Antimicrobial Activity of Cultivable Endophytic Fungi Associated with Hancornia Speciosa Gomes Bark

In this study, we evaluated the antimicrobial potential of cultivable endophytic fungi associated with Hancornia speciosa Gomes stem bark.

Plant samples were collected in rainy (July 2010) and dry (January 2011) seasons. In total, 116 endophytic fungi strains were isolated from 90 fragments (64.4% frequency of colonization). Higher fungi frequency was observed in the rainy season (84.4%). The strains were grouped into 14 species; the most frequent were Phoma cava (13.8%), Colletotrichum gloeosporioides (12.1%), and Lasiodiplodia theobromae (11.2%). Fungal diversity was similar in both the seasons. Among the 116 strains, 39 (33.6%) showed antimicrobial activity in preliminary screening. The ten most active isolates were subjected to semi-solid fermentation using rice or corn as substrates. Methanolic extracts were obtained from each fermentation medium and the minimum inhibitory (MIC) and minimum microbicide concentrations (MMC) were determined.

The best antimicrobial results (MIC < 100 µg/mL) were observed for fungi strains grown in rice medium: Aspergillus niger FHS061 against Proteus mirabilis (MIC = 19 µg/mL) and Staphylococcus aureus (MIC = 39 µg/mL). These strains also showed good results when cultivated in corn medium against P. mirabilis (MIC = 78 µg/mL).

Thus, the stem bark of H. speciosa harbors diverse endophytic fungi with antimicrobial potential.