Antimicrobial activity of extracts and fractions from culture in vitro of Lentinula edodes against Xanthomonas axonopodis pv passiflorae, Guignardia citricarpa, Colletotrichum sublineolum and Tobacco mosaic virus / Atividade antimicrobiana de extratos e frações do cultivo in vitro de Lentinula edodes contra Xanthomonas axonopodis pv passiflorae, Guignardia citricarpa, Colletotrichum sublineolum e Tobacco mo

AUTOR(ES)
DATA DE PUBLICAÇÃO

2008

RESUMO

Edible mushrooms contain functional compounds, such as proteins and glucans, which exhibit antimicrobial potential against bacteria, fungi and antiviral activity. The aim of this work was to identify extracts from submerged mycelium of Lentinula edodes with antimicrobial properties against phytopathogens. Two strains of L. edodes were grown in small scale in three different culture media and after 0, 20, 40 and 60 days, the mycelium and the filtrate were extracted with solvents of different polarities. Extracts were bioassayed against Xanthomonas axonopodis pv passiflorae and Guignardia citricarpa to verify the best condition for growth to produce bioactive compounds. After this, L. edodes was grown in large scale in the selected media, GPL (glucose, peptone and yeast extract) and SML (sucrose, malt extract and yeast extract). After 60 days, the mycelium was extracted with ethanol, ethanol 70% and water. The filtrate was extracted through liquid-liquid partition with ethyl acetate. The extracts were bioassayed against G. citricarpa, Colletotrichum sublineolum and Tobacco Mosaic Virus (TMV). The ethanol and ethanol 70% extracts from medium SML were active in vitro against the fungi and it was verified through H1NMR, the possible presence of sugars in these extracts, which were absent in the culture medium. The TMV suspensions were mechanically inoculated in Nicotiana tabacum TNN (local lesion host) grown in greenhouse, through the half-leaf method. Only the mycelium aqueous extract of strain LE 96/17 inhibited the expression of symptoms of local lesions by TMV and the inhibition ratio was around 82% at 0.5 mg/mL. This active extract was purified by Sephadex column, yielding 16 fractions. Active fractions 6/7 and 8/9 reduced infectivity by 95.5 and 79%, respectively. The H1NMR spectra suggested that fractions 6/7 and 8/9 possibly have peptides and aromatic compound. The results of mass spectrometry revealed the possible presence of compounds already described in the literature and exhibiting antimicrobial activity. The experiments showed that the active crude extract did not exhibit viricidal effect and that such extract and its resulting subfraction inhibited the infectivity of TMV and did not induce resistance in tobacco plants.

ASSUNTO(S)

cogumelos comestíveis phytopathogens lentinula edodes agentes antimicrobianos vírus de plantas. mancha bacteriana fitopatógenos antimicrobial activity mancha preta shiitake.

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