Analysis of CRISPR systems of types II-A, I-E and I-C in strains of Lacticaseibacillus

Abstract

A total of 49 strains of Lacticaseibacillus were screened for the presence of CRISPR-Cas systems. Type II-A CRISPR-Cas loci were sequenced for 8 Lacticaseibacillus paracasei and 3 Lacticaseibacillus rhamnosus strains. They contained 21 to 49 spacers, a few of them with similarity to plasmids. Cas9 identity was well correlated with spacer content of the strains. Only strain L. paracasei 85 contained a type I-E CRISPR locus, uncommon in this species, with highly conserved Cas proteins and 79 spacers not previously reported, a high percentage of them (23%) matching L. paracasei phage genomes. PAM sequences were 5′-NGAA-3´ (type II-A) and 5′-aAA-3´ (type I-E). Protospacer selection in type I-E was highly biased towards genes involved in lysis and morphogenesis. Our results improve the knowledge about distribution and diversity of CRISPR-Cas systems in Lacticaseibacillus strains of industrial interest, not profoundly studied despite the economic impact of phage infections.