Figure 2.

Schematic diagram showing the CRISPR-Cas systems carried by environmental C. difficile isolates examined in this study. Typical operon organization is shown for each CRISPR-Cas system. Class 1 subtype I-B1 Cas system identified in 81.8% of the genomes code for the two mainly conserved clusters of cas genes that identified in this type. Cluster casA that encodes partial cas gene set (casb6, casb8, casb7, casb5, and casb3), and cluster casB codes for a complete set of subtype I-B1 cas genes (casb6, casb8, casb7, casb5, and casb3) and (casb1, casb2, and casb4). Class 2 V-type Cas system founded in 27.3% of the genomes encode for a single large effector protein (cas12f). Cas type other founded in only 9% of the genomes has only two genes homologous to cas6b and cas8b. Homologous cas genes are shown with coloured arrows. Colour coding is the same for homologous cas genes.