| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
1 Department of Biological and Biomedical Sciences, Glasgow Caledonian University, Cowcaddens Road, Glasgow G4 0BA, UK
2 Vakgroep BFM WE10V, Laboratorium voor Microbiologie, Universiteit Gent, K.L. Ledeganckstraat 35, B-9000 Gent, Belgium
3 Grupo de Microbiología Ambiental, Departamento de Microbiología, Campus de Cartuja s/n, Universidad de Granada, 18071 Granada, Spain
Correspondence
Niall A. Logan
N.A.Logan{at}gcal.ac.uk
 |
ABSTRACT |
|---|
 TOP ABSTRACT MAIN TEXTREFERENCES |
|---|
The GenBank/EMBL/DDBJ accession numbers for the 16S rRNA and nifH gene sequences of Paenibacillus wynnii LMG 22176T are AJ633647 and AJ867247, respectively.
A map showing the location of Alexander Island, an additional phylogenetic tree based on nifH gene sequences, two tables detailing fatty acid content and a similarity matrix of nifH gene sequences of Paenibacillus species are available as supplementary material in IJSEM Online.
|
MAIN TEXT |
|---|
|
TOPABSTRACTMAIN TEXTREFERENCES |
|---|
) (Supplementary Fig. S1 available in IJSEM Online). From the austral summer of 1993/94 onwards, Mars Oasis was developed as a research site by the late Dr David Wynn-Williams to study ‘survival and colonization at biological limits’. Dr Wynn-Williams described the site as remarkable due to the presence of two pools which have abundant algal and cyanobacterial communities. These communities are also present in fine soils. Green moss is locally abundant, rather than the blackened form prevalent on exposed ridges (Wynn-Williams, 1993).
Aerobic endospore-forming bacteria have been isolated from Antarctic soils in the past. Most of the recently described species from these habitats are thermoacidophiles belonging to the genus Alicyclobacillus (Nicolaus et al., 1998) or to the genus Bacillus (Hudson et al., 1989; Llarch et al., 1997; Logan et al., 2000; Nicolaus et al., 1996). Other isolates belong to established neutrophilic species of Bacillus or remain unidentified (Forsyth & Logan, 2000; Hudson & Daniel, 1988; Hudson et al., 1988; Logan et al., 2002, 2004a; Ramana et al., 2000; Van Trappen et al., 2002; Xiao et al., 1994). Four species of Paenibacillus have been reported from Antarctic soils, all from maritime Antarctica (location map available as Supplementary Fig. S1 in IJSEM Online). Paenibacillus macquariensis (Marshall & Ohye, 1966; transferred to Paenibacillus by Ash et al., 1993) was isolated from Macquarie Island. Paenibacillus cineris and Paenibacillus cookii (Logan et al., 2004b) were both isolated from soil samples from Candlemas Island. Paenibacillus antarcticus (Montes et al., 2004) was isolated from the sediment of a lake on Livingston Island. Bacterial isolations from ice samples of the Dyer Plateau, near Alexander Island, did not yield any endospore-forming bacteria (Christner et al., 2000).
For the present study, 12 samples of soil collected from Mars Oasis in December 1999 were examined for the presence of endospore-forming bacteria as described by Logan et al. (2000). Endospore-forming isolates were purified and maintained on slopes of nutrient agar (NA; Oxoid) containing 5 mg MnSO4 l–1. Eleven out of the 12 soil samples yielded aerobic endospore-formers giving a total of 25 isolates. These isolates were subjected to a phenotypic analysis using the API 20E and API 50CH kits in conjunction with 50CHB/E medium (bioMérieux). Data were subjected to numerical analysis using Gower's general similarity coefficient (SG) as described by Logan et al. (2000). Three strains were identified as Bacillus cereus, Bacillus licheniformis and Bacillus megaterium (data not shown). Thirteen isolates that produced spherical endospores were morphologically similar to Bacillus sphaericus, but they were not identifiable as members of this species and await further study. Five of the soil samples yielded nine strains that showed similar microscopic appearances and biochemical profiles. Although plate cultures of these strains grew more slowly when incubated at 20 °C rather than at 30 °C, they produced larger numbers of colonies. Strains R-16774 and R-16897 were isolated from a soil sample taken from under a moss bank by a pond. R-16781 was from a silty moraine soil that had no moss cover and R-16780 was from soil lying beneath a moss mat in a pond. LMG 22176T, R-16777, R-16778 and R-16779 were repeated isolations from a sample of gypsum-encrusted soil. R-22540 was isolated from a sample of exposed polygon soil by a pond heavily colonized by cyanobacteria. Polygon soils are so named because of their surface patterning owing to the action of frost. The strains were characterized by phenotypic tests, amplified rDNA restriction analysis (ARDRA; using five restriction enzymes HaeIII, DpnII, RsaI, BfaI and Tru9I), SDS-PAGE analysis [with cells grown on NA supplemented with glucose (NAG) for 48 h and on trypticase soy agar (TSA; Oxoid) for 24 h] and gas chromatography of fatty acid methyl esters (FAME), as described by Logan et al. (2002). The 16S rRNA gene sequence and DNA base composition of strain LMG 22176T were determined as described by Logan et al. (2000).
