Análise filogenética de bactérias rizosféricas de duas espécies frutíferas da amazônia central pela construção de biblioteca genômica 16s rrna

Abstract

The microorganisms present great phenotypic and genetic diversity, performing unique and crucial functions in the maintenance of the most varied ecosystem. Due to this complexibility, conventional methods that use means of selective culture are limited, since only a small fraction of the microorganisms can be cultivated. Molecular techniques are being applied, successfully, to maximize the characterization of microbial communities. Considering the scarcity of studies related to the bacterial diversity of soils in central Amazon, the present study had the objective of estimating and comparing the bacterial community in rhizospheric soil of two fruit species of great regional importance, the cupuaçu (CUP) and the camu-camu (CAM), cultivated in two different types of soil. Physical and chemical analyses of the rhizospheric soil were made to determine if there is influence in the composition of the bacterial communities found in the soil. The total genomic DNA of the four extracted rhizospheric soil samples were purified to remove humic acids and other contaminations, in order to use it as a mold in a polymerase chain reaction (PCR) using specific primers of the 16S rRna gene to the bacteria domain. The amplicons were cloned in a vector TOPO TA and 1.536 clones were selected. The sequences were compared in public data banks, such as GenBank and RDP II. When analyzed on the species level, most of the sequences were found to be in the condition of unknown and/or non-cultivated. Comparing the sequences by classes, sixteen classes were found. Given these results, the predominance in all the libraries belonged to the acidbacteria, corresponding to 41, 40 and 50% of the CAM2, CUP1 e CUP 2 constitution, respectively, which suggests that the pH of the Amazon soils exerts selective function in the bacterial communities where it was found.