SREL Reprint #3590

Co-occurrence of antibiotic, biocide, and heavy metal resistance genes in bacteria from metal and radionuclide contaminated soils at the Savannah River Site

Jesse C. Thomas IV1, Adelumola Oladeinde2, Troy J. Kieran1, John W. Finger Jr.3,
Natalia J. Bayona-Vásquez1,4, John C. Cartee5, James C. Beasley6,7, John C. Seaman6,
J. Vaun McArthur6, Olin E. Rhodes Jr.6,8, and Travis C. Glenn1,4

1Department of Environmental Health Science, University of Georgia, Athens, GA 30602, USA
2Bacterial Epidemiology and Antimicrobial Resistance Research Unit,
United States Department of Agriculture, Athens, GA 30605, USA
3Department of Biological Sciences, Auburn University, Auburn, AL 36849, USA
4Institute of Bioinformatics, University of Georgia, Athens, GA 30602, USA
5Division of STD Prevention, Centers for Disease Control and Prevention, Atlanta, GA 30329, USA
6Savannah River Ecology Laboratory, University of Georgia, PO Drawer E, Aiken, SC 29802, USA
7Warnell School of Forestry and Natural Resources, University of Georgia, Athens, GA 30602, USA
8Odum School of Ecology, University of Georgia, Athens, GA 30602, USA

Summary: Contaminants such as heavy metals may contribute to the dissemination of antimicrobial resistance (AMR) by enriching resistance gene determinants via co-selection mechanisms. In the present study, a survey was performed on soils collected from four areas at the Savannah River Site (SRS), South Carolina, USA, with varying contaminant profiles: relatively pristine (Upper Three Runs), heavy metals (Ash Basins), radionuclides (Pond B) and heavy metal and radionuclides (Tim’s Branch). Using 16S rRNA gene amplicon sequencing, we explored the structure and diversity of soil bacterial communities. Sites with legacies of metal and/or radionuclide contamination displayed significantly lower bacterial diversity compared to the reference site. Metagenomic analysis indicated that multidrug and vancomycin antibiotic resistance genes (ARGs) and metal resistance genes (MRGs) including those associated with copper, arsenic, iron, nickel and zinc were prominent in all soils including the reference site. However, significant differences were found in the relative abundance and diversity of certain ARGs and MRGs in soils with metal/radionuclide contaminated soils compared to the reference site. Co-occurrence patterns revealed significant ARG/MRG subtypes in predominant soil taxa including Acidobacteriaceae, Bradyrhizobium, Mycobacterium, Streptomyces, Verrumicrobium, Actinomadura and Solirubacterales. Overall, the study emphasizes the potential risk of human activities on the dissemination of AMR in the environment.

SREL Reprint #3590

Thomas IV, J. C., A. Oladeinde, T. J. Kieran, J. W. Finger Jr., N. J. Bayona-Vásquez, J. C. Cartee, J. C. Beasley, J. C. Seaman, J. V. McArthur, O. E. Rhodes Jr., and T. C. Glenn. 2020. Co-occurrence of antibiotic, biocide, and heavy metal resistance genes in bacteria from metal and radionuclide contaminated soils at the Savannah River Site. Microbial Biotechnology 13(4): 1179-1200.

This information was provided by the University of Georgia's Savannah River Ecology Laboratory (srel.uga.edu).