CRISPR-Cas systems are present predominantly on mobile genetic elements in Vibrio species.

Background: Bacteria are prey for many viruses that hijack the bacterial cell in order to propagate, which can result in bacterial cell lysis and death. Bacteria have developed diverse strategies to counteract virus predation, one of which is the clustered regularly interspaced short palindromic repeat (CRISPR) and CRISPR associated (Cas) proteins immune defense system. Species within the bacterial family Vibrionaceae are marine organisms that encounter large numbers of phages.

CRISPR-Cas and Contact-Dependent Secretion Systems Present on Excisable Pathogenicity Islands with Conserved Recombination Modules.

Pathogenicity islands (PAIs) are mobile integrated genetic elements that contain a diverse range of virulence factors. PAIs integrate into the host chromosome at a tRNA locus that contains their specific bacterial attachment site, , via integrase-mediated site-specific recombination generating and sites. We identified conserved recombination modules (integrases and sites) previously described in choleragenic PAIs but with novel cargo genes.