Diversity of aerobic and facultative alkalitolerant and halotolerant endospore formers in soil from the Alvord Basin, Oregon.

Abstract: Many proteins produced by Bacillus species isolated from extreme environments have been utilized for industrial purposes, as these extreme environments often promote evolution of unique protein properties. The Borax Lake area is unusual due to its geothermal activity, elevated pH, and high arsenic and salt concentrations in its soils. Soils from this region are likely to harbor alkalitolerant, halotolerant, endospore-forming strains that may be of potential ecological and/or commercial interest. The objectives of this study were to develop new PCR primers that could target Bacillus or closely related 16S rRNA genes, to characterize the diversity of alkalitolerant, halotolerant, endospore-forming organisms in the soils surrounding Borax Lake, and to identify novel organisms that may ultimately provide new enzymes for applied use. A three-pronged approach was used to identify such bacteria in soil samples. Organisms were isolated using two different techniques. Finally, metagenomic DNA from soil samples was subjected to 16S rRNA gene amplification using the newly designed primers. Assays were performed to characterize the halotolerance and alkalitolerance of isolates. Four different endospore-forming genera and 22 different species were identified by sequencing their 16S rRNA genes. Twenty-five organisms had 96% or less identity to known organisms. Thus, the newly designed Bacillus-related PCR primer sets proved useful for the detection of new species of endospore-forming bacteria in these unique soils. Results indicate that the collection of strains obtained from the Borax Lake region represents a rich source of alkalitolerant, halotolerant, endospore formers. [Copyright &y& Elsevier]