Resumo

The adaptation of a method for DNA extraction from the environment, aiming the reduction of cost should not only focus in the quantity and quality of obtained DNA, but should also consider the structure and composition of microbial community that can be evaluated from this sample by DGGE (Denaturing Gradient Gel Electrophoresis). This fingerprint technique that consists of the amplification of a determined gene sequence from a sample of environmental DNA and the separation of amplicons through a chemical denaturing gradient in polyacrilamyde gel, gives an overview of the most abundant members, evidenced by patterns of bands. The objective of this work was to test the efficiency of soil DNA extraction using a hand held mixer (mini-mixer Britania®) to achieve representative DNA from bacteria community of soil. To certify the efficiency of this protocol a comparison was made with the UltraClean® Soil DNA Isolation kit from MOBIO that is largely applied to studies of bacterial community by the DGGE (denaturing gradient gel electrophoresis) technique. Samples of DNA, in triplicate, obtained from soil samples of three areas localized inside the APAEP, São Gonçalo-RJ, were obtained by phenol-chloroform extraction followed by a purification step with cesium chloride and also extracted by commercial kit from MOBIO. The DNA samples were used as template to amplify the 16S rDNA gene using specific primers to α and β-Proteobacteria communities. The products amplified were used for a second amplification using the primers F968GC and R1401. The products from the second amplification were submitted to DGGE. The band profiles obtained from the protocol that used a mini-mixer were intense as those from commercial kit and showed high similarity among the triplicates of each area studied. Although both methods were capable to achieve representative DNA from bacteria community of soil, the band profiles produced by them for the same areas were different. The results indicated that DGGE was a useful tool to compare the two DNA extraction protocols and the methods were complementary to each other aiming the study of bacterial communities of soil.