|Mayton, Holly - University Of California|
|Cook, Kimberly - Kim|
|Walker, Sharon - University Of California|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 11/1/2015
Publication Date: 12/2/2015
Citation: Mayton, H., Cook, K.L., Walker, S. 2015. Characterization of Potential Surrogates for Produce Pathogens. University of California, UCLA Water Resources Group. December 2-4, 2015. Los Angeles, CA.
Technical Abstract: Background Escherichia coli (E. coli) is commonly used as a surrogate for pathogens in research to identify sources of agricultural contamination and to characterize how pathogens persist on plant surfaces. However, E. coli strains are highly diverse, exhibiting differences in physical, chemical and biological properties which contribute to fitness in secondary habitats. Objectives An important step in selecting E. coli for use as pathogen surrogates is to identify strains with characteristics (including adhesion, motility and biofilm formation) that contribute to their occurrence and survival in a manner similar to that of pathogens. Methods To this end, strain-level differences in genotype (adhesions (iha, agn43, eaeA and fimH, kpsMTII) and siderophores (iroNE.coli, chuA)) and phenotype (biofilm formation, curli expression, and growth rate) were evaluated for isolates from livestock (swine, poultry, dairy) and water sources. Selected E.coli isolates (n=18 of 1,300), a common E. coli control strain (ATCC 25922), and Salmonella (ATCC 13311) were used in soil studies to evaluate adhesion to plastic, sandy loam or clay soils. Conclusions Average adhesion of environmental isolates to plastic was two-fold higher than that of the control strain. Salmonella and one of the environmental isolates had adhesion rates seven-fold higher than the control strain. That isolate had extremely high adhesion to clay (91.3 ± 2.7%) and sandy loam (91.7 ± 0.1%) soils, but had none of the genes commonly associated with adherence or biofilm formation. These results suggest that E. coli strain choice should be an important consideration in its use as a pathogen surrogate.