Abstract
Klebsiella
variicola (K. variicola ) is an emerging human pathogen, which
poses a threat to public health. The horizontal gene transfer (HGT) of
plasmids is an important driver for the emergence of multiple
antibiotic-resistant K. variicola . The clustered regularly
interspersed short palindromic repeats coupled with the
CRISPR-associated genes (CRISPR/Cas) constitute an adaptive immune
system in bacteria, which provide acquired immunity against HGT.
However, the information about CRISPR/Cas system in K. variicolais still limited. In this study, a total of 487 genomes from NCBI
database were used to analyze the characterization of CRISPR/Cas
systems. 105 of the 487 genomes harbored at least one confirmed CRISPR
array. Three types of CRISPR/Cas system, including types I-E, I-E*, and
Ⅳ-A systems, were identified among 105 strains. The distribution of type
I system was strongly associated with MLST, whereas type IV system was
randomly distributed. Approximately one-third of spacer origins were
homologous with plasmids or phages, indicating the role of CRISPR/Cas
systems in controlling HGT. Moreover, spacers in K. variicolatended to target mobile genetic elements (MGEs) from Klebsiella
pneumoniae , which provides new evidence for their interaction during
evolution. Collectively, our results provide valuable insights into the
role of CRISPR/Cas systems in K. variicola .