Microflora of extreme arid Atacama Desert soils

Surface and subsurface soil samples from the most arid region within the Atacama Desert, Chile, were analyzed for total organic carbon (TOC), phospholipid fatty acids (PLFA) and culturable bacteria. TOC content was determined to range between 560 and 765 μg/g. PLFA analysis indicated 2.0×106–1.0×107 cell equivalents/g. Culturing of soil extracts on R2A and TSA media yielded 1.6×103–4.6×103 CFU/g, and 200–300 CFU/g heat shock survivors. Twenty isolated strains were identified based on analysis of 16S rRNA gene sequences, and divided into eight phylogenetic groups, including Rhodopseudomonas, Sphingomonas sp., Mesorhizobium sp., Asticcacaulis sp., Bradyrhizobium sp., Bacillus subtilis, Bacillus pumilus, and Burkholderia sp.