Fungos isolados da Antártica com atividade antibacteriana a fitopatógenos
Carregando...
Data
2019-02-21
Autores
Ferrarezi, Juliano Henrique [UNESP]
Título da Revista
ISSN da Revista
Título de Volume
Editor
Universidade Estadual Paulista (Unesp)
Resumo
As bactérias fitopatogênicas do gênero Xanthomonas são capazes de atingir diversos cultivares de interesse comercial, causando anualmente perdas severas na produção. Um exemplo deste gênero é a Xanthomonas citri subsp. citri, causadora do cancro cítrico em diversas espécies de citros. O controle desta doença atualmente conta com o uso de quebraventos, erradicação de plantas contaminadas e desinfecção de equipamentos, embora o modo mais eficiente seja o uso de produtos químicos a base de cobre. Outra bactéria pertencente ao mesmo gênero é a X. albilineans, causadora da escaldadura-das-folhas na cana-de-açúcar. O controle dessa doença ainda é pouco efetivo, sendo aconselhada a desinfecção de equipamentos e mudas. Pensando no problema fitossanitário relacionado a essas bactérias e nos efeitos negativos associados aos produtos químicos à base de metais pesados, torna-se indispensável a busca por compostos naturais capazes de controlar estas doenças e que possam ser menos nocivos ao ambiente. Neste contexto, micro-organismos de ambientes extremos podem produzir metabólitos secundários ainda desconhecidos. Assim, o objetivo deste trabalho foi obter extratos brutos de fungos filamentosos isolados do solo antártico e avaliar seu potencial de bioatividade contra X. citri e X. albilineans através de ensaios de viabilidade celular. Foram testados 122 extratos contra ambas as bactérias. Nove destes extratos inibiram de forma satisfatória (>90%) o crescimento celular de X. citri e dois extratos apresentaram inibição satisfatória para X. albilineans. A partir destes dados foi determinada a concentração mínima de cada extrato para a atividade bactericida e para inibição de 90% das células das culturas. O extrato bioativo de B-FE (Pseudogymnoascus) foi fracionado por cromatografia em coluna normal e HPLC. As frações obtidas foram testadas e embora ainda não tenha sido possível purificar completamente os compostos bioativos, estas frações mostraram resultados promissores. Assim, com este trabalho foi possível verificar que os fungos antárticos podem se tornar uma alternativa viável no controle às bactérias fitopatogênicas do gênero Xanthomonas.
Phytopathogenic bacteria of the genus Xanthomonas able of attain several cultivars of commercial interest, causing yearly severe production losses. An example of bacterium of this genus is Xanthomonas citri subsp. citri, which causes citrus canker in various species of citrus. The control of this disease currently counts on the use of windbreaks, eradication of contaminated plants and disinfection of equipment, although the most efficient way is the use of copper-based chemicals. Another bacterium belonging to the same genus is X. albilineans, which causes leaf scald in sugarcane. The control of this disease is still not very effective, being advised the disinfection of equipment and seedlings. Thinking about the phytosanitary problem related to these bacteria and the negative effects associated with heavy metal chemicals, it is essential to search for natural compounds capable of controlling these diseases and that are less harmful to the environment. In this sense, microorganisms from extreme environments can produce secondary metabolites that are still unknown. Thus, the aim of this work was to obtain crude extracts of filamentous fungi isolated from the Antarctic soil and to evaluate their bioactivity potential against X. citri and X. albilineans through cell viability assays. In total, 122 extracts were tested against both bacteria. Nine of the 122 extracts inhibited satisfactorily (>90%) the cell growth of X. citri and two of the 122 extracts showed satisfactory inhibition against X. albilineans. The minimum bactericidal concentration of each extract was determined, as well the minimum concentration that inhibited 90% of cell growth. The positive extract from B-FE (Pseudogymnoascus) was fractionated by normal column chromatography and HPLC. The fractions obtained were tested and they showed promising results, although the compounds were not completely purified. Thus, we can conclude that Antarctic fungi may become a viable alternative in the fight against phytopathogenic bacteria of the genus Xanthomonas
Phytopathogenic bacteria of the genus Xanthomonas able of attain several cultivars of commercial interest, causing yearly severe production losses. An example of bacterium of this genus is Xanthomonas citri subsp. citri, which causes citrus canker in various species of citrus. The control of this disease currently counts on the use of windbreaks, eradication of contaminated plants and disinfection of equipment, although the most efficient way is the use of copper-based chemicals. Another bacterium belonging to the same genus is X. albilineans, which causes leaf scald in sugarcane. The control of this disease is still not very effective, being advised the disinfection of equipment and seedlings. Thinking about the phytosanitary problem related to these bacteria and the negative effects associated with heavy metal chemicals, it is essential to search for natural compounds capable of controlling these diseases and that are less harmful to the environment. In this sense, microorganisms from extreme environments can produce secondary metabolites that are still unknown. Thus, the aim of this work was to obtain crude extracts of filamentous fungi isolated from the Antarctic soil and to evaluate their bioactivity potential against X. citri and X. albilineans through cell viability assays. In total, 122 extracts were tested against both bacteria. Nine of the 122 extracts inhibited satisfactorily (>90%) the cell growth of X. citri and two of the 122 extracts showed satisfactory inhibition against X. albilineans. The minimum bactericidal concentration of each extract was determined, as well the minimum concentration that inhibited 90% of cell growth. The positive extract from B-FE (Pseudogymnoascus) was fractionated by normal column chromatography and HPLC. The fractions obtained were tested and they showed promising results, although the compounds were not completely purified. Thus, we can conclude that Antarctic fungi may become a viable alternative in the fight against phytopathogenic bacteria of the genus Xanthomonas
Descrição
Palavras-chave
Cancro cítrico, Escaldadura-das-folhas, Antártica, Atividade antimicrobiana, Extratos naturais, Citrus canker, Leaf scald, Antimicrobial activity, Natural extracts