title: Contribution of the thermotolerance genomic island to increased thermal tolerance in Cronobacter strains.
abstract: Cronobacter spp. are opportunistic pathogens associated with serious infections in neonates. Increased stress tolerance, including the thermotolerance of some Cronobacter strains, can promote their survival in production facilities and thus raise the possibility of contamination of dried infant formula which has been identified as a potential source of infection. Some Cronobacter strains contain a genomic island, which might be responsible for increased thermotolerance. By analysis of Cronobacter sequenced genomes this determinant was found to be present in only 49/73 Cronobacter sakazakii strains and in 9/14 Cronobacter malonaticus strains. The island was also found in 16/17 clinical isolates originating from two hospitals. Two configurations of the locus were detected; the first one with the size of 18 kbp containing the thrB-Q genes and a shorter version (6 kbp) harbouring only the thrBCD and thrOP genes. Strains containing the thermotolerance island survived significantly better at 58 °C comparing to a C. sakazakii isogenic mutant lacking the island and strains with the longer version of the island were 2-10 times more tolerant than those with the shortened sequence. The function of the genomic island was further confirmed by its cloning into a low-copy vector and transforming it into the isogenic mutant. Different levels of rpoS, encoding for stress-response sigma factor, expression were also associated with variability in strain thermotolerance.
authors.affiliation: Department of Molecular Biology, Faculty of Natural Sciences, Comenius University, Ilkovičova 6, 842 15, Bratislava, Slovak Republic.
authors.forename: Maria
authors.initials: M
authors.lastname: Orieskova
authors.affiliation: Department of Molecular Biology, Faculty of Natural Sciences, Comenius University, Ilkovičova 6, 842 15, Bratislava, Slovak Republic.
authors.forename: Michal
authors.initials: M
authors.lastname: Kajsik
authors.affiliation: Department of Molecular Biology, Faculty of Natural Sciences, Comenius University, Ilkovičova 6, 842 15, Bratislava, Slovak Republic.
authors.forename: Tomas
authors.initials: T
authors.lastname: Szemes
authors.affiliation: Department of Preventive Medicine, Faculty of Medicine and Dentistry, Palacký University, Olomouc, Olomouc, Czech Republic.
authors.forename: Ondrej
authors.initials: O
authors.lastname: Holy
authors.affiliation: Pathogen Research Group, School of Science and Technology, Nottingham Trent University, Clifton Lane, Nottingham, NG11 8NS, UK.
authors.forename: Stephen
authors.initials: S
authors.lastname: Forsythe
authors.affiliation: Department of Molecular Biology, Faculty of Natural Sciences, Comenius University, Ilkovičova 6, 842 15, Bratislava, Slovak Republic.
authors.forename: Jan
authors.initials: J
authors.lastname: Turna
authors.affiliation: Department of Molecular Biology, Faculty of Natural Sciences, Comenius University, Ilkovičova 6, 842 15, Bratislava, Slovak Republic. drahovska@fns.uniba.sk.
authors.forename: Hana
authors.initials: H
authors.lastname: Drahovska
mesh_terms: D000220:Adaptation, Biological / Q000235:genetics*; D003001:Cloning, Molecular; D059126:Cronobacter / Q000145:classification / Q000235:genetics* / Q000378:metabolism*; D003428:Cross Infection; D004756:Enterobacteriaceae Infections / Q000382:microbiology; D023061:Gene Order; D005798:Genes, Bacterial; D005816:Genetic Complementation Test; D016680:Genome, Bacterial; D044404:Genomic Islands; D018869:Heat-Shock Response / Q000235:genetics; D006801:Humans; D058885:Multilocus Sequence Typing; D010957:Plasmids / Q000235:genetics; D013696:Temperature
keywords: Cronobacter spp.; Heat stress; Thermotolerance; Thermotolerance island; rpoS