Diversidade taxonômica e produção de antimicrobianos produzidos por fungos isolados de amostras de água de um igarapé poluído da cidade de Manaus - Amazonas

Abstract

Escherichia coli is a Gram-negative bacillus that can cause serious infections such as urinary tract or systemic infections. The inappropriate use of antibiotics has given some strains adaptations that have given resistance genes to most conventional antibiotics. Recently, polluted aquatic environments have been investigated in the search for microorganisms with antimicrobial potential. This approach is justified by the hypothesis that polluted environments cause biological pressure that can result in fungi that produce secondary but potent metabolites with antimicrobial functions. The aim of this study was to investigate the diversity and production of antimicrobials by fungi in a polluted stream in the city of Manaus/Amazonas. Thus, water samples were collected at three points on the Mindú creek (Manaus-AM) divided into headwater, central point and estuary. Based on the isolation, antimicrobial-producing fungi were selected, which were later identified through micromorphological and macromorphological aspects and ITS DNA sequencing. In order to select the best antimicrobial producers, the fungi were developed in liquid medium and then extracts were obtained using the solvents hexane and ethyl acetate, which were evaluated for inhibition of the growth of E. coli ATCC 25922 and E. coli ESBL producer in agar diffusion assay. The extracts of the best isolates were evaluated for their minimum inhibitory concentration (MIC) and subjected to chromatographic and spectrometric methods for the chemical determination of substances with antibacterial activity. In total, five fungi Annulohypoxylon stygium (ID WL1B5), Colletotrichum fructicola (ID WL3B9), Clonostachys rosea (ID WL5B18), Clonostachys rosea (ID WL8B28) and Trichoderma harzianum (ID WL9B49) showed bioactive potential against the tested bacteria. The isolated Annulohypoxylon stygium (ID WL1B5) obtained the best antimicrobial activity results. From the chemical characterization analyses, it is inferred that the substance 3,4,5-trihydroxy-1-tetralone can be associated with antimicrobial activity.