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Title: Microarray-based Comparative Genomic Indexing of the Cronobacter genus (Enterobacter sakazakii)

Author
item HEALY, BRENDAN - UNIV. COLLEGE, DUBLIN,IRE
item Huynh, Steven
item MULLANE, NIALL - UNIV. COLLEGE, DUBLIN,IRE
item O'BRIAN, S. - UNIV. COLLEGE, DUBLIN,IRE
item IVERSON, C. - UNIV. COLLEGE, DUBLIN,IRE
item STEPHEN, R. - UNIV. OF ZURICH, SZ.
item Parker, Craig
item FANNING, S. - UNIV. COLLEGE, DUBLIN,IRE

Submitted to: International Journal of Food Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/3/2009
Publication Date: 12/21/2009
Citation: Healy, B., Huynh, S., Mullane, N., O'Brian, S., Iverson, C., Stephen, R., Parker, C., Fanning, S. 2009. Microarray-based Comparative Genomic Indexing of the Cronobacter genus (Enterobacter sakazakii). International Journal of Food Microbiology. 136:159-64

Interpretive Summary: Cronobacter, a recently described genus synonymous with Enterobacter sakazakii, currently consists of 6 different species; C. sakazakii, C. malonaticus, C. dublinensis, C. muytjensii, C. turicensis and C. genomospecies 1. Cronobacter spp. are described as opportunistic pathogens, causing bacteremia, necrotizing enterocolitis (NEC) and meningitis in immunocompromised neonates. To extend our understanding of the genetic relationship between Cronobacter sakazakii BAA-894 and the other species of this genus, microarray-based comparative genomic indexing (CGI) was undertaken to determine the presence/absence of genes identified in the former sequenced genome and to compare 276 selected open reading frames within the different Cronobacter strains. Seventy-eight Cronobacter strains (60 C. sakazakii, 8 C. malonaticus, 5 C. dublinensis, 2 C. muytjensii, 1 C. turicensis, 1 C. genomospecies 1, and 1 Cronobacter sp.) representing clinical and environmental isolates from various geographical locations were investigated. Hierarchical clustering of the CGI data showed that the species grouped as clusters. The 5 C. dublinensis and 2 C. muytjensii strains examined formed distinct species clusters. Moreover, all of the C. sakazakii and 3 of 8 C. malonaticus strains formed a large cluster. The remaining C. malonaticus strains formed a sub-group within a larger cluster that also contained C. turicensis, C. genomospecies 1, and an unknown Cronobacter sp. Cronobacter sakazakii and 3 of 8 C. malonaticus strains could be distinguished from the others within the collection by the presence of 10 fimbrial related genes. Similarly, capsule and/or lipopolysaccharide (LPS) related glycosyltransferases differentiated several of the C. sakazakii strains from each other.

Technical Abstract: Cronobacter is a recently defined genus synonymous with Enterobacter sakazakii. This new genus currently comprises 6 genomospecies. To extend our understanding of the genetic relationship between Cronobacter sakazakii BAA-894 and the other species of this genus, microarray-based comparative genomic indexing (CGI) was undertaken to determine the presence/absence of genes identified in the former sequenced genome and to compare 276 selected open reading frames within the different Cronobacter strains. Seventy-eight Cronobacter strains (60 C. sakazakii, 8 C. malonaticus, 5 C. dublinensis, 2 C. muytjensii, 1 C. turicensis, 1 C. genomospecies 1, and 1 Cronobacter sp.) representing clinical and environmental isolates from various geographical locations were investigated. Hierarchical clustering of the CGI data showed that the species grouped as clusters. The 5 C. dublinensis and 2 C. muytjensii strains examined formed distinct species clusters. Moreover, all of the C. sakazakii and 3 of 8 C. malonaticus strains formed a large cluster. The remaining C. malonaticus strains formed a sub-group within a larger cluster that also contained C. turicensis, C. genomospecies 1, and an unknown Cronobacter sp. Cronobacter sakazakii and 3 of 8 C. malonaticus strains could be distinguished from the others within the collection by the presence of 10 fimbrial related genes. Similarly, capsule and/or lipopolysaccharide (LPS) related glycosyltransferases differentiated several of the C. sakazakii strains from each other.