As the levels of nitrogen in Antarctic soils are considered to be low (Holdgate et al., 1967; Lewis Smith, 1988; Wynn-Williams, 1996), we searched for the presence of the nitrogenase reductase structural gene, nifH, in our isolates. Strains belonging to Paenibacillus durus (LMG 4659), Paenibacillus borealis (LMG 21603T) and Rhizobium leguminosarum bv. viciae (patent strain CECT 4585) were included as positive controls and two strains of P. cookii (LMG 18419T and R-11600) and the type strain of P. cineris (LMG 18439T; Logan et al., 2004b) were also screened for the presence of the nifH gene. Universal degenerate primers PolF and PolR (Poly et al., 2001) were synthesized by Sigma-Genosys and used to amplify a 360 bp fragment from the nifH gene. The PCR amplification was performed from fresh colonies grown at room temperature for 2 days on NA as described by Pozo et al. (2002). The thermal cycling profile used was that of Poly et al. (2001), except that the initial denaturation step was extended to 7 min at 94 °C, as the Taq Gold polymerase used for this work (Applied Biosystems) requires a hot-start step, according to the manufacturer. Strains R-16780 and R-16781 did not yield any PCR products until the annealing temperature and time were set to 52 °C and 1·5 min, respectively. The nifH fragments obtained for strains LMG 22176T, R-16774, R-16780, R-16781, R-16897 and R-22540 were sequenced by the dideoxy chain terminator method, using the ABI-PRISM Big Dye Terminator Cycle Sequencing Ready Reaction kit and an automated sequencer (ABI 377; Applied Biosystems). The Mars Oasis Paenibacillus strains and the P. cineris and P. cookii type strains were also tested for nitrogenase activity by the acetylene-reduction method (Hardy et al., 1968). All strains were inoculated in screw-capped tubes with 5 ml semisolid (0·2 % agar) Burk's medium (Wilson & Knight, 1952) supplemented with 1 % glucose and 0·01 % yeast extract. Strains were stab-inoculated from fresh colonies grown on tryptone-yeast extract plates (Beringer, 1974) and incubated for 15 h at 28 °C. After incubation, the caps were replaced by silicone stoppers and 10 % of the inner atmosphere of the tubes was replaced by acetylene, generated from calcium carbide (Sigma) in distilled water. Tubes were incubated at 28 °C for 2 h after which 500 µl samples were removed from the tubes and analysed by gas chromatography as described by Rodelas et al. (1998).
