Characterization of type I-F CRISPR-Cas system in Laribacter hongkongensis isolates from animals, the environment and diarrhea patients

Int J Food Microbiol. 2021 Mar 11;346:109153. doi: 10.1016/j.ijfoodmicro.2021.109153. Online ahead of print.ABSTRACTLaribacter hongkongensis is a foodborne organism that is associated with gastroenteritis and diarrhea in humans. Here we describe the structural characteristics and potential function of CRISPR systems to obtain insight into the genotypic diversity of L. hongkongensis. Specifically, we analyzed the genomic content of six L. hongkongensis genomes and identified two CRISPR loci (CRISPR1 and CRISPR2) belonging to the I-F subtype of CRISPR systems. CRISPR1 was flanked on one side by cas genes and a 170 bp-long putative leader sequence, while CRISPR2 arrays located further and processed by the same cas genes. Then a combination of PCR and sequencing was used to determine the prevalence and distribution of the two CRISPR arrays in 112 L. hongkongensis strains isolated from patients, animals, and water reservoirs. In total, the CRISPR1-Cas system of complete subtype I-F was detected in 91.5% (108/118) of the isolates, whereas CRISPR2 locus existed in 72.0% (85/118). Ten strains only possessed part of the cas genes of subtype I-F and four of them with CRISPR2 array. The two loci contained highly conserved and identical direct repeat sequences which were stable in their RNA secondary structure. Additionally, 2564 total spacers including 980 unique spacers arranged in 59 alleles were identified. Homology analysis showed only 1.8% (18/980) of the spacers matched with plasm...
Source: International Journal of Food Microbiology - Category: Food Science Authors: Source Type: research