Sun, January 02, 2011
Sci-Tech > Science

U.S. researchers discover how microbes cooperate

2011-01-01 21:06:34 GMT2011-01-02 05:06:34 (Beijing Time)  Xinhua English

LOS ANGELES, Jan. 1 (Xinhua) -- U.S. researchers have discovered that "interspecies electron transfer" entails one microorganism forming a direct electrical connection to another.

Scientists have known since the 1960s that microorganisms can indirectly exchange electrons through a process called hydrogen transfer, in which one microbe produces hydrogen and then another microbe consumes it.

But the new discovery goes a step further -- rather than a baton pass of sorts, it is two species directly plugging into each other.

The study findings were published by the Los Angeles Times on Saturday.

Researchers at the University of Massachusetts focused on Geobacter microbes, because of their role in environmental restoration. For example, the organisms can destroy petroleum contaminants and remove radioactive metal from polluted groundwater.

"We know that the microorganisms living in soil and water are essential for a healthy environment, but we have very little information on how different microbes live together," said lead researcher Zarath Summers. "We wanted to learn more about how they cooperate."

The researchers took two different microbes - Geobacter sulfurreducens and Geobacter metallireducens. Only the latter can consume ethanol for energy.

As the two grow in clumps, the second microbe attaches to the first and, rather than transfer substrates between each other, they are "wired" together and transfer electrons directly. In order to live, the G. sulfurreducens are sucking electrons off of the G. metallireducens.

"What we discovered is that different types of microbes can make electrical connections and pass electricity from one microbe to the other. This allows them to share energy in a highly efficient way that no one has ever seen before," Summers said

This way of transfer is a much more streamlined way to transfer electrons between microbes, said Summmers, adding that it's like taking an extension cord and plugging it into a neighbor.

With this new information in hand, scientists can possibly help optimize these systems for faster waste degradation, and more effectively produce valuable biofuels from that waste, Summers said.

"In wastewater treatment plants, we can take what we know and test different reactors processing all types of waste around the world, to see if there is a direct form of electron transfer happening."

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