Atividade antimicrobiana de basidiomicetos ocorrentes na Amazônia.

Abstract

The increase in microbial resistance to available antibiotics and the continuous decrease observed in the number of the new antimicrobial agents approved by Food and Drug Administration creates a constant search for new compounds. To do so, one of the strategies to be followed consists in exploring understudied natural sources, as often organisms obtained new ecosystems are associated with new chemical diversity. In this context are the basidiomycetes, which have been reported as promising sources of antimicrobial and, despite this potential and great biological diversity, the species found in the Amazon have been insufficiently studied. The objective of this study was to evaluate the antimicrobial activity of eight basidiomycetes isolated from Manaus and Boa Vista. The fungi were grown in two liquid media (malt and GLP) and malt-agar medium, in the latter case were held in two incubation conditions: absence and presence of light. The fungi were maintained at room temperature in all treatments. The tests used the filtered liquid from the growth medium for seven to 63 days, besides extracts with ethyl acetate from growing on solid media (ten days). The pathogens tested were Escherichia coli CBAM 001, Staphylococcus aureus CBAM 324, Candida albicans CFAM 1342, Aspergillus niger CFAM 161 and Penicillium sp. CFAM 059, by agar diffusion method. The filtered with positive activity, were submitted to microdilution test for identification of minimum inhibitory concentration. Molecular identification was performed by amplification and sequencing of the rDNA fragment, with subsequent comparison of the sequences obtained with those deposited in the National Center for Biotechnology Information database. Of filtered tested, seven inhibited the growth of C. albicans CFAM 1342, all of Oudemansiella canarii 1528 cultivation, as medium malt, as in GLP. At medium malt, this basidiomycete produced antifungal compounds at seven and 49 days of cultivation, while in the medium GLP produced from the 21 days of cultivation, until the 49th day. The minimum inhibitory concentration was found for the filtrate obtained after 28 days of GLP cultivation medium (2.5 mg/ml) and the filtrate obtained after 49 days malt medium (5 mg/ml). The extracts obtained with ethyl acetate inhibited C. albicans CFAM 1342, Penicillium sp. CFAM 059, E. coli CBAM 001 and S. aureus CBAM 324. This method was found more satisfactory results, as well as Oudemansiella canarii 1528, six other basidiomycetes (Basidiomycete 347, Pleurotus sp. 474, Gloeophyllum sp. 1153, Trametes sp. 1232, Trametes sp. 1540 e Earliella scabrosa 1552) showed antimicrobial activity. Thus, the results allow to observe the influence of culture conditions for the production of antimicrobial compounds, as well as choice of solvents, further studies are needed to determine the optimum conditions for production and extraction thereof.