INTERNATIONAL
JOURNAL
OF SYSTEMATIC
BACTERIOLOGY,
Oct. 1987, p. 449-450
0020-7713/87/040449-02$02.00/0
Copyright 0 1987, International Union of Microbiological Societies
Vol. 37, No. 4
Guanine-Plus-Cytosine Contents of Type Strains of the
Genus Providencia
ROBERT J. OWEN,l* AFSAR U. AHMED,* AND CHRISTINE A. DAWSON'
National Collection of Type Cultures, Central Public Health Laboratory, London NW9 SHT, England,' and Type Culture
Collection, Institute of Nutrition and Food Science, Dhaka University, Dhaka, Bangladesh'
The guanine-plus-cytosine contents of the type strains of Providencia alcalijiiciens, P . friedericiana, P .
stuartii, P . rettgeri, P . rustigianii, and P . heimbachae were determined by thermal denaturation and were found
to be between 39 and 43 mol%. These results agreed with the values previously reported for members of the
genus Providencia.
TABLE 1. G + C contents of type strains of Providencia species
The classification of the genus Providencia has undergone
considerable revision during the past decade, and the latest
arrangement reported by Farmer et al. (3) and based on
extensive deoxyribonucleic acid-deoxyribonucleic acid hybridization and phenotypic analyses (1, 5) recognizes four
species: P. alcalifaciens (the type species), P. rustigianii
(formerly known as P. alcalifaciens biogroup 3 and by the
junior synonym P . friedericiana), P . rettgeri (formerly
known as Proteus rettgeri), and P . stuartii. Recently, Miiller
et al. (7) described a fifth species for which the name P.
heimbachae was proposed.
The guanine-plus-cytosine (G + C) contents of Providencia
species were reported to be 39 to 42 mol% (2), and these
values were included in the description of the species given
in Bergey 's Manual of Systematic Bacteriology (9). However, Penner (9) pointed out that the G+C mol% data on
Providencia were uncertain because of past confusion in the
classification of species within the genus, and no values were
listed for individual species or reference strains. The purpose of the present study was to determine the deoxyribonucleic acid base contents of the type strains of species of
Providencia, because to date none have published values
except for P. friedericiana (now P. rustigianii), which was
reported to have a G+C content of 39 ? 1.5 mol% (6).
Strains were obtained from the National Collection of
Type Cultures (NCTC), and their numbers are listed in Table
1. Cultures were grown in Oxoid nutrient broth no. 2 (CM67)
supplemented with L-cysteine hydrochloride (0.1 g/liter) for
24 h at 37"C, and deoxyribonucleic acid was extracted and
purified as described previously (7a, 8). The G+C contents
were estimated from the thermal denaturation temperature
(T,,J,which was determined in triplicate either in 0.33 x SSC
(Ix
SSC is 0.15 M NaCl plus 0.015 M trisodium citrate, pH
7.0) or in 0 . 1 ~SSC buffer (8). The base composition was
expressed relative to a chemically determined value of 51.1
mol% G+C for Escherichia coli NCTC 9001 (K. Komagata,
personal communication).
The G+C results for the five type strains and the reference
strain of P. Ji.iedericiana, which were between 39.6 and 43.0
mol%, are listed in Table 1. The error, expressed as the
pooled standard deviation, was +0.3%. Our results on the
type strains agreed almost exactly with previously published
G+C data on Providencia (2,6) and confirmed that members
of the genus had a relatively narrow and homogeneous range
Providencia
species
Type strain"
P. alcalifaciens
NCTC
NCTC
NCTC
NCTC
NCTC
NCTC
P. heimbachae
P . rettgeri
P. rustigianii
P. stuartii
~~~
10286 (= ATCC 9886)
12003 (= ATCC 35613)
11801 (= ATCC 29944)
11802 (= ATCC 33673)
11667h(= DSM 2620)
11800 (= ATCC 29914)
G+C (mol%)
43.0
39.6
40.5
41.8
41.5
40.7
~
" Abbreviations used: NCTC, National Collection of Type Cultures, Lon-
don, England; ATCC, American Type Culture Collection, Rockville, Md. ;
DSM, Deutsche Sammlung von Mikroorganism, Gottingen, Federal Republic
of Germany.