The Mars Oasis isolates were found to be Gram-negative, facultatively anaerobic, motile rods which formed ellipsoidal or oval spores, lying subterminally and paracentrally in swollen and unswollen sporangia; swelling sometimes occurred at the opposite pole of the sporangium to the spore (Fig. 1). This sporangial morphology and a characteristic pattern of medium to strong acid production reactions from a wide range of carbohydrates in the API 50CHB gallery suggested that this group of strains might represent a species of the genus Paenibacillus. However, the reaction profiles in the API 20E strip and API 50CHB gallery and their microscopic morphologies did not allow the strains to be identified confidently with an established species of this genus (Table 1). Strains R-16774, R-16777, R-16778 and R-22540 clustered together at 90 % SG, R-16897 joined this cluster at 85 % SG and all merged with LMG 22176T, R-16781 and R-16779 at 80 % SG. Strain R-16780 showed a slightly narrower range of reactions and clustered with the other isolates at only 75 % SG. Notwithstanding this, the overall profile of the Mars Oasis isolates separated them from other Paenibacillus species in a cluster analysis based upon these phenotypic data. In the ARDRA study (data not shown), all of the Mars Oasis isolates showed identical profiles, which indicated that their 16S rRNA gene sequences are very similar. Comparison of ARDRA profiles of the strains with a database of over 1000 authentic strains of species of aerobic endospore-forming bacteria (including P. macquariensis and P. odorifer) did not yield any positive identification. The closest ARDRA pattern was that of P. macquariensis, with 80·9 % similarity. The 16S rRNA gene sequence of LMG 22176T, according to a FASTA search (Pearson & Lipman, 1988), showed highest similarity to the established species P. odorifer (96·1 %; Berge et al., 2002), P. borealis (95·2 %; Elo et al., 2001), P. macquariensis (95·2 %; Marshall & Ohye, 1966) and P. antarcticus (95·2 %; Montes et al., 2004). In a phylogenetic cluster (Fig. 2) based on the neighbour-joining algorithm (Saitou & Nei, 1987), LMG 22176T grouped with P. macquariensis and P. antarcticus (bootstrap value of 92 %). As the 16S rRNA gene sequence similarity of LMG 22176T with all established Paenibacillus species was well below 97 %, the Mars Oasis isolates can be considered as a novel genomospecies according to the current guidelines for the definition of a bacterial species (Stackebrandt et al., 2002). In the SDS-PAGE analysis of cultures grown on NAG, the medium on which the laboratory database is based, reproducible profiles were obtained for seven of the nine isolates, but R-16674 and R-22540 grew poorly on this medium. Strains LMG 22176T, R-16777, R-16778, R-16779, R-16781 and R-16897 clustered at 95 % similarity, while R-16780 joined this cluster at 89 %. These results reflect limited intraspecies variation (Fig. 3) and are consistent with these strains being representatives of the same species. R-16780 was the least typical member of the group in the phenotypic analysis based upon API tests. Cluster analysis of the SDS-PAGE profiles of the isolates together with those of the type strains of P. odorifer and P. macquariensis (also grown on NAG; data not shown) revealed that the Mars Oasis isolates could be readily separated from these species, showing similarities of 68 and 49 %, respectively. As strains R-16674 and R-22540 grew poorly on NAG, SDS-PAGE profiles were also determined for cells of all isolates grown on TSA; the profiles obtained in this way clearly clustered in two distinct groups (Fig. 3). One of these groups contained profiles that were quite similar to those derived from cells grown on NAG (84–91 % similarity), while the other group was clearly distinct (72 % similarity). These groupings of TSA-grown cells were not seen in the analyses of API characters or of fatty acid profiles (see below). Strain R-16774 showed 97 % similarity to R-16781 in the TSA-based analysis, while the latter strain showed 96 % similarity to R-16777, R-16778 and LMG 22176T in the NAG-based analysis, which implies that R-16774 and R-16781 probably belong to the same species. Less clear is the position of R-22540, which shows only 86 % similarity to R-16897; however, as the latter grouped with the five other isolates at 95 % similarity in the NAG-based analysis and showed a typical profile for the group in the API analysis, we may be confident that R-22540 also belongs to the species represented by the core strains LMG 22176T, R-16777, R-16778, R-16779, R-16780, R-16781 and R-16897. The variability of the SDS-PAGE profiles derived from cells grown on TSA might be explained solely by the composition of the medium, particularly the larger amounts of amino acids it contains. Another possible explanation is that better growth on TSA resulted in a shift, for some strains, of the growth phase at which cell extracts were prepared. The metabolism of spore-formers changes when spore formation starts and the Mars Oasis isolates would not sporulate on TSA.
