Candida stellimalicola e rhodotorula minuta para o biocontrole do bolor azul em frutos cítricos
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Data
2020-10-09
Autores
Paula, Fernanda Barbosa Francisco de
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Universidade Estadual Paulista (Unesp)
Resumo
- A citricultura tem uma importância social e econômica para o país, especialmente, no Estado de São Paulo e Triângulo Mineiro, onde a atividade é predominante. Dentre as doenças de maior importância econômica que ocorrem na fase de pós-colheita dos citros, encontra-se o bolor azul, causado pelo fungo Penicillium italicum. Tal doença acarreta prejuízos na qualidade e na quantidade dos frutos e o controle mais comum da doença é o uso de fungicida, como o imazalil. No entanto, devido à falta de novos produtos, o uso frequente e excessivo de imazalil, durante o beneficiamento dos frutos, têm ocasionado problemas ao meio-ambiente; à saúde pública, devido à quantidade de resíduos nos frutos; além de estar favorecendo o surgimento de linhagens resistentes do fungo a esse princípio ativo. A busca por métodos alternativos de controle se faz necessária e, o uso de leveduras para controle de patógenos, que ocorrem na pós-colheita, tem sido o mais indicado. Diante do exposto, o presente trabalho teve por objetivo avaliar a capacidade antagonista de dois isolados ACBL-05 e ACBL-10 de Candida stellimalicola, e um isolado ACBL-23 de Rhodotorula minuta avaliados quanto: (i) à adição de fontes nutricionais em meio de cultivo da levedura e o seu efeito na sua atividade antagônica e na sua produção de células viáveis; (ii) à competição por nutrientes entre a levedura e o fitopatógenos; (iii) à produção de biofilme pelos microrganismos e, finalmente, (iv) à sua atividade antifúngica in vivo contra Penicillium italicum. Os resultados in vitro mostraram que, a adição de fontes nutricionais em meio de cultivo dos isolados de C. stellimalicola favoreceu a sua atividade antagônica e a sua produção de células viáveis. Embora C. stellimalicola produza biofilme, o aumento da sua produção pode, ou não, ser favorecido pela adição de uma fonte nutricional no meio de cultivo, dependendo do isolado. Neste estudo, foi observado que, a adição de cloreto de cobalto (1 mM) aumentou a produção de biofilme pelo isolado ACBL-10, porém, o acréscimo de uma fonte nutricional, em meio de cultivo, não favoreceu o aumento de biofilme para o ACBL-05. Para o isolado ACBL-23 verifica-se, que a adição de sulfato de cobre (0,2 mM) em meio de cultivo da levedura favoreceu a atividade antagônica e manteve a sua produção de células viáveis; R. minuta, independente da adição de fontes nutricionais, inibe a germinação de P. italicum; a adição de fontes de carbono sugere uma possível competição entre a levedura e o fitopatógeno; a levedura produz biofilme e a adição de sulfato de cobre (0,2 mM), em seu meio de cultivo, estimula a produção. Sob condições in vivo os isolados apresentaram potencial para o controle do bolor azul, porém a sua atividade antagônica depende da variedade de citros avaliada.
