Salt Plains (Oklahoma)
- 1 Introduction
- 2 Environment
- 3 Microbial communities
- 3.1 Halotolerant and Halophilic Bacteria, Archaea, Cyanobacteria, Algae, and Fungi
- 3.2 Cyanobacteria, Diatoms, and chlorophyte algae
- 3.3 Isolated Archaea
- 3.4 Halophiles in Hypersaline Environments
- 4 Microbial processes
- 5 Current Research
- 6 References
The Great Salt Plains is an 840-acre Oklahoma state park located in Alfalfa County, Oklahoma. This area is a natural hyper-saline environment. Permian brine comes up from deep in the plains to the surface where it evaporates. The salt appeared through millions of years of water-level changes of a shallow sea. There is a body of saline groundwater lying several feet below the salty sediment. As the rains come and go, the water evaporates in between the cycles and evaporates to create a new layer of salt. In this salty sediment, selenite crystals form, creating an attraction for many visitors . When the rains arrive, they dissolve the top layer of salt creating small waterways and pools of water. These small areas of water change the concentration of salt very quickly from low to high concentrations. With a huge expanse of no vegetation, there is no shade/protection from the sun's ultra violet rays. Over a typical 24-hour day the average temperature range of the sediment's surface is around 30°C. The combination of the salinity, temperature, and UV makes this an extreme environment. This environment contains Halophiles which are photoheterotrophs, using light for energy and methane as a carbon source. They can be in either aerobic or anaerobic conditions. 
This 7x3 mile land is known for Selenite crystals. It is made up of mud and is covered in a thin layer of salt from a sea millions of years ago. A few feet under the plains, there is saline ground water running that periodically floods up onto the surface in small pool after it rains. The process of evaporating will then start again.
The adjacent lake has a salinity of 50% that of sea water. The Selenite is gypsum, chemically hydrous calcium sulfate. The gypsum and saline solutions in the soil promote crystal growth especially when the temperatures are in ideal conditions. During times of high rainfall, the Selenite will dissolve back into solution until conditions return.
Halotolerant and Halophilic Bacteria, Archaea, Cyanobacteria, Algae, and Fungi
The Salt Plains Microbial Observatory (SPMO) isolated and identified soils yielding 105 aerobic bacteria showing 46 phylotypes. They also isolated over 200 halotolerant cyanobacteria, diatoms and chlorophyte algae. 
Cyanobacteria, Diatoms, and chlorophyte algae
Cyanobacteria are also known as blue-green algae/bacteria. From the phylum Cyanophyta, they obtain their energy through photosynthesis.  Chlorophyte algae is a group of green algae mostly of the aquatic type. Diatoms are a group of unicellular algae. They are usually in colonies of filaments, ribbons, fans, zigzags, or stars. Their cell walls are made of silica called frustule.
Current research finds around a dozen different archaea isolates phylogenetically related to Haloarcula, Haloferax, Halorubrum, Haloterrigena, and Natrinema. 
Characteristics of Halophilic Archaea
"Halophilic Archaea (whose name comes from Greek for "salt-loving") thrive even in concentration of salt five times greater than the salt concentration of the ocean and in salt concentrations higher than those used in any food pickling processes. They in fact require salt for growth and they are adapted to environments which have little or no oxygen available for respiration. Instead, their cellular machinery contains charged amino acids on their surfaces, which react to the salt." 
Halophiles in Hypersaline Environments
These microbes have to overcome high salt environments, overcome intense UV, and avoid desiccation (the state of extreme dryness or the process of extreme drying). 
Overcoming high salt
To prevent water loss, the halophiles accumulate solutes in their cytoplasm. They use Na+ pump to push Na out of the cell as well as keeping a concentration of K+ ions (about 5M) to balance out the osmotic pressure. 
Halophiles have very efficient DNA repair to survive the UV. They use their pinkish pigment to help photoprotect themselves. They also possess Bacteriorhodopsin, which is a purple proton pump that drives ATP synthesis. 
The state of extreme dryness or the process of extreme drying. As crystals grow, small amounts of brine are trapped within the crystals as well as the halophilic Archaea. 
The microbes of the salt plains are photoheterotrophs, using light for energy and methane as a carbon source. They can be in either aerobic or anaerobic conditions. They keep the salinity of the land at a stable amount but do not promote the growth of vegetation. Their processes are sparse.
