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Determining the prevalence,identity and possible origin of bacterial pathogens in soil |
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| Authors: | Jacopo Ferraresso Benedict Lawton Sion Bayliss Samuel Sheppard Barbara Cardazzo Will Gaze Angus Buckling Michiel Vos |
| Institution: | 1. European Centre for Environment and Human Health, Environment and Sustainability Institute, University of Exeter Medical School, Exeter, UK
Department of Comparative Biomedicine and Food Science, University of Padova, Bologna, Italy These authors contributed equally to this work.;2. European Centre for Environment and Human Health, Environment and Sustainability Institute, University of Exeter Medical School, Exeter, UK These authors contributed equally to this work.;3. The Milner Centre for Evolution, Department of Biology and Biochemistry, University of Bath, Bath, UK;4. Department of Comparative Biomedicine and Food Science, University of Padova, Bologna, Italy;5. European Centre for Environment and Human Health, Environment and Sustainability Institute, University of Exeter Medical School, Exeter, UK;6. Department of Biosciences, University of Exeter, Exeter, UK |
| Abstract: | Soil biomes are vast, exceptionally diverse and crucial to the health of ecosystems and societies. Soils also contain an appreciable, but understudied, diversity of opportunistic human pathogens. With climate change and other forms of environmental degradation potentially increasing exposure risks to soilborne pathogens, it is necessary to gain a better understanding of their ecological drivers. Here we use the Galleria mellonella insect virulence model to selectively isolate pathogenic bacteria from soils in Cornwall (UK). We find a high prevalence of pathogenic soil bacteria with two genera, Providencia and Serratia, being especially common. Providencia alcalifaciens, P. rustigianii, Serratia liquefaciens and S. plymuthica strains were studied in more detail using phenotypic virulence and antibiotic resistance assays and whole-genome sequencing. Both genera displayed low levels of antibiotic resistance and antibiotic resistance gene carriage. However, Serratia isolates were found to carry the recently characterized metallo-β-lactamase blaSPR-1 that, although not conferring high levels of resistance in these strains, poses a potential risk of horizontal transfer to other pathogens where it could be fully functional. The Galleria assay can be a useful approach to uncover the distribution and identity of pathogenic bacteria in the environment, as well as uncover resistance genes with an environmental origin. |
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