%0 Journal Article
%T Analysis of Nucleotide Sequences of the 16S rRNA Gene of Novel Escherichia coli Strains Isolated from Feces of Human and Bali Cattle
%A I Wayan Suardana
%J Journal of Nucleic Acids
%D 2014
%I Hindawi Publishing Corporation
%R 10.1155/2014/475754
%X Livestock especially cattle are known as a main reservoir of Escherichia coli O157:H7. This bacterium is considered as a pathogenic agent characterized by producing toxins, which are familiarly known as Shiga-like toxin-1 (Stx1) and Stx2. The aim of this work was to analyse the novel sequence of the 16S rRNA gene of strains isolated in this study in order to know the phylogenetic relationships between these sequences and those between the sequences of bacteria available in databanks. The results of this analysis showed that the strains KL-48(2) and SM25(1) that originated from human and cattle feces, respectively, are closely related among them and with respect to E. coli EDL 933, E. coli Sakai, E. coli ATCC 43894, E. coli O111:H-, E. coli O121:H19, E. coli O104:H4, and Shigella sonnei with more than 99% similarity values. 1. Introduction The identification of pathogenic bacteria was traditionally performed by isolating the organism and studying it phenotypically by means of Gram staining and culture and biochemical methods, which has been the gold standard of bacterial identification [1]. With the invention of polymerase chain reaction (PCR) and automated DNA sequencing, the genome of some bacteria has been sequenced completely. A comparison of the genomic sequences of bacterial species showed that the 16S ribosomal RNA (rRNA) gene is highly conserved within a species and among species of the same genus and, hence, can be used as the new gold standard for the specification of bacteria [2]. To study bacterial phylogeny and taxonomy, the 16S rRNA gene sequences are very useful. With the gene presence in almost all bacteria, often existing as a multigene family, or operons, the function of the 16S rRNA gene over time has not changed, suggesting that random sequence changes are a more accurate measure of time and the 16S rRNA gene (1500£¿bp) is large enough for informatics purposes [3]. Using 16S rRNA sequences, numerous bacterial genera and species have been reclassified and renamed; classification of uncultivable bacteria has been made possible, phylogenetic relationships have been determined, and the discovery and classification of novel bacterial species have been facilitated [4]. This method has been successful in identifying Enterobacteriaceae species from a bone marrow transplant recipient [2], and the use of this method to identify or discover novel bacteria in clinical microbiology laboratories has successfully been reported also [4, 5]. Escherichia coli O157:H7 as one of enterohemorrhagic Escherichia coli (EHEC) are predominant strains causing
%U http://www.hindawi.com/journals/jna/2014/475754/