InterPore2025

Exploratory Modeling of the transport of nptII antibiotic-resistance gene and its interactions with ambient DNA in real soil columns

20 May 2025, 10:05

1h 30m

Poster Presentation (MS05) Microbial Dynamics in Porous Media: Advances in Biofilms, Biogeochemistry, and Biotechnology Poster

Speaker

Timothy Ginn (Washington State University)

Description

Use of antibiotic-resistance genes (ARGs) in agriculture is growing as is the recognition of the associated potentially catastrophic threats to human health if such ARGs transfer into pathogenic soil bacteria. Here we summarize previously reported data from our column experiments involving the fate and transport of the ARG nptII in soil from a farm in north-central Oregon, and then detail our approach to simulation of these data. NptII is widely used as a selection marker in genetically-modified crops and is also naturally produced by ambient soil biota. The experiments are designed to evaluate the persistence and motility of nptII in true soils under rain events with contribution of decaying litter to ARG in influent solution. As a result, while the dataset affords observation of transport and interactions in a realistic setting, it has a number of unknowns that precludes predictive modeling. By application of Occam's razor and the casting of several testable assumptions, we developed a modeling approach that works pretty well and more importantly prioritizes new hypotheses for examination. Specifically, we combined an irreversible first-order leaching model for native DNA and nptII, with reversible immobilization for both leached and injected solutes represented via first-order kinetics with memory (Ginn et al., 2017). Further, the data reveal dramatic interaction between injected nptII and native DNA in the effluent samples, for which we develop several simple models for testing. These exercises help in the design of the next suite of experiments.