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In: Beaches, e. coli, Lake Michigan, Ryan Newton, Sandra McLellan, University of Wisconsin-Milwuakee School of Freshwater Sciences
Two undergraduate students collect use buckets to collect water samples from Lake Michigan.

Two undergraduate students collect water samples from Lake Michigan for E. coli and other microbial DNA testing. Photo: Ryan Newton

Nothing ruins a day at the lake like E. coli. At elevated levels, the bacteria — which is prevalent in the guts and feces of both humans and animals — can make people sick, forcing beach managers to post advisories or close beaches entirely. And while current testing methods provide an accurate snapshot of E. coli levels in beach water, the results aren’t always timely.

“There’s a 24-hour lag before you get those results,” said Ryan Newton, a professor at the University of Wisconsin–Milwaukee School of Freshwater Sciences who studies microbes in aquatic environments. “It’s not ideal because you have to wait 24 hours to close a beach or take some sort of action. And at that point, the conditions may not be the same as what they were when you took the sample.”

That delay in getting results can mean people are swimming in unsafe waters or, alternatively, a beach is needlessly closed, which can have negative economic consequences.

That’s where Newton’s research comes in. With funding from Wisconsin Sea Grant, he and his team are developing a faster way to test for E. coli and identify its source so beach managers can make quick, informed decisions about the safety of their beaches and identify ways to prevent future pollution. 

Rapid results using RNA

Purple colonies of E. coli grow in Petri dishes

Results from E. coli testing. Each purple colony on the plate represents E. coli from the sample. Photo: Ryan Newton

Professor Ryan Newton wears a gray sweater and glasses

Ryan Newton. Submitted photo.

Newton explained E. coli is traditionally tested by culturing the bacteria: filtering a water sample, swabbing it onto a Petri dish, warming it up, and waiting to see what grows. It’s an accurate method, but the incubation period takes at least 24 hours. The method he’s developing, on the other hand, won’t require incubation. Instead, it will make use of RNA to detect E. coli in water samples.

A quick flashback to high school biology: RNA, or ribonucleic acid, is an essential molecule that helps make proteins in living organisms, including E. coli. Like DNA, RNA features unique molecular sequences, called “signatures,” that can be used to identify organisms.

The new process Newton is developing will be able to quickly identify if E. coli signatures are present, skipping the incubation period that slows down the current process. Currently Newton’s team is fine-tuning the method in the lab before trying it out on lake water, which will present its own set of challenges. 

“Things in nature don’t always play as nicely as clean water in the lab,” he said.

But whose poop is it?

A seagull stands on a concrete ledge near Bradford Beach in Milwaukee

A seagull at Bradford Beach. Photo: Wisconsin Sea Grant

In addition to developing a faster way to detect E. coli in lake water, Newton’s team is also working on a method to identify its source. Such information will help public health officials assess the threat — human feces are generally considered riskier to human health than those of cows or dogs — but also help beach managers prevent future pollution. 

“Right now, we’re envisioning [the test] as a way to do a quick survey of your beach and understand which pollution sources are most likely,” said Newton. “If you know it’s coming from sewage, then you just have to identify where that sewage might be coming from, whether it’s a leaky pipe or infrastructure or misconnection.”

While tests to identify individual sources exist, Newton is developing a method to identify multiple sources in one water sample. He’ll use a handheld, portable DNA sequencer to identify the types of microorganisms present, which can then reveal whether the fecal contamination is coming from humans, cows, dogs, or gulls. 

It’s useful information for municipalities looking to address longstanding E. coli issues at beaches. Newton pointed to the work of colleague and Sea Grant-funded researcher Sandra McLellan, who identified seagulls and stormwater runoff as the primary sources of E. coli at Milwaukee’s popular Bradford Beach a little over 15 years ago. As a result of the study, the city implemented strategies to prevent stormwater from running across the beach during heavy rains and used dogs to scare birds off the beach. 

The changes made a difference.

“Bradford became much, much cleaner after those processes were implemented,” said Newton.

He hopes the methodologies he’s developing will give beach managers timely, accurate information about water quality on their beaches that they can use. His team already works closely with the Milwaukee Health Department. 

“We have a ton of partners that we work with, and our building [School of Freshwater Sciences] contains four nonprofits and three federal agencies. And so I walk down the hall and talk to them,” said Newton. “The work is fulfilling in that you can see actual change.”

***

The University of Wisconsin Aquatic Sciences Center administers Wisconsin Sea Grant, the Wisconsin Water Resources Institute, and Water@UW.  The center supports multidisciplinary research, education, and outreach for the protection and sustainable use of Wisconsin’s water resources. Wisconsin Sea Grant is one of 34 Sea Grant programs supported by the National Oceanic and Atmospheric Administration in coastal and Great Lakes states that encourage the wise stewardship of marine resources through research, education, outreach, and technology transfer.

