Vol.:(0123456789) 1 3 World J Microbiol Biotechnol (2017) 33:46 DOI 10.1007/s11274-017-2216-7 ORIGINAL PAPER Antimicrobial activity of endophytic fungi from olive tree leaves Cynthia Malhadas 1  · Ricardo Malheiro 1  · José Alberto Pereira 1  · Paula Guedes de Pinho 2  · Paula Baptista 1   Received: 4 December 2016 / Accepted: 18 January 2017 © Springer Science+Business Media Dordrecht 2017 species. In the next step, various organic extracts from both A. alternata mycelium and cultured broth were pre- pared; being ethyl acetate extracts displayed the widest spectrum of anti-microorganisms at a minimum inhibitory concentration ≤0.095 mg/mL. The volatile composition of the fungi that displayed the highest (A. alternata) and the lowest (P. canescens) antimicrobial activity against yeasts revealed the presence of six volatiles, being the most abun- dant components (3-methyl-1-butanol and phenylethyl alcohol) ascribed with antimicrobial potentialities. Overall the results highlighted for the first time the antimicrobial potential of endophytic fungi from O. europaea and the possibility to be exploited for their antimicrobial agents. Abstract In this study, the antimicrobial potential of three fungal endophytes from leaves of Olea europaea L. was evaluated and the host plant extract effect in the anti- microbial activity was examined. The volatile compounds produced by endophytes were identified by GC/MS and further correlated with the antimicrobial activity. In potato dextrose agar, both Penicillium commune and Penicillium canescens were the most effective inhibiting Gram-positive and -negative bacteria (up to 2.7-fold compared to 30 µg/ mL chloramphenicol), whereas Alternaria alternata was most effective inhibiting yeasts (up to 8.0-fold compared to 25 μg/mL fluconazole). The presence of aqueous leaf extract in culture medium showed to induce or repress the antimicrobial activity, depending on the endophytic Electronic supplementary material The online version of this article (doi:10.1007/s11274-017-2216-7) contains supplementary material, which is available to authorized users. * Paula Baptista pbaptista@ipb.pt 1 REQUIMTE-LAQV, School of Agriculture, Polytechnic Institute of Bragança, Campus de Santa Apolónia, 5300-253 Bragança, Portugal 2 REQUIMTE/Laboratory of Toxicology, Faculty of Pharmacy, Porto University, Rua Jorge Viterbo Ferreira 228, 4050-313 Porto, Portugal