Date of Award
9-28-2023
Publication Type
Thesis
Degree Name
M.Sc.
Department
Earth and Environmental Sciences
Keywords
cyanoHABs;degradation;Lake Erie;microbial community;multi-omic;sand filtration
Supervisor
Christopher Weisener
Rights
info:eu-repo/semantics/embargoedAccess
Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 International License.
Abstract
As one of five Laurentian Great Lakes, Lake Erie ranks among the top freshwater drinking sources and ecosystems globally. Historical and current agriculture mismanagement and climate change sustains the environmental landscape for late summer cyanobacterial harmful algal blooms, and consequently, cyanotoxins such as microcystin (MC). Microbial degradation of microcystin is a promising mitigation strategy, however the mechanisms controlling the breakdown of MCs in Lake Erie are not well understood. Pelee Island, Ontario, Canada is located in the western basin of Lake Erie and the bacterial community in the sand has demonstrated the capacity of metabolizing the toxin. Through a multi-omics approach, the metabolic, functional and taxonomical signatures of the Pelee Island microbial community during MC-LR degradation was investigated over a 48-hour period to comprehensively study the degradation mechanism. Cleavage of bonds surrounding nitrogen atoms and the upregulation of nitrogen deamination (dadA, alanine dehydrogenase, leucine dehydrogenase) and assimilation genes (glnA, gltB) suggests a targeted isolation of nitrogen by the microbial community for energy production. Methylotrophic pathways RuMP and H4¬MPT control assimilation and dissimilation of carbon, respectively and differential abundance of Methylophilales supports an interconnected role through electron exchange of denitrification and methylotrophic pathways. The detected metabolites did not resolve a clear breakdown pathway, but rather the diversity of products in combination with taxonomic and functional results supports that a variety of strategies are applied, such as epoxidation, hydroxylation, and aromatic degradation. Annual repeated exposure to the toxin may have allowed the community to adaptatively establish a novel pathway through functional plasticity and horizontal gene transfer. The culmination of these results reveals the complexity of the Pelee Island sand microbial community and supports a mutualistic metabolism is employed between microbial species to achieve MC degradation.
Recommended Citation
Salter, Chelsea, "Elucidating Microbial Mechanisms of Microcystin-LR Degradation in Lake Erie Beach Sand through Metabolomics and Metatranscriptomics" (2023). Electronic Theses and Dissertations. 9249.
https://scholar.uwindsor.ca/etd/9249