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ARS Home » Pacific West Area » Albany, California » Western Regional Research Center » Produce Safety and Microbiology Research » Research » Publications at this Location » Publication #152625

Title: SURVIVAL OF A HUMAN PATHOGEN IN A PLANT PATHOGEN BIOFILM.

Author
item Barak Cunningham, Jeri
item CHARKOWSKI, AMY

Submitted to: American Society for Microbiology
Publication Type: Abstract Only
Publication Acceptance Date: 8/5/2003
Publication Date: N/A
Citation: N/A

Interpretive Summary: Escherichia coli and Erwinia chrysanthemi are related bacteria with interconnected roles in food safety and quality. Some E. coli strains are human pathogens and have caused foodborne outbreaks associated with produce. E. chrysanthemi is a plant pathogen that causes soft rot diseases on produce and has been associated with a higher incidence of human pathogens on produce. Although E. coli infects animals and E. chrysanthemi infects plants, these species share environmentals such as water, fresh produce, and insects, and they carry homologous virulence genes. We hypothesize that the presence of E. chrysanthemi on plants will increase populations of E. coli O157:H7 due to biofilm formation. We have identified laboratory growing conditions that differentially promote biofilm formation on glass in each species. Our results suggest that E. chrysanthemi and E. coli use the same genes for biofilm formation and the presence of E. chrysanthemi helps induce E. coli O157:H7 biofilm formation on glass under conditions in which E. coli O157:H7 does not form biofilm in pure culture. To determine whether co-inoculation of both species could effect the growth on and adherence of E. coli O157:H7 to plant tissue, alfalfa sprouts were used as a model system. Under the conditions tested, the presence of E. chrysanthemi increased the initial numbers of E. coli O157:H7 that attached to alfalfa seed; however, the populations of E. coli O157:H7 on sprouts on subsequent days were reduced compared to those inoculated with only E. coli O157:H7. These results suggest that E. chrysanthemi may promote initial colonization of plant tissue by E. coli O157:H7; however, the human pathogen is less fit than the plant pathogen for survival in this environmental niche.

Technical Abstract: Escherichia coli and Erwinia chrysanthemi are related bacteria with interconnected roles in food safety and quality. Some E. coli strains are human pathogens and have caused foodborne outbreaks associated with produce. E. chrysanthemi is a plant pathogen that causes soft rot diseases on produce and has been associated with a higher incidence of human pathogens on produce. Although E. coli infects animals and E. chrysanthemi infects plants, these species share environmental niches such as water, fresh produce, and insects, and they carry homologous virulence genes. We hypothesize that the presence of E. chrysanthemi on plants will increase populations of E. coli O157:H7 due to biofilm formation. We have identified culture conditions that differentially promote biofilm formation on glass in each species. Our results suggest that E. chrysanthemi and E. coli use homologous genes for biofilm formation and the presence of E. chrysanthemi helps induce E. coli O157:H7 biofilm formation on glass under conditions in which E. coli O157:H7 does not form biofilm in pure culture. To determine whether co-inoculation of both species could effect the growth on and adherence of E. coli O157:H7 to plant tissue, alfalfa sprouts were used as a model system. Under the conditions tested, the presence of E. chrysanthemi increased the initial numbers of E. coli O157:H7 that attached to alfalfa seed; however, the populations of E. coli O157:H7 on sprouts on subsequent days were reduced compared to those inoculated with only E. coli O157:H7. These results suggest that E. chrysanthemi may promote initial colonization of plant tissue by E. coli O157:H7; however, the human pathogen is less fit than the plant pathogen for survival in this environmental niche.