Genome mining approach reveals the CRISPR-Cas characteristics and diversity of targeting phages in Lactobacillus iners strains

This study utilized a genomic approach to investigate CRISPR-Cas systems, focusing on Lactobacillus iners strains, which are crucial for bacterial defense against bacteriophage attacks. Genome sequences were analyzed to understand the diversity, occurrence, and evolution of these systems. Spacer sequences within CRISPR arrays were examined to identify targeted phages. The research explored the evolutionary paths of spaceromes within each CRISPR array subtype, considering acquisition and deletion events influenced by phage pressure. Results revealed that approximately 50 % of L. iners strains possess complete CRISPR-Cas systems, predominantly subtype II-A and I-E. Homology analysis indicated that subtype I-E systems target a wider range of foreign phages compared to subtype II-A systems. Overall, the findings underscore the varied components and structure of CRISPR-Cas systems in L. iners strains, highlighting their role as active immune defenses against phages and foreign DNA.