Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 10/20/2014
Publication Date: N/A
Technical Abstract: Escherichia coli is a leading cause of bacterial mastitis in dairy cattle. Milk is the environment in which bacteria must grow to establish an infection of the mammary gland. However, milk is not a rich growth media for bacteria. In fact, milk naturally contains many mechanisms to inhibit bacterial growth. How bacteria adapt to the mammary gland environment will likely be linked to the pathogenicity of the organism. We have used shotgun expression proteomics to determine the changes in protein expression when E. coli were grown in laboratory media compared to bacteria grown in whole fresh bovine milk. We found many proteins involved in the metabolism of lactose and various amino acids were up regulated when bacteria were grown in milk. We have also compared various strains of E. coli that are known to generate transient or persistent infection. Three persistent and three transient mastitis-derived strains of E. coli were compared using iTRAQ in a shotgun proteomics experiment. Expression data for 1127 proteins were determined. Of these, 27 proteins were associated with expression changes correlated with a difference in disease phenotype. Of particular interest were proteins that have been shown to be essential for bacterial swimming and swarming. Bacterial swimming and swarming assays showed that the strains from the persistent mastitis cases were significantly more mobile than the strains from the transient cases. This work identifies important protein expression differences between E. coli strains that cause a persistent versus a transient infection as well as demonstrates a corresponding difference in the associated bacterial motility phenotypes.