DFG Trilateral collaboration Deutschland-Israel-Palestine: Nematodes as potential vectors for human pathogens
Zusammenfassung der Projektergebnisse
Foodborne pathogens mainly originate from contaminated irrigation water, sewage sludge and animal manure in agricultural practice. For their establishment the autochthonous soil fauna can play a key role by acting as predator or propagator. The present project investigated nematodes as potential vectors for human enteric pathogens in dry Mediterranean soil ecosystems. Field experiments in the Palestinian Authority were installed with comparison of the application of fresh water, recycled wastewater, sewage sludge and chicken manure over two years with three successive crop cycles each, and the effects on the soil microbial and nematode communities were assessed. Moreover long-term waste water application sites in Israel were investigated. The results revealed that fecal coliforms introduced by agricultural practice were able to establish in the soil, thus the autochthonous microbial community was no effective in suppressing allochthonous enteropathogens. Moreover, nematodes populations increased with organic input across crops and sites. In sum, treated wastewater and chicken manure form a potential source for human pathogens and can result in establishment of human enteric pathogens in soil as well as in higher densities of nematodes as their potential vectors. Till now the capacity of nematodes to carry human pathogens was mainly documented using Caenorhabditis elegans, which is infrequent in soil. This project employed the bacterial feeder Acrobeloides buetschlii, a cosmopolitan, commonly found across soils types. A specific model system was designed to investigate interactions, e.g. food choice, foraging and feeding strategy, under semi natural conditions in the laboratory. It revealed that A. buetschlii had a preference for Salmonella enterica over several dominant soil bacteria. A. buetschlii was further exposed to mCherry-tagged S. enterica and Escherichia coli O157:H7. Salmonella cells were not detected on the cuticle but frequently within the digestive tract of 54% (7% for E. coli) of the tested nematodes. Salmonella survived internally for at least 7 days without affecting nematodes' viability. Thereby environmental temperature and nematode life stage modulate the interactions. Finally, a screening of the RIVET library by incubation of the bacterial pool with A. buetschlii resulted in a total of 49 distinct promoter regions of upregulated genes, which belonged to several functional categories (e.g. regulatory systems, cell cycle, stress response, carbon & amino acid metabolism). Considering the ubiquitous nature of pathogen and vector, these findings suggest that A. buetschlii can serve as a superior and more relevant model for studying nematode- Salmonella interactions in an agricultural setting and of potential transport foodborne pathogen from soil to crops. Hühnerdung im Taxi - Chicken manure in a taxi (2013). HU Wissen, Ausgabe 5, 102-105 (https://www.hu-berlin.de/de/pr/medien/publikationen/pdf/hu_wissen5.pdf)
Projektbezogene Publikationen (Auswahl)
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Acrobeloides buetschlii as a potential vector for enteric pathogens. Nematology, Volume 17, Issue 4, pages 447 – 457
Y. Kroupitski, R. Pinto, P. Bucki, E. Belausov, L. Ruess, Y. Spiegel, S. Sela
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Fertilization and irrigation practice as source of microorganisms and the impact on nematodes as their potential vectors. Applied Soil Ecology, 90, June 2015, Pages 68-77
E. Roth, N. Samara, M. Ackermann, R. Seiml-Buchinger, A. Saleh, L. Ruess
