Genetic diversity of CRISPR1 and CRISPR2 systems in Salmonella enterica isolates in Babylon Governorate, Iraq

CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) refers to a particular arrangement of nucleotides in which there is an alternation between short, direct repeats and short spacer sequences in between them. In addition to the system of CRISPR, they express a bacterial-acquired immunity that protects the bacterial cell against infection by bacteriophages and plasmids. This study was aimed to detection of genetic diversity among bacterial isolates which was performed by using CRISPR and were assessed for their potential in 18 Salmonella enterica (S. enterica) isolates. In this study, a total of 18 S. enterica isolates from different clinical specimens (stool & blood) were subjected to detection of CRISPR 1 and 2; of these, 18 (100%) and 13(72%) isolates were PCR – positive for CRISPR Ι & ΙΙ respectively. The number of the spacer of CRISPR 1 and 2 were between 5-13 and1-12 spacers, respectively. The length of the CRISPR1 and CRISPR2 DR was 29 nucleotides. The polymorphism of DR of CRISPR-Ι by phylogenetic tree construction indicated that all 18 patterns can divided into six linages (A-F), whereas among 13 diverse patterns of CRISPR-ΙΙ can classified into four linages (A-D). CRISPR-I had a different number of spacers than CRISPR- ΙΙ according to our research. Based on these findings, it can be deduced that the CRISPR array has the potential to serve as a molecular marker for an epidemiological study involving S. enterica.