Location: Egg Safety and Quality
Title: Detection of Polymorphism in a Diguanylate Cyclase of Egg-Contaminating Salmonella enteritidis Deficient in Biofilm Formation Authors
Submitted to: American Society for Microbiology Meeting
Publication Type: Abstract Only
Publication Acceptance Date: February 20, 2008
Publication Date: June 4, 2008
Citation: Bouldin, J.G., Morales, C. 2008. Detection of Polymorphism in a Diguanylate Cyclase of Egg-Contaminating Salmonella enteritidis Deficient in Biofilm Formation. American Society for Microbiology Meeting.p.653. Technical Abstract: Salmonella enterica serotype Enteritidis (S. enteritidis) is a model organism for evaluating how genetic drift impacts phenotype, because mutational mapping of clonally related pathotypes has been completed and small scale evolutionary events (SSEE) are being linked to the ability of this food-borne pathogen to contaminate eggs, to form biofilm, or to do both (http://www.ncbi.nlm.nih.gov/genomes/static/Salmonella_SNPS. html). Over 400 putative SSEE have been identified and 139 have been confirmed by 2X sequencing. We report here the largest confirmed SSEE discovered to date, which is a 215bp deletion in a diguanylate cyclase (DGC1) that has similarity to hsmT of Yersinia spp and STM4551 of S. typhimurium LT2. In the minus strand, 80bp were deleted from the first part of the ORF and 135bp were deleted from preceding intergenic sequence. The deletion resulted in joining a different leader sequence to the remainder of the gene so that the DGC1 ORF of 1065bp was shortened to a 996bp ORF in the alternative sequence (DGC2; sequence submitted to GenBank). The DUF1 GGDEF motif was conserved and no ribosomal binding site in either strand was disrupted by the deletion. Evidence exists from other investigators that the deletion could result in a change in biofilm dynamics due to either loss of production or increased degradation. However, the mutation is not linked to the loss of egg contamination. Thus, other SSEE are more likely to impact the ability of S. enteritidis to contaminate eggs, which is the biological marker most often associated with its emergence as the world’s leading cause of food borne salmonellosis. This research emphasizes that combinatorial convolutions introduced by SSEE complicate identification of evolutionary determinants of pandemic spread of pathogenic microbes.