ANTIBACTERIAL AND ANTIFUNGAL ACTIVITY OF ORGANIC AND PEPTIDIC EXTRACTS OF ECUADORIAN ENDOPHYTIC FUNGI

Antibacterial and antifungal activities of 32 organic and 14 peptidic extracts obtained from twelve endophytic fungi of the Collection of Endophytes Quito-Catolica were tested against the pathogenic bacteria Staphylococcus aureus, Pseudomonas aeruginosa, Serratia marcescens, Escherichia coli and Salmonella enteritidis, and against the fungal oomycete Pythium ultimum. It was observed that the extracts of Marasmiellus candidus (CEQCA-O1113), Xylaria laevis (CEQCA-O1399), Fusarium solani (CEQCA-O1393), Diaporthe helianthi (CEQCA-O1394) and Xylaria sp. (CEQCA-O1400) partially or totally inhibited the microorganisms tested. The extracts CEQCA-O1399.P1 and CEQCA-O1113.D1 showed fungistatic and fungicidal effects against P. ultimum, respectively. Six extracts strongly inhibited S. aureus, and E. coli was strongly inhibited by the extract CEQCA-O1113.E2. Based on a bioassay-guided approach, the extracts with strong bioactivity in the antibacterial assays by an agar diffusion method were also tested by a disk diffusion method, and the minimal inhibitory concentrations were determined by a microdilution assay. The most bioactive extract, CEQCA-O1113.D1, was also purified by high performance liquid chromatography. The extract recovered its initial bioactivity against S. aureus in two fractions after the purification. Overall, the results of this study highlight the potential of the fungal endophytes as producers of bioactive compounds.