Salt Plains Microbial Observatory found examples of many of the organisms important for biogeochemical cycling have not been isolated from terrestrial hypersaline habitats. Nitrogen fixation activity was measured and nitrogenase (nifH) gene sequences detected.  Nitrogen fixation is when N2 in the air is converted into NH3. Nitrogen fixation provides biologically available N and N is essential for all life. .
Majority of current research focuses on the ability of microbes to survive incredibly harsh conditions that barely change throughout the year.
Dr. Bill Henley
His research focused on the phylogeny and physiological ecology of broadly halotolerant algae and cyanobacteria from the Salt Plains National Wildlife Refuge near Cherokee in northwestern Oklahoma. This work comprised two NSF-funded projects:
Collaborative Research: Salt Plains Microbial Observatory (MCB-0132097).
LExEn: Response of photosynthetic microbes of the Salt Plains National Wildlife Refuge to dynamic extreme conditions (MCB-9978203).
Response of Photosynthetic Microbes of the Salt Plains National Wildlife Refuge to Dynamic Extreme Conditions
"Few studies have addressed multiple variable stress factors likely to be even more adverse to life. Evaporitic salt flats, such as at the Salt Plains National Wildlife Refuge in Oklahoma, represent such a dynamically stressful habitat: direct sunlight, up to 20-30° C diel (60-70° C annual) surface temperature range, episodically varying interstitial and surface pool salinities from near 0 to over 300 g/L, and potentially wide diel fluctuation in pH, redox potential, and dissolved gases and nutrients. Thus, the mostly undescribed photosynthetic and heterotrophic microbes in this habitat may provide unique insights into the evolution of life beyond the limits of tolerance for virtually all species on Earth. The proposed general hypothesis is that interacting stress factors determine survival, productivity and competitive outcomes in hypersaline photoautotrophs, and that halophiles are tolerant of wide fluctuations in physiocochemical conditions in addition to steady-state extreme conditions." They are focusing on how photosynthetic microbes survive in the extreme salinity.
Colorimetric microbial diversity analysis and halotolerance along a soil salinity gradient at the Great Salt Plains of Oklahoma
"Microbial diversity was measured along a salinity gradient at the Great Salt Plains of Oklahoma using colony color quantified as RGB components of microbial isolate streaks. Surface soil samples along a 6-m salinity gradient (from hypersaline soil with 7.5% salinity to oligohaline rangeland soil) at WP68 were dilution-plated on SP medium of various salinities and hundreds of random colonies were collected. These results are complementary to previous molecular genetic analyses of 16S rRNA clone libraries from soils at the Great Salt Plains. Great diversity at lower taxonomic levels supports the suggestion that gene flow is not highly fragmented, a result of less specialization, as expected given the highly variable salinity observed at the salt flats with rain events."  They are trying to find how the colors of the microbial life affects how they survive in the extreme salinity.
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- | Caton, T. M.; Caton, I. R.; Witte, L. R.; Schneegurt, M. A., Archaeal Diversity at the Great Salt Plains of Oklahoma Described by Cultivation and Molecular Analyses, Microbial Ecology;Oct2009, Vol. 58 Issue 3, p519
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- | Grant, W. D., eds., Extremophiles: Microbial Life in Extreme Environments, Wiley-Liss, Inc. pp 93-132.
- | William J. Henley, Department of Botany, Oklahoma State University LExEn: Response of photosynthetic microbes of the Salt Plains National Wildlife Refuge to dynamic extreme conditions (MCB-9978203).
- | Res Microbiol. 2013 Jan;164(1):83-9. doi: 10.1016/j.resmic.2012.10.004. Epub 2012 Oct 12. Department of Biological Sciences, Wichita State University, Wichita, KS 67260, USA.
- | P. Dutta, S. A. Perkins, S. L. Castro, D. K. Gutzmer, M. D. Howell, D. L. Weber, J. A. Buchheim, M. A. Buchheim, M. A. Schneegurt; N-087. Revealing Further Microbial Diversity at the Great Salt Plains of Oklahoma, Wichita State University, Wichita, KS.
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- | Fendrihan, S., Legat, A., Pfaffenhuemer, M., Gruber, C., Weidler, G., Gerbl, F., Stan- Lotter H. (2006) Extremely halophilic archaea and the issue of long-term microbial survival. Rev Environ Sci Biotechnol 5, 203-218.
Edited by Brian Chan, a student of Angela Kent at the University of Illinois at Urbana-Champaign.