 

 

The post Developing a faster way to detect E. coli and identify its source at public beaches first appeared on Wisconsin Sea Grant.

Original Article

News Releases | Wisconsin Sea Grant

News Releases | Wisconsin Sea Grant

https://www.seagrant.wisc.edu/news/developing-a-faster-way-to-detect-ecoli/

Jenna Mertz

On:
In: Cladophera, e. coli, Gyaneshwar Prasad, how many public beaches are in Wisconsin, nutrients and E. coli survival, persistent E.coli in beach sand, Sandra McLellan, University of Wisconsin-Milwaukee

Ah, a summer day at the beach: cool water, warm sand and a beverage at hand. Wisconsin’s 180 public beaches are one of the state’s most-valued assets. They provide recreational opportunities, economic benefits for coastal communities and enhance the quality of life for residents.

Keeping those beaches safe for people to use is a continuing process. Beach managers use levels of Escherichia coli (E. coli), a bacterium from fecal pollution in water to know when to keep beaches open or closed. It’s far from a perfect indicator, however. E. coli can come from many sources, not all of it harmful to humans, and it can persist in the environment sometimes for weeks after it was introduced. In fact, sand can contain more E. coli than water. This can make a beach manager’s job complicated.

Microcosms containing E. coli samples were buried in sand for six weeks at several beaches in a related project by McLellan. Image credit: Natalie Rumball

Sea Grant-funded researchers Sandra McLellan and Gyaneshwar Prasad, both with the University of Wisconsin-Milwaukee, are building on previous research to find ways to decomplicate beach managers’ lives by determining what factors could limit long-term survival of E. coli on beaches.

McLellan, a professor in the School of Freshwater Sciences, explained the pros and cons of E. coli as an indicator.

“It’s a great indicator because it’s so easy for people to culture in the lab. It’s easy to count. Where it’s not a good indicator is it really doesn’t tell you anything about the source of what’s there. You don’t know where to direct your management strategies. Should I be chasing away the birds or should I be looking for a leaking sewage pipe nearby? And then to top it off, the other downside is the E. coli survives outside of a host. There’s prolonged survival in the sand and maybe even growth if enough nutrients are available,” McLellan said.

Once outside a human or animal gut, E. coli usually only live a couple of days. But under certain circumstances, it can live for week or even indefinitely in sand.

With graduate student Sophia Ward’s help, McLellan and Prasad are studying sand and water at six Lake Michigan beaches: two in Kenosha County, two in Manitowoc County and two in Milwaukee County. McLellan thinks this array of beaches will provide good representation of what goes on around the Lake Michigan shoreline.

Sandra McLellan interacts with high school students who are studying E. coli in a program she ran in partnership with the Sixteenth Street Clinic in Milwaukee in 2021. Image credit: Wisconsin Sea Grant

They are also testing for levels of nutrients such as carbon, nitrogen, phosphorus and iron. In addition, they are conducting laboratory experiments to “starve” long-lived E. coli of these nutrients to see what drives their survival.

For the lab experiments, E. coli is mixed with sand and packed into small microcosms (miniature environments). McLellan describes them as four-inch diameter PVC pipes cut into four-inch sections. “We bury them in a bed of sand and keep them nice and moist. This helps us mimic what happens at the beach. The water can pass through, but the E. coli can’t escape from those little microcosms.”

The E. coli contain an extra piece of DNA that has a green fluorescent protein engineered in such a way that when the cell is starved, it lights up. The researchers then feed them with water containing varying amounts carbon, nitrogen, phosphorus and iron. They remove the microcosms periodically and count the E. coli to see how many have survived and see if any display the fluorescent-green markers of starvation.

From preliminary experiments, McLellan suspects carbon might be the most important factor that allows E. coli to persist. In beach environments, carbon is often provided by decaying plant life, especially leaves and the nuisance algae, Cladophora.

Once this limiting factor is confirmed, McLellan and her team will develop a scorecard for the potential of long-term E. coli reservoirs for each beach. “By scoring how easily or how much E. coli is growing in the sand at these beaches, it can help beach managers direct their attention to what might be some probable sources at their beaches,” McLellan said. They are also taking nutrient levels into account.

“The scorecard is developing. I think once we understand the dynamic range of what these beaches look like, then we’ll have a better idea of what the scorecard will actually look like,” she added. The information will also be useful to the Wisconsin Department of Natural Resources, which heads the Wisconsin beach monitoring program.

The post Persistent Pollution: Researchers investigate the key to E. coli bacteria survival in Lake Michigan beach sand and water first appeared on Wisconsin Sea Grant.

Original Article

News Releases | Wisconsin Sea Grant

News Releases | Wisconsin Sea Grant

https://www.seagrant.wisc.edu/news/persistent-pollution-researchers-investigate-the-key-to-e-coli-bacteria-survival-in-lake-michigan-beach-sand-and-water/

Marie Zhuikov