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Leaching of Mycobacterium avium Subsp paratuberculosis in Soil under In Vitro Conditions
Eran A Raizman1, Mussie Y Habteselassie, Ching C Wu
1Department of Comparative Pathobiology School of Veterinary Medicine, Purdue University, West Lafayette, IN 47907, USA.
Abstract:
Mycobacterium avium subsp paratuberculosis (Map), the causative agent of Johne's disease, has a robust ability to survive in the environment. However, the ability of Map to migrate through soil to drainage tiles or ground water, leave the farm, and leak into local watersheds is inadequately documented. In order to assess the ability of Map to leach through soil, two laboratory experiments were conducted. In the first study, 8 columns (30 cm long each) of a sandy loam soil were treated with pure cultures of Map. Two soil moisture levels and two Map concentrations were used. The columns were leached with 500 mL of water once a week for three weeks, the leachate was collected, and detection analysis was conducted. In the second experiment, manure from Map negative cows (control) and Map high shedder cows (treatment) were deposited on 8 similar columns and the columns were leached with 500 mL of water once a week for four weeks. Map detection and numeration in leachate samples were done with RT-PCR and culture techniques, respectively. Using RT-PCR, Map could be detected in the leachates in both experiments for several weeks but could only be recovered using culture techniques in experiment one. Combined, these experiments indicate the potential for Map to move through soil as a result of rainfall or irrigation following application.
Insights
Mycobacterium avium subsp paratuberculosis (Map) can migrate through soil, potentially contaminating water sources. This study demonstrates Map
Area of Science:
- Environmental Microbiology
- Soil Science
- Veterinary Epidemiology
Background:
- Mycobacterium avium subsp paratuberculosis (Map) causes Johne's disease in livestock and persists in the environment.
- Limited data exists on Map's soil migration potential and subsequent contamination of water resources.
- Understanding Map's environmental mobility is crucial for preventing Johne's disease spread.
Purpose of the Study:
- To investigate the leaching potential of Map through sandy loam soil.
- To assess Map's migration in soil under different moisture and concentration conditions.
- To evaluate Map's movement from contaminated manure through soil columns.
Main Methods:
- Two laboratory experiments using soil columns (30 cm) were conducted.
- Experiment 1: Columns treated with pure Map cultures under varying moisture and concentrations, leached weekly for three weeks.
- Experiment 2: Columns treated with manure from Map-negative (control) and Map-positive (shedder) cows, leached weekly for four weeks.
- Leachate analysis using RT-PCR for detection and culture techniques for enumeration.
Main Results:
- Map was detectable via RT-PCR in leachates for several weeks in both experiments.
- Map was only recoverable by culture techniques in the first experiment.
- These findings indicate Map's capacity for soil translocation.
Conclusions:
- Laboratory experiments confirm the potential for Mycobacterium avium subsp paratuberculosis to move through soil.
- Map migration is influenced by factors such as soil moisture and the presence of contaminated organic matter.
- Findings suggest Map can leach into drainage systems or groundwater following rainfall or irrigation events.
