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A Bacterial Hat Trick: Tiny Organisms Subject of Three Papers

by Bill Chameides | August 26th, 2011
posted by Erica Rowell (Editor)

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Elkhorn coral, so named because of its large, sturdy antler-like branches, was once the dominant coral species in the Caribbean but in recent years has been on the decline. A new study suggests a bacterium is playing a large role in its demise. (NOAA)

Bacteria may be very small but they’re actually the most abundant organisms on Earth. And last week, they were the topic of at least three scientific papers.

Having survived the East Coast’s version of the “earthquake of the decade” this week, we are now busy battening down the hatches in preparation for Hurricane Irene. At the moment the predictions place New York City in this lady’s path, hopefully by then a much diminished storm.

In the meantime, here’s a summary of an interesting set of papers that appeared in the literature last week all on the subject of bacteria in the environment.

1. Human Fecal Material Putting the Kibosh on Caribbean Coral

Corals are on the decline throughout the ocean for a variety of reasons including global warming and pollution. Especially hard hit has been the elkhorn coral; once the most common coral in the Caribbean, it is now listed for protection under the U.S. Endangered Species Act. Why such a rapid decline in elkhorn? Global warming may be playing a role, but at least for the elkhorn it appears that disease — and specifically a disease called white pox — is the primary cause. (To learn more about elkhorn coral and white pox, check out this National Geographic video.)

It has been known for some time that white pox is caused by a bacterium called Serratia marcescens and that this bacterium is commonly found in the guts and intestines of animals. (This same bacterium is the stuff that’s been known to “cause meningitis and pneumonia in humans.”) But where is the S marcescens that is killing the elkhorn coming from? Researchers Kathryn Sutherland of Rollins College and her colleagues think they have found out. Using genomic analysis, Sutherland et al were able to uniquely trace the bacteria causing white pox in the elkhorn to the form of S marcescens found in human waste. In other words the spread of white pox in the coral reef community is likely due to “reverse zoonosis” caused by the release of untreated or inadequately treated wastewater containing the bacterium from human fecal material. They reported their results in the online journal PLoS ONE.

2. Who Let the Dogs’ Shxx Out?

First, take a deep breath. OK, now, did you know that air is typically loaded with bacteria? Yep, every breath you take — including the one you just took — contains lots of tiny invisible particles (folks in the know call them fine particles), and many of these particles have little bits of bacteria in them.

For the most part these bacteria come from soils and plants … no big deal. But a new paper in the journal Applied Environmental Biology by Robert Bowers of the University of Colorado Boulder and co-authors has added a new wrinkle to the bacteria-in-the-air-we-breathe story. They found that during the winter, when soil and plant sources are suppressed, the major source of airborne bacteria in the two Midwestern cities of Cleveland and Detroit was fecal matter from dogs. Kinda puts breathing and pooper-scoopering on common ground, so to speak.

3. Bacteria Get Around

Those of you who don’t live in Cleveland or Detroit might have found the above story about dog feces interesting but not alarming — not your city, right? It may not be your city, but that may not matter. A paper published in the Journal of Biogeography by David Wilkinson of Liverpool John Moores University and co-authors reports on global model simulations that demonstrate that small bacteria, once released, can travel across continents and cover entire hemispheres.

All this is food for thought as we hunker down for Irene, whose ~100-mile-an-hour winds are no doubt sending the air hither and thither around the East Coast and beyond.

filed under: bacteria, climate change, coral reefs, faculty, oceans, Planetary Watch
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