Taxonomic characterization and antimicrobial activity of actinomycetes associated with foliose lichens from the amazonian ecosystems

Abstract

The study of habitats that have been few explored with purpose of obtaining composts with biotechnological interest that has been produced by the Amazonian's biological diversity it's a strategy that will allow the discovery of important bioactive principles. In microbial biodiversity, the actinomycetes represents the most important bacterial group. They have a filamentous organization that occur in great varieties of substrata and present a great application in pharmaceutical industry. The scope of this work was to analyze taxonomically the actinomycetes associated at lichens and to determine the capability of these bacteria for antibiotic producing. Ten samples of foliose lichens were collected in area of Universidade Federal do Amazonas (UFAM), South Section. For the isolation of actinomycetes were utilized the culture media Yeast Extract-Malt Extract Agar-Starch (ISP-2A), Casein-Starch Agar (CAA), Raffinose-Histidin Agar (RHA) and Water Agar (AA), added with antifungics. Were isolated 71 actinomycetes associated to foliose lichens. The isolated were tested for antimicrobial activity against eight microorganisms-test by the techniques with cultivation in solid medium and broth culture. Among the actinomycetes tested by solid medium 80% shown antimicrobial activity, mainly against Aspergillus niger, Candida albicans and Staphylococcus aureus. In assay by broth cultivation 79% of the actinomycetes inhibited the growth of microorganisms-test, although the higher activities were against Mycobacterium smegmatis and Staphylococcus aureus. The isolated antimicrobial activity varied from moderate (halo=13 at 18 mm) to high (halo=19 at 35 mm) activity. It was observed that 68% of isolated presented high antimicrobial activity. The identification of the actinomycetes was done by the macro and micromorphological determination, physiologic tests and by the determination of aminoacids from the cell wall, and most of them belonging to genus Streptomyces. The microorganisms were preserved by freezing at -20°C and by preservation of actinomycetes colony directly in water (Castellani's method).