Atividade antimicrobiana de fungos endofíticos isolados de plantas de ecossistemas de Ipucas no estado do Tocantins

Abstract

Endop hytes are microo rganisms that live inside plant tissues without causing symp toms o f disease. They are relatively poorly studied as source of new bioactive mo lecules that could be use in medicine, agricultu re and industr y. The pu rpose of this wor k was to screenfaonrt im icrobial activity the endop hytic fungi isolated from plants found in natural forest fragments, ip ucas, in the state of Tocantins, Brazil. Endop hytic fungi were isolated from three plant species, Calophyllum brasiliense, Voch ysia sp. and Sclerolobium sp. The fungalisolates were d eposited at the culture collection of the Laboratório de Eco logia e Biotecnolo gia de Leved uras, Departamento de Microbio logia, Universid ade Federal de Minas Gerais. Tissu e plu gs of the fungi were cultivated on the su rfaces o f agar-solid ified 24-wells in micro titer plates, and the extraction was carried out using methanol. Extr actswere tested for antimicrobial activity b y agar diffusion method against the following microorganisms: Candida albican s ATCC 18804, C. krusei ATCC 2159 , Escherichia coli ATCC 25922 and Staphylococcus aureus ATCC 12600. For Cladosporium sphaero spermum CCT 1740 was used a susp ensio n o f sp ores that was inoculated in a paper filter where the extracts wer e previously applied. Fungal molecular identificatio n was based on internal transcrib ed spacer (ITS) o f nu clear ribosomal DNA. Leaf samples of 2 81 individual p lants were co llected, and a total of 121 endophyte fu ngi were isolated from these plants. A total o f 436 extracts were produ ced from which 42 (9.06%) presented antimicrobial activity for one or more microorganisms tested. These extracts correspondedto 33 d istinct fu ngal isolates, representing 27.27% o f the total isolated microorganisms. Amongst the active extracts, 19 (45%) were able to inhib ited C. sphaerophorum, 11 (26%) C. albicans, 10 (24%) C. krusei and o nly two (5%) extracts were active fo r S. aureus. None of the extr acts was capab le to inhibit E. coli. Six iso lates were id entif ied b yIsTeqSu e ncing. The species fo unded were Giberella fugikuroi, Curvularia aff. sp., C. eragro stides, Pseudallescheria boydii e Pseudocercospora aff luzardii. The analysis of the results obtained in our work indicates that some endophytic fungi from the three plantsoccurring in ipu cas could rep resent a potential source of bio active compounds with antimicrobial activity.