Aggregative adherence fimbriae I (AAF/I) mediate colonization of fresh produce and abiotic surface by Shiga toxigenic enteroaggregative Escherichia coli O104:H4.
The Shiga toxigenic Escherichia coli O104:H4 isolated during the 2011 European outbreak expresses Shiga toxin 2a and possess virulence genes associated with the enteroaggregative E. coli (EAEC) pathotype. It produces plasmid encoded aggregative adherence fimbriae I (AAF/I) which mediate cell aggregation and biofilm formation in human intestine and promote Shiga-toxin adsorption, but it is not clear whether the AAF/I fimbriae are involved in the colonization and biofilm formation on food and environmental matrices such as the surface of fresh produce. We deleted the gene encoding for the AAF/I fimbriae main subunit (AggA) from an outbreak associated E. coli O104:H4 strain, and evaluated the role of AAF/I fimbriae in the adherence and colonization of E. coli O104:H4 to spinach and abiotic surfaces. The deletion of aggA did not affect the adherence of E. coli O104:H4 to these surfaces. However, it severely diminished the colonization and biofilm formation of E. coli O104:H4 on these surfaces. Strong aggregation and biofilm formation on spinach and abiotic surfaces were observed with the wild type strain but not the isogenic aggA deletion mutant, suggesting that AAF/I fimbriae play a crucial role in persistence of O104:H4 cells outside of the intestines of host species, such as on the surface of fresh produce.
Environmental Microbial and Food Safety Laboratory, Electron and Confocal Microscopy Unit, United States Department of Agriculture, Agricultural Research Service, Beltsville, MD 20705, USA.
Attila
A
Nagy
Environmental Microbial and Food Safety Laboratory, Electron and Confocal Microscopy Unit, United States Department of Agriculture, Agricultural Research Service, Beltsville, MD 20705, USA.
Yunfeng
Y
Xu
Environmental Microbial and Food Safety Laboratory, Electron and Confocal Microscopy Unit, United States Department of Agriculture, Agricultural Research Service, Beltsville, MD 20705, USA.
Gary R
GR
Bauchan
Environmental Microbial and Food Safety Laboratory, Electron and Confocal Microscopy Unit, United States Department of Agriculture, Agricultural Research Service, Beltsville, MD 20705, USA.
Daniel R
DR
Shelton
Environmental Microbial and Food Safety Laboratory, Electron and Confocal Microscopy Unit, United States Department of Agriculture, Agricultural Research Service, Beltsville, MD 20705, USA. Electronic address: xiangwu.nou@ars.usda.gov.
Xiangwu
X
Nou
D001422:Bacterial Adhesion / Q000235:genetics; D018441:Biofilms; D029968:Escherichia coli Proteins / Q000235:genetics; D036781:Fimbriae Proteins / Q000235:genetics; D010861:Fimbriae, Bacterial / Q000235:genetics* / Q000378:metabolism*; D005516:Food Microbiology; D017353:Gene Deletion; D010957:Plasmids / Q000235:genetics; D054323:Shiga-Toxigenic Escherichia coli / Q000235:genetics* / Q000254:growth & development*; D018724:Spinacia oleracea / Q000382:microbiology*
C079725:AggA protein, E coli; D029968:Escherichia coli Proteins; D036781:Fimbriae Proteins
Aggregation; Aggregative adherence fimbriae; Biofilms; Colonization; E. coli O104:H4; Enteroaggregative E. coli; Fresh produce