Abstract
Streptococci form a wide group of bacteria and are involved in both human and animal pathologies. Among pathogenic isolates, differences have been highlighted especially concerning their adaptation and virulence profiles. CRISPR-Cas systems have been identified in bacteria and many streptococci harbor one or more systems, particularly subtypes I-C, II-A, and III-A. Since the demonstration that CRISPR-Cas act as an adaptive immune system in Streptococcus thermophilus, a lactic bacteria, the diversity and role of CRISPR-Cas were extended to many germs and functions were enlarged. Among those, the genome editing tool based on the properties of Cas endonucleases is used worldwide, and the recent attribution of the Nobel Prize illustrates the importance of this tool in the scientific world. Another application is CRISPR loci analysis, which allows to easily characterize isolates in order to understand the interactions of bacteria with their environment and visualize species evolution. In this review, we focused on the distribution, diversity and roles of CRISPR-Cas systems in the main pathogenic streptococci.
Highlights
Streptococci are cocci Gram positive bacteria arranged typically in pairs or chains
Streptococci are a wide group of bacteria and an important genus in human and animal medicine (Lamagni et al, 2008; Haas and Grenier, 2018; Raabe and Shane, 2019)
Research on CRISPR-Cas systems has shown that sequencing CRISPR loci can provide numerous isolate information, about their virulence, foreign mobile genetic elements (MGE), adaptation and evolution (Bolotin et al, 2005; Horvath et al, 2008; Mojica et al, 2009)
Summary
Streptococci are cocci Gram positive bacteria arranged typically in pairs or chains. They form a large group of bacteria, composed of 103 species (Patel and Gupta, 2018). They are widely distributed and are found at the surface of mucous membranes, like upper respiratory, gastrointestinal, or genito-urinary tracts of humans and many animals. Other streptococci belong to animal microbiota, like Streptococcus suis, which is an important cause of various clinical diseases in swine and domestic animals (Staats et al, 1997; Haas and Grenier, 2018). Several species are involved in both human and animal pathology, like Streptococcus agalactiae, which represents
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