| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
MICROBIOLOGY COMMENT |
Advanced Research Centre for Applied Microbiology, Department of Biotechnology, University of the Western Cape, Bellville 7535, Cape Town, South Africa
Correspondence
Lemese Ah Tow
(lah-tow{at}uwc.ac.za)
The genus Staphylococcus is virtually ubiquitous and, at the time of writing, represented by 37 species and numerous subspecies (http://www.bacterio.cict.fr/s/staphylococcus.html). At least 12 of these staphylococcal species/subspecies are human commensals that can become opportunistic pathogens (Kloos et al., 1992
). For example, Staphylococcus epidermidis (the most prevalent colonizer of the human skin) can cause nosocomial infections (von Eiff et al., 2002), while Staphylococcus aureus (which occupies the anterior nares in 50–75 % of healthy individuals) can cause scalded skin syndrome and toxic shock syndrome (Ellis et al., 2003; Hanakawa et al., 2002).
As part of a programme investigating microbial contamination of pristine Antarctic Dry Valley environments resulting from human activities, we chose Staphylococcus as a target organism. PCR amplification of community DNA extracts from human-impacted and pristine Antarctic field sites using a published set of Staphylococcus-specific primers [TstaG422 (5'-GGC CGT GTT GAA CGT GGT CAA ATC A-3') and TStag765 (5'-TIA CCA TTT CAG TAC CTT CTG GTA A-3')] (Martineau et al., 2001) resulted in strong and reproducible signals in all samples, suggesting that Staphylococcus was widely disseminated (L. Ah Tow & D. A. Cowan, unpublished data).
Martineau et al. (2001) have reported that the specificity of this primer set, which targets the tuf gene, is extremely high. Certain regions in the tuf genes are conserved within bacterial species belonging to the same genus. Ke et al. (1999) and Martineau et al. (2001) have used this characteristic as an effective bacterial phylogenetic marker. The tuf gene encodes the elongation factor Tu (EF-Tu), which plays an important role in protein synthesis (Weijland et al., 1992). tuf gene sequences have been cloned and sequenced from both Gram-negative and Gram-positive bacteria (Filer & Furano, 1981; Sela et al., 1989). Martineau et al. (2001) have shown that a 370 bp PCR product could be amplified from 27 different staphylococcal species, but not from 53 non-staphylococcal species tested. Macrococcus caseolyticus, which is phylogenetically closely related to members of the genus Staphylococcus, was amongst the 53 non-staphylococcal species that yielded a negative result in the Staphylococcus-specific PCR.
To confirm our contention that Staphylococcus spp. were widely disseminated in Antarctic Dry Valley soils, samples collected from Bratina Island and McMurdo station, Ross Dependency, Eastern Antarctica, were cultured on mannitol salt agar (a selective medium for the isolation of staphylococci and a few halophilic species; OXOID Manual). Numerous orange-pigmented colonies were observed on the selective medium. When the Staphylococcus-specific primers were tested on DNA extracts of the orange-pigmented colonies isolated from the Antarctic Dry Valley soil samples, a 370 bp PCR product was amplified (Fig. 1), indicating that they were possibly staphylococci. However, PCR amplification with 16S rDNA eubacterial primers E9F (5'-GAG TTT GAT CCT GGC TCA G-3'; Farrelly et al., 1995) and U1510R (5'-GGT TAC CTT GTT ACG ACT T-3'; Reysenbach & Pace, 1995) and subsequent sequencing of the 16S rDNA genes revealed that the orange-pigmented colonies showed highest sequence identity with Planococcus psychrophilus (99 % sequence identity across 559 bp) and a Planomicrobium sp. (99 % sequence identity across 527 bp). To date, there have been no tuf gene sequences published for Planococcus and Planomicrobium spp. Planococcus psychrophilus, a Gram-positive, rod-shaped bacterium (Reddy et al., 2002), is one of five Planococcus species within the family Planococcaceae (http://www.bacterio.cict.fr/p/planococcus.html). Planococcus spp. have been isolated from a variety of marine environments and some Antarctic lakes (Bowman et al., 1997; Engelhardt et al., 2001; Reddy et al., 2002; Sheridan & Brenchley, 2000), and many of these species have been reported to produce an orange/yellow pigment (Engelhardt et al., 2001; Reddy et al., 2002; Sheridan & Brenchley, 2000). Planomicrobium, a new genus belonging to the family Planococcaceae, contains two previously assigned planococcal species, namely Planomicrobium mcmeekinii and Planomicrobium okeanokoites (Yoon et al., 2001). Although these species have been assigned to a separate genus, Planomicrobium and Planococcus are clearly closely related genera (Fig. 2).
|
|
). They are, thus, more distantly related to Staphylococcus than Staphylococcus is to other members of the family Staphylococcaceae, such as the genus Macrococcus, the latter showing no positive PCR signal in the published studies by Martineau et al. (2001). Our results allow us to conclude that there appears to be significant conservation between the tuf genes of Planococcus, Planomicrobium and Staphylococcus spp., and that although the primer set TstaG422/TStag765 has been shown to possess high specificity, its use for the definitive identification of Staphylococcus spp. must be treated with some caution.
