Location: Egg Safety and Quality
Title: Linking Phenotype to Genotype of Epidemiologically Prevalent Salmonella by Comparative Microarray Analysis Author
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: March 6, 2008
Publication Date: March 20, 2008
Citation: Bouldin, J.G. 2008. Linking phenotype to genotype of epidemiologically prevalent salmonella by comparative microarray analysis. Florence Conference on Phenotype Mciroarray Analysis of Microorganisms,March 19-21,2008. Technical Abstract: : Salmonella enterica subsp. I includes over 1400 serovars, but only about 20 of these pose a threat to the public health on a routine basis. In spite of years of mutational analysis, it has been difficult to identify genetic markers associated with pandemic potential. METHODOLOGY: We combined whole genome sequencing with Phenotype Microarray (PM') to analyze which genes and biochemical pathways of Salmonella enterica serovar Enteritidis (S. Enteritidis) are linked to epidemiological trends. S. Enteritidis was used as the index organism, because it has a more clonal population structure than many other Salmonellae and because it is the world’s leading cause of food-borne salmonellosis. RESULTS: A panel of 12 ORF-disrupting genes was identified that could be used as markers of virulence as defined by the ability of S. Enteritidis to contaminate eggs. BLAST analysis of other Salmonella whole genome databases was performed to evaluate conservation of ORFs across other serotypes. Five genes appeared to be linked more specifically to the ability of S. Enteritidis to contaminate eggs. One of these appears to involve ß-lactam antibiotic resistance as confirmed by PM'. Another was D-serine dehyratase (dsdA), which converts L-serine to the D form. The ability to catalyze the production of ATP sulfurylase (APS) and pyrophosphate (PPi) from ATP and sulfate could be important, because spontaneous mutation of cysN correlated with suppressed utilization of many nitrogenous compounds in the PM' panel. Two genes of S. Typhi that were absent in S. Typhimurium were linked to either egg contamination or to oral colonization, but not both. The ability to couple PM' with high-throughput genomics thus helped identify unexpected genetic markers that could be linked to panoramic physiological profiles of Salmonella enterica. SUMMARY: Combinatorial convolutions occurring within Salmonella enterica are an indication that multiple markers of pandemic potential are needed when conducting epidemiological surveys. Phenotype Microarray analysis identified specific metabolic properties linked to genetic markers and also helped to reduce the use of animals in research.