Type strain of P. friedericiana (6).
of base compositions. The G+C content of 41.5 mol% for
NCTC 11667 (P. friedericiana) was almost identical to the
value for the type strain of P . rustigiunii and was consistent
with the two species being synonymous (4). We propose that
the G+C range for Providencia is 39 to 43 mol%.
A.U.A. was supported by a fellowship from the United Nations
University, Tokyo, Japan.
LITERATURE CITED
1. Brenner, D. J., J. J. Farmer 111, G. R. Fanning, A. G. Steigerwalt,
P. Klykken, H. G. Wathen, F. W. Hickman, and W. H. Ewing.
1978. Deoxyribonucleic acid relatedness of Proteus and
Providencia species. Int. J. Syst. Bacteriol. 28:269-282.
2. Falkow, S., I. R. Ryman, and 0. Washington. 1962. Deoxyribonucleic acid base composition of Proteus and Providencia organisms. J . Bacteriol. 83:1318-1321.
3. Farmer, J. J., 111, B. R. Davis, F. W. Hickman-Brenner, A.
McWhorter, G. P. Huntley-Carter, M. A. Asbury, C. Riddle,
H. G. Wathern-Grady, C. Elias, G. R. Fanning, A. G. Steigerwalt, C. M. O'Hara, G. K. Morris, P. B. Smith, and D. J.
Brenner. 1985. Biochemical identification of new species and
biogroups of Enterobacteriaceae isolated from clinical specimens. J. Clin. Microbiol. 21:46-76.
4. Hickman-Brenner, F. W., G. R. Fanning, H. E. Miiller, and D. J.
Brenner. 1986. Priority of Providenciu rustigianii HickmanBrenner, Farmer, Steigerwalt , and Brenner 1983 over Providencia friedericiana Muller 1983. Int. J. Syst. Bacteriol. 36565.
5. Hickman-Brenner, F. W., J. J. Farmer 111, A. G. Steigerwalt, and
D. J. Brenner. 1983. Providencia rustigianii: a new species in the
family Enterobacteriaceae formerly known as Providenciaal
cal(faciens biogroup 3. J. Clin. Microbiol. 17:1057-1060.
6. Miiller, H. E. 1983. Providencia friedericiana, a new species
isolated from penguins. Int. J. Syst. Bacteriol, 33:709-715.
* Corresponding author.
449
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450
INT. J. SYST.BACTERIOL.
NOTES
7. Muller, H. E., C. M. O’Hara, G. R. Fanning, F. W. HickmanBrenner, J. M. Swenson, and D. J. Brenner. 1986. Providencia
heimbachae, a new species of Enterobacteriaceae isolated from
animals. Int, J. Syst. Bacteriol.1986 36252-256.
7a.Owen, R. J., and P. Bormah. 1987. A rapid biochemical method
for purifying high-molecular-weight bacterial chromosomal DNA
for restriction enzyme analysis. Nucleic Acids Res. 15:3631.
8. Owen, R. J., and D. Pitcher. 1985. Current methods for estimat-
ing DNA base composition and levels of DNA-DNA hybridization, p. 67-93. In M. Goodfellow and D. Minnikin (ed.), Chemical
methods in bacterial systematics. Academic Press, Inc., Orlando, Fla.
9. Penner, J. L. 1984. Genus XI1 Providencia Ewing 1962,96 AL, p,
494-496. In N. R. Krieg and J. G. Holt (ed.), Bergey’s manual of
systematic bacteriology, vol. 1. The Williams & Wilkins Co.,
Baltimore.
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