Document Type : Original Article (s)
Authors
1
Molecular Biology Research Center, Baqiyatallah University of Medical Sciences, Tehran, Iran
2
Associate Professor, Molecular Biology Research Center, Baqiyatallah University of Medical Sciences, Tehran, Iran
3
Assistant Professor, Department of Molecular Biology, Pasteur Institute of Iran, Tehran, Iran
4
Associate Professor, Clinical Microbiology Research Center, Ilam University of Medical Sciences, Ilam, Iran
5
Department of Microbiology, Islamic Azad University, Science and Research Branch, Tehran, Iran
6
Department of Microbiology, School of Sciences, Islamic Azad University, Karaj Branch, Karaj, Iran
Abstract
Background: Ribosomal DNA (rDNA) genes contain signature structures which are unique for groups of organisms. Considering their great number in cells and their protected areas, they render ideal targets for specific nucleic acid probes. The present study aimed to investigate the capability of some specific regions of 23S rDNA gene as a DNA target for differentiation and screening of Escherichia coli, Salmonella enterica, and Shigella dysenteriae. Methods: Bacterial reference strains used in this study were E. coli, S. enterica and Sh. dysenteriae that were provided by the centers for microbial culture collection (CMCC) at Pasture Institute of Iran. DNA extraction was performed by boiling method. Alignment of the 23S rDNA sequences of bacterial species was performed by using AlignX (a component of Vector NTI Advance 11.0) and areas displaying sequence divergence among species were used for designing universal primers and individual bacteria specific probe. Findings: The universal polymerase chain reaction (PCR) products of each bacterial species showed bands of approximately 880 bp to be being equivalent to the fragment size of 23S rDNA gene. Different size bands of 23S rDNA probes were produced and included 228 bp for E. coli, 444 bp for S. enterica, and 776 bp for Sh. dysenteriae. Conclusion: Comparative sequence analysis of variable and specific regions of 23S rDNA genes among the studied bacterial species showed that we were able to amplify specific target among universal region for the detection of many enteric pathogenic bacteria. Keywords: 23S ribosomal DNA, Pathogenic bacteria, Vector NTI
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