Color Changing Bacteria Detector

  • A team at Tufts University is working on sensors that could change color to tell you if a bag of lettuce has dangerous bacteria in it. (Photo by Ken Hammond, courtesy of the USDA)

Researchers are working on a tool
that could tell you if your food is safe
to eat before you break open the bag.
Rebecca Williams has more:

Transcript

Researchers are working on a tool
that could tell you if your food is safe
to eat before you break open the bag.
Rebecca Williams has more:

A team at Tufts University is working on sensors that could change color to
tell you if a bag of lettuce has dangerous bacteria in it.

The special ingredient is silk. They boiled silkworm cocoons. And made a
thin silk film out of the proteins. The silk film has color changing properties
– like a butterfly’s wing.

Fio Omenetto is the lead researcher. He says it could be possible to activate
the film so it detects the presence of E. coli. Then the film could be put in a
bag of spinach.

“So immediately by looking at color change you will be able to tell whether
the spinach is good to eat or not.”

Omenetto says this is still pretty futuristic at this point. He says it’ll
probably be at least five years before you might see this at the grocery store.

For The Environment Report, I’m Rebecca Williams.

Related Links

Ten Threats: Bacteria Hits the Beaches

  • Lake Michigan dunes with a power plant in the background. (Photo courtesy of EPA)

If you swim or play on the beaches around the Great Lakes, you’ve
probably heard about ‘beach closings.’ At best, the situation is an inconvenience.
At worst, it’s a serious health risk for some people. That’s because the
beaches are closed due to dangerous levels of bacteria in the water.
Beach closures are not all that new, but Shawn Allee reports… the
science behind them could change dramatically in the next few years:

Transcript

We’re continuing our series, Ten Threats to the Great Lakes. Our field guide through the series is Lester Graham. He says anyone who visits Great Lakes beach is familiar with one of the Ten Threats.


If you swim or play on the beaches around the Great Lakes, you’ve
probably heard about ‘beach closings.’ At best, the situation is an inconvenience.
At worst, it’s a serious health risk for some people. That’s because the
beaches are closed due to dangerous levels of bacteria in the water.
Beach closures are not all that new, but Shawn Allee reports… the
science behind them could change dramatically in the next few years:


(Sound of dog and beach)


During the summer, dogs and their owners usually play together in the
water along this Lake Michigan beach, but today, several dog owners
scowl from the sand while their dogs splash around.


“It’s e coli day … it’s a hardship.”


This beachgoer’s upset, and like she said, e coli’s to blame.


Park officials tested the water the previous day and found high levels of
the bacterium. Missing a little fun on the beach doesn’t sound like a big
deal, but there’s more at stake than recreation.


Cameron Davis is with the Alliance for the Great Lakes, a regional
advocacy group.


“Beaches are most peoples biggest, tightest connection to the Great
Lakes, so when beaches close, they really impact our quality of life in the
region.”


And ultimately, health is at stake too. For a long time, scientists tested
beach water for e coli because it’s associated with human feces. That is,
if e coli’s in the water, there’s a good chance sewage is there too, and
sewage can carry dangerous organisms – stuff that can cause hepatitis,
gastric diseases, and rashes.


Sewage can get into the Great Lakes after heavy rains. That’s because
some sewers and drains can’t keep up with the flow, and waste heads to
the lakes.


For a long time, scientists thought human feces was the only source of e
coli in Great Lakes water, but a puzzling phenomenon has them looking
for other causes, too. Experts say cities have been dumping less sewage
into the Great Lakes in recent years, but we’re seeing more e coli and
more beach closings.


Paul Bertram is a scientist with the U.S. Environmental Protection
Agency. He says, we’re closing more beaches because we’re testing
them more often.


“But I don’t think it’s because the Great Lakes are getting more polluted,
and more filled with pathogens, I think we’re just looking for it more.”


If we’re finding more e coli because we’re testing more often, we still
have a problem. We still need to know where the e coli’s coming from.
Bertram says there might be another culprit besides sewage.


“There is some evidence that it may in fact be coming from birds, flocks
of seagulls, things like that.”


But some researchers doubt sewage and bird droppings can account for
high e coli levels.


(Sound of research team)


A few researchers are sorting vials of water in a lab at the Lake Michigan
Ecological Research Station in Indiana.


Richard Whitman leads this research team. He says, in the past,
scientists could predict beach closings by looking out for certain events.
For example, they would take note of sewer overflows after heavy rains.
Whitman says researchers can’t rely on those triggers anymore.


“A large number, maybe even a majority of closures remain unexplained.
Today, we have closures and there’s no rainfall, may not even be
gulls, and we don’t know why the bacteria levels are high.”


Whitman has a hunch that e coli can grow in the wild, and doesn’t
always need human feces to thrive.


“This is my theory. E coli was here before we were. It has an ecology of
its own that we need understand and recognize.”


The idea’s pretty controversial. It runs against the prevailing theory that
e coli only grows in waste from warm-blooded animals, such as human
beings and gulls, but the idea’s also a kind of political bombshell.


