Cronobacter Support
06-03-2009, 04:31 PM
1st International Conference on Cronobacter Poster Abstract 60
Optical maps of subgroups of Cronobacter (formerly Enterobacter sakazakii) show large chromosomal regions of homology and differences among isolates
Optical maps are whole genome restriction fragment maps made by spreading bacterial chromosomes on derivatized glass slides. The chromosomes are digested with a restriction enzyme and optically scanned with an automated CCD camera across nearly full-length chromosomes. Multiple scans create assemblies of contiguous restriction fragments and these are assembled into a complete whole genome map. Alignment software allows the whole chromosome maps of different isolates to be compared and referenced to sequenced in silico genome maps. These barcode-like whole genome scans and alignments can be used to measure similarities between different isolates as well as identify the chromosomal positions and sizes of deletions, insertions and replacements from 2 kb to >100,000 kb. The genomes of isolates representative of the five Cronobacter type-species and sub-species groups (formerly Enterobacter sakazakii) were optically mapped. These included isolates from Cronobacter subgroup 1, C. sakazakii; subgroup 2, C. turicensis; subgroup 3, C. muytjensii; and subgroup 4, C. dublinensis. An isolate from subgroup 2a, C. genomospecies 1 and several clinical and powdered infant formula isolates were also optically mapped. Alignments of the maps to each other and to the in silico map of the sequenced reference group 1 strain from the 2001 Tennessee Enterobacter sakazakii outbreak, ATCC BAA894, were performed. The optical map of an independent isolate from the implicated powdered infant formula was indistinguishable from the in silico map of the sequenced outbreak strain BAA894. Isolates from within groups 1 and 3 show large regions of chromosomal homology and large differences between isolates within a group. There are fewer homologies between groups. We detailed chromosomal changes including prophage insertions, deletions and large replacements between isolates. These results support the taxonomic scheme proposed by Iversen et al. in that the genus Cronobacter is composed of several species and a number of sub-species with considerable sequence and genomic diversity.
Mike L. Kotewicz and Ben D. Tall.
U. S. FDA, CFSAN, OARSA, Laurel, MD 20708 USA.
Optical maps of subgroups of Cronobacter (formerly Enterobacter sakazakii) show large chromosomal regions of homology and differences among isolates
Optical maps are whole genome restriction fragment maps made by spreading bacterial chromosomes on derivatized glass slides. The chromosomes are digested with a restriction enzyme and optically scanned with an automated CCD camera across nearly full-length chromosomes. Multiple scans create assemblies of contiguous restriction fragments and these are assembled into a complete whole genome map. Alignment software allows the whole chromosome maps of different isolates to be compared and referenced to sequenced in silico genome maps. These barcode-like whole genome scans and alignments can be used to measure similarities between different isolates as well as identify the chromosomal positions and sizes of deletions, insertions and replacements from 2 kb to >100,000 kb. The genomes of isolates representative of the five Cronobacter type-species and sub-species groups (formerly Enterobacter sakazakii) were optically mapped. These included isolates from Cronobacter subgroup 1, C. sakazakii; subgroup 2, C. turicensis; subgroup 3, C. muytjensii; and subgroup 4, C. dublinensis. An isolate from subgroup 2a, C. genomospecies 1 and several clinical and powdered infant formula isolates were also optically mapped. Alignments of the maps to each other and to the in silico map of the sequenced reference group 1 strain from the 2001 Tennessee Enterobacter sakazakii outbreak, ATCC BAA894, were performed. The optical map of an independent isolate from the implicated powdered infant formula was indistinguishable from the in silico map of the sequenced outbreak strain BAA894. Isolates from within groups 1 and 3 show large regions of chromosomal homology and large differences between isolates within a group. There are fewer homologies between groups. We detailed chromosomal changes including prophage insertions, deletions and large replacements between isolates. These results support the taxonomic scheme proposed by Iversen et al. in that the genus Cronobacter is composed of several species and a number of sub-species with considerable sequence and genomic diversity.
Mike L. Kotewicz and Ben D. Tall.
U. S. FDA, CFSAN, OARSA, Laurel, MD 20708 USA.