BUFFALO, N.Y. – Beachgoers and anglers may despise algae,
but bacteria such as E. coli and salmonella revel in it.
That’s according to University at Buffalo researchers who
have found that green algae in the Great Lakes not only protect
bacteria from destruction by the sun’s ultraviolet rays, but
feed the organisms as well.
The research, a cover article published in the journal Royal
Society of Chemistry’s Environmental Science: Processes and
Impacts, offers new insight into how algae affect the health of
the Great Lakes, the world’s largest surface freshwater
“Because algae are a nuisance, we don’t think that
they are harmful. But some may be harboring bacteria,” says
Berat Haznedaroglu, PhD, a researcher at RENEW,
a new interdisciplinary initiative at UB that focuses on energy,
environment and water research.
E. coli – most strains of which are non-pathogenic –
and algae are typically present in freshwater, and officials
regularly test the water for bacteria levels. Although salmonella
often finds its way into the waterways in fecal matter through
runoff from sewers and farms, these bacteria are usually killed by
However, an algae bloom – a boom in algae population
– can act as a barrier between radiation and the organisms,
allowing bacteria populations to grow unheeded. Extreme amounts of
bacteria can force officials to close a beach for public
Haznedaroglu, an assistant professor in UB’s Department of
Civil, Structural and Environmental Engineering in the School of
Engineering and Applied Sciences, and graduate students collected
algae samples from beaches at Beaver Island State Park and tested
them with lab-grown E. coli and salmonella. The samples were
continuously illuminated at the same conditions with a controlled
amount of UV radiation similar to daylight.
In samples of water from the Niagara River containing 1,000
units of E. coli and salmonella per milliliter, without the
protection of algae, the bacteria survived for nearly six hours and
14 days, respectively. However, when algae were introduced, the E.
coli lasted for 16 hours, while the salmonella experienced hardly
any drop off.
Once samples were increased to 100,000 units, E. coli thrived
for 11 days with an algae presence, compared to two days without.
The larger salmonella sample shielded by algae experienced some
decline, but subsisted at a greater rate than the exposed
Researchers found that the bacteria don’t infect the algae
as they would a host, but instead, hide beneath them to avoid
sunlight. And since there are few food sources for the bacteria to
feed on outside of a host, the bacteria also crowd around the algae
to feed on organic molecules they release.
But removing algae from lakes does more harm than good. They
produce needed oxygen for other aquatic life in the water and are a
vital part of the food chain.
To prevent algae blooms, which are caused by an excess of
nutrients, Haznedaroglu suggests people use fewer household
cleaning products, soaps and detergents. These products often
contain phosphate, a major nutrient for algae.
In addition to research on water quality, Haznedaroglu’s
lab also focuses on several positive uses for algae, including its
potential as a biofuel, a protein supplement in juices and
smoothies, and for nitrogen and phosphorous removal during waste