and O₂. Moreover, F. limneticum is capable of Fe(III) reduction. Strain MA-1^T was not able to grow by Fe(III) reduction, similar to other chlorate-reducing bacteria (Coates et al., 1999). It has already been concluded that F. limneticum is indeed a member of a separate genus distinct from Dechloromonas (Achenbach et al., 2001). Taken together, these data imply that strain MA-1^T should be classified as a separate species within the genus Dechloromonas, and we propose the name Dechloromonas hortensis sp. nov.

Strain MA-1^T was unable to grow in anoxic medium reduced with sulfide, which indicated that sulfide cannot serve as an alternative electron donor, as was described for Dechloromonas agitata DSM 13637^T (Achenbach et al., 2001). Results of the physiological characterization are given in the species description. The results of a physiological comparison of the three strains described above are available in Table 2. Optimal growth of strain MA-1^T was obtained at pH 7·2 and at a temperature of 30 °C. In cell extracts, the specific activity of chlorate reductase was 3·12 U mg^–1, while the chlorite dismutase had a specific activity of 155 U mg^–1. Strain MA-1^T was isolated from a garden soil with no known history of (per)chlorate contamination. Gram-staining showed that strain MA-1^T is a Gram-negative bacterium.

Gram-negative, facultatively anaerobic, motile bacterium. Colonies on (aerobic) nutrient agar plates are circular and have a yellow colour. In anoxic medium, which is not reduced with sulfide, optimal growth is obtained at pH 7·2 and at a temperature of 30 °C. Growth occurs with acetate and propionate as electron donors. No growth is found with citrate, gluconate, glucose, mannitol, maltose, starch, ethanol, methanol or sulfide. Perchlorate, chlorate, nitrate and oxygen are used as electron acceptors. Cell extract contains perchlorate, chlorate, nitrate and bromate reductase activities. Chlorite is converted to chloride and oxygen. The specific activity of the chlorite dismutase in cell extracts is 155 U mg^–1. The species belongs to the ‘Betaproteobacteria’. The 16S rRNA gene sequence is 99·9 % similar to that of Dechloromonas sp. strain SIUL. The highest similarity to a species with a validly published name is 97·6 %, to Dechloromonas agitata DSM 13637^T. DNA–DNA hybridization between the type strain and Dechloromonas agitata DSM 13637^T shows 37 % relatedness. The G+C content of the type strain is 63·6 mol%.

The type strain, MA-1^T (=DSM 15637^T=ATCC BAA-776^T), was obtained from a garden soil.

	ACKNOWLEDGEMENTS

 
We thank H. G. Trüper for advice concerning the nomenclature of strain MA-1^T. This work was supported by the Earth and Life Sciences Foundation (ALW), which is subsidized by the Netherlands Organization for Scientific Research (NWO).

	REFERENCES

TOP ABSTRACT MAIN TEXT REFERENCES

 
Achenbach, L. A., Michaelidou, U., Bruce, R. A., Fryman, J. & Coates, J. D. (2001). Dechloromonas agitata gen. nov., sp. nov. and Dechlorosoma suillum gen. nov., sp. nov., two novel environmentally dominant (per)chlorate-reducing bacteria and their phylogenetic position. Int J Syst Evol Microbiol 51, 527–533.[Abstract]

Bradford, M. M. (1976). A rapid and sensitive method for the quantification of microgram quantities of protein utilizing the principle of protein-dye binding. Anal Biochem 72, 248–254.[CrossRef][Medline]

Cashion, P., Holder-Franklin, M. A., McCully, J. & Franklin, M. (1977). A rapid method for the base ratio determination of bacterial DNA. Anal Biochem 81, 461–466.[CrossRef][Medline]

Coates, J. D. & Achenbach, L. A. (2004). Microbial perchlorate reduction: rocket-fueled metabolism. Nat Rev Microbiol 2, 569–580.[CrossRef][Medline]

