Culture-Independent Analysis of Microbial Diversity at the Great Salt Plains of Oklahoma
Ingrid R. Caton and Mark A. Schneegurt
The Great Salt Plains (GSP) in north-central Oklahoma is a barren 65-km2 salt flat where an evaporite crust of mainly NaCl is maintained with brine from subterranean salt deposits. Salt Plains Microbial Observatory has isolated a wide variety of halotolerant and halophilic bacteria, archaea, cyanobacteria, algae, and fungi. Initial heterotrophic enrichments and plating of GSP soils yielded 105 diverse aerobic bacteria representing 46 phylotypes. More than a dozen different halophilic archaea and over 200 halotolerant cyanobacteria, diatoms and chlorophyte algae also have been isolated. The culturing campaign has now been supported by culture-independent molecular analyses. Direct DNA extracts from soils were used to generate 16S rRNA gene libraries. Bacterial sequence libraries were generated from two different areas of the GSP. At the WP3 site, the library was rich in sequences from cyanobacteria, including Aphanothece and Cyanothece species. The library also was rich in Bacteroidetes, Halomonas, and Salinibacter species. At the WP6 site, a greater number of anaerobic bacteria were observed, including Desulfuromonas, Thiohalomonas, and Clostridium species. Bacteroidetes and Salinibacter also were in high abundance. The archaeal sequence library from WP3 was found to consist of only Euryarchaeota in the Halobacteriales, including Haloarcula and Haloferax species, but also several novel clusters. Overall diversity was high at the GSP, increasing at lower taxonomic levels. Correspondence between the cultured isolates and the molecular isolates was generally low. This work was supported by grants from NSF Microbial Observatories, NIH KINBRE program of the NCRR, and NSF Graduate Fellows in K-12 Education.