REFERENCES
Bowman, J. P., McCammon, S. A., Brown, M. V., Nichols, D. S. & McMeekin, T. A. (1997). Diversity and association of psychrophilic bacteria in Antarctic sea ice. Appl Environ Microbiol 63, 3068–3078.[Abstract]
Ellis, M., Serreli, A., Colque-Navarro, P., Hedstrom, U., Chacko, A., Siemkowicz, E. & Mollby, R. (2003). Role of staphylococcal enterotoxin A in a fatal case of endocarditis. J Med Microbiol 52, 109–112.
Engelhardt, M. A., Daly, K., Swannell, R. P. J. & Head, I. M. (2001). Isolation and characterization of a novel hydrocarbon-degrading, Gram-positive bacterium, isolated from intertidal beach sediment, and description of Planococcus alkanoclasticus sp. nov. J Appl Microbiol 90, 237–247.[CrossRef][Medline]
Farrelly, V., Rainey, F. A. & Stackebrandt, E. (1995). Effect of genome size and rrn gene copy number on PCR amplification of 16S rRNA genes from a mixture of bacterial species. Appl Environ Microbiol 61, 2798–2801.[Abstract]
Filer, D. & Furano, A. V. (1981). Duplication of the tuf gene, which encodes peptide chain elongation factor Tu, is widespread in Gram-negative bacteria. J Bacteriol 148, 1006–1011.
Hanakawa, Y., Schechter, N. M., Lin, C. & 8 other authors (2002). Molecular mechanisms of blister formation in bullous impetigo and staphylococcal scalded skin syndrome. J Clin Invest 110, 53–60.[CrossRef][Medline]
Ke, D., Picard, F. J., Martineau, F., Ménard, C., Roy, P. H., Ouellette, M. & Bergeron, M. G. (1999). Development of a PCR assay for rapid detection of enterococci. J Clin Microbiol 37, 3497–3503.
Kloos, W. E., Schleifer, K.-H. & Götz, F. (1992). The genus Staphylococcus. In The Prokaryotes, 2nd edn, pp. 1369–1420. Edited by A. Balows, H. G. Trüper, M. Dworkin, W. Harder & K.-H. Schleifer. New York: Springer-Verlag.
Martineau, F., Picard, F. J., Ke, D., Paradis, S., Roy, P. H., Ouellette, M. & Bergeron, M. G. (2001). Development of a PCR assay for identification of staphylococci at genus and species levels. J Clin Microbiol 39, 2541–2547.
Reddy, G. S. N., Prakash, J. S. S., Vairamani, M., Prabhakar, S., Matsumoto, G. I. & Shivaji, S. (2002). Planococcus antarcticus and Planococcus psychrophilus spp. nov. isolated from cyanobacterial mat samples collected from ponds in Antarctica. Extremophiles 6, 253–261.[CrossRef][Medline]
Reysenbach, A.-L. & Pace, N. R. (1995). Reliable amplification of hyperthermophilic archaeal 16S rRNA genes by the polymerase chain reaction. In Archaea: a Laboratory Manual – Thermophiles. Edited by F. T. Robb & A. R. Place. Cold Spring Harbor, NY: Cold Spring Harbor Laboratory.
Sela, S., Yogev, D., Razin, S. & Bercovier, H. (1989). Duplication of the tuf gene: a new insight into the phylogeny of eubacteria. J Bacteriol 171, 581–584.
Sheridan, P. P. & Brenchley, J. E. (2000). Characterization of a salt-tolerant family 42 
-galactosidase from a psychrophilic Antarctic Planococcus isolate. Appl Environ Microbiol 66, 2438–2444.
von Eiff, C., Peters, G. & Heilmann, C. (2002). Pathogenesis of infections due to coagulase-negative staphylococci. Lancet Infect Dis 2, 677–685.[CrossRef][Medline]
Weijland, A., Harmark, K., Cool, R. H., Anborgh, P. H. & Parmeggiani, A. (1992). Elongation factor Tu: a molecular switch in protein biosynthesis. Mol Microbiol 6, 683–688.[CrossRef][Medline]
Yoon, J.-H., Kang, S.-S., Lee, K.-C., Lee, E. S., Kho, Y. H., Kang, K. H. & Park, Y. H. (2001). Planomicrobium koreense gen. nov., sp. nov., a bacterium isolated from the Korean traditional fermented seafood jeotgal, and transfer of Planococcus okeanokoites (Nakagawa et al. 1996) and Planococcus mcmeekinii (Junge et al. 1998) to the genus Planomicrobium. Int J Syst Evol Microbiol 51, 1511–1520.[Abstract]
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| INT J SYST EVOL MICROBIOL | MICROBIOLOGY | J GEN VIROL |
| J MED MICROBIOL | ALL SGM JOURNALS | |
