Fornefeld, Eva

Smalla, Kornelia

Zimmerling, Ute

English

JKI Open Journal Systems (Julius Kühn-Institut)

Nachwuchswissenschaftlerforum / Young Scientists Meeting 2014 Fornefeld et al.     Factors influencing the fate of human patho-gens in the plant environment  Eva Fornefeld1, Ute Zimmerling1, Kornelia Smalla1 1 Julius Kühn-Institut, Federal Research Centre for Cultivated Plants, Institute for Epidemiology and Pathogen Diagnostics, Braunschweig Email of corresponding author: eva.fornefeld@jki.bund.de  Fresh fruits and vegetables contami-nated with human pathogenic bacteria can cause illnesses. As foodborne out-breaks associated with fresh produce are a growing concern, there is a need to further analyse the dissemination of human pathogens to plants and their persistence in the plant environment. The factors influencing survival need to be better understood aiming at optimi-sation of agricultural practices and pos-sibly reducing outbreaks of produce associated illnesses.  Here, we analysed the influence of the factors preadaptation and the presence of sludge as a fertilizer on the survival of Salmonella in soil. In a greenhouse experiment Salmonella enterica LT2, was applied to soil and its survival was monitored. The experiment included six different treatments: soil amended with sludge or not and each inoculated with (i) Salmonella, (ii) preadapted Sal-monella or (iii) no inoculums. Soil was sampled regularly and numbers of Sal-monella were monitored using culture-dependent and -independent methods.  The Salmonella-CFU decreased from about 106 to 103 per g dry soil within five weeks. Direct plating showed sig-nificantly higher numbers of Salmonella in the treatment with preadapted Sal-monella without sludge compared to the other treatments from 10 days after inoculation (dpi).   The significant differences were con-firmed using qPCR for 14 and 21 dpi. Salmonella was detected in soils 98 dpi using PCR-Southern blot hybridization and after 119 days using enrichment culture and plating. Furthermore the effect of sludge on the soil microbiome was analysed. Bacterial communities were compared by dena-turing gradient gel electrophoresis (DGGE). 16S fingerprints showed a strong influence of sludge on the bacte-rial community of soil. Inoculated sam-ples showed distinct Salmonella-bands at 0 dpi which were weaker at 21 dpi. Soil samples were also analysed with regard to abundance of mobile genetic elements like class 1 integrons and genes conferring resistances to antibi-otics or disinfectants which were de-tected at similar levels in all soil sam-ples indicating that sludge did not have an effect on their abundance.  The results indicate that the factor preadaptation promoted survival of Salmonella in soil and show a lower survival of Salmonella in the presence of sludge. Despite of a rapid decline of Salmonella in soil our data showed a long term survival at low abundance.  Berichte aus dem Julius Kühn-Institut 177 25

Factors influencing the fate of human pathogens in the plant environment

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Factors influencing the fate of human pathogens in the plant environment

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