Abstract Microbial communities in oil-polluted desert soilshave been rarely studied compared to their counterparts fromfreshwater and marine environments. We investigated bacterialdiversity and changes therein in five desert soils exposedto different levels of oil pollution. Automated rRNAintergenic spacer (ARISA) analysis profiles showed that thebacterial communities of the five soils were profoundly different(analysis of similarities (ANOSIM), R=0.45,P<0.0001) and shared less than 20 % of their operationaltaxonomic units (OTUs). OTU richness was relatively higherin the soils with the higher oil pollution levels. Multivariateanalyses of ARISA profiles revealed that the microbial communitiesin the S soil, which contains the highest level ofcontamination, were different from the other soils and formeda completely separate cluster. A total of 16,657 ribosomalsequences were obtained, with 42–89 % of these sequencesbelonging to the phylum Proteobacteria. While sequencesbelonging to Betaproteobacteria, Gammaproteobacteria,Bacilli, and Actinobacteria were encountered in all soils,sequences belonging to anaerobic bacteria from the classesDeltaproteobacteria, Clostridia, and Anaerolineae were onlydetected in the S soil. Sequences belonging to the genusTerriglobus of the class Acidobacteria were only detected inthe B3 soil with the lowest level of contamination. Redundancyanalysis (RDA) showed that oil contamination level wasthe most determinant factor that explained variations in themicrobial communities. We conclude that the exposure todifferent levels of oil contamination exerts a strong selectivepressure on bacterial communities and that desert soils are richin aerobic and anaerobic bacteria that could potentially contributeto the degradation of hydrocarbons.
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