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

Abstract

Introduction:In this study, we evaluated the antimicrobial potential of cultivable endophytic fungi associated withHancornia speciosaGomes stem bark.Methods and Materials: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 werePhoma cava(13.8%),Colletotrichum gloeosporioides(12.1%), andLasiodiplodia 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.Results:The best antimicrobial results (MIC < 100 µg/mL) were observed for fungi strains grown in rice medium:Aspergillus nigerFHS061 againstProteus mirabilis(MIC = 19 µg/mL) andStaphylococcus aureus(MIC = 39 µg/mL). These strains also showed good results when cultivated in corn medium againstP. mirabilis(MIC = 78 µg/mL).Conclusion:Thus, the stem bark ofH. speciosaharbors diverse endophytic fungi with antimicrobial potential.