|
|
|
|
When the Mars Oasis Paenibacillus isolates were screened for the nifH gene, all strains showed a band of the same molecular mass as described for the nifH fragment by Poly et al. (2001), while strains of P. cookii and P. cineris did not show any bands. Comparison of the nifH gene partial sequences of isolates LMG 22176T, R-16774, R-16780, R-16781, R-16897 and R-22540 with the EMBL database revealed that none of the fragments was identical to a previously known sequence. The closest nifH sequence (identity of 84·51 % for R-16781, to 86·78 % for LMG 22176T) was the one from ‘uncultured nitrogen fixing clone C5’ (GenBank accession no. AF099797; Widmer et al., 1999). Closest matches (81–76 %) of nifH sequences for species with validly published names were with P. graminis (GenBank accession no. AJ229394), P. macerans (AJ223993) and P. odorifer (AJ223992). Comparison of translated nifH sequences to NifH proteins from databases (not shown) gave in all cases the highest similarity to sequence AAD17884 (‘uncultured nitrogen-fixing bacterium C5’; Widmer et al., 1999). Several strains showed a typical aerotactic pattern of growth as described for microaerophilic nitrogen-fixing organisms (Döbereiner & Pedrosa, 1987). Acetylene-reduction was positive for P. cineris and P. cookii type strains and for Mars Oasis strains LMG 22176T, R-16774, R-16775, R-16778, R-16779, R-16781, R-16897 and R-22540. Mars Oasis strains R-16777 and R-16780 released little or no ethylene from acetylene. Results for acetylene reduction were, however, highly variable between different inoculations. The P. cineris and P. cookii type strains also grew in the other media tested (Döbereiner & Day, 1976; Mollica et al., 1985, supplemented with 0·01 % yeast extract and 0·2 % agar), while the Mars Oasis isolates failed to grow in either of them. Although considerable variability of the band strengths was found when screening for the nifH gene in the Mars Oasis Paenibacillus strains and no bands were found for P. cineris and P. cookii, all the strains tested were positive for acetylene reduction. These apparently contradictory observations are reminiscent of the experience of Achouak et al. (1999), who reported weak acetylene reduction reactions for different Paenibacillus amylolyticus, P. larvae, P. macquariensis and P. peoriae strains, although no nifH gene amplicon could be detected in their genomes. The sequences of the nifH gene obtained for strains R-16774 and R-22540 clustered with the sequences obtained for the other four Mars Oasis Paenibacillus isolates (nifH sequence similarity tree, Supplementary Fig. S2 and similarity matrix, Supplementary Table S3, available in IJSEM Online). It is interesting to note that the nifH gene sequence for an uncultivated organism from an Oregon forest site (Widmer et al., 1999) clusters together with those of the Mars Oasis isolates. Hamelin et al. (2002) commented that nifH gene sequences are well conserved and may be as effective taxonomic tools as 16S rRNA gene sequences. The high similarity of the nifH sequences of strains R-16774 and R-22540 to the nifH sequence of the representative strain of the Mars Oasis Paenibacillus isolates represents further confirmation that these strains belong to the same species.
Our failure to identify the Mars Oasis Paenibacillus isolates by the phenotypic and genotypic methods described and the high similarities of the strains to each other in these analyses support the proposal of a novel species, Paenibacillus wynnii sp. nov.
Description of Paenibacillus wynnii sp. nov.
Paenibacillus wynnii (wynn'i.i. N.L. gen. n. wynnii of Wynn, in honour of the late Dr. David Wynn-Williams, the Antarctic microbiologist who developed Mars Oasis as a research site).
Facultatively anaerobic, Gram-negative, motile, curved rods that occur singly or in pairs and have slightly tapered ends. Endospores are ellipsoidal or oval and lie paracentrally and subterminally in sporangia that may be swollen. Occasionally, the swelling may be at the opposite pole of the sporangium to the spore (Fig. 1
