Identification of Genes of CRISPR Associated Proteins CAS in the Genomes of Enteric Microorganisms

CRISPR-Cas systems are RNA-based immune systems present in many prokaryotes that prevent viral infections and other plasmid to incorporate into them. There were many cas genes identified previously but due to the progressive genome sequencing some strains of bacteria have not been searched for cas identification. Here we have presented the location and asses for their particular pattern of order in various gut microorganisms. Our findings suggest that the common order of cas genes in gut microbial is cas2-cas1-cas5-cas3-cas4 while, the common orders for subtype specific cse gene in all species were: cse3-cse4-cse2-cse1. Though it is established that cas1 is the one that play vital role in CRISPR-Cas systems immunity but some strains were found to be contain only cas2 and cas4 genes suggesting alternative mechanism other than cas1 mediated immunity. The hidden markov model was not retrieved from TIGR database, instead hidden markov model was build for each microorganism separately. There is a possibility that some cas genes were not included due to poor bit score and e-value although they are present in the genomes.