Antimicrobial activity of endophytic fungi associated with Orchidaceae in Brazil

Abstract

The purpose of this study was to examine antimicrobial activity of endophytic fungi isolated from the leaves, stems, and roots of 54 species of Orchidaceae collected in a Brazilian tropical ecosystem. In total, 382 filamentous fungi and 13 yeast isolates were obtained and cultured to examine the production of crude extracts. Thirty-three percent of the isolates displayed antimicrobial activity against at least one target microorganism. The multivariate statistical analyses conducted indicate that the extracts of endophytic fungi isolated from leaves of terrestrial orchids in semideciduous forest were more active against Escherichia coli, whereas extracts of endophytic fungi from roots of rupicolous orchids collected in rock fields were more active against Candida krusei and Candida albicans. Among the fungi that were screened in the study, 22 isolates held their antimicrobial activities after replication and were therefore selected for assessment of the minimum inhibitory concentration (MIC), which ranged from 62.5 to 250 microg/mL and 7.8 to 250 microg/mL against bacteria and fungi, respectively. One isolate of Alternaria sp. and one isolate of Fusarium oxysporum presented the strongest antibacterial activity. Three Fusarium isolates, Epicoccum nigrum, and Sclerostagonospora opuntiae showed the greatest MIC values against the pathogenic yeasts. This study is the first survey investigating the bioactive potential of endophytic fungi associated with tropical Orchidaceae species present in Brazilian ecosystems.

Diversity and Biological Activities of Endophytic Fungi Associated with Micropropagated Medicinal Plant <i>Echinacea purpurea</i> (L.) Moench

“…The genus Colletotrichum includes several morphologically similar taxa and can be found as phytopathogenic, saprophytic, and endophytic species [22]. Similar findings have been reported for the species of the genus Fusarium, which was reported as endophytes symbionts associated with orchids [23] and angiosperms [5]. An interesting isolate found in E. purpurea was the phylotype M. indicus, a tropical to subtropical species, which generally cause necrosis on leaves of many monocotyledonous plants [24].…”

“…The phylotyes F. oxysporum UM16 and UM78 showed phylogenetic similarities to two other strains of F. oxysporum (FJ605243, FJ605244), recovered from orchid species, Epidendrum secundum and Acianthera teres. Vaz et al [23] reported that extracts of these F. oxyporum strains had antimicrobial properties against Candida species.…”

The diversity, extracellular enzymatic activities and photoprotective compounds of yeasts isolated in Antarctica

“…ITS-amplification and sequencing protocols were performed as described by Vaz et al. (39). The amplified DNA was concentrated and cleaned using Wizard Plus SV columns (Promega, USA), and sequenced in a MegaBACE TM 1000 automated sequencing system (GE Healthcare, USA).…”

Antimicrobial activity of metabolites extracted from Zanthoxylum gilletii, Markhamia lutea and their endophytic fungi against common bean bacterial pathogens

“…Different species of the isolated fungal endophytes displayed varied activity against the test organisms. As noted by Gong and Guo (2009) and Vaz et al (2009), different Fusarium species exhibited different rates of activity. This trend was also seen in the activity of the isolated Fusarium species in this study.…”