Diversidade genética, antagonismo microbiano e produção de fitases por bactérias endofíticas de folhas de feijoeiro comum (Phaseolus vulgaris)

• Ano de defesa: 2010
• Autor(a) principal: Costa, Leonardo Emanuel de Oliveira
• Orientador(a): Queiroz, Marisa Vieira de
• Banca de defesa: Nascimento, Antonio Galvão do , Tótola, Marcos Rogério , Mantovani, Hilário Cuquetto , Azevedo, João Lúcio de
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Viçosa
• Programa de Pós-Graduação: Doutorado em Microbiologia Agrícola
• Departamento: Associações micorrízicas; Bactérias láticas e probióticos; Biologia molecular de fungos de interesse
• País: BR
• Palavras-chave em Português: Bactérias endofíticas; Feijoeiro; Fitase; Diversidade genética; rDNA 16S
• Palavras-chave em Inglês: Endophytic bacteria; Bean; Phytase; Genetic diversity; 16S rDNA
• Área do conhecimento CNPq: CNPQ::CIENCIAS AGRARIAS::AGRONOMIA::FITOSSANIDADE::MICROBIOLOGIA AGRICOLA
• Link de acesso: http://locus.ufv.br/handle/123456789/1549

Common beans are one of the most important legume for human diet and little is known about the endophytic bacteria associated with their leaves. The objective of this work were: (i) characterize the cultivable endophytic bacteria from leaves of common bean (Phaseolus vulgaris) from three different cultivars (Vermelhinho, Talismã and Ouro Negro) growning in the same field conditions in Brazil, (ii) evaluate the production of siderophores and lytic enzymes (pectinase, cellulase and protease) of these isolates, as well as, the potential for antagonism against the phytopathogenic fungi Colletotrichum lindemuthianum, Rhizoctonia solani and Fusarium oxysporum, causal agent of anthracnose, root rot and fusarium wilt-of-bean, respectively, (iii) evaluate the ability of isolates to produce phytases and characterize these enzymes. Of the 158 isolates obtained 36.7%, 32.9%, 29.7% and 0.6% respectively belong to the phyla Proteobacteria, Firmicutes, Actinobacteria and Bacteroidetes. Based on 16S rDNA sequences, 23 different genera were obtained. The three cultivars P. vulgaris cultivars showed differences in the diversity of the classes Actinobacteria, Alphaproteobacteria and Bacilli, and the isolates from the cultivar Talismã were less diversity than isolates from other cultivars. Thus, the present results indicated that the cultivar of the plant contributes to the endophytic community structure associated with the common bean. Among the 158 isolates analyzed, 20 microorganisms produce cellulase, 8 produce pectinase and 96 secreted proteases. Additionaly, 49 isolates showed some degree of antagonism against at least one of the fungi tested, among these, two isolates of genus Pseudomonas and four isolates of the genus Stenotrophomonas showed promising results against the fungi analyzed. Sixteen isolates produced siderophores and this is the first report of siderophore production by a strain of the species Agromyces mediolanus. Amongall the isolates 45 produce phytase and four were selected for characterization of phytase activity. The phytases of the four isolates showed phosphatase activity with other substrates such as ATP, ADP, pyrophosphate and β-glycerophosphate, but its highest activity occurs in the presence of phytate. Another unusual feature of the phytases examined is the presence of other peaks of activity beyond the optimum pH of activity. This is the first report of phytase production by bacteria of the genus Rhodococcus and Microbacterium. The genera Bacillus, Delftia, Paenibacillus, Methylobacterium, Microbacterium, Staphylococcus and Stenotrophomonas are presentin all three cultivars, demonstrating the adaptation of these genera to different cultivars. The study of endophytic microorganisms of common bean is promising for obtaining bacteria with potential for Biol. Contr. of plant pathogens and for obtaining bacteria that produce phytase.