2. Catholic University of Brasília, Graduate Program in Genomic Sciences and Biotechnology, SGAN 915, Brasília - DF, 70790-160, Brazil.
Cultivation and molecular approaches were combined to recover and detect Acidobacteria from Amazon soils on culture medium. The strategy of the cultivation procedure included the following: the use of VL55 growth medium supplemented with 0.05% xylan as the carbon source and solidified with gellan gum; incubation under hypoxic conditions (2% O2 [vol/vol], 2% CO2 [vol/vol], and 96% N2 [vol/vol]) for a relatively long period; inclusion of aluminium potassium sulphate in the growth medium; and soil dilution and plating. Of the 456 colonies recovered on the growth medium and subjected to PCR screening, three colonies belonging to Acidobacteria subdivision 1 and one colony belonging to Acidobacteria subdivision 3 were detected. The use of 16S rRNA gene based clone libraries comprising 437 clones confirmed that members of the phylum Acidobacteria grew primarily on plates on wich acidobacterial colonies were detected by PCR screening. The clones in the libraries consisted predominantly of Proteobacteria (orders Burkholderiales and Xanthomonadales). In summary, this work reports the recovery and molecular detection on VL55 growth medium of representatives of Acidobacteria subdivisions 1 and 3 concomitantly with to other bacterial groups inhabiting pasture and soybean cropland soils from the Amazon region.
Keywords: Soil microbiology, tropical rainforest soils, molecular PCR screening, Acidobacteria subdivisions 1 and 3