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Assessing the faecal source sensitivity and specificity of ruminant and human genetic microbial source tracking markers in the central Ethiopian highlands |
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| Authors: | RB Linke G Kebede D Mushi A Lakew DS Hayes W Graf AH Farnleitner |
| Institution: | 1. Research Group of Environmental Microbiology and Molecular Diagnostics, Institute for Chemical, Biological and Environmental Engineering, Technical University Vienna, Vienna, Austria;2. Department of Biological Sciences, Ambo University, Ambo, Ethiopia
Institute of Hydrobiology and Aquatic Ecosystem Management (IHG), University of Natural Resources and Life Sciences, Vienna, Austria;3. Department of Biosciences, Solomon Mahlangu College of Science and Education, Sokoine University of Agriculture, Morogoro, Tanzania;4. National Fishery and Aquatic Life Research Centre, Ethiopian Institute of Agricultural Research (EIAR), Sebeta, Ethiopia;5. Institute of Hydrobiology and Aquatic Ecosystem Management (IHG), University of Natural Resources and Life Sciences, Vienna, Austria Centro de Estudos Florestais (CEF), Instituto Superior de Agronomia, University of Lisbon, Lisbon, Portugal;6. Institute of Hydrobiology and Aquatic Ecosystem Management (IHG), University of Natural Resources and Life Sciences, Vienna, Austria;7. Research Group of Environmental Microbiology and Molecular Diagnostics, Institute for Chemical, Biological and Environmental Engineering, Technical University Vienna, Vienna, Austria Research Division Water Quality and Health, Karl Landsteiner University for Health Sciences, Krems, Austria |
| Abstract: | This study tested genetic microbial source tracking (MST) methods for identifying ruminant- (BacR) and human-associated (HF183/BacR287, BacHum) bacterial faecal contaminants in Ethiopia in a newly created regional faecal sample bank (n = 173). BacR performed well, and its marker abundance was high (100% sensitivity (Sens), 95% specificity (Spec), median log10 8·1 marker equivalents (ME) g−1 ruminant faeces). Human-associated markers tested were less abundant in individual human samples (median: log10 5·4 and 4·2 (ME + 1) g−1) and were not continuously detected (81% Sens, 91% Spec for BacHum; 77% Sens, 91% Spec for HF183/BacR287). Furthermore, the pig-associated Pig2Bac assay was included and performed excellent (100% Sens, 100% Spec). To evaluate the presence of MST targets in the soil microbiome, representative soil samples were tested during a whole seasonal cycle (n = 60). Only BacR could be detected, but was limited to the dry season and to sites of higher anthropogenic influence (log10 3·0 to 4·9 (ME + 1) g−1 soil). In conclusion, the large differences in marker abundances between target and non-target faecal samples (median distances between distributions ≥log10 3 to ≥log10 7) and their absence in pristine soil indicate that all tested assays are suitable candidates for diverse MST applications in the Ethiopian area. |
| Keywords: | assay evaluation Ethiopia faeces human marker microbial source tracking ruminant soil |