Melody Vachon (Ontario) coauthored a paper entitled “Fifteen Shades of Clay: Distinct Microbial Community Profiles Obtained from Bentonite Samples by Cultivation and Direct Nucleic Acid Extraction,” published in Scientific Reports on November 16, 2021.

Melody was the lead author; her coauthors were Katja Engel, Rachel Beaver, Josh Neufeld (University of Waterloo); Greg Slater (McMaster University); and W. Jeffrey Binns, (Nuclear Waste Management Organization, Toronto, ON).

Based in Ontario, Melody Vachon is a Laboratory Technician for SiREM, a Geosyntec company. A biologist, Melody carries out molecular testing and research for bioremediation projects. Her master’s degree focused on the microbiology of bentonite clay for use in Canada’s nuclear waste management.

Scientific Reports is a peer-reviewed open-access journal publishing original research from across all areas of the natural sciences, psychology, medicine, and engineering. The journal is a publication of Nature Portfolio, which serves the research community on behalf of Nature, the weekly international journal of science.


Characterizing the microbiology of swelling bentonite clays can help predict the long-term behavior of deep geological repositories (DGRs), which are proposed as a solution for the management of used nuclear fuel worldwide. Such swelling clays represent an important component of several proposed engineered barrier system designs and, although cultivation-based assessments of bentonite clay are routinely conducted, direct nucleic acid detection from these materials has been difficult due to technical challenges. In this study, we generated direct comparisons of microbial abundance and diversity captured by cultivation and direct nucleic acid analyses using 15 reference bentonite clay samples. Regardless of clay starting material, the corresponding profiles from cultivation-based approaches were consistently associated with phylogenetically similar sulfate-reducing bacteria, denitrifiers, aerobic heterotrophs, and fermenters, demonstrating that any DGR-associated growth may be consistent, regardless of the specific bentonite clay starting material selected for its construction. Furthermore, dominant nucleic acid sequences in the as-received clay microbial profiles did not correspond with the bacteria that were enriched or isolated in culture. Few core taxa were shared among cultivation and direct nucleic acid analysis profiles, yet those in common were primarily affiliated with StreptomycesMicrococcaceaeBacillus, and Desulfosporosinus genera. These putative desiccation-resistant bacteria associated with diverse bentonite clay samples can serve as targets for experiments that evaluate microbial viability and growth within DGR-relevant conditions. Our data will be important for global nuclear waste management organizations, demonstrating that identifying appropriate design conditions with suitable clay swelling properties will prevent growth of the same subset of clay-associated bacteria, regardless of clay origin or processing conditions.

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