RESUMO
Soil microbial communities are an important component of biological diversity and terrestrial ecosystems which is responsible for processes such as decomposition, mineralization of nutrients, and accumulation of organic matter. One of the factors that provide information on the mechanisms regulating biodiversity is spatial scaling. We characterized the microbial communities using 16S rRNA gene sequences from DNA isolated from halite at various locations and correlated these to geographic distance in the Uyuni salt flat (Bolivia). Sequences from each site were analyzed to determine any spatial patterns of diversity, as well as to describe the microbial communities. Results suggest that different taxa are able to disperse over Uyuni's surface crust regardless of distance. As expected, ubiquitous taxa included members of Halobacteriaceae such as Haloarcula, Halorubrum, Halorhabdus, Halolamina, and halophilic bacteria Salinibacter, Halorhodospira, and unclassified members of the Gammaproteobacteria. Archaeal communities were homogeneous across the salt flat. In contrast, bacterial communities present strong local variations which could be attributed to external factors. Likely sources for these variations are the Rio Grande river influent in the south shore and the Tunupa volcano influencing the northern area
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Assuntos
Microbiologia do Solo , Bactérias/classificação , Biota , Archaea/classificação , RNA Ribossômico 16S/genética , Bolívia , Bactérias/genética , Archaea/genética , Análise por Conglomerados , DNA Bacteriano/química , DNA Bacteriano/genética , DNA Ribossômico/química , DNA Ribossômico/genética , DNA Arqueal/química , DNA Arqueal/genética , Metagenômica , FilogeniaRESUMO
The composition of the microbial community inhabiting the anoxic coastal sediments of the Bay of Cádiz (southern Spain) was investigated using a molecular approach consisting of PCR cloning and denaturing gradient gel electrophoresis (DGGE), based on 16S rRNA sequences. The total cell count was 1-5 × 10⁸ cells/g sediment and, as determined by catalyzed reporter deposition-fluorescent in situ hybridization (CARD-FISH), the proportion of Bacteria to Archaea was about 70:30. The analysis of 16S-rRNA gene sequences revealed a wide spectrum of microorganisms, which could be grouped into 111 operational taxonomic units (OTUs). Many of the OTUs showed high phylogenetic similarity to microorganisms living in marine sediments of diverse geographic origin. The phylogenetic groups that were predominantly detected were Firmicutes, Deltaproteobacteria, and Gammaproteobacteria, accounting for 23, 15, and 14% of the clones, respectively. Diversity in the domain Archaea was significantly lower than in the domain Bacteria. The majority of the archaeal OTUs belonged to the Crenarchaeota phylum. Since most of the sequences could not be identified precisely at the genus/species level, the functional roles of the microorganisms in the ecosystem could not be inferred. However, seven OTUs affiliated with the Delta- and Epsilonproteobacteria were identified down to the genus level, with all of the identified genera known to occur in sulfate-rich marine environments (AU)
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Assuntos
Sedimentos Geológicos/microbiologia , Células Procarióticas/microbiologia , Proteobactérias/isolamento & purificação , Biblioteca Gênica , DNA Bacteriano/análise , DNA Arqueal/análise , Células Clonais/classificaçãoRESUMO
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