Life at Interfaces: Biocomplexity in Extreme Environments

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WELCOME to the NEW VERSION of the Idaho EPSCoR "Biocomplexity in Extreme Environments" webpage!

MICROBIOLOGY:

 

Principal Investigators: Tim Magnuson (ISU), Susan Childers (UI), Tom Hess (UI)

Project microbiologists use a number of methods to isolate and understand organisms living in geothermal springs. In the field, microbes are encouraged to grow on small "coupons" of test materials that are sewn into mesh bags and placed in springs for later recovery. Alternatively, samples of spring water and solid materials may be collected and used for laboratory-based enrichments of microorganisms that can grow under a variety of conditions. Other measurements that are made in the field include enumeration of total cells within the water column of a hot spring, measurements of microbial activities such as the reduction or oxidation of arsenic species, and determination of changes in community dynamics of attached populations. Information gained from these types of studies, when combined with geochemical, hydrologic, and geologic data, are used to develop an understanding of environmental factors controlling ecological diversity of a geothermal environment.



Microbial Diversity (...more)

The diversity of microbial communities living within geothermal systems is governed by environmental factors such as temperature and geochemical conditions including availability of nutrients. Microbiologists working on the Biocomplexity project are looking closely at the effect of spring temperature on both cell density and bacterial diversity in the Borax Lake area. Although the springs near Borax Lake display a wide range of temperatures, they show similar geochemical characteristics which makes the Borax system ideal for studying changes in microbial ecology and biocomplexity as a function of temperature variation in both attached and unattached communities. To date, our studies show that planktonic communities (those suspended in the water column) appear to have slightly higher diversity than attached communities. Furthermore, cooler springs have a higher planktonic cell density and diversity than hotter springs. Single spring analysis suggests that seasonal dynamics in the bacterial community profiles have little influence on the microbial mat community, but may have greater effects on the planktonic community.

For additional microbial diversity studies, click HERE.

Please contact Tim Magnuson at Idaho State University for additional information.

microbial diversity in an individual hot spring measured by comparing fragment lengths (base pairs)

Analysis of fragment lengths to evaluate seasonal dynamics in the bacterial community profiles. Fragment peaks are used as surrogates of species, and generally assumes that each peak represents a species.



Biogeochemical Cycling (...more)

Geomicrobiological explorations at Mickey Hot Springs has resulted in the discovery of a diverse ecosystem, represented by many groups of microorganisms never before cultured or studied in detail. Focused efforts on individual hot springs using novel culture-dependent techniques has resulted in the isolation of several new bacterial species, including sulfate- and arsenate-reducing microorganisms. These organisms influence biogeochemical cycling of sulfur and arsenic in this system and are being intensively studied. For example, YEAS, a potential co-culture, forms a biogenic arsenic-sulfide mineral (beta-realgar) never before observed in microbial cultures. This illustrates the importance for further study of this metabolism as it pertains to the biogeochemistry of the hot springs system. For more information, please contact Tim Magnuson at Idaho State University. beta-realgar production by YEAS growing on yeast extract and As
Beta-realgar production by YEAS growing on Yeast Extract and As.

Microbe-Mineral Interactions

Microbial processes are important to the formation and/or dissolution of solid geological materials in the natural environment as microorganisms such as bacteria depend upon the oxidation or reduction of various elements to provide energy for their growth. Most often, these reactions result in the precipitation of insoluble materials. Geothermal springs with temperatures of >70°C typically are associated with sinter deposits which form on the edges of the springs. Although mostly whitish gray in color, sinters can have multiple colors as a result of the presence of a diversity of bacteria within the matrix.

It is not clear whether bacteria actively participate in the deposition of sinters or whether the sinters form as a result of purely geochemical mechanisms. Chemical analysis of sinter material from hot springs at Borax determined the material to consist of mostly amorphous silica and some calcite. Scanning electron microscopy of sinter showed the presence of a diversity of bacteria encased within the material. Identification of the microorganisms within the sinter using molecular methods will provide information regarding the metabolic capacity of the microbes and whether the microbes are actively precipitating sinter material. An understanding of how these formations are produced within present-day geothermal environments will provide knowledge regarding past processes that were instrumental to the evolution of the planet. For more information, please contact Susan Childers at University of Idaho.

photo of hot spring sinter material

Fragments of sinter material removed from the edge of a hot spring. Microorganisms are evident by the various orange and green colors.
scanning electron micrograph of sinter material
Scanning electron micrograph of sinter material showing filamentous and coccoidal microorganisms within the amorphous silica and calcite deposit.
last update: June 2006 | webmaster: jhinds@uidaho.edu