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Hygienic risk of the agricultural use of sewage sludge due to the uptake of human pathogens in crop plants: Research into the uptake of human pathogens by crop plants via soil and water

Project

Food and consumer protection

This project contributes to the research aim 'Food and consumer protection'. Which funding institutions are active for this aim? What are the sub-aims? Take a look:
Food and consumer protection


Project code: JKI-EP-08-2220
Contract period: 01.11.2012 - 31.12.2016
Purpose of research: Applied research

In the frame of the project the survival of Escherichia coli O157:H7, Salmonella enterica, Pseudomonas aeruginosa and Acinetobacter sp. in soil after the application of sewage sludge or contaminated irrigation water as well as the attachment, colonisation and proliferation of human pathogens on crop plants will be monitored using cultivation-independent and cultivation-dependent methods. The focus will be on cultivation-independent methods as enterobacteria frequently enter the viable but non-culturable state upon environmental stresses such as temperature, pH value, UV. Although they are not able to form colonies on plates they remain infectious. The microscopic investigation will be used to follow gfp-marked E. coli and Acinetobacter strains. We will test the hypothesis that the presence of plasmids such as IncP1 or lowGC in these hosts will influence their ability to colonise plants and provide them with a selective advantage. In the reporting period, factors influencing the persistence of human pathogens (HP) in the plant environment were analyzed in greenhouse experiments employing the model strains Salmonella enterica serovar Typhimurium and Escherichia coli O157:H7. The experiments aimed at analyzing the influence of sludge and pre-adaption of HP on the survival of HP in soil. Using Illumina sequencing, the influence of sludge on the microbial community composition in soil was analyzed as well as the influence on the abundance of mobile genetic elements and resistance genes in soil. E. coli O157:H7 was also reisolated from soil samples in order to look for mobile genetic elements which can be transferred to E. coli O157:H7. Further greenhouse experiments with lettuce plants were carried out investigating whether inoculating soil with HP could lead to contamination of lettuce plants and if sludge has an influence on this contamination. Moreover, the influence of inoculation of phytopathogens on colonization of lettuce plants with HP was analyzed. Under the experimental conditions analyzed so far, no internalization of HP into leaf material of lettuce plants was detected. Using an in vitro biofilm assay a set of HP strains was analyzed with respect to its ability of biofilm formation. It was also investigated whether pre-adaptation has an effect on biofilm formation. The ability to form biofilms could be an important factor determining the colonization of plants by HP. The project contributes to the new BMEL research focus on human pathogens on fresh produce.

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Subjects

Framework programme

BMEL Frameworkprogramme 2008

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