). Cell diameter is 0·5–0·7 µm and cell lengths range from 3–5 µm. After 3 days incubation on nutrient agar at 20 °C, the maximum colony diameter is 2 mm. Colonies are circular, convex and glossy with entire margins. Smaller colonies are transparent and whitish, while larger colonies are pale yellow–orange with whitish margins and darker centres. They bear a watery biomass, but may be mucoid. Older colonies are firmly attached to the agar. The optimum temperature for growth is 20 °C. Some strains grow at 37 °C, but none grow at 40 °C. Growth in broth at 4 °C appears within 7 days. Minimum pH for growth lies between 6·0 and 6·5, optimum pH is 7·0–8·0 and the maximum pH lies between 9·5 and 10·0. Catalase-positive and oxidase-negative. Does not tolerate the presence of 3 % NaCl. Growth on skimmed milk agar plates is scarce and casein is not hydrolysed. Starch is hydrolysed. The species fixes nitrogen as demonstrated by the presence of the nifH gene in all strains and acetylene reduction in most of them. In the API 20E strip, o-nitrophenyl 
-D-galactopyranoside hydrolysis is variable and nitrate is reduced. Arginine dihydrolase, lysine decarboxylase, ornithine decarboxylase, citrate utilization, hydrogen sulphide production, urease, tryptophan deaminase, indole production, Voges–Proskauer reaction and gelatin hydrolysis reactions are negative. In the API 50CH gallery using the CHB suspension medium, hydrolysis of aesculin is positive. Acid without gas is produced from the following carbohydrates: amygdalin, D-cellobiose, D-fructose, galactose, D-gentiobiose, D-glucose, glycogen, lactose, maltose, mannitol, D-mannose, D-melibiose, N-acetylglucosamine, D-raffinose, salicin, starch, sucrose, D-trehalose, D-turanose and D-xylose. Acid production is variable for L-arabinose, arbutin, gluconate, glycerol, inulin, D-melezitose, methyl-xyloside, rhamnose, ribose, sorbitol and xylitol. Acid is not produced from: adonitol, D-arabinose, D- and L-arabitol, dulcitol, erythritol, D- and L-fucose, 2-keto- and 5-keto-D-gluconate, D-lyxose, myo-inositol, methyl D-glucoside, methyl D-mannoside, L-sorbose, D-tagatose and L-xylose. The main cellular fatty acids are anteiso-C15 : 0 and C16 : 0, each present at about 33 %. The following fatty acids are present in smaller, decreasing amounts (between about 7 and 1 %) C16 : 1
11c, C14 : 0, iso-C15 : 0, iso-C14 : 0, iso-C16 : 0, C18 : 0 and iso-C17 : 0 (detailed FAME data are given in Supplementary Tables S1 and S2 available in IJSEM Online). The DNA G+C composition of LMG 22176T is 44·6 mol%. In the variable reactions listed above, the type strain is positive or weakly positive for: o-nitrophenyl -D-galactopyranoside hydrolysis and acid production from gluconate, glycerol, inulin, D-melezitose, rhamnose, sorbitol and xylitol.
The type strain, LMG 22176T (=CIP 108306T), was isolated from a soil sample collected from the Mars Oasis, Antarctica.
|
ACKNOWLEDGEMENTS |
|---|
|
REFERENCES |
|---|
|
TOPABSTRACTMAIN TEXTREFERENCES |
|---|
Ash, C., Priest, F. G. & Collins, M. D. (1993). Molecular identification of rRNA group 3 bacilli (Ash, Farrow, Wallbanks and Collins) using a PCR probe test. Proposal for the creation of a new genus Paenibacillus. Antonie van Leeuwenhoek 64, 253–260.[CrossRef][Medline]
Berge, O., Guinebretiere, M. H., Achouak, W., Normand, P. & Heulin, T. (2002). Paenibacillus graminis sp. nov. and Paenibacillus odorifer sp. nov., isolated from plant roots, soil and food. Int J Syst Evol Microbiol 52, 607–616.[Abstract]
Beringer, J. E. (1974). R factor transfer in Rhizobium leguminosarum. J Gen Microbiol 84, 188–189.
Christner, B. C., Mosley-Thompson, E., Thompson, L. G., Zagorodnov, V., Sandman, K. & Reeve, J. N. (2000). Recovery and identification of viable bacteria immured in glacial ice. Icarus 144, 479–485.
Döbereiner, J. & Day, J. M. (1976). Associative symbiosis in tropical grasses: characterization of microorganisms and dinitrogen fixing sites. In Proceedings of the 1st International Symposium on Nitrogen Fixation, vol. 2, pp. 518–538. Edited by W. E. Newton & C. J. Nyman. Pullman: Washington State University Press.
Döbereiner, J. & Pedrosa, F. O. (1987). Nitrogen Fixing Bacteria in Non-Leguminous Crop Plants. Berlin: Springer.
Elo, S., Suominen, I., Kämpfer, P., Juhanoja, J., Salkinoja-Salonen, M. & Haahtela, K. (2001). Paenibacillus borealis sp. nov., a nitrogen-fixing species isolated from spruce forest humus in Finland. Int J Syst Evol Microbiol 51, 535–545.[Abstract]
Forsyth, G. & Logan, N. A. (2000). Isolation of Bacillus thuringiensis from Northern Victoria Land, Antarctica. Lett Appl Microbiol 30, 263–266.[CrossRef][Medline]
Hamelin, J., Fromin, N., Tarnawski, S., Teyssier-Cuvelle, S. & Aragno, M. (2002). nifH gene diversity in the bacterial community associated with the rhizosphere of Molinia coerulea, an oligonitrophilic perennial grass. Environ Microbiol 4, 477–481.[CrossRef][Medline]
Hardy, R. W. F., Holsten, R. D., Jackson, E. K. & Burns, R. C. (1968). The acetylene-ethylene assay for nitrogen fixation: laboratory and field evaluation. Plant Physiol 36, 139–150.
