Chelsea Salter spent her master’s studies combing through Lake Erie sand investigating microbes because they were doing something unique. They were cleaning water tainted with an algal bloom toxin called cyanotoxin.

Salter (BSc 2020, MSc 2023) first heard of the phenomenon happening off the coast of Pelee Island when she was an undergraduate working in Chris Weisener’s lab. Dr. Weisener is a School of the Environment professor and researcher with the Great Lakes Institute for Environmental Research (GLIER).

“It is really unique, and we don’t know of other natural bacterial communities that are doing this,” says Salter.

“As climate change intensifies and water resource demands increase, proper management and protection of freshwater resources must be prioritized to ensure water security.”

Harmful algal blooms are collections of cyanobacteria which can produce toxic secondary metabolites, such as microcystin, and release them into freshwater bodies, creating potentially significant human health risks. The western basin of Lake Erie, bordered by Michigan, Ohio, and southwestern Ontario, is frequently contaminated by toxic algal blooms.

Yet monitoring programs of public well waters on Pelee Island, also situated in the western basin of Lake Erie, have shown an absence of contamination of microcystin in their drinking water supplies.

Pelee Island’s municipal water supply and residential drinking wells both gather their water directly from the lake, which has passed through sand-filled trenches along the shoreline of the island. Salter looked at how and why the resilient and adaptive bacterial community in that sand were degrading the toxin from several aspects: the metabolic breakdown, gene transcription and taxonomic response to the toxin.

“Because of where it is located and the repeated exposure, it adaptively acquired all the tools it needed to break down this toxin as if it was a food source,” she says.

“Bacteria are extremely resilient and will utilize any resource in their means to survive.”

To recreate this degradation in the lab, Salter performed a benchtop batch experiment to monitor the breakdown of microcystin and the associated microbial activity over 48 hours to gain insights into the mechanisms controlling toxin degradation.

Overall, the results revealed a complex metabolism and supported that the community established a novel breakdown pathway, says Salter.

She says this complex community is very effective at degrading microcystin which means there is great potential for a water treatment application to treat outbreaks as they happen elsewhere in Lake Erie.

“We need more research but using bacteria as a potential biological sand filter application when there is toxin in the water would offer a safe and effective means to eliminate microcystin toxins without the need for chemical treatments,” she says.

Salter recently published her findings in the journal, Water Research, in the article, “Elucidating Microbial Mechanisms of Microcystin-LR Degradation in Lake Erie Beach Sand through Metabolomics and Metatranscriptomics.” She was also featured in the fall 2023 Great Lakes HABs Collaborative Newsletter.

“I’m definitely interested in the water quality of Lake Erie because I’ve lived here my whole life — Lake Erie is my great lake,” she says.

“Hopefully my research bridges the gap to get us to a place where it is more viable to harness the power of bacteria to mitigate the risks posed by toxic algal blooms, which frankly are not going to go away anytime soon.”

During her master’s at the University of Windsor, Salter was awarded a graduate research fellowship with the Cooperative Institution for Great Lake Research (CIGLR) at the University of Michigan. She is currently working as a microbial ecology laboratory technician at the Agriculture and Agri-food Canada Harrow Research Station.