Coates, J. D., Michaelidou, U., Bruce, R. A., O'Connor, S. M., Crespi, J. N. & Achenbach, L. A. (1999). Ubiquity and diversity of dissimilatory (per)chlorate-reducing bacteria. Appl Environ Microbiol 65, 5234–5241.[Abstract/Free Full Text]

Coyle, C. L., Zumft, W. G., Kroneck, P. M., Korner, H. & Jakob, W. (1985). Nitrous oxide reductase from denitrifying Pseudomonas perfectomarina. Purification and properties of a novel multicopper enzyme. Eur J Biochem 153, 459–467.[Medline]

Cummings, D. E., Caccavo, F., Jr, Spring, S. & Rosenweig, R. F. (1999). Ferribacterium limneticum, gen. nov., sp. nov., an Fe(III)-reducing microorganism isolated from mining-impacted freshwater lake sediments. Arch Microbiol 171, 183–188.[CrossRef]

De Ley, L., Cattoir, H. & Reynaerts, A. (1970). The quantitative measurement of DNA hybridization from renaturation rates. Eur J Biochem 12, 133–142.[Medline]

Escara, J. F. & Hutton, J. R. (1980). Thermal stability and renaturation of DNA in dimethyl sulfoxide solutions: acceleration of the renaturation rate. Biopolymers 19, 1315–1327.[CrossRef][Medline]

Hungate, R. E. (1969). A roll tube method for cultivation of strict anaerobes. Methods Microbiol 3B, 117–132.

Hurek, T. & Reinhold-Hurek, B. (1995). Identification of grass-associated and toluene-degrading diazotrophs, Azoarcus spp., by analyses of partial 16S ribosomal DNA sequences. Appl Environ Microbiol 61, 2257–2261.[Abstract]

Huß, V. A. R., Festl, H. & Schleifer, K. H. (1983). Studies on the spectrometric determination of DNA hybridization from renaturation rates. Syst Appl Microbiol 4, 184–192.

Jahnke, K.-D. (1992). Basic computer program for evaluation of spectroscopic DNA renaturation data from Gilford System 2600 spectrometer on a PC/XT/AT type personal computer. J Microbiol Methods 15, 61–73.

Kengen, S. W. M., Rikken, G. B., Hagen, W. R., van Ginkel, C. G. & Stams, A. J. M. (1999). Purification and characterization of (per)chlorate reductase from the chlorate-respiring strain GR-1. J Bacteriol 181, 6706–6711.[Abstract/Free Full Text]

Lovley, D. R. & Phillips, E. J. P. (1987). Rapid assay for microbially reducible ferric iron in aquatic sediments. Appl Environ Microbiol 53, 1536–1540.[Abstract/Free Full Text]

Ludwig, W. & Strunk, O. (1996). ARB, a software environment for sequence data. http://www.arb-home.de/

Matsubara, T., Frunzke, K. & Zumft, W. G. (1982). Modulation by copper of the products of nitrite respiration in Pseudomonas perfectomarinus. J Bacteriol 149, 816–823.[Abstract/Free Full Text]

Mesbah, M., Premachandran, U. & Whitman, W. B. (1989). Precise measurement of the G+C content of deoxyribonucleic acid by high-performance liquid chromatography. Int J Syst Bacteriol 39, 159–167.

Plugge, C. M., Zoetendal, E. G. & Stams, A. J. M. (2000). Caloramator coolhaasii sp. nov., a glutamate-degrading, moderately thermophilic anaerobe. Int J Syst Evol Microbiol 50, 1155–1162.[Abstract]

Rainey, F. A., Ward-Rainey, N., Kroppenstedt, R. M. & Stackebrandt, E. (1996). The genus Nocardiopsis represents a phylogenetically coherent taxon and distinct actinomycete lineage: proposal of Nocardiopsaceae fam. nov. Int J Syst Bacteriol 46, 1088–1092.[Abstract/Free Full Text]

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, 649–659.[Abstract]

Renner, R. (1998). Perchlorate-tainted wells spur government action. Environ Sci Technol 32, 210A.