Citriculture has a social and economic importance for the country, especially in the state of São Paulo and Triângulo Mineiro, where the activity is predominant. Among the diseases of greater economic importance that occur in the post-harvest phase of citrus, is the blue mold, caused by the Penicillium italicum. This disease causes losses in the quality and quantity of fruits and the most common control of the disease is the use of fungicide, such as imazalil. However, due to the lack of new products, the frequent and excessive use of imazalil, during the fruit processing, has caused problems to the environment; to public health, due to the amount of residues in the fruit; besides being favoring the appearance of resistant lineages of the fungus to this active principle. The search for alternative methods of control is necessary and the use of yeasts to control pathogens, which occur after harvest, has been the most indicated. In view of the above, the present work aimed to evaluate the antagonistic capacity of two isolates ACBL-05 and ACBL-10 of Candida stellimalicola, and one isolate ACBL-23 of Rhodotorula minuta evaluated how much: (i) the addition of nutritional sources in yeast culture medium and its effect on its antagonistic activity and on its production of viable cells; (ii) the competition for nutrients between yeast and phytopathogens; (iii) the production of biofilm by microorganisms and, finally, (iv) its in vivo antifungal activity against Penicillium italicum. The in vitro results showed that the addition of nutritional sources in culture medium of C. stellimalicola isolates favored its antagonistic activity and its production of viable cells. Although C. stellimalicola produces biofilm, the increase in its production may or may not be favored by the addition of a nutritional source in culture medium, depending on the isolate. In this study, it was observed that the addition of cobalt chloride (1 mM) increased the production of biofilm by the ACBL-10 isolate, however, the addition of a nutritional source in culture medium did not favor the increase of biofilm for ACBL-05.The results obtained showed that the addition of copper sulfate (0.2 mM) in yeast culture medium favored the antagonistic activity and maintained its production of viable cells; R. minuta, independent of the addition of nutritional sources, inhibits the germination of P. italicum; the addition of carbon sources suggests a possible competition between the yeast and the phytopathogen; the yeast produces biofilm and the addition of copper sulfate (0.2 mM), in its culture medium, stimulates the production. Under in vivo conditions, it was found that yeasts presents potential for the control of blue mold, however, it depends on the isolate and the variety of citrus evaluated.
Citriculture has a social and economic importance for the country, especially in the state of São Paulo and Triângulo Mineiro, where the activity is predominant. Among the diseases of greater economic importance that occur in the post-harvest phase of citrus, is the blue mold, caused by the Penicillium italicum. This disease causes losses in the quality and quantity of fruits and the most common control of the disease is the use of fungicide, such as imazalil. However, due to the lack of new products, the frequent and excessive use of imazalil, during the fruit processing, has caused problems to the environment; to public health, due to the amount of residues in the fruit; besides being favoring the appearance of resistant lineages of the fungus to this active principle. The search for alternative methods of control is necessary and the use of yeasts to control pathogens, which occur after harvest, has been the most indicated. In view of the above, the present work aimed to evaluate the antagonistic capacity of two isolates ACBL-05 and ACBL-10 of Candida stellimalicola, and one isolate ACBL-23 of Rhodotorula minuta evaluated how much: (i) the addition of nutritional sources in yeast culture medium and its effect on its antagonistic activity and on its production of viable cells; (ii) the competition for nutrients between yeast and phytopathogens; (iii) the production of biofilm by microorganisms and, finally, (iv) its in vivo antifungal activity against Penicillium italicum. The in vitro results showed that the addition of nutritional sources in culture medium of C. stellimalicola isolates favored its antagonistic activity and its production of viable cells. Although C. stellimalicola produces biofilm, the increase in its production may or may not be favored by the addition of a nutritional source in culture medium, depending on the isolate. In this study, it was observed that the addition of cobalt chloride (1 mM) increased the production of biofilm by the ACBL-10 isolate, however, the addition of a nutritional source in culture medium did not favor the increase of biofilm for ACBL-05.The results obtained showed that the addition of copper sulfate (0.2 mM) in yeast culture medium favored the antagonistic activity and maintained its production of viable cells; R. minuta, independent of the addition of nutritional sources, inhibits the germination of P. italicum; the addition of carbon sources suggests a possible competition between the yeast and the phytopathogen; the yeast produces biofilm and the addition of copper sulfate (0.2 mM), in its culture medium, stimulates the production. Under in vivo conditions, it was found that yeasts presents potential for the control of blue mold, however, it depends on the isolate and the variety of citrus evaluated.
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Palavras-chave
Antagonismo, Citrus spp., Penicillium italicum, Biofilme, Competição por nutriente, Fontes nutricionais, Antagonism, Citrus spp., Penicillium italicum, Biofilm, Competition for nutrients, Nutritional sources