Bioprospecting of Actinobacteria in Rhizosphere of Amazonic Soils and Evaluation of Biotechnological Potential for the Production of Antimicrobials - Igarapé-Açu, Pará, Brazil

Abstract

Actinobacteria are important components of the microbial population in most soils and are widely distributed and abundant, especially in the rhizosphere. The phylum Actinobacteria, particularly the genus Streptomyces, is recognized for its potential to produce a vast quantity of secondary metabolites, among which there are bioactive compounds used as antibiotics. The present study sought to isolate and identify actinobacteria from secondary forest rhizosphere in the region of Igarapé-Açu and to evaluate the biotechnological potential of these strains for the production of antimicrobials. Thirty rhizospheric soil samples were collected, pre-treated and seeded on Czapeck Dox and Saboraud Dextrose Agar. The methodology applied consisted of phenotypic analysis, morphological (macroscopic and microscopic) and biochemical characterization. In addition, the isolated strains were submitted to antimicrobial potential evaluation tests in order to verify if they were effective in inhibiting the growth of the multi-resistant pathogenic bacteria Escherichia coli and Klebsiella pneumoniae. We identified 18 strains of actinobacteria with the following presumptive genera: Streptomyces, Nocardia and Actinoplanes. Among the 18 strains, 10 were able to form at least a halo of inhibition against one of the pathogenic bacteria.