| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
ena M. Korczak2
1 Cantonal Institute of Microbiology, Microbial Ecology, CH-6500 Bellinzona, Switzerland
2 Institute of Veterinary Bacteriology, University of Bern, CH-3001 Bern, Switzerland
Correspondence
Antonella Demarta
antonella.demarta{at}ti.ch
 |
ABSTRACT |
|---|
 TOP ABSTRACT INTRODUCTIONMETHODSRESULTS AND DISCUSSIONREFERENCES |
|---|
The GenBank/EMBL/DDBJ accession numbers for the new gyrB and rpoB sequences obtained in this paper are given in Fig. 2
.
|
INTRODUCTION |
|---|
|
TOPABSTRACTINTRODUCTIONMETHODSRESULTS AND DISCUSSIONREFERENCES |
|---|
; Crivelli et al., 2001). The taxonomy of the genus is complex and has been submitted to ongoing change due to newly described species (Pidiyar et al., 2002; Harf-Monteil et al., 2004; Miñana-Galbis et al., 2004) as well as reclassification and emended or extended descriptions of existing taxa (Pavan et al., 2000; Huys et al., 2002, 2003, 2005; Esteve et al., 2003; Demarta et al., 2004b). At present, the genus Aeromonas comprises at least 18 species validated on the basis of DNA–DNA hybridizations (Martin-Carnahan & Joseph, 2005).
Phylogenetic analysis based on the 16S rRNA gene is considered an appropriate tool for the reconstruction of evolutionary history and phylogenetic relationships of bacterial genera and it is universally used (Woese et al., 1990; Stackebrandt & Goebel, 1994; Amann et al., 1995). In the case of Aeromonas, 16S rRNA gene sequences indicated that the genus is composed of a very tight group of species, some of them differing by only a few nucleotides (Martinez-Murcia et al., 1992). Moreover, some discrepancies have been observed between 16S rRNA gene sequencing and DNA–DNA hybridization results (Sneath, 1993; Martínez-Murcia, 1999) and the existence of 16S rRNA gene polymorphism has been reported recently, particularly in Aeromonas media and Aeromonas veronii strains (Morandi et al., 2005). Other genes have therefore been evaluated as tools for the phylogenetic and taxonomic analysis of this genus.
Housekeeping genes are considered to be better molecular markers than the 16S rRNA gene for the study of phylogenetic and taxonomic relationships at the species level. In several species of bacteria, nucleotide sequence analysis at multiple protein-encoding loci has led to reliable phylogenies that have improved our understanding of population structure as well as epidemiology (Stackebrandt et al., 2002; Urwin & Maiden, 2003).
Yamamoto & Harayama (1995) designed a set of primers that allowed both the amplification and the nucleotide sequencing of portions of the gyrB gene (which encodes the B-subunit of DNA gyrase) from various bacteria and demonstrated that phylogenetic analyses of gyrB nucleotide sequences reflected the evolutionary relationships of closely related species (Yamamoto & Harayama, 1996; Yamamoto et al., 1999). gyrB sequence analysis has already been used to clarify interspecies phylogenetic relationships within Aeromonas (Yáñez et al., 2003; Soler et al., 2004) and to characterize novel species (Pidiyar et al., 2003).
DNA-dependent RNA polymerase is a multisubunit enzyme that consists of two 
subunits (encoded by the rpoA gene), one 
subunit (rpoB) and one ' subunit (rpoC). Comparison of rpoB sequences has been used as a basis for phylogenetic analyses among some archaea and bacteria (Klenk & Zillig, 1994; Mollet et al., 1997, Korczak et al., 2004, 2006), but it has never been applied, to our knowledge, to study relationships among Aeromonas strains.
The use of rpoB sequences for phylogenetic and taxonomic studies of Aeromonas strains was therefore evaluated in comparison to gyrB using the 16S rRNA gene as a reference. The sequences obtained from these genes were used to characterize 33 Aeromonas strains isolated from human and animal specimens (carriers or patients) and environmental samples (freshwater, tap water, surface swabs) in order to investigate their taxonomic position and their genetic relatedness within the genus.
|
METHODS |
|---|
|
TOPABSTRACTINTRODUCTIONMETHODSRESULTS AND DISCUSSIONREFERENCES |
|---|
. The strains were subcultured overnight at 30 °C under aerobic conditions on Columbia agar base (Oxoid) supplemented with 5 % sheep erythrocytes.
|
) from cells harvested from blood agar and then resuspended in TE buffer (10 mM Tris/HCl, 1 mM EDTA, pH 8.0). Alternatively, genomic DNA was prepared using an EZNA Bacterial DNA kit (PeqLab) and finally resuspended in water.
PCR amplification and sequencing.
The sets of primers used for amplification and sequencing of 16S rRNA, gyrB and rpoB genes are listed in Table 2. Nearly complete 16S rRNA gene sequences of the strains were determined by PCR-based DNA sequencing following a protocol described previously (Demarta et al., 1999). Amplification of gyrB was performed as described by Yamamoto & Harayama (1995) using primers UP-1 and UP-2r. Primers UP-1S, UP-2Sr as well as newly designed ones (Table 2) were used to obtain gyrB sequences of approximately 1100 bp according to a method described previously (Demarta et al., 2004a). A fragment of about 560 bp from the rpoB gene was amplified and sequenced as reported by Korczak et al. (2004). The accession numbers of 16S rRNA, gyrB and rpoB gene sequences are given on the trees.
|
). Phylogenetic trees were constructed using the neighbour-joining method with genetic distances computed by employing Kimura's 2-parameter method. A phylogenetic tree was also constructed from combined sequences of rpoB and gyrB genes. |
RESULTS AND DISCUSSION |
|---|
|
TOPABSTRACTINTRODUCTIONMETHODSRESULTS AND DISCUSSIONREFERENCES |
|---|
. Analyses of a fragment of approximately 1330 bp (positions 45–1394 in Escherichia coli), comprising the two main hypervariable regions of Aeromonas, allowed the construction of the phylogenetic tree in Fig. 1. The taxonomic identification of isolates F544A, F713E, V30 and V168 could not be properly assessed because their sequences were too divergent from those of known hybridization groups (HGs) or genospecies. Moreover, nine strains shared an identical fragment sequence with Aeromonas salmonicida and Aeromonas bestiarum, species which are hardly differentiated on the basis of 16S rRNA genes (Martinez-Murcia et al., 1992).
|
), we could amplify and sequence gyrB fragments of approximately 1100 nucleotides (positions 346–1467 in E. coli K-12). Maximal interspecies divergence of gyrB sequences was found to be 15.2 %, whereas the mean divergence was 7.76 %, values close to those reported by Yáñez et al. (2003).
Primers used to amplify and sequence the rpoB genes of bacteria belonging to the family Pasteurellaceae (Table 2) proved also to be suitable for Aeromonas, allowing the amplification and the sequencing of a 558 nucleotide fragment, which was used to draw the phylogenetic tree in Fig. 2(a). The rpoB region amplified corresponded to codons 500–686 of the 1342 amino acid subunit in E. coli (Ovchinnikov et al., 1981). This segment represents the most variable part of the gene in many bacterial species (Mollet et al., 1997). The maximal interspecies divergence was 13 %, with a mean interspecies divergence of 6.07 %. rpoB sequences were therefore found to be more conserved than gyrB sequences among Aeromonas strains.
|
), the reference strains A. allosaccharophila CECT 4199T (HG15), A. culicicola CIP 107763T and A. veronii ATCC 35624T (HG10) showed a mean interspecies divergence of 1 %. The same low interspecies resolution among these species was reported previously from rpoD sequence analysis (Soler et al., 2004). The rpoB sequences of A. culicicola CIP 107763T and A. veronii ATCC 35624T (HG10) were hard to differentiate, presenting a divergence of only 0.58 %. Recent investigations (Huys et al., 2005) concluded that members of the species A. culicicola in fact belong to the species A. veronii. Analysis of rpoB sequences, as well as gyrB and rpoD (Soler et al., 2004), confirmed that A. culicicola could be considered as a synonym of A. veronii. Strains JF2638, JF2689, JF2853 and F474 were consequently allocated to the latter species (Fig. 2a). The strain A. veronii biogroup Sobria CDC 0437-84 (HG8) was found to be very similar to A. veronii biogroup Veronii ATCC 35624T (HG10) when rpoB sequences were analysed.
The partial gyrB sequences for this group of species showed an interspecies divergence of about 4 %. The mean intraspecies divergence for the subgroup formed by strains JF2638, JF2689, JF2853, F474, A. veronii ATCC 35624T (HG10) and A. culicicola CIP 107763T was 2.3 %. The partial gyrB sequence of the strain A. veronii biogroup Sobria CDC 0437-84 was more closely related to that of A. allosaccharophila CECT 4199T (HG15) than to that of A. veronii biogroup Veronii ATCC 35624T, as found by Pidiyar et al. (2003), but an almost identical rpoB sequence to A. veronii biogroup Veronii ATCC 35624T. This finding therefore represents a case of inconsistency similar to that reported by Yáñez et al. (2003) regarding strain CECT 4911, classified as A. veronii by Huys et al. (1996) but possessing gyrB and 16S rRNA gene sequences similar or identical to those of A. allosaccharophila CECT 4199T. It should be mentioned that the strain A. veronii biogroup Sobria CDC 0437-84 was found to carry at least two divergent copies of the 16S rRNA gene (Morandi et al., 2005)
The A. bestiarum/A. salmonicida/A. popoffii group
Six strains of animal origin (V1, V130, V183, V32, V155 and V23) as well as three strains isolated from tap water (F666I, F553E and F530D) showed identical 16S rRNA gene sequences to the A. salmonicida and A. bestiarum type strains when the stretch of 1321 bp was considered (Fig. 1). These two species are difficult to separate on this basis because they are reported to differ in only two nucleotide positions over the entire 16S rRNA gene sequence (Martin-Carnahan & Joseph, 2005).
These species could be separated using gyrB (Yáñez et al., 2003; this study) or rpoD (Soler et al., 2004), which showed a resolving power to distinguish A. salmonicida from A. bestiarum ranging from 6.8 to 8.7 %. rpoB sequences could also separate these species, although with a lower resolving power (interspecies divergence of 2.6 %). Our collection strains were placed in A. salmonicida genospecies HG3 (strains V1, V130, V183, V32, V155, V23 and F553E) and in A. bestiarum genospecies HG2 (F530D and F666I) by both rpoB and gyrB sequence analysis. Strains belonging to A. salmonicida, comprising the subspecies we analysed, formed a very uniform group, with respective intraspecies substitution rates of 1.3 and 0.8 % for gyrB and rpoB.
Strains of A. popoffii (LMG 17541T, F533E, F548B and F600C) appeared to be closely related to the two above-mentioned species by both rpoB and gyrB, in agreement with previous reports (Pidiyar et al., 2003; Yáñez et al., 2003) as well as DNA–DNA hybridization results (Huys et al.; 1997b). Probably the best resolution to separate these species can be obtained by using rpoD sequences (Soler et al., 2004). The finding of perfect matches between the two markers rpoB and gyrB in strains F533E, F548B and F600C suggests that they could be clonally related.
The A. encheleia/Aeromonas sp. HG11/A. eucrenophila group
A lasting controversy within the genus Aeromonas is represented by the species A. encheleia HG16 and the unnamed Aeromonas sp. HG11. DNA–DNA relatedness levels reported by Huys et al. (1997a) regarding the strains used in our study clearly allocated Aeromonas sp. HG11 strain ATCC 35941 to the species A. encheleia, despite some atypical reactions in phenotypic tests. As already found for rpoD (Soler et al., 2004), rpoB sequences, showing an interspecies divergence of only 0.78 %, did not highlight any phylogenetic divergence between these strains and were therefore congruent with the suggestion that these two taxa should be considered as a single species. The interspecies divergence based on our gyrB sequences was 2.3 %, in agreement with results reported by Yáñez et al. (2003); this value was also close to the intraspecies nucleotide substitution threshold of 2 % found by Yáñez et al. (2003) for most Aeromonas species. Since only one field isolate (strain F544A) clustered within these strains by both methods, further insight in this group was not possible.
Two strains (F713E and F729F) clustered in the A. eucrenophila branch, but strain F713E showed an rpoB sequence divergence from A. eucrenophila NCIMB 74T of 3 % (4.36 % for gyrB). 16S rRNA gene analysis showed that this strain possessed the same nucleotide sequence as a group of Aeromonas strains described by Demarta et al. (2004b). rpoB and gyrB sequencing results strengthened the hypothesis of the existence of a novel species in the genus Aeromonas, closely related to A. eucrenophila.
The A. media HG5A/A. media HG5B group
rpoB, gyrB and 16S rRNA gene sequences were established for A. media ATCC 33907T (HG5B) and A. media CDC 862-83 (HG5A) and for strains V168, V47, V69, F674P, V6 and V15. Apart from strain V168, which clustered with Aeromonas caviae HG4, these strains were grouped in a heterogeneous cluster with Aeromonas hydrophila ATCC 7966T in the 16S rRNA gene tree (Fig. 1). rpoB sequence analysis (Fig. 2a) divided these strains into two related subgroups, diverging by 1.9 %. The same topology was found with the gyrB tree (Fig. 2b), with a divergence rate for this marker of 3.74 %. The gyrB sequences of strains V47, V69, V168 and A. media CDC 0862-83 showed a mean similarity of 97.8 % with isolates 57, 480 and 610, strains analysed by Soler et al. (2004) which formed a phylogenetically distinct cluster in their gyrB tree.
These results confirmed previous outcomes on the differentiation of the genospecies A. media HG5 into two distinct lines matching the subgroups 5A and 5B, which might constitute two subspecies (Martin-Carnahan & Joseph, 2005).
The remaining groups
The rpoB sequence of A. caviae ATCC 15468T (HG4) clustered with five sequences derived from our environmental strains (four of animal origin and one from a pipe swab), as well as with A. hydrophila subsp. anaerogenes CIP 76.15T, which is considered to belong to the species A. caviae. The mean sequence diversity of this species was calculated to be 1.23 % for rpoB and 1.83 % for gyrB.
Strains F458, F589 (isolated from stools of patients) and F567A (isolated from a surface swab) showed identical 16S rRNA, rpoB and gyrB gene sequences, classifying them as A. hydrophila HG1. The identical genetic profiles in three independent markers showed the possible clonal origin of these strains, which were epidemiologically unrelated. The strain A. hydrophila subsp. dhakensis CIP 107500T was found to be the more divergent, regardless of the gene used to draw the phylogenetic tree, among the strains belonging to the species A. hydrophila. The 16S rRNA gene sequence placed this strain close to the type strains of A. caviae and Aeromonas trota.
A. sobria (HG7), Aeromonas jandaei (HG9), Aeromonas schubertii (HG12), Aeromonas sp. group 501 (HG13), A. trota (HG14) and Aeromonas simiae were represented in our trees by their type (or reference) strains only. The gyrB-derived tree for these species (Fig. 2b) did not differ from those obtained by other authors (Pidiyar et al., 2003; Yáñez et al., 2003; Soler et al., 2004). In the rpoB tree, only the relative branching positions were subject to change (Fig. 2a).
Since the resolving power of gyrB and rpoB differed in separating some species, a tree (not shown) was derived using the combined sequences joined end to end (
1600 nucleotides). Overall, the combined tree confirmed the positions of species and strains already found in the individual trees. Its reliability in differentiating closely related taxa was improved, as attested by bootstrap values greater than those obtained in single gene analysis.
The majority of the strains isolated from tap water were identified as A. bestiarum or A. popoffii or they were found to belong to the group A. eucrenophila/A. encheleia/Aeromonas sp. HG11. No further distribution of the strains in the phylogenetic tree was noticed related to their origin. Strains isolated from animal droppings were scattered among different genospecies, regardless of the kind of the animal or its health status. It is therefore conceivable that the pathogenic potential of aeromonads is related both to certain host determinants and to strain properties such as the presence of virulence factors.
In conclusion, the use of rpoB and gyrB allowed us to clarify the taxonomy and the phylogenetic relationships of Aeromonas strains isolated from humans, animals and the environment. 16S rRNA gene sequencing was useful to define isolates at the genus level only. In contrast, gyrB sequences were a powerful tool in differentiating Aeromonas genospecies, confirming previous work on Aeromonas (Yáñez et al., 2003; Soler et al., 2004) and similar findings in other bacterial genera (Fukushima et al., 2002; Radice et al., 2006). Moreover, due to the sequence diversity that we could observe in our strains at the intraspecies level, we can agree completely with the suggestion of using gyrB sequences not only for the identification of species in a phylogenetic framework but also for strain differentiation, as proposed by Yáñez et al. (2003). Although rpoB sequences are more conserved than gyrB sequences in the genus Aeromonas, the present work demonstrated that the resolution of rpoB was sufficient to infer phylogenetic relationships and taxonomic identifications within Aeromonas. Moreover, a similar reliability to gyrB for differentiating related Aeromonas species could be obtained from analysis of an rpoB fragment of only 560 bp. In fact, these sequences allowed differentiation between A. salmonicida and A. bestiarum, as well as A. media HG5A and A. media HG5B. Furthermore, strain groupings obtained with rpoB were in agreement with the taxonomic classification of all species and subspecies currently recognized in the genus Aeromonas. Finally, rpoB sequences contributed to a clearer understanding of some still controversial taxa of the genus Aeromonas.
|
ACKNOWLEDGEMENTS |
|---|
|
REFERENCES |
|---|
|
TOPABSTRACTINTRODUCTIONMETHODSRESULTS AND DISCUSSIONREFERENCES |
|---|
Crivelli, C., Demarta, A. & Peduzzi, R. (2001). Intestinal secretory immunoglobulin A (sIgA) response to Aeromonas exoproteins in patients with naturally acquired Aeromonas diarrhea. FEMS Immunol Med Microbiol 30, 31–35.[CrossRef][Medline]
Demarta, A., Tonolla, M., Caminada, A.-P., Ruggeri, N. & Peduzzi, R. (1999). Signature region within the 16S rRNA sequences of Aeromonas popoffii. FEMS Microbiol Lett 172, 239–246.[CrossRef][Medline]
Demarta, A., De Respinis, S., Dolina, M. & Peduzzi, R. (2004a). Molecular typing of Yersinia frederiksenii strains by means of 16S rRNA and gyrB genes sequence analyses. FEMS Microbiol Lett 238, 423–428.[Medline]
Demarta, A., Huys, G., Tonolla, M., Swings, J. & Peduzzi, R. (2004b). Polyphasic taxonomic study of "Aeromonas eucrenophila-like" isolates from clinical and environmental sources. Syst Appl Microbiol 27, 343–349.[CrossRef][Medline]
Demarta, A., Tonolla, M., Caminada, A. P., Beretta, M. & Peduzzi, R. (2000). Epidemiological relationships between Aeromonas strains isolated from symptomatic children and household environments as determined by ribotyping. Eur J Epidemiol 16, 447–453.[CrossRef][Medline]
Esteve, C., Valera, L., Gutiérrez, C. & Ventosa, A. (2003). Taxonomic study of sucrose-positive Aeromonas jandaei-like isolates from faeces, water and eels: emendation of A. jandaei Carnahan et al. 1992. Int J Syst Evol Microbiol 53, 1411–1419.
Fukushima, M., Kakinuma, K. & Kawaguchi, R. (2002). Phylogenetic analysis of Salmonella, Shigella, and Escherichia coli strains on the basis of the gyrB gene sequence. J Clin Microbiol 40, 2779–2785.
Harf-Monteil, C., Le Flèche, A., Riegel, P., Prévost, G., Bermond, D., Grimont, P. A. D. & Monteil, H. (2004). Aeromonas simiae sp. nov., isolated from monkey faeces. Int J Syst Evol Microbiol 54, 481–485.
Huys, G., Coopman, R., Janssen, P. & Kersters, K. (1996). High-resolution genotypic analysis of the genus Aeromonas by AFLP fingerprinting. Int J Syst Bacteriol 46, 572–580.
Huys, G., Kämpfer, P., Altwegg, M., Coopman, R., Janssen, P., Gillis, M. & Kersters, K. (1997a). Inclusion of Aeromonas DNA hybridization group 11 in Aeromonas encheleia and extended descriptions of the species Aeromonas eucrenophila and A. encheleia. Int J Syst Bacteriol 47, 1157–1164.
Huys, G., Kämpfer, P., Altwegg, M. & 7 other authors (1997b). Aeromonas popoffii sp. nov., a mesophilic bacterium isolated from drinking water production plant reservoirs. Int J Syst Bacteriol 47, 1165–1171.
Huys, G., Kämpfer, P., Albert, M. J., Kühn, I., Denys, R. & Swings, J. (2002). Aeromonas hydrophila subsp. dhakensis subsp. nov., isolated from children with diarrhoea in Bangladesh, and extended description of Aeromonas hydrophila subsp. hydrophila (Chester 1901) Stanier 1943 (Approved Lists 1980). Int J Syst Evol Microbiol 52, 705–712.[Abstract]
Huys, G., Pearson, M., Kämpfer, P., Denys, R., Cnockaert, M., Inglis, V. & Swings, J. (2003). Aeromonas hydrophila subsp. ranae subsp. nov., isolated from septicaemic farmed frogs in Thailand. Int J Syst Evol Microbiol 53, 885–891.
Huys, G., Cnockaert, M. & Swings, J. (2005). Aeromonas culicicola Pidiyar et al. 2002 is a later subjective synonym of Aeromonas veronii Hickman-Brenner et al. 1987. Syst Appl Microbiol 28, 604–609.[CrossRef][Medline]
Joseph, S. W. & Carnahan, A. M. (2000). Update on the genus Aeromonas. ASM News 66, 218–223.
Klenk, H.-P. & Zillig, W. (1994). DNA-dependent RNA polymerase subunit B as a tool for phylogenetic reconstructions: branching topology of the archeal domain. J Mol Evol 38, 420–432.[CrossRef][Medline]
Korczak, B., Christensen, H., Emler, S., Frey, J. & Kuhnert, P. (2004). Phylogeny of the family Pasteurellaceae based on rpoB sequences. Int J Syst Evol Microbiol 54, 1393–1399.
Korczak, B. M., Stieber, R., Emler, S., Burnens, A. P., Frey, J. & Kuhnert, P. (2006). Genetic relatedness within the genus Campylobacter inferred from rpoB sequences. Int J Syst Evol Microbiol 56, 937–945.
Kumar, S., Tamura, K. & Nei, M. (2004). MEGA3: integrated software for molecular evolutionary genetics analysis and sequence alignment. Brief Bioinform 5, 150–163.
Martin-Carnahan, A. & Joseph, S. W. (2005). Genus I. Aeromonas Stanier 1943, 213AL. In Bergey's Manual of Systematic Bacteriology, 2nd edn, vol. 2, part B, pp. 557–578. Edited by D. J. Brenner, N. R. Krieg, J. T. Staley & G. M. Garrity. New York: Springer.
Martínez-Murcia, A. J. (1999). Phylogenetic positions of Aeromonas encheleia, Aeromonas popoffii, Aeromonas DNA hybridization group 11 and Aeromonas group 501. Int J Syst Bacteriol 49, 1403–1408.
Martinez-Murcia, A. J., Benlloch, S. & Collins, M. D. (1992). Phylogenetic interrelationships of members of the genera Aeromonas and Plesiomonas as determined by 16S ribosomal DNA sequencing: lack of congruence with results of DNA-DNA hybridization. Int J Syst Bacteriol 42, 412–421.
Miñana-Galbis, D., Farfán, M., Fusté, M. C. & Lorén, J. G. (2004). Aeromonas molluscorum sp. nov., isolated from bivalve molluscs. Int J Syst Evol Microbiol 54, 2073–2078.
Mollet, C., Drancourt, M. & Raoult, D. (1997). rpoB sequence analysis as a novel basis for bacterial identification. Mol Microbiol 26, 1005–1011.[CrossRef][Medline]
Morandi, A., Zhaxybayeva, O., Gogarten, J. P. & Gral, J. (2005). Evolutionary and diagnostic implications of intragenomic heterogeneity in the 16S rRNA gene in Aeromonas strains. J Bacteriol 187, 6561–6564.
Ovchinnikov, Y. A., Monastyrskaya, G. S., Gubanov, V. V. & 9 other authors (1981). The primary structure of Escherichia coli RNA polymerase. Nucleotide sequence of the rpoB gene and amino-acid sequence of the -subunit. Eur J Biochem 116, 621–629.[Medline]
Pavan, M. E., Abbott, S. L., Zorzopulos, J. & Janda, J. M. (2000). Aeromonas salmonicida subsp. pectinolytica subsp. nov., a new pectinase-positive subspecies isolated from a heavily polluted river. Int J Syst Evol Microbiol 50, 1119–1124.[Abstract]
Pidiyar, V., Kaznowski, A., Badri Narayan, N., Patole, M. & Shouche, Y. S. (2002). Aeromonas culicicola sp. nov., from the midgut of Culex quinquefasciatus. Int J Syst Evol Microbiol 52, 1723–1728.[Abstract]
Pidiyar, V. J., Jangid, K., Dayananda, K. M., Kaznowski, A., Gonzalez, J. M., Patole, M. S. & Shouche, Y. S. (2003). Phylogenetic affiliation of Aeromonas culicicola MTCC 3249T based on gyrB gene sequence and PCR-amplicon sequence analysis of cytolytic enterotoxin gene. Syst Appl Microbiol 26, 197–202.[CrossRef][Medline]
Radice, F., Orlandi, V., Massa, V., Cavalca, L., Demarta, A., Wood, T. K. & Barbieri, P. (2006). Genotypic characterization and phylogenetic relations of Pseudomonas sp. (formerly P. stutzeri) OX1. Curr Microbiol 52, 395–399.[CrossRef][Medline]
Sneath, P. H. A. (1993). Evidence from Aeromonas for genetic crossing-over in ribosomal sequences. Int J Syst Bacteriol 43, 626–629.
Soler, L., Yáñez, M. A., Chacon, M. R., Aguilera-Arreola, M. G., Catalán, V., Figueras, M. J. & Martínez-Murcia, A. J. (2004). Phylogenetic analysis of the genus Aeromonas based on two housekeeping genes. Int J Syst Evol Microbiol 54, 1511–1519.
Stackebrandt, E. & Goebel, B. (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.
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]
Urwin, R. & Maiden, M. C. (2003). Multi-locus sequence typing: a tool for global epidemiology. Trends Microbiol 11, 479–487.[CrossRef][Medline]
Woese, C. R., Kandler, O. & Wheelis, M. L. (1990). Towards a natural system of organisms: proposal for the domains Archaea, Bacteria, and Eukarya. Proc Natl Acad Sci U S A 87, 4576–4579.
Yamamoto, S. & Harayama, S. (1995). PCR amplification and direct sequencing of gyrB genes with universal primers and their application to the detection and taxonomic analysis of Pseudomonas putida strains. Appl Environ Microbiol 61, 1104–1109.[Abstract]
Yamamoto, S. & Harayama, S. (1996). Phylogenetic analysis of Acinetobacter strains based on the nucleotide sequences of gyrB genes and on the amino acid sequences of their products. Int J Syst Bacteriol 46, 506–511.
Yamamoto, S., Bouvet, P. J. M. & Harayama, S. (1999). Phylogenetic structures of the genus Acinetobacter based on gyrB sequences: comparison with the grouping by DNA–DNA hybridization. Int J Syst Bacteriol 49, 87–95.
Yáñez, M. A., Catalán, V., Apráiz, D., Figueras, M. J. & Martínez-Murcia, A. J. (2003). Phylogenetic analysis of members of the genus Aeromonas based on gyrB gene sequences. Int J Syst Evol Microbiol 53, 875–883.
This article has been cited by other articles:
|
|
 |
|
  O. O. Glazunova, D. Raoult, and V. Roux Partial sequence comparison of the rpoB, sodA, groEL and gyrB genes within the genus Streptococcus Int J Syst Evol Microbiol, September 1, 2009; 59(9): 2317 - 2322. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
D. Minana-Galbis, A. Urbizu-Serrano, M. Farfan, M. C. Fuste, and J. G. Loren Phylogenetic analysis and identification of Aeromonas species based on sequencing of the cpn60 universal target Int J Syst Evol Microbiol, August 1, 2009; 59(8): 1976 - 1983. [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 | |
