Daniel HeathDaniel Heath with a DNA sequencer.

DNA sequencing for water monitoring gets half million in NSERC support

A team of UWindsor researchers will soon begin monitoring the sanitary conditions of Essex County’s recreational beaches using a new technique called next-generation DNA sequencing, which could revolutionize how testing is done in the future. They will analyze bacterial DNA from water samples to precisely identify the presence of potentially harmful bacteria.

Daniel Heath, Chris Weisener and Doug Haffner from the Great Lakes Institute of Environmental Research (GLIER) have teamed with civil and environmental engineering professor Rajesh Seth, scientists from Environment Canada, and partners from government agencies and Ontario corporations.

The team received a half million dollar grant from the Natural Sciences and Engineering Research Council of Canada (NSERC) recently to determine possible contamination sources and identify environmental factors that could contribute to harmful bacteria outbreaks.

DNA sequencing can filter for such pathogens as streptococcus, and identify the danger level to human health, which dictates beach closures. Pathogens are anything that can produce illness or spread disease.

“Now we are not guessing,” Dr. Heath says. “We can be sure when we find human E. coli or other human pathogens, and when there are no human pathogens. This could keep beaches open when previously they would close.”

The team will also study environmental factors that can drive beach contamination variation from day to day or even hour to hour, and will combine this information with spatial mapping to build a model for predicting and preventing future outbreaks.

“Modelling water movement is a very advanced process,” says Heath. “Say there is an outbreak at Holiday Beach and we collect samples further up the Detroit River and in tributaries—these samples could help us locate the source of the pathogen. We could possibly pinpoint it to, say, particular houses with old septic tanks that aren’t functioning properly.”

Once pathogens are identified, modelled and mapped, Heath says they will test an innovative idea for possibly killing them at their source. The team is partnering with Trojan UV, a company that uses ultraviolet light to treat drinking water and sewage with equipment capable of sterilizing water for a house or an entire city.

“If we mapped out an outbreak and found out it was coming from Windsor sewage, Trojan could bring down a pump to sterilize contaminated water at the point source,” says Heath. “If we can identify the source, Trojan’s equipment could clean it up or at least drop the danger level.”

Currently, based on jurisdiction, Environment Canada or the Essex Region Conservation Authority (ERCA) monitors water quality using a coliform count, which tests for a group of bacteria that includes E. coli. For the past 50 years, coliform count has been the only test available. It provides slow results because it requires growing the bacteria over time. In comparison, the next-generation DNA sequencer can process hundreds of samples a day.

Although coliform bacteria do not generally pose a human health risk, Heath says, they are usually associated with fecal matter and are used as indicators of sewage contamination. The test cannot distinguish between human and animal sewage and fecal matter from birds.

He says potential health hazards from E. coli and other coliforms are less concerning than such human pathogens as streptococcus and other bugs associated with human waste.

“When you see those guys, there’s a good chance there’s human waste contaminating the beach, and human waste means a potential for a host of human pathogens.”

The project starts testing this spring and will include citizen scientists interested in monitoring recreational water safety.

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