Antifungal activity of secondary metabolites produced by Bacillus pumilus MAIIIM4a, an endophytic from cassava. / Atividade antifúngica de metabólitos secundários produzidos pelo endófito de mandioca Bacillus pumilus MAIIIM4a.

AUTOR(ES)
DATA DE PUBLICAÇÃO

2005

RESUMO

Endophytic microorganisms are defined as organisms that inhabit the interior of a vegetable at least during a period of the vital cycle, without causing any apparent damage. In the search for new organisms and new secondary metabolites, a study was conducted to evaluate the chemical diversity of endophytic bacteria through the isolation and identification of secondary metabolites produced by endophytic bacteria of cassava cultivated by Brazilian Amazon Indian tribes. Sixty seven endophytic bacteria isolated from cassava were screened using in vitro antagonisms tests. An endophytic bacterium, the Bacillus pumilus, which showed a strong inhibitory activity against Rhizoctonia solani, Pythium aphanidermatum and Sclerotium rolfsii was selected. This bacterium was identified by sequencing of 16S rRNA genes and by FAME. The bacterial endophytic localization was confirmed by cassava cell tissue examination using scanning electron microscopy. The bacterial metabolites were extracted from the culture media using the solvents hexan, ethyl acetate and dichloromethane. After concentrate the extracts their chemical constituents were analyzed using thin layer chromatography (TLC), chromatography column, gas chromatography coupled with mass spectrometry (GC/MS) and liquid chromatography coupled with mass spectrometry (LC/MS). The extracts obtained with dichloromethane and ethyl acetate contained different chemical compounds that showed inhibitory activity against the three plant-pathogenic fungi tested. The LC/MS method allowed the identification of an antifungal compound produced by the B. pumilus, which is known as pumilacidin.

ASSUNTO(S)

microbiology mandioca microscopia eletronônica de varredura antifungal bactéria endofítica fungo fitopatogênico scanning electron microscope controle biológico (fitossanidade) phytopathogenic fungi cassava endophitic bacterium antifúngico microbiologia biological control (phytosanity)

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