G-439 scientists will study microbial weathering of volcanic rocks in the Antarctic extreme environments of McMurdo Sound. Distinct corrosion features in volcanic rocks indicate the activity of “rock-eating” microbes that may use chemical energy from volcanic rocks for their growth, possibly fixing carbon that may also be supplied by volcanic gas emissions. The abundance of bioalteration textures in glass suggest that this type of primary production of organic carbon in volcanic systems may be a major process in the global biosphere and might control geochemical fluxes between the hydrosphere and volcanoes that formed more than 2/3rd of the Earth's surface. Furthermore, such bioalteration traces have been found in rocks as old as 3.5 billion years suggesting that these processes may have played an important role in the origin of life on Earth. Very little is known about these “rock-eating” microbes. Scientists still struggle to understand the microbial communities involved, how these microbes interact with the rock, what benefits they may gain from this interaction and the underlying molecular machinery that controls it all. G-439 is venturing to Antarctica to collect such microbial communities along with the rocks they colonize for laboratory studies. The investigators will characterize these communities, study their interaction with rocks and explore the underlying genetic controls of their “rock-eating habit”. This study is funded by the National Science Foundation and runs over five years with three Antarctic field seasons (2008/9, 2010/11 and 2012/13).

The G-439 strategy for studying rock-eating microbes (“da microbe”) includes field experiments and sampling in Antarctic extreme environments, followed by laboratory investigations of the materials recovered during these field efforts. Field exposure experiments consist of an array of materials, including microbial traps that will attract highly specialized “rock-eaters” to substances that specifically serve their needs or metabolic capabilities, such as the oxidation of iron or manganese. In addition, polished slabs of these materials record the physical corrosion by colonizing microbes eating the material. These experiments were deployed, in duplicate, during the 2008/9 Antarctic summer season. The first set will be recovered after an exposure period of two years during this upcoming 2010/11 season and the other ones after four years of exposure during the 2012/13 field season. G-439 scientists will also collect natural rock surfaces to compare their exposure experiments to the microbial communities and the biofilms that cover these rocks. All samples will be brought back to McMurdo station, where they will be processed for studies in the home laboratories in California, Maine and Oregon. This work will include high resolution imaging of microbes, biofilms or corrosion features, culturing, and a wide range of molecular microbiology investigations.

The extreme environments of the McMurdo Sound area of Antarctica offer a unique opportunity to study microbial communities that live on and within volcanic rocks. For starters, volcanic rocks are the dominant rock type in the region as McMurdo Station is built on a volcanic island with an active volcano as its central peak, the 3,794 m (12,448 ft) tall Mt. Erebus (http://en.wikipedia.org/wiki/Mount_Erebus). Many more volcanoes are scattered throughout the area, all of them inactive, but well preserved in the inhospitable Antarctic climate. It is also important to this study that soils and rock surfaces in this area of Antarctica are relatively poor in organic material that would provide an alternate and superior energy yielding fuel for microbial growth than the chemical fuels from volcanic rock. G-439 bets that these environments are more likely to yield “rock eating” microbes than other places on Earth where such processes have been studied in the presence (and high abundance) of dissolved or particulate organic carbon. The physical environmental conditions for rock weathering in Antarctica are extremely diverse so microbes must adapt to a wide range of conditions, from sub-freezing temperatures to 65°C hydrothermal vents, from extremely dry to wet in seasonal streams or in continuous submergence in seawater or in glacially formed lakes. Exposures includes bright sunlight in the Antarctic summer (in some places) or darkness in deep ice caves of Mt. Erebus where the absence of organics and lack of photosynthesis simulates conditions as they can be expected in subterranean settings. G-439 scientists chose representative locations that reflect these diverse environments.

 

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