Utilização de DNA metagenômico para caracterização e bioprospecção de comunidades microbianas de solo de cerrado

AUTOR(ES)
DATA DE PUBLICAÇÃO

2008

RESUMO

Cerrado is an important and not very well studied biome found in Brazil. In the last two decades, this area has been rapidly converted to pastures and agricultural fields. Soil fungal microbial communities play a key role in the soil ecosystem. In the case of Cerrado stricto sensu, they are being lost before they are studied. As only a small fraction of the fungal population present in the soil can be cultured in vitro, a molecular approach was chosen to characterize the soil fungal communities present in four different areas of the Cerrado biome: a native Cerrado stricto sensu, a former stricto sensu area converted to a soybean plantation, a riverbank forest and a former stricto sensu area converted to pasture. Firstly the technique Ribosomal RNA intergenic spacer analysis (RISA) revealed remarkable differences in the fungal communities studied. DNA bands unique to each area were identified. Using specific primers that hybridize to conserved regions of fungal DNA that flank variable regions, polymerase chain reaction was performed to amplify 18S rDNA from soil DNA. The PCR products obtained were cloned to construct four 18S rDNA libraries, one for each area studied. To assess the fungal diversity in these areas and allow comparisons among the areas, sequencing of approximately 200 clones from each library was performed. Our results show that anthropic activity is reducing diversity in Cerrado areas. In silico analysis using the computer program DOTUR and ∫-Libshuff estimate the diversity and coverage of each library and the program assessed differences between libraries. DOTUR analysis showed that there are approximately 75, 85, 85 and 75 OTUs to cerrado, pasture, riverbank forest and soybean plantation. Comparison between the four rarefaction curves with a similarity cutoff value as low as 1% reveals that the number of OTUs for soybean plantation decreased by 50% and cerrado by 35% demonstrating that microbial community soil cerrado is more diversity than others. The computer program ∫-Libshuff showed significant P-values of <0.0001, demonstrating strong evidence that the four libraries analyzed are significantly different.

ASSUNTO(S)

diversidade biológica cerrados ciências agrárias dna

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