If he’s right, it would mean our tests for e coli aren’t very accurate – they
don’t tell us whether there’s sewage around. After all, if e coli is nearly
everywhere, how can we assume it’s a sign of sewage?


“As a pollution indicator, you don’t want it to multiply. If it’s got an
ecology of its own, multiplying on its own, doing its own thing, then it’s
not a very good indicator.”


Whitman wants us to try other kinds of tests to find sewage. One idea is
to look for caffeine in the water. Caffeine’s definitely in sewage but it’s
not found naturally in the Great Lakes, but until we change our water
tests, Whitman will continue his work. He says we still need to know
how much e coli’s in nature and how much is there because of us.


Environmentalists want the government to keep a close watch on the new
science. They say we can’t let questions about the relationship between
e coli and sewage stop our effort to keep sewage and other waste out of
the Great Lakes.


For the GLRC, I’m Shawn Allee.

Related Links

Tracking Livestock to Limit Diseases

Those worried about food safety say it’s time for a uniform animal identification system – one that could rapidly isolate animals suspected of carrying contagious diseases. Wisconsin agriculture officials have taken the lead on this type of preventative action but will need the help of all the Great Lakes states to make it work. The Great Lakes Radio Consortium’s Mary Jo Wagner has more:

Transcript

Those worried about food safety say it’s time for a uniform animal identification system, one that could rapidly isolate animals suspected of carrying contagious diseases. Wisconsin AG officials have taken the lead on this type of preventive action but will need the help of all the Great Lakes States to make it work. The Great Lakes Radio Consortium’s Mary Jo Wagner has more.


There’s growing consensus among agricultural officials that some type of universal animal identifier is needed to trace animals from birth to the marketplace. Especially in light of recent occurrences of “mad cow” and “foot and mouth” diseases in live animals overseas and the nasty form of e coli in meat products here. Wisconsin secretary of agriculture, Jim Harsdorf says the ID system started in Europe. Now it’s moved to Canada, where it’s mandatory, and Harsdorf says Holland has a central database containing information on all the nation’s animals.


“It’s housed in one location and the producers within 48 hours have an animal ID’d after it’s born and that animal ID stays with it for life.”


Federal officials in the United States have been slow to implement such a system though, so Harsdorf says state officials are working to come up with one. It might be tied to different identification networks that farmers already use to keep production and reproduction records, herd health, vaccinations and the location of cattle that are sold, or it could be a totally new system that keeps some or all of those records on one central computer database managed by state, private or non-profit organizations.


Wisconsin state veterinarian Clarence Siroky says public feedback surprised them. State officials were expecting farmers to want only a voluntary system but what they found at public meetings was that producers want a more comprehensive mandatory system nationwide


“We move cattle all over the United States rapidly…we can have one cow at least touch 27 other states within a week…one pig can touch 19 other states within 24 hours.”


For those reasons, Siroky says, all animals will have to be included, not only cows, but sheep, horses and pigs. In England for example, cows are identified, but sheep are not, and he says sheep were implicated in the rapid spread of foot and mouth disease there.


That concerns Ted Johnson. He’s a Wisconsin dairy farmer who likes the idea of a universal identification system because it would quickly pinpoint the location of animals that might have come in contact with a disease.


“If in the event of an outbreak of some highly contagious disease, it could be stopped very quickly and we wouldn’t have to have wholesale slaughtering of cattle.”


Still Johnson says many farmers are concerned about how much the ID would cost, who would maintain the records, and who would have access to them.


“The worst case scenario would be if that information is released and there is some doubt about the information or if the information is used in an incorrect manner, the perception can be there’s a problem on individual farms.”


State veterinarian Clarence Siroky says that’s why input from farmers, processors, privacy advocates and consumers is important as the technology is developing.


Still to be decided is the type of animal ID that would be used. Siroky says it could be a tag placed on the animal’s ear. However, some animals already have so many different ear tags, he says one ear can look like a Christmas tree. Other possibilities include a computer chip or other type of recyclables monitor placed inside an animal.


Meanwhile, AG secretary Harsdorf says the records included in a computerized type of system could be very beneficial to consumers at the supermarket.


“At some point in time, you’re gonna have the ability to go through a grocery store and see up on a screen when you buy that package where it came from, a picture of the operation — it’s almost mind boggling to see what could happen down the road.”


Still, farmer Ted Johnson worries all the talk right now about the need for animal identification might create a consumer backlash.


“I feel as a producer our food supply is very safe. I don’t want the perception to be that an animal ID program is being instituted because we have a problem.”


But a potential problem without plans to deal with it could create havoc for the agricultural industry, and so far veterinarian Siroky doesn’t know when a system with wide support might be in place. He does say animal health officials are on high alert for the appearance of any contagious diseases. At the same time, he says even if Wisconsin comes up with a proactive plan, unless other states adopt a similar identification method, any tracking system would have limited effectiveness. For the Great Lakes Radio Consortium, I’m Mary Jo Wagner.