Halotolerant aerobic heterotrophic bacteria from the Great Salt Plains of Oklahoma

Abstract

The Salt Plains National Wildlife Refuge (SPNWR) near Cherokee, Oklahoma, contains a barren salt flat where Permian brine rises to the surface and evaporates under dry conditions to leave a crust of white salt. Rainfall events dissolve the salt crust and create ephemeral streams and ponds. The rapidly changing salinity and high surface temperatures, salinity, and UV exposure make this an extreme environment. The Salt Plains Microbial Observatory (SPMO) examined the soil microbial community of this habitat using classic enrichment and isolation techniques and phylogenetic rDNA studies. Rich growth media have been emphasized that differ in total salt concentration and composition. Aerobic heterotrophic enrichments were performed under a variety of conditions. Heterotrophic enrichments and dilution plates have generated 105 bacterial isolates, representing 46 phylotypes. The bacterial isolates have been characterized phenotypically and subjected to rDNA sequencing and phylogenetic analyses. Fast-growing isolates obtained from enrichments with 10% salt are predominantly from the gamma subgroup of the Proteobacteria and from the low GC Gram-positive cluster. Several different areas on the salt flats have yielded a variety of isolates from the Gram-negative genera Halomonas, Idiomarina, Salinivibrio, and Bacteroidetes. Gram-positive bacteria are well represented in the culture collection including members of the Bacillus, Salibacillus, Oceanobacillus, and Halobacillus.