Rikken, G. B., Kroon, A. G. M. & van Ginkel, C. G. (1996). Transformation of (per)chlorate into chloride by a newly isolated bacterium: reduction and dismutation. Appl Microbiol Biotechnol 45, 420–426.[CrossRef]

Scholten, J. C. M. & Stams, A. J. M. (1995). The effect of sulfate and nitrate on methane formation in a freshwater sediment. Antonie van Leeuwenhoek 68, 309–315.[CrossRef][Medline]

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, 846–849.[Abstract/Free Full Text]

Stams, A. J. M., van Dijk, J. B., Dijkema, C. & Plugge, C. M. (1993). Growth of syntrophic propionate-oxidizing bacteria with fumarate in the absence of methanogenic bacteria. Appl Environ Microbiol 59, 1114–1119.[Abstract/Free Full Text]

Stepanyuk, V. V., Smirnova, G. F., Klyushnikova, T. M., Kanyuk, N. I., Panchenko, L. P., Nogina, T. M. & Prima, V. I. (1992). New species of the Acinetobacter genus, Acinetobacter thermotoleranticus sp. nov. Mikrobiologiia 61, 490–500 (in Russian).

Tan, Z. & Reinhold-Hurek, B. (2003). Dechlorosoma suillum Achenbach et al. 2001 is a later subjective synonym of Azospira oryzae Reinhold-Hurek and Hurek 2000. Int J Syst Evol Microbiol 53, 1139–1142.[Abstract/Free Full Text]

Thalen, M., van de IJsel, J., Jiskoot, W., Zomer, B., Roholl, P. J. M., de Gooijer, C., Beuvery, C. & Tramper, J. (1999). Rational medium design for Bordetella pertussis: basic metabolism. J Biotechnol 75, 147–159.[CrossRef][Medline]

Urbansky, E. T. (1998). Perchlorate chemistry: implications for analysis and remediation. Bioremediat J 2, 81–95.

Urbansky, E. T. (2002). Perchlorate as an environmental contaminant. Environ Sci Pollut Res Int 9, 187–192.[Medline]

US Environmental Protection Agency (2000). The effect of ammonium perchlorate on thyroids. Pathology Working Group Report. Washington, DC: National Center for Environmental Assessment, US EPA. http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=15262

van Ginkel, C. G., Plugge, C. M. & Stroo, C. A. (1995). Reduction of chlorate with various energy substrates and inocula under anaerobic conditions. Chemosphere 31, 4057–4066.[CrossRef]

van Ginkel, C. G., Rikken, G. B., Kroon, A. G. M. & Kengen, S. W. M. (1996). Purification and characterization of chlorite dismutase: a novel oxygen-generating enzyme. Arch Microbiol 166, 321–326.[CrossRef][Medline]

Wolterink, A. F. W. M., Jonker, A. B., Kengen, S. W. M. & Stams, A. J. M. (2002). Pseudomonas chloritidismutans sp. nov., a non-denitrifying, chlorate-reducing bacterium. Int J Syst Evol Microbiol 52, 2183–2190.[Abstract]

Wu, J., Unz, R. F., Zhang, H. & Logan, B. E. (2001). Persistence of perchlorate and the relative numbers of perchlorate- and chlorate-respiring microorganisms in natural waters, soils, and wastewater. Bioremediat J 5, 119–130.[CrossRef]

This article has been cited by other articles:

				M. Balk, T. van Gelder, S. A. Weelink, and A. J. M. Stams (Per)chlorate Reduction by the Thermophilic Bacterium Moorella perchloratireducens sp. nov., Isolated from Underground Gas Storage Appl. Envir. Microbiol., January 15, 2008; 74(2): 403 - 409. [Abstract] [Full Text] [PDF]

This Article Abstract Full Text (PDF) Supplementary Figures Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Wolterink, A. Articles by Kengen, S. W. M. Search for Related Content PubMed PubMed Citation Articles by Wolterink, A. Articles by Kengen, S. W. M. Agricola Articles by Wolterink, A. Articles by Kengen, S. W. M.