Newly discovered microbe Is key in climate change

Daniel Stolte at the University of Arizona News: Tiny soil microbes are among the world's biggest potential amplifiers of human-caused climate change, but whether microbial communities are mere slaves to their environment or influential actors in their own right is an open question. Now research by an international team of scientists from the U.S., Sweden and Australia, led by University of Arizona scientists, shows that a single species of microbe, discovered only recently, is an unexpected key player in climate change.

The findings, published in the journal Nature, should help scientists improve their simulations of future climate by replacing assumptions about the different greenhouse gases emitted from thawing permafrost with new understanding of how different communities of microbes control the release of these gases.

Earlier this year, the international team discovered that a single species of microbe, previously undescribed by science, was prominent in permafrost soils in northern Sweden that have begun to thaw under the effect of globally rising temperatures. Researchers suspected that it played a significant role in global warming by liberating vast amounts of carbon stored in permafrost soil close to the Arctic Circle in the form of methane, a powerful greenhouse gas trapping heat in the Earth's atmosphere. But the actual role of this microbe — assigned the preliminary name Methanoflorens stordalenmirensis, which roughly translates to "methane-bloomer from the Stordalen Mire" — was unknown.

The new research nails down the role of the new microbe, finding that the sheer abundance of Methanoflorens, as compared to other microbial species in thawing permafrost, should help to predict the collective impact on future climate change.
"If you think of the African savanna as an analogy, you could say that both lions and elephants produce carbon dioxide, but they eat different things," said senior author Scott Saleska, an associate professor in the UA’s Department of Ecology and Evolutionary Biology and director of the UA's new Ecosystem Genomics Institute. "In Methanoflorens, we discovered the microbial equivalent of an elephant, an organism that plays an enormously important role in what happens to the whole ecosystem."…

"Autumn landscape with fox," Bruno Liljefors - Bukowskis,public domain

Researchers discover global warming may affect microbe survival

Newswise via Arizona State University: Arizona State University researchers have discovered for the first time that temperature determines where key soil microbes can thrive — microbes that are critical to forming topsoil crusts in arid lands. And of concern, the scientists predict that in as little as 50 years, global warming may push some of these microbes out of their present stronghold in colder U.S. deserts, with unknown consequences to soil fertility and erosion. The findings are featured as the cover story of the June 28 edition of the journal Science.

An international research team led by Ferran Garcia-Pichel, microbiologist and professor with ASU’s School of Life Sciences, conducted continental-scale surveys of the microbial communities that live in soil crusts. The scientists collected crust samples from Oregon to New Mexico, and Utah to California and studied them by sequencing their microbial DNA.

While there are thousands of microbe species in just one pinch of crust, two cyanobacteria —bacteria capable of photosynthesis — were found to be the most common. Without cyanobacteria, the other microbes in the crust could not exist, as every other species depends on them for food and energy. “We wanted to know which microbes are where in the crust and whether they displayed geographic distribution patterns at the continental scale,” said Garcia-Pichel, also dean of natural sciences in ASU’s College of Liberal Arts and Sciences. “To our surprise, where we thought a single cyanobacterium would dominate, we found that two had neatly split the territory between themselves. We used to think that one, called Microcoleus vaginatus, was the most important and dominant, but now we know that Microcoleus steenstrupii, the other one, is just as important, particularly in warmer climates,” he added.

While the two look very much alike, M. vaginatus and M. steenstrupii are not even closely related. They have evolved to appear alike because their shape and behavior help them stabilize soil and form soil crusts. Crusts are crucial to the ecological health of arid lands, as they protect the soil from erosion and contribute to land fertility by fixing carbon and nitrogen into the soil and by extracting other nutrients from trapped dust.

After considering data about soil types and chemistry, rainfall, climate and temperature, researchers used a mathematical model that showed temperature best explained the geographic separation of the two microbes. While both are found throughout the studied area, M. vaginatus dominate the crusts in cooler deserts and M. steenstrupii are more prevalent in the southern deserts. “But this was just a correlation,” Garcia-Pichel explained. “To prove the role temperature plays, we tested cultivated forms of the microbes and confirmed that it does indeed make a difference — temperature is what keeps them apart. The point now is that temperature is no longer stable because of global warming.”...

Microcoleus vaginatum and other cyanobacteria, public domain

Amazon deforestation brings loss of microbial communities

EurekAlert via the University of Massachusetts at Amherst: An international team of microbiologists led by Klaus Nüsslein of the University of Massachusetts Amherst has found that a troubling net loss in diversity among the microbial organisms responsible for a functioning ecosystem is accompanying deforestation in the Amazon rainforest.

Nüsslein, an expert in tropical rain forest microbial soil communities, says, "We found that after rainforest conversion to agricultural pastures, bacterial communities were significantly different from those of forest soils. Not only did the pasture soils show increased species numbers, these species were also less related to one another than in rainforest soil. This is important because the combination of lost forest species and the homogenization of pasture communities together signal that this ecosystem is now a lot less capable of dealing with additional outside stress."

He and colleagues studied a large farm site over the past four years at the frontier where farmers drive agriculture into pristine rainforest in Rondonia, Brazil, to convert rainforest to agricultural use. Findings in part validated previous research showing that bacteria in the soil became more diverse after conversion to pasture. However, in its fourth year, their study overcame limitations of earlier investigations to show that changes in microbial diversity occurred over larger geographic scales. Results appear in the current issue of Proceedings of the National Academy of Sciences.

In addition to Nüsslein at UMass Amherst, the research group includes first author Jorge Rodrigues at the University of Texas at Arlington with Brendan Bohannan at the University of Oregon, James Tiedje at Michigan State University, and others at the University of Sao Paulo. Lead investigators Nüsslein and Rodrigues emphasize that the study is an equal collaboration among the four research groups.

Findings do not support earlier study conclusions, instead they show that the loss of restricted ranges for different bacteria communities results in a biotic homogenization and net loss of diversity overall. Scientists worry that the loss of genetic variation in bacteria across a converted forest could reduce ecosystem resilience. The researchers hope their work will provide valuable data to those making decisions about the future of the Amazon rainforest....

From NASA: The 38-kilometer-long Lago do Erepecu (Lake Erepecu) in Brazil runs parallel to the lower Rio Trombetas (Trombetas River), which snakes along the upper half of this astronaut photograph. Water-bodies in the Amazon Rainforest are often so dark they can be difficult to distinguish. In this image, however, the lake and river stand out from the uniform green of the forest in great detail as a result of sun-glint on the water surface. Sun-glint is the mirror-like reflection of sunlight off of a surface directly back towards the viewer, in this case an astronaut on-board the International Space Station. Forest soil is red, as shown by airfield clearings near Porto Trombetas (image far upper left), a river port on the south side of the Trombetas River.