Microbes versus mercury

In a research lab, Daniel Grégoire holds up two beakers containing liquid bacteriological samples at eye level.
Fighting pollution with colourful bacteria

University of Ottawa PhD candidate Daniel Grégoire and Professor Alexandre Poulain believe they have found a way to clean up mercury pollution by using light-loving bacteria naturally found in the environment.

Mercury is a powerful poison. It can cause brain damage, tremors, paralysis and death.

But two researchers at the University of Ottawa’s Department of Biology have found a way to neutralize this toxic metal by pitting it against a small but mighty foe — a group of microorganisms known as purple non-sulphur bacteria.

PhD candidate Daniel Grégoire and Professor Alexandre Poulain have established Microbright, a new company that aims to put their discovery to good use, namely by removing mercury from wastewater generated by the Canadian mining industry.

“I’ve always been interested in bioremediation, which is the use of biological organisms to help clean up the environment,” Grégoire said. “We thought: the time is right to be a Canadian company that tries to push for more sustainable ways to deal with mercury pollution.”

Purple non-sulphur bacteria are single-celled organisms that occur naturally in lakes. These microbes use photosynthesis to generate energy but, unlike plants, they do not produce oxygen as a by-product. Their photosynthetic process results in surplus electrons, but these extra electrons jam up the bacteria’s metabolic functions and impede its growth.

To prevent this from happening, the bacteria off-load their surplus electrons onto molecules naturally found in the environment, such as carbon dioxide or nitrogen — and, as Grégoire and Poulain have discovered, onto mercury, a toxic metal. This process lies at the crux of Microbright’s solution for dealing with mercury pollution.

Grégoire and Poulain have shown that when water containing mercury is run through a bioreactor filled with purple non-sulphur bacteria, the transfer of electrons causes the mercury to change from a soluble ionic form into a gas that can easily be removed. This gas can be captured in special filters and safely stored, allowing the mercury-free wastewater to be discharged into lakes or rivers.

In addition to working on his PhD, Grégoire is enrolled in the Entrepreneurship Foundry Course at the Telfer School of Management. There, professors and entrepreneurs guide students in developing a business plan, and students gain academic credits for working on their start-up companies.

“I want to find an industrial partner that’s willing to work with us, so we can gain access to the sites where metals are a problem, start scaling up the small prototypes we have, and start dealing with actual waste,” he said. “It’s a two-to-three year plan to get a pilot-scale study going. These studies take a long time and we need to make sure the science behind it is very strong.”

In addition to research funding from NSERC, Grégoire receives a yearly Excellence Scholarship from the University of Ottawa.

“I don’t need to worry about paying for tuition, which means I don’t need to TA, which means I have a lot more time to do my research,” he said.  “It alleviates a lot of stress and makes it a lot easier to focus on grad school, and pursue entrepreneurship.”

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Five beakers containing liquid bacteriological samples of various colours sit in a row on a window sill.


In a research lab, Daniel Grégoire and Alexandre Poulain discuss and share a laugh.

PhD candidate Daniel Grégoire with Professor Alexandre Poulain


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