Biological activities of the fermentation extract of the endophytic fungus Alternaria alternata isolated from Coffea arabica L.

Abstract

A total of 22 endophytic fungi isolated from coffee (Coffea arabica L.) were cultivated in vitro and their crude extracts tested. The screening was carried out using the agar diffusion method against Staphylococcus aureus, Escherichia coli and Candida albicans. The most effective isolate was Alternaria alternata, and subsequently, its extract was assayed. The total phenolic content was 3.44 μg GAE/mg of the crude extract. For the antibacterial and antifungal activity assays, minimum inhibitory concentrations (MIC) and minimum bactericidal and fungicidal concentrations (MBC and MFC) were determined. The ranges of MIC values were 50-100 μg/mL for S. aureus and 400-800 μg/mL for E. coli. The extract did not show activity in the tested concentrations for C. albicans. The fungal crude extract was assayed for antioxidant activities. Its ability to scavenge DPPH radicals and antioxidant activity by β-carotene/ linoleic acid system oxidation was not significant. In addition, antitumor activity was studied using the MTT assay. At a dilution of 400 μg/mL, the extract displayed a cytotoxic activity of approximately 50% towards HeLa cells in vitro. The results indicate that endophytic fungi could be a promising source of bioactive compounds and warrant further study.Uniterms: Endophytic fungi. Bioactive compounds. Alternaria alternata/extract/antioxidant activity.Total de 22 fungos endofíticos isolados de café (Coffea arabica L.) foi cultivado in vitro e seus extratos testados. A triagem foi conduzida pelo método de difusão em agar contra bactérias Gram-positiva, Gram-negativa e uma levedura. O isolado mais efetivo foi Alternaria alternata e, subsequentemente, seu extrato foi analisado. O conteúdo de fenólicos totais do extrato bruto foi de 3,44 μg EAG/mg de extrato. Para os testes de atividade antimicrobiana, a concentração inibitória mínima (CIM) e concentração bactericida e fungicida mínima (CBM e CFM) contra Staphylococcus aureus, Escherichia coli e Candida albicans foram determinadas. Resultados da CIM variaram entre 50-100 μg/mL para S. aureus e 400-800 μg/mL para E. coli. O extrato bruto não apresentou atividade nas concentrações testadas para C. albicans. Foram analisadas as atividades antioxidantes do extrato bruto. Sua habilidade para seqüestrar radicais DPPH e a atividade antioxidante pela oxidação do sistema β-caroteno/ácido linoléico não foram significativas. Além disso, a atividade antitumoral foi estudada pelo teste do MTT. À diluição de 400 μg/mL, o extrato apresentou atividade de aproximadamente 50% sobre as células HeLa in vitro. Os resultados indicam que fungos endófitos poderiam ser uma fonte promissora de compostos bioativos necessitando de estudos futuros.Unitermos: Fungos endofíticos. Compostos bioativos. Alternaria alternata/extrato/atividade antioxidante.

Antimicrobial activity of endophytic fungi from olive tree leaves

“…We also found that ethyl acetate extracts of A. alternata mycelium and culture broth were more active against yeast (MIC ≤ 0.095 mg/mL) than against bacteria (MIC ranging from 0.095 to 25 mg/mL). Most of our MIC values were in range or slightly lower than those reported by Fernandes et al (2009) and by Ramesha et al (2013) for ethyl acetate extract of A. alternata against S. aureus, B. cereus, E. coli and P. aeruginosa (MIC = 0.02 mg/mL). Some of the antimicrobial compounds produce by fungi belonging to the genus Alternaria have been already identified.…”

“…This endophyte may also have potential utility as antibacterial agent due to its capacity to inhibit significantly the bacteria B. cereus, B. subtilis, S. aureus and P. aeruginosa. Extracts of A. alternata inhabiting coffee plants (Fernandes et al 2009), silver trumpet tree (Sadananda et al 2011) and sweet wormwood (Qadri et al 2013) have been previously found to displayed antimicrobial activity against an array of bacteria and yeasts, including C. albicans (Qadri et al 2013). The various organic extracts from both A. alternata mycelium and cultured broth were also found to displayed different antimicrobial effects.…”

Endophytic Fungi from Cathranthus roseus: A Potential Resource for the Discovery of Antimicrobial Polyketides

“…have previously shown antimicrobial activities against Gram positive and Gram negative bacteria, as well as fungi [38,52]. It is not known if the bioactivity from our endophytes is due to the compounds previously reported.…”

“…The regular occurrence of the Alternaria genera within C. roseus indicates that certain strains belonging to this genus may exhibit host specificity towards C. roseus. Additionally, Alternaria strains may have been selectively targeted due to their established production of antimicrobial compounds [38]. The other fungal genera represented in the endophyte community included Botryosphaeria sp.…”

Immobilization of Lipases Produced by the Endophytic Fungus Cercospora kikuchii on Chitosan Microparticles

“…Endophytic fungi have also drawn attention as potential producers of many products, including industrially interesting enzymes. Endophytic fungi exhibit a complex web of interactions with the host plants and have been extensively studied over the last several years as prolific sources of new bioactive natural products, including new enzymes with interesting properties for industrial application (Verza et al 2009;Borges et al 2009;Fernandes et al 2009). However, very few endophytic fungi have been reported as producers of lipase.…”