Colletotrichum gloeosