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Journal of Clinical Microbiology, April 2000, p. 1615-1622, Vol. 38, No. 4
Biotechnology Centre of Oslo and Institute of
Pharmacy, University of Oslo, 0316 Oslo,1
Department of Bacteriology, National Institute of Public
Health, 0462 Oslo,2 and Department
of Oral Biology, University of Oslo, 0317 Oslo,3
Norway
Received 22 September 1999/Returned for modification 8 December
1999/Accepted 29 December 1999
The genetic diversity and relationships among 35 Bacillus
cereus and Bacillus thuringiensis isolates recovered
from marginal and apical periodontitis in humans and from various other
human infections were investigated using multilocus enzyme
electrophoresis. The strains were isolated in Norway, except for three
strains isolated from periodontitis patients in Brazil. The genetic
diversity of these strains was compared to that of 30 isolates from
dairies in Norway and Finland. Allelic variation in 13 structural gene loci encoding metabolic enzymes was analyzed. Twelve of the 13 loci
were polymorphic, and 48 unique electrophoretic types (ETs) were
identified, representing multilocus genotypes. The mean genetic diversity among the 48 genotypes was 0.508. The genetic diversity of
each source group of isolates varied from 0.241 (periodontal infection)
to 0.534 (dairy). Cluster analysis revealed two major groups separated
at a genetic distance of greater than 0.6. One cluster, ETs 1 to 13, included solely isolates from dairies, while the other cluster, ETs 14 to 49, included all of the human isolates as well as isolates from
dairies in Norway and Finland. The isolates were serotyped using
antiflagellar antiserum. A total of 14 distinct serotypes were
observed. However, little association between serotyping and genotyping
was seen. Most of the strains were also analyzed with pulsed-field gel
electrophoresis, showing the presence of extrachromosomal DNA in the
size range of 15 to 600 kb. Our results indicate a high degree of
heterogeneity among dairy strains. In contrast, strains isolated from
humans had their genotypes in one cluster. Most strains from patients
with periodontitis belonged to a single lineage, suggesting that
specific clones of B. cereus and B. thuringiensis are associated with oral infections.
Periodontal diseases, whether
marginal or apical, are initiated and sustained by factors produced by
the microbiota of dental plaque. Plaque microorganisms may damage
cellular and structural components of the periodontium via release of
proteolytic and noxious waste products. Among the enzymes released by
these bacteria are proteases capable of digesting collagen, elastin,
fibronectin, fibrin, and various other components of the intercellular
matrix of epithelial and connective tissue (22). These
organisms also release numerous metabolic products such as ammonia,
indole, hydrogen sulfide, and butyric acid.
A growing literature has suggested some reasonable candidates for
destructive periodontal disease, among which are Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis,
Bacteroides forsythus, Prevotella intermedia,
Fusobacterium nucleatum, Campylobacter rectus,
Eikenella corrodens, Peptostreptococcus micros,
Selenomonas spp., Eubacterium spp., spirochetes,
and Streptococcus intermedius (34). However, all
periodontal pathogens have probably not yet been identified. The
presence of unusual species in periodontal lesions suggests the
possibility that they may play a role in the etiology of periodontal diseases.
Bacillus cereus is frequently isolated as a contaminant of
milk, cereals, and various other foods and has been the cause of isolated cases and outbreaks of food poisoning. Occasionally it can be
responsible for wound and eye infections, as well as systemic infections (10, 38). This organism may produce an emetic or diarrheal syndrome induced by an emetic toxin and enterotoxins, respectively. Other toxins produced during growth include
phospholipases, proteases, and hemolysins (10), which may
contribute to the pathogenicity of B. cereus in
nongastrointestinal disease. B. cereus isolated from
clinical material other than feces and vomitus was commonly dismissed
as a contaminant, but it is likely to contribute to disease when it is
part of the predominant microflora of the site. The possible role of
B. cereus in periodontitis has not previously been assessed.
Bacillus thuringiensis is primarily a biopesticide for
insects due to its production of insecticidal toxins, which is the only
established difference from B. cereus (reviewed by Crickmore
et al. [7]). It is also isolated from human wounds
(8) and gastroenteritis infection (19).
We have previously analyzed the genetic diversity of B. cereus and B. thuringiensis isolates from soil
(18). In the present study we have extended our analyses of
the genetic diversity of B. cereus and B. thuringiensis by focusing mainly on the genetic diversity of
strains isolated from human infections, including periodontal infections.
To analyze the genetic diversity of B. cereus and B. thuringiensis, multilocus enzyme electrophoresis was used. The
strains were also serotyped using antiserum raised against flagellar
antigen of B. thuringiensis. Since it is well known that
most B. cereus and B. thuringiensis strains
contain large plasmids (1, 3, 4, 15), several strains were
also analyzed by pulsed-field gel electrophoresis (PFGE) for the
detection of large extrachromosomal DNA.
In this study we wanted to determine whether strains of B. cereus isolated from patients differed from those in the
environment that we have previously examined (18). Since
strains isolated from dairies were available, we included those in this
study to get an even broader view of the genetic diversity and
population structure of B. cereus and B. thuringiensis.
Strain isolation.
The 35 human strains were isolated from
diverse sources, i.e., oral cavity, urine, blood, and skin (Table
1). Of the 20 strains from the oral
cavity, 11 were isolated from marginal periodontitis, 8 were isolated from apical periodontitis, and 1 was isolated from lichen
planus. Bacillus isolates were among the most predominant in
all of the clinical samples. Sixteen of the patients lived in different
counties or cities of Norway, and three were from Brazil. Two of the
patients in Norway were immigrants. All of the oral strains had been
isolated from consecutive samples submitted to the Microbiological
Diagnostic Service, Department of Oral Biology, University of Oslo,
during a 26-month period. Bacillus identification had been
based on cultivation under aerobic and anaerobic atmospheres, colony
morphology, hemolysis, Gram stain, spore formation, and biochemical
reactions using the API 50 CHB Medium and CH kit (bioMérieux Sa,
Marcy l'Etoile, France). The biochemical tests were read by an
automatic reader (ATB 1525 Reader; bioMérieux), and the results
were transformed into numerical codes which were submitted to a
database (API Plus; bioMérieux) for identification.
0095-1137/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.
Genetic Structure of Population of Bacillus
cereus and B. thuringiensis Isolates Associated
with Periodontitis and Other Human Infections
ABSTRACT
Top
Abstract
Introduction
Materials and Methods
Results
Discussion
References
INTRODUCTION
Top
Abstract
Introduction
Materials and Methods
Results
Discussion
References
MATERIALS AND METHODS
Top
Abstract
Introduction
Materials and Methods
Results
Discussion
References
TABLE 1.
Characteristics of 65 B. cereus and B. thuringiensis isolates from dairies, periodontal infections,
and other human infections and of three culture collection strains
Serotyping. H serotyping based on flagellar antigens was performed by the agglutination method, as described by de Barjac (9).
Electrophoresis of enzymes. Protein extracts of the isolates were electrophoresed on starch-gel, and selective enzyme staining was performed as described by Selander et al. (32). Thirteen enzymes (see Table 3) were assayed as previously described (18).
Statistical analysis.
Genetic diversity at an enzyme locus
among the electrophoretic types (ETs) or isolates was calculated as
h = 1 
xi2 [n/(n 1)], where xi is the frequency of the
ith allele and n is the number of ETs or
isolates. The mean genetic diversity (H) is the arithmetic
average of h values over all loci (32). The
genetic distance between pairs of ETs was expressed as the proportion
of enzyme loci at which dissimilar alleles occurred (mismatches).
Clustering was performed from a matrix of genetic distances by the
average-linkage method (33).
Digestion of DNA. The restriction enzymes AscI and NotI were obtained from New England BioLabs, Beverly, Mass. Agarose blocks were treated as plugs as described previously (5, 23).
PFGE. A PFGE instrument from Beckman was used. Electrophoresis was done in 25 mM Tris-borate buffer-0.05 mM EDTA (pH 8.3) at 14°C with a pulse time of 4 s for the first 10 min at 170 mA, after which the pulse time was 30 or 60 s for 20 h at 150 mA. The bacterial DNA was isolated in agarose plugs as described previously (5, 23) and electrophoresed in 1% agarose. Size markers used were Saccharomyces cerevisiae chromosomes (New England BioLabs) and a mixture of phage lambda DNA concatemers and HindIII fragments of lambda (New England BioLabs). After electrophoresis, gels were stained for 10 min in ethidium bromide (100 µg/ml) and destained for about 1 h in water. After treatment for 10 min in 0.25 M HCl, twice for 30 min each in 0.5 M NaOH-1.5 M NaCl, and twice for 30 min each in 0.5 M Tris (pH 8)-1.5 M NaCl, the gels were blotted overnight in 20× SSC (1× SSC is 0.15 M NaCl plus 0.015 M sodium citrate) onto nitrocellulose membrane filters (Micron Separations Inc.). The filters were baked for 2 h at 80°C after blotting.
Probes.
An extrachromosomal DNA of about 300 kb from strain
AH 818 was used as a probe. This strain is from the cluster ET 24-25 and was randomly chosen. The probe DNA was isolated from a
low-melting-point agarose gel by cutting out the band of interest and
digesting it with 
-agarase as described by the manufacturers (New
England BioLabs). The probe was labeled using the Klenow enzyme (New
England BioLabs) and 32P-labeled dCTP and dATP (13,
14).
Hybridization. The filters were prehybridized in 3× SSC-0.1% sodium dodecyl sulfate (SDS)-10× Denhardt solution (0.1% bovine serum albumin, 0.1% FIcoll, 0.1% polyvinylpyrrolidone) for 2 h at 68°C and hybridized in 25 ml of 3× SSC-0.1% SDS-10× Denhardt solution-10% dextran sulfate (Pharmacia, Uppsala, Sweden) with a denatured labeled probe overnight at 68°C. The filters were washed twice for 30 min each in 3× SSC-0.1% SDS at 68°C, twice for 30 min each in 1× SSC-0.1% SDS at 68°C, and once for 30 min in 0.3× SSC-0.1% SDS at 68°C.
Parasporal crystal observation. The bacteria were grown aerobically on Schaeffer sporulation medium (31) plates for 5 to 7 days at 28°C. The bacterial cells were stained with carbolfuchsin and observed under a microscope (Labophot-2; Nikon).
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RESULTS |
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Top
Abstract
Introduction
Materials and Methods
Results
Discussion
References
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Overall genetic diversity.
In the collection of 65 strains, 12 of the 13 enzyme loci were polymorphic. The number of alleles per locus
ranged from 2 to 8 with an average of 4.5 alleles per locus (Tables
2 and 3). Among the 65 strains, a total of 48 ETs were distinguished. Among all
ETs, the mean genetic diversity over all loci (H) was 0.508 (Table 2).
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), moss (soil
sample) (
), other soil samples (
), and dairies (
). Arrows
indicate reference strains: a, B. cereus ATCC 10987; b,
B. cereus ATCC 4342; c, B. cereus type strain
ATCC 14579.
Genetic diversity within and between source groups. The genetic diversity of each source group of ETs varied from 0.241 (periodontal infection) to 0.534 (dairy isolates) (Tables 2 and 3). Only two ETs contained isolates from different sources, periodontal infection and another human infection (ET 21 and ET 41). No isolate from dairies shared ETs with isolates from humans, and no dairy isolates from Norway and Finland shared ETs.
The genetic diversity for ETs of the periodontal infection strains was 0.241, with an isolate diversity of 0.150 (Tables 2 and 3). This low isolate diversity compared to ET diversity indicated that many isolates shared the same ET. Only 6 out of 13 loci were polymorphic for the periodontal infection isolates (Table 3). Of the 20 strains isolated from periodontal infections, 12 were identical except for the lack of activity (null allele) at ACO (ETs 24 and 25), and three differed from these by expressing an allele at one locus. The B. cereus reference strain ATCC 4342, isolated from milk in the 1950s, had the same genotype as most of the periodontal isolates (Fig. 1; Table 1). All of the 15 isolates of ETs 22 to 25 had been isolated from different patients except AH 812 and AH 819, which were from the same patient but from two different types of periodontitis (Table 1).Index of association. The degree of association between alleles at different loci was measured by the index of association. When a given population has an IA value significantly different from zero, the population exhibits linkage disequilibrium; i.e., it is clonal (28).
The IA was calculated for the two clusters I and II. For cluster I, the IA for the ETs was 0.48 ± 0.29, and for cluster II, it was 0.17 ± 0.12 (Table 4). The IA in both clusters was significantly different from zero and therefore indicated a clonal structure. However, considering human isolates as a specific source or environmental niche, clonality disappears for the ETs, with an IA of 0.26 ± 1.00. This population, however, shows a clonal structure when the calculation is done for the isolates, with an IA of 0.92 ± 0.68. According to Maynard-Smith et al. (28), this indicates an epidemic structure for all of the human isolates.
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Genetic variation in relation to serotype. The serotype classification was previously developed exclusively for B. thuringiensis strains. Of the 58 serovars (45 H serotypes and their subgroups) described worldwide among B. thuringiensis strains (25), 14 were represented among the 65 sample isolates in this study (Table 1). The number of isolates assigned to each serotype varied from one to five, and the most common serotypes were H13 and H18. Except for a few strains that were autoagglutinable (and thus nontypeable), the remaining isolates (48%) did not cross-react with any of the known B. thuringiensis antisera. Of the 13 isolates of ETs 24 and 25, three different serotypes were found, while six strains were nontypeable. There was no close association between serotypes and genotypes, which is in agreement with previous studies (3, 18, 40).
PFGE of digested DNA.
PFGE of strains of ETs 24 and 25 showed
at least two different profiles, with the third profile being that of
the reference strain ATCC 4342 (Fig. 2).
|
PFGE of undigested DNA and hybridization.
PFGE analysis of 62 strains showed that most of them (51 strains) contain extrachromosomal
DNA with an apparent size of 15 to 600 kb. Examples of the results are
given in Fig. 3. Sixteen strains had
extrachromosomal DNA of about 300 kb, including 11 of the 12 strains in
ETs 24 and 25 isolated from patients with periodontitis (Fig. 3; Table
1). The reference strain ATCC 4342 of the same ET cluster did not
contain the extrachromosomal element of 300 kb. Three of the strains
containing and 300-kb extrachromosomal DNA were from periodontal
infection and belong to ET 18 and ETs 22 and 23, while two were
isolated from dairies and belonged to ET 48 and ET 29. The
extrachromosomal DNAs in the strains of ETs 24 and 25 appeared to be
linear, since they always migrated in a pulse time-dependent manner
(data not shown).
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Parasporal crystal observation. Only one strain, AH 400, isolated from a dairy, produced an obvious parasporal inclusion.
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DISCUSSION |
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Top
Abstract
Introduction
Materials and Methods
Results
Discussion
References
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The genetic diversity of B. cereus and B. thuringiensis isolates was analyzed using multilocus enzyme electrophoresis. The advantage of this method is that the characters tested are minimally subject to evolutionary convergence, because the electrophoretic variants (allozymes) are essentially selectively neutral or nearly so (11, 12, 17, 39).
The total genetic diversity of the strains in this study (0.508) was somewhat lower than the genetic diversity found among B. cereus and B. thuringiensis from reference strains and culture collections (0.556) (3) and from soil samples (0.526) (18). The high genetic diversity observed in these and other strains is not surprising, since the genetic diversity of rRNA gene restriction patterns displayed by B. thuringiensis was greater than those for all other species examined by that technique (30). The genetic diversity of the ETs from dairies was also high (0.526) (Table 2), although 13 out of 30 strains formed a separate cluster that differed from all other isolates by more than 0.6 (Fig. 1). Several of the dairy strains, found in both clusters I and II of the dendrogram, are psychrotrophic (16). A cold shock protein has been described for B. cereus (29), and expression of this gene may be common in B. cereus strains that live in the cold environment of dairies. Some or all of those strains probably belong to a new psychrotolerant B. cereus-like group of isolates that recently has been described as a new species, Bacillus weihenstephanensis (26). All psychrotrophic strains in that study were found to belong to this new species. B. weihenstephanensis was found to be more related to Bacillus mycoides than to B. cereus and B. thuringiensis (26). This is thus possibly the reason why some of the psychrotrophic strains in ETs 6 to 12 cluster together with a distance of 0.45 with respect to other isolates, but whether those strains belong to this new species remains to be elucidated.
In the results presented here we find the IAs for ETs in clusters I and II to be 0.481 ± 0.29 and 0.171 ± 0.12, respectively, which indicates a clonal population structure (28), although some DNA uptake is likely to occur. Calculation of the IA value for isolates from patients (0.92 ± 0.68) indicates linkage disequilibrium, i.e., restriction in recombination, and thus a clonal population. On the other hand, the calculation of IA values for the patient ETs (0.26 ± 1.00) did not indicate linkage disequilibrium, hence suggesting a recombinant population. The isolates from the patients are thus consistent with the epidemic model of population structure described by Maynard-Smith et al. (28).
We find the high clonality observed for the strains isolated from patients with periodontal infections very interesting. This probably indicates a more stable and homogenous virulent clone of B. cereus as is found for its close relative Bacillus anthracis (21). A high clonality has also been reported for Porphyromonas gingivalis and Prevotella intermedia recovered from persons with periodontal disease, where most subjects appeared to be colonized by the same genotypes of those species (36).
Reduced genetic diversity is often observed in disease-causing bacteria. For example, in Neisseria meningitidis, most of the disease-causing strains belong to a few clones or complexes of related clones in comparison to the genotypic diversity observed in strains from healthy carriers (6, 27).
PFGE analysis of the NotI and AscI DNA fragment profiles of the strains from ETs 24 and 25 isolated from patients divides this lineage further into at least two subclasses (Fig. 2). This heterogeneity indicates that these strains may not have originated from a single source during the sampling period. Still, the strains in this cluster are very similar and possibly have kept the same virulence factor(s). Although the reference strain ATCC 4342 belongs to this cluster, the DNA fragment profile was clearly divergent compared to the other strains of the cluster (Fig. 2). In addition it lacks the extrachromosomal DNA fragment of 300 kb. This may not be so surprising, taking into account that the strain was originally isolated from milk almost 50 years ago (35).
Many survival traits are located on plasmids, such as genes coding for virulence factors and antibiotic resistance (20). B. anthracis, belonging to the B. cereus group and thus a close relative of B. cereus and B. thuringiensis (and the causative agent of anthrax) (2), has its crucial virulence factors located on two plasmids, and when one or both are lost the B. anthracis is not virulent (37). One may speculate that the extrachromosomal DNA of 300 kb observed in the strains from the patients with periodontitis has a virulence factor(s) that makes the strains capable of adhering to type I collagen, laminin, and fibronectin, as observed for strains OH 599 (AH 812) and OH 600 (AH 819) (24). It would be interesting to test whether the patient strains lacking the 300-kb plasmid have reduced adherence to type I collagen, laminin, and fibronectin.
Although it is interesting that all strains isolated from patients were in cluster II, together with the soil isolates from southern Norway (Moss) (18), none of the patients from whom strains were isolated were living in the central or northern part of Norway, where the soil samples in cluster I were from. Yet, the strains from periodontitis infections belonging to the ET cluster 24-25 were from patients living more than 400 km apart in Norway, or in Brazil, indicating that these strains most likely have important virulence factors in common.
In conclusion, this study indicated low genetic diversity among B. cereus and B. thuringiensis isolates from patients but high genetic diversity among dairy isolates, as observed previously for soil isolates. The B. cereus strains isolated from patients show an epidemic population structure, where 60% of the isolates share the same ET.
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ACKNOWLEDGMENTS |
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We acknowledge M.-M. Lecadet for serotyping strains and B. E. Kristiansen and P. E. Granum for gifts of strains. We thank B. G. Spratt for letting us use his computer program.
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FOOTNOTES |
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* Corresponding author. Mailing address: Biotechnology Centre of Oslo, University of Oslo, PB 1125, 0316 Oslo, Norway. Phone: 47 22958460. Fax: 47 22694130. E-mail: annebko{at}biotek.uio.no.
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REFERENCES |
|---|
|
Top
Abstract
Introduction
Materials and Methods
Results
Discussion
References
|
|---|
| 1. | Andrup, L., O. Jorgensen, A. Wilcks, L. Smidt, and G. B. Jensen. 1996. Mobilization of "nonmobilizable" plasmids by the aggregation-mediated conjugation system of Bacillus thuringiensis. Plasmid 36:75-85[CrossRef][Medline]. |
| 2. |
Ash, C.,
J. A. Farrow,
M. Dorsch,
E. Stackebrandt, and M. D. Collins.
1991.
Comparative analysis of Bacillus anthracis, Bacillus cereus, and related species on the basis of reverse transcriptase sequencing of 16S rRNA.
Int. J. Syst. Bacteriol.
41:343-346 |
| 3. |
Carlson, C. R.,
D. Caugant, and A.-B. Kolstø.
1994.
Genotypic diversity among Bacillus cereus and Bacillus thuringiensis strains.
Appl. Environ. Microbiol.
60:1719-1725 |
| 4. |
Carlson, C. R.,
T. Johansen,
L. M.-M., and A.-B. Kolstø.
1996.
Genomic organization of the entomopathogenic bacterium Bacillus thuringiensis subsp. berliner 1715.
Microbiology
142:1625-1634 |
| 5. |
Carlson, C. R., and A. B. Kolstø.
1993.
A complete physical map of a Bacillus thuringiensis chromosome.
J. Bacteriol.
175:1053-1060 |
| 6. | Caugant, D. A. 1998. Population genetics and molecular epidemiology of Neisseria meningitidis. APMIS 106:505-525[Medline]. |
| 7. |
Crickmore, N.,
D. R. Zeigler,
J. Feitelson,
E. Schnepf,
J. Van Rie,
D. Lereclus,
J. Baum, and D. H. Dean.
1998.
Revision of the nomenclature for the Bacillus thuringiensis pesticidal crystal proteins.
Microbiol. Mol. Biol. Rev.
62:807-813 |
| 8. | Damgaard, P. H., P. E. Granum, J. Bresciani, M. V. Torregrossa, J. Eilenberg, and L. Valentino. 1997. Characterization of Bacillus thuringiensis isolated from infections in burn wounds. FEMS Immunol. Med. Microbiol. 18:47-53[CrossRef][Medline]. |
| 9. | de Barjac, H. 1981. Identification of H-serotypes of Bacillus thuringiensis. Coordinating ed., H. D. Burges. Academic Press, Inc., Ltd., London, United Kingdom. |
| 10. |
Drobniewski, F. A.
1993.
Bacillus cereus and related species.
Clin. Microbiol. Rev.
6:324-338 |
| 11. |
Dykhuizen, D., and D. L. Hartl.
1980.
Selective neutrality of 6PGD allozymes in E. coli and the effects of genetic background.
Genetics
96:801-817 |
| 12. |
Dykhuizen, D. E., and D. L. Hartl.
1983.
Functional effects of PGI allozymes in Escherichia coli.
Genetics
105:1-18 |
| 13. | Feinberg, A. P., and B. Vogelstein. 1983. A technique for radiolabeling DNA restriction endonuclease fragments to high specific activity. Anal. Biochem. 132:6-13[CrossRef][Medline]. |
| 14. | Feinberg, A. P., and B. Vogelstein. 1984. A technique for radiolabeling DNA restriction endonuclease fragments to high specific activity. Addendum. Anal. Biochem. 137:266-267[CrossRef][Medline]. |
| 15. |
Gonzales, J. M. J.,
B. S. Brown, and B. C. Carlton.
1982.
Transfer of Bacillus thuringiensis plasmids coding for  -endotoxin among strains of Bacillus thuringiensis and Bacillus cereus.
Proc. Natl. Acad. Sci. USA
79:6951-6955 |
| 16. | Granum, P. E., S. Brynestad, and J. M. Kramer. 1993. Analysis of enterotoxin production by Bacillus cereus from dairy products, food poisoning incidents and non-gastrointestinal infections. Int. J. Food Microbiol. 17:269-279[CrossRef][Medline]. |
| 17. |
Hartl, D. L., and D. E. Dykhuizen.
1981.
Potential for selection among nearly neutral allozymes of 6-phosphogluconate dehydrogenase in Escherichia coli.
Proc. Natl. Acad. Sci. USA
78:6344-6348 |
| 18. | Helgason, E., D. A. Caugant, M. M. Lecadet, Y. Chen, J. Mahillon, A. Lövgren, I. Hegna, K. Kvaløy, and A. B. Kolstø. 1998. Genetic diversity of Bacillus cereus/B. thuringiensis isolates from natural sources. Curr. Microbiol. 37:80-87[CrossRef][Medline]. |
| 19. | Jackson, S. G., R. B. Goodbrand, R. Ahmed, and S. Kasatiya. 1995. Bacillus cereus and Bacillus thuringiensis isolated in a gastroenteritis outbreak investigation. Lett. Appl. Microbiol. 21:103-105[Medline]. |
| 20. | Kado, C. I. 1998. Origin and evolution of plasmids. Antonie Leeuwenhoek 73:117-126. |
| 21. |
Keim, P.,
A. Kalif,
J. Schupp,
K. Hill,
S. E. Travis,
K. Richmond,
D. M. Adair,
M. Hugh-Jones,
C. R. Kuske, and P. Jackson.
1997.
Molecular evolution and diversity in Bacillus anthracis as detected by amplified fragment length polymorphism markers.
J. Bacteriol.
179:818-824 |
| 22. | Kinane, D. F., and J. Lindhe. 1997. Pathogenesis of periodontitis, p. 189-225. In J. Lindhe, T. Karring, and N. P. Lang (ed.), Clinical periodontology and implant dentistry, 3rd ed. Munksgaard, Copenhagen, Denmark. |
| 23. |
Kolstø, A. B.,
A. Grønstad, and H. Oppegaard.
1990.
Physical map of the Bacillus cereus chromosome.
J. Bacteriol.
172:3821-3825 |
| 24. |
Kotiranta, A.,
M. Haapasalo,
K. Kari,
E. Kerosuo,
I. Olsen,
T. Sorsa,
J. H. Meurman, and K. Lounatmaa.
1998.
Surface structure, hydrophobicity, phagocytosis, and adherence to matrix proteins of Bacillus cereus cells with and without the crystalline surface protein layer.
Infect. Immun.
66:4895-4902 |
| 25. | Lecadet, M.-M. 1994. Collection of Bacillus thuringiensis and Bacillus sphaericus (classified by H serotypes). Catalogue of strains no. 1. Unité des bacteries entomopathogenes. Institut Pasteur, Paris, France. |
| 26. |
Lechner, S.,
R. Mayr,
K. P. Francis,
B. M. Pruss,
T. Kaplan,
E. Wiessner-Gunkel,
G. S. Stewart, and S. Scherer.
1998.
Bacillus weihenstephanensis sp. nov. is a new psychrotolerant species of the Bacillus cereus group.
Int. J. Syst. Bacteriol.
48:1373-1382 |
| 27. | Maiden, M. C. J., and I. M. Feavers. 1995. Population genetics and global epidemiology of the human pathogen Neisseria meningitidis, p. 269-293. In S. Baumberg, J. P. W. Young, E. M. H. Wellington, and J. R. Saunders (ed.), Population genetics of bacteria. Cambridge University Press, Cambridge, United Kingdom. |
| 28. |
Maynard-Smith, J.,
N. H. Smith,
M. O'Rourke, and B. G. Spratt.
1993.
How clonal are bacteria?
Proc. Natl. Acad. Sci. USA
90:4384-4388 |
| 29. |
Mayr, B.,
T. Kaplan,
S. Lechner, and S. Scherer.
1996.
Identification and purification of a family of dimeric major cold shock protein homologs from the psychrotrophic Bacillus cereus WSBC 10201.
J. Bacteriol.
178:2916-2925 |
| 30. |
Priest, F. G.,
D. A. Kaji,
Y. B. Rosato, and V. P. Canhos.
1994.
Characterization of Bacillus thuringiensis and related bacteria by ribosomal RNA gene restriction fragment length polymorphisms.
Microbiology
140:1015-1022 |
| 31. |
Schaeffer, P.,
J. Millet, and J. P. Aubert.
1965.
Catabolic repression of bacterial sporulation.
Proc. Natl. Acad. Sci. USA
54:704-711 |
| 32. |
Selander, R. K.,
D. A. Caugant,
H. Ochman,
J. M. Musser,
M. N. Gilmour, and T. S. Whittam.
1986.
Methods of multilocus enzyme electrophoresis for bacterial population genetics and systematics.
Appl. Environ. Microbiol.
51:873-884 |
| 33. | Sneath, P. H. A., and R. R. Sokal. 1973. Numerical taxonomy: the principles of numerical classification. W. H. Freeman & Co., San Francisco, Calif. |
| 34. | Socransky, S. S., and A. D. Haffajee. 1997. Microbiology of periodontal disease. In J. Lindhe, T. Karring, and N. P. Lang (ed.), Clinical periodontology and implant dentistry, 3rd ed. Munksgaard, Copenhagen, Denmark. |
| 35. | Stewart, A. 1952. RF15745. U.S. Department of Agricultural Monograph, vol. 16. , p. 59. . |
| 36. | Teanpaisan, R., C. W. Douglas, A. R. Eley, and T. F. Walsh. 1996. Clonality of Porphyromonas gingivalis, Prevotella intermedia and Prevotella nigrescens isolated from periodontally diseased and healthy sites. J. Periodontal Res. 31:423-432[CrossRef][Medline]. |
| 37. | Turnbull, P. C., R. A. Hutson, M. J. Ward, M. N. Jones, C. P. Quinn, N. J. Finnie, C. J. Duggleby, J. M. Kramer, and J. Melling. 1992. Bacillus anthracis but not always anthrax. J. Appl. Bacteriol. 72:21-28[Medline]. |
| 38. | Turnbull, P. C. B., J. Kramer, and M. J. Melling. 1990. Principles of bacteriology, virology and immunity, p. 187-210. In M. T. Parker, and B. I. Duerden (ed.), Bacillus, vol. 2. /Systematic. Edward Arnold, London, United Kingdom. |
| 39. |
Whittam, T. S.,
H. Ochman, and R. K. Selander.
1983.
Multilocus genetic structure in natural populations of Escherichia coli.
Proc. Natl. Acad. Sci. USA
80:1751-1755 |
| 40. | Zahner, V., H. Momen, C. A. Salles, and L. Rabinovitch. 1989. A comparative study of enzyme variation in Bacillus cereus and Bacillus thuringiensis. J. Appl. Bacteriol. 67:275-282[Medline]. |
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