This Microbiologist Is Saving Wisconsin's Poopy Beaches With DNA Sequencing

Less than a decade ago, Bradford Beach in Milwaukee, Wisconsin was mysteriously contaminated. The city would shut the beach down all the time, worried that it could threaten the health of visitors.

Then Sandra McLellan, an environmental microbiologist at the University of Wisconsin Milwaukee (UWM) School of Freshwater Sciences, diagnosed the problem. Her lab tested water and sand samples at Bradford Beach to determine that sea gulls congregating in the area, and stormwater drainage pipes, were the source of much of the beach's contamination. Armed with that knowledge, the city rerouted the outfalls and in 2016, Bradford Beach was named the third best urban beach in the country.

The backbone of McLellan's research—and success—is the rapid advancement in gene sequencing. In 1990, the idea of sequencing genes was just a hypotheses. The Human Genome Project, which mapped human DNA, took almost fifteen years to complete, cost upwards of $2.5 million, and was a massive undertaking by the US government and international partners. But the project's impact extends beyond the human body.

Previously, the only major testing of water was for E. coli, a very simple bacteria that can cause dangerous, sometimes deadly, health problems. The problem is that E. coli, carried through fecal matter, is present in a number of different contaminants from even more possible locations. So testing only for E. coli shows that the water (or sand) is contaminated, but provides no information on how to fix the problem or where it's coming from.

Today, scientists like McLellan can go well beyond that. She can sequence the DNA in multiple water samples in her lab shortly after collecting them to examine the bacteria and investigate water pollution. This information drastically changes how scientists and health departments can react to and correct water contamination by helping them treat water at the source.

Much of McLellan's work is geared toward local impact. Milwaukee provides an ideal location for the School of Freshwater Sciences and McLellan's lab. The Great Lakes contain one-fifth of the world's fresh surface water and the school sits directly on Lake Michigan. In addition, there are three rivers that converge on Milwaukee's port and each of them represent the three areas of concern for scientists studying water contamination and pollution—agricultural runoff, suburban land use and a dense urban area.

But in 2013, the National Resource Defense Council reported Wisconsin's beach water was the second poorest in the nation. So Milwaukee's South Shore Beach is the next focus for McLellan and her team. Samples showed that there was little E. coli in the water, but the numbers spiked on the beach. The lab has already attributed much of the problem to storm water runoff from nearby parking lots and grants have been acquired to start addressing the problem.

"The research of Dr. Sandra McLellan has greatly assisted the City of Milwaukee Health Department in better understanding actual health risks associated with microbial contamination at public beaches, including Bradford Beach located within the at City of Milwaukee," said Paul A. Biedrzycki, Director of Disease Control and Environmental Health for the City of Milwaukee Health Department.

McLellan's research could have far reaching implications for public health, both in the US and internationally. Globally, 1.8 billion people still drink contaminated water, according to the World Health Organization. And an estimated 842,000 people die each year from diarrhea caused by unsafe water, often because of fecal matter, and lack of sanitation.

"What our lab is doing is trying to come up with better indicators of fecal pollution that are very specific to sources. Is it from a human is it from a bird is it from cattle? So we take it a step further to see if we can trace where fecal pollution is coming from in the environment," McLellan said.

She was recently awarded a $1.5 million dollar grant from the National Institute of Health (NIH) to continue her work and research. It's the third grant they've awarded McLellan—she's spent almost a decade advancing her research. And McLellan hypothesizes that in less than two decades, she and her team will be able to complete sequencing on site, as soon as a sample is collected.

"It's almost like the preventative medicine of water. Instead of figuring out the pathology, let's just make sure people don't get sick in the first place," she said.

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