{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,11,5]],"date-time":"2026-11-05T12:04:39Z","timestamp":1793880279014,"version":"4.7.0"},"reference-count":48,"publisher":"MDPI AG","issue":"21","license":[{"start":{"date-parts":[[2022,10,23]],"date-time":"2022-10-23T00:00:00Z","timestamp":1666483200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Babes-Bolyai University","award":["doctoral grant of Dumitrana Iordache"],"award-info":[{"award-number":["doctoral grant of Dumitrana Iordache"]}]},{"name":"Babes-Bolyai University","award":["GS-UBB-2022-Butiuc-KeulA"],"award-info":[{"award-number":["GS-UBB-2022-Butiuc-KeulA"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["IJMS"],"abstract":"<jats:p>CRISPR-Cas is an adaptive immunity system of prokaryotes, composed of CRISPR arrays and the associated proteins. The successive addition of spacer sequences in the CRISPR array has made the system a valuable molecular marker, with multiple applications. Due to the high degree of polymorphism of the CRISPR loci, their comparison in bacteria from various sources may provide insights into the evolution and spread of the CRISPR-Cas systems. The aim of this study was to establish a correlation between the enterobacterial CRISPR loci, the sequence of direct repeats (DR), and the number of spacer units, along with the geographical origin and collection source. For this purpose, 3474 genomes containing CRISPR loci from the CRISPRCasdb of Salmonella enterica, Escherichia coli, and Klebsiella pneumoniae were analyzed, and the information regarding the isolates was recorded from the NCBI database. The most prevalent was the I-E CRISPR-Cas system in all three studied taxa. E. coli also presents the I-F type, but in a much lesser percentage. The systems found in K. pneumoniae can be classified into I-E and I-E*. The I-E and I-F systems have two CRISPR loci, while I-E* has only one locus upstream of the Cas cluster. PCR primers have been developed in this study for each CRISPR locus. Distinct clustering was not evident, but statistically significant relationships occurred between the different CRISPR loci and the number of spacer units. For each of the queried taxa, the number of spacers was significantly different (p &lt; 0.01) by origin (Africa, Asia, Australia and Oceania, Europe, North America, and South America) but was not linked to the isolation source type (human, animal, plant, food, or laboratory strains).<\/jats:p>","DOI":"10.3390\/ijms232112766","type":"journal-article","created":{"date-parts":[[2022,10,24]],"date-time":"2022-10-24T04:40:36Z","timestamp":1666586436000},"page":"12766","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":4,"title":["Correlation between CRISPR Loci Diversity in Three Enterobacterial Taxa"],"prefix":"10.3390","volume":"23","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-9811-270X","authenticated-orcid":false,"given":"Dumitrana","family":"Iordache","sequence":"first","affiliation":[{"name":"Doctoral School of Integrative Biology, Babe\u0219-Bolyai University, 44 Republicii street, 400015 Cluj-Napoca, Romania"},{"name":"Department of Molecular Biology and Biotechnology, Faculty of Biology and Geology, Babe\u0219-Bolyai University, 1 M. Kogalniceanu Street, 400084 Cluj-Napoca, Romania"},{"name":"Centre for Systems Biology, Biodiversity and Bioresources, Babe\u0219-Bolyai University, 5\u20137 Clinicilor Street, 400006 Cluj-Napoca, Romania"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9832-4016","authenticated-orcid":false,"given":"Gabriela-Maria","family":"Baci","sequence":"additional","affiliation":[{"name":"Faculty of Animal Science and Biotechnology, University of Agricultural Sciences and Veterinary Medicine, 400372 Cluj-Napoca, Romania"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Oana","family":"C\u0103pri\u021b\u0103","sequence":"additional","affiliation":[{"name":"Department of Molecular Biology and Biotechnology, Faculty of Biology and Geology, Babe\u0219-Bolyai University, 1 M. Kogalniceanu Street, 400084 Cluj-Napoca, Romania"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Anca","family":"Farkas","sequence":"additional","affiliation":[{"name":"Department of Molecular Biology and Biotechnology, Faculty of Biology and Geology, Babe\u0219-Bolyai University, 1 M. Kogalniceanu Street, 400084 Cluj-Napoca, Romania"},{"name":"Centre for Systems Biology, Biodiversity and Bioresources, Babe\u0219-Bolyai University, 5\u20137 Clinicilor Street, 400006 Cluj-Napoca, Romania"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6657-3245","authenticated-orcid":false,"given":"Andreea","family":"Lup","sequence":"additional","affiliation":[{"name":"Department of Molecular Biology and Biotechnology, Faculty of Biology and Geology, Babe\u0219-Bolyai University, 1 M. Kogalniceanu Street, 400084 Cluj-Napoca, Romania"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6523-6845","authenticated-orcid":false,"given":"Anca","family":"Butiuc-Keul","sequence":"additional","affiliation":[{"name":"Department of Molecular Biology and Biotechnology, Faculty of Biology and Geology, Babe\u0219-Bolyai University, 1 M. Kogalniceanu Street, 400084 Cluj-Napoca, Romania"},{"name":"Centre for Systems Biology, Biodiversity and Bioresources, Babe\u0219-Bolyai University, 5\u20137 Clinicilor Street, 400006 Cluj-Napoca, Romania"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2022,10,23]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"5429","DOI":"10.1128\/jb.169.12.5429-5433.1987","article-title":"Nucleotide sequence of the iap gene, responsible for alkaline phosphatase isoenzyme conversion in Escherichia coli, and identification of the gene product","volume":"169","author":"Ishino","year":"1987","journal-title":"J. Bacteriol."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"174","DOI":"10.1007\/s00239-004-0046-3","article-title":"Intervening sequences of regularly spaced prokaryotic repeats derive from foreign genetic elements","volume":"60","author":"Mojica","year":"2005","journal-title":"J. Mol. 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