Holdgate, M. W., Allen, S. E. & Chambers, M. J. G. (1967). A preliminary investigation of the soils of Signy Island, South Orkney Islands. Br Antarct Surv Bull 12, 53–71.
Hudson, J. A. & Daniel, R. M. (1988). Enumeration of thermophilic heterotrophs in geothermally heated soils from Mount Erebus, Ross Island, Antarctica. Appl Environ Microbiol 54, 622–624.
Hudson, J. A., Daniel, R. M. & Morgan, H. W. (1988). Isolation of a strain of Bacillus schlegelii from geothermally heated Antarctic soil. FEMS Microbiol Lett 51, 57–60.
Hudson, J. A., Daniel, R. M. & Morgan, H. W. (1989). Acidophilic and thermophilic Bacillus strains from geothermally heated Antarctic soil. FEMS Microbiol Lett 60, 279–282.[CrossRef]
Lewis Smith, R. I. (1988). Bryophyte oases in ablation valleys on Alexander Island, Antarctica. Bryologist 91, 45–50.[CrossRef]
Llarch, A., Logan, N. A., Castellvi, J., Prieto, M. J. & Guinea, J. (1997). Isolation and characterization of thermophilic Bacillus spp. from geothermal environments on Deception Island, South Shetland Archipelago. Microb Ecol 34, 58–65.[CrossRef][Medline]
Logan, N. A. & Berkeley, R. C. W. (1984). Identification of Bacillus strains using the API system. J Gen Microbiol 130, 1871–1882.
Logan, N. A., Lebbe, L., Hoste, B. & 7 other authors (2000). Aerobic endospore-forming bacteria from geothermal environments in northern Victoria Land, Antarctica, and Candlemas Island, South Sandwich archipelago, with the proposal of Bacillus fumarioli sp. nov. Int J Syst Evol Microbiol 50, 1741–1753.
Logan, N. A., Lebbe, L., Verhelst, A., Goris, J., Forsyth, G., Rodríguez-Díaz, M., Heyndrickx, M. & De Vos, P. (2002). Bacillus luciferensis sp. nov., from volcanic soil on Candlemas Island, South Sandwich archipelago. Int J Syst Evol Microbiol 52, 1985–1989.[Abstract]
Logan, N. A., Lebbe, L., Verhelst, A., Goris, J., Forsyth, G., Rodríguez-Díaz, M., Heyndrickx, M. & De Vos, P. (2004a). Bacillus shackletonii sp. nov., from volcanic soil on Candlemas Island South Sandwich archipelago. Int J Syst Evol Microbiol 54, 373–376.
Logan, N. A., De Clerck, E., Lebbe, L., Verhelst, A., Goris, J., Forsyth, G., Rodríguez-Díaz, M., Heyndrickx, M. & De Vos, P. (2004b). Paenibacillus cineris sp. nov. and Paenibacillus cookii sp. nov. from Antarctic volcanic soils and a gelatin processing plant. Int J Syst Evol Microbiol 54, 1071–1076.
Marshall, B. J. & Ohye, D. F. (1966). Bacillus macquariensis n. sp., a psychrotrophic bacterium from sub-Antarctic soil. J Gen Microbiol 44, 41–46.
Mollica, M. J., van Elsas, J. D. & Penido, E. G. C. (1985). An improved method to detect acetylene-reducing activity in Bacillus strains. J Microbiol Methods 3, 147–157.
Montes, M. J., Mercadé, E., Bozal, N. & Guinea, J. (2004). Paenibacillus antarcticus sp. nov., a novel psychrotolerant organism from the Antarctic environment. Int J Syst Evol Microbiol 54, 1521–1526.
Nicolaus, B., Lama, L., Esposito, E., Manca, M. C., di Prisco, G. & Gambacorta, A. (1996). "Bacillus thermoantarcticus" sp. nov., from mount Melbourne, Antarctica: a novel thermophilic species. Polar Biol 16, 101–104.
Nicolaus, B., Improta, R., Manca, M. C., Lama, L., Esposito, E. & Gambacorta, A. (1998). Alicyclobacilli from an unexplored geothermal soil in Antarctica: Mount Rittmann. Polar Biol 19, 133–141.[CrossRef]
Pearson, W. R. & Lipman, D. J. (1988). Improved tools for biological sequence comparison. Proc Natl Acad Sci U S A 85, 2444–2448.
Poly, F., Monrozier, L. J. & Bally, R. (2001). Improvement in the RFLP procedure for studying the diversity of nifH genes in communities of nitrogen fixers in soil. Res Microbiol 152, 95–103.[Medline]
Pozo, C., Rodelas, B., De La Escalera, S. & González-López, J. (2002). D,L-Hydantoinase activity of an Ochrobactrum anthropi strain. J Appl Microbiol 92, 1028–1034.[CrossRef][Medline]
Priest, F. G., Goodfellow, M. & Todd, C. (1988). A numerical classification of the genus Bacillus. J Gen Microbiol 134, 1847–1882.
Ramana, K. V., Singh, L. & Saxena, N. (2000). Psychrotrophic hydrolytic bacteria from Antarctica and other low temperature habitats. Def Sci J 50, 177–182.
Rodelas, B., González-López, J., Salmerón, V., Martínez-Toledo, M. V. & Pozo, C. (1998). Symbiotic effectiveness and bacteriocin production by Rhizobium leguminosarum bv. viceae isolated from agricultural soils in Spain. Agric Ecosyst Environ Appl Soil Ecol 8, 51–60.
Saitou, N. & Nei, M. (1987). The neighbor-joining method: a new method for reconstructing phylogenetic trees. Mol Biol Evol 4, 406–425.[Abstract]
Stackebrandt, E., Frederiksen, W., Garrity, G. M. & 10 other authors (2002). Report of the ad hoc committee for the re-evaluation of the species definition in bacteriology. Int J Syst Evol Microbiol 52, 1043–1047.[Abstract]
Van Trappen, S., Mergaert, J., Van Eygen, S., Dawyndt, P., Cnockaert, M. C. & Swings, J. (2002). Diversity of 746 heterotrophic bacteria isolated from microbial mats from ten Antarctic lakes. Syst Appl Microbiol 25, 603–610.[CrossRef][Medline]
Widmer, F., Shaffer, B. T., Porteous, L. A. & Seidler, R. J. (1999). Analysis of nifH gene pool complexity in soil and litter at a Douglas fir forest site in the Oregon Cascade Mountain Range. Appl Environ Microbiol 65, 374–380.
Wilson, P. W. & Knight, S. G. (1952). Experiments in Bacterial Physiology. Minneapolis: Burgess.
Wynn-Williams, D. D. (1993). Terrestrial Research at Alexander Island, 1992–93. Biological investigations of terrestrial Antarctic systems. Biotas Newsl 8, 9–11.
Wynn-Williams, D. D. (1996). Response of pioneer soil microalgal colonists to environmental change in Antarctica. Microb Ecol 31, 177–188.
Xiao, C., Dali, L. & Peijin, Z. (1994). The survey of total number of bacteria and fungi isolated from the Fildes peninsula in Antarctica. Antarct Res Ser 6, 67–72.
This article has been cited by other articles:
|
|
 |
|
  Y.-C. Ma and S.-F. Chen Paenibacillus forsythiae sp. nov., a nitrogen-fixing species isolated from rhizosphere soil of Forsythia mira Int J Syst Evol Microbiol, February 1, 2008; 58(2): 319 - 323. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
Y. Ma, Z. Xia, X. Liu, and S. Chen Paenibacillus sabinae sp. nov., a nitrogen-fixing species isolated from the rhizosphere soils of shrubs Int J Syst Evol Microbiol, January 1, 2007; 57(1): 6 - 11. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
P. Kampfer, R. Rossello-Mora, E. Falsen, H.-J. Busse, and B. J. Tindall Cohnella thermotolerans gen. nov., sp. nov., and classification of 'Paenibacillus hongkongensis' as Cohnella hongkongensis sp. nov. Int J Syst Evol Microbiol, April 1, 2006; 56(Pt 4): 781 - 786. [Abstract] [Full Text] [PDF]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| INT J SYST EVOL MICROBIOL | MICROBIOLOGY | J GEN VIROL |
| J MED MICROBIOL | ALL SGM JOURNALS | |
