FEB 12, 2014 12:00 AM PST

Versatile Protein May Have Existed on Earth Before Oxygen

WRITTEN BY: Jen Ellis
It's tough to be a microbe. Microbes often live in extreme environments and feed on waste materials-processing them in ways that are often useful-and they perform their tasks every day without any fanfare. Your day doesn't seem so bad now, does it?

A recent study looked at a particular type of microbe within the class of methanogens-microbes that often live in anaerobic (oxygen-free) environments and produce methane as they break down waste materials. Researchers with Virginia Tech and the University of California-Berkeley examined archaea, a single-celled microorganism in the methanogen family. They concluded that thioredoxin, a protein component of the archaea and also a key component in plant photosynthesis, predates oxygen's appearance on Earth. Their work was published in a recent online edition of the Proceedings of the National Academy of Sciences.

The research team studied Methanocaldococcus jannaschii, a type of methanogen found in the harsh environments near volcanoes or hydrothermal vents deep on the ocean floor, and determined that thioredoxin was able to repair any of the organism's proteins that were damaged by exposure to oxygen. This discovery raises the possibility that prior to the appearance of oxygen in the early Earth, thioredoxin performed useful metabolic regulation functions in the ancient anaerobic environment, just as it plays an important role in the plant photosynthesis of today.

How does this conclusion about the early Earth help us today? It is possible that by understanding the versatility of methanogens in general, we may be able to make advancements in many fields-from fuel conversion to agricultural processes to climate control, and perhaps even to human health.

Methanogens live within the large intestines of humans, and assist in the digestion process. If the role of methanogens can be manipulated in useful ways, it may be possible to assist in controlling weight and therefore reducing obesity. Since methanogens also exist in the digestive systems of livestock, research in this field could also produce healthier livestock, improved production of meat and milk products, and an overall improved food supply.

Methanogen management could be applied to other fields as well. Methanogens regularly feed on plant biomass to produce methane. Other organisms in turn can convert this methane to carbon dioxide, which will in turn be utilized by living plants. Regulating and controlling this flow could have useful effects on both climate change and agricultural efficiency.

The methane produced by these microbes can also be used to treat industrial wastes and provide fuel (through mechanisms such as methane production in landfills and controlled digestion of agricultural byproducts). If the mechanisms can be optimized to produce fuel cheaply and efficiently out of waste material, we all benefit.

Extrapolating the general principle of this work to specific applications will take quite a bit of research time and money. Even so, by studying and further understanding thioredoxins and the anaerobic path of methane production, researchers have more paths to consider that may apply directly to any one of these fields. We look forward to the practical discoveries this field may lead to.

Meanwhile, please join us in saluting the hard-working microbes of the world, at least for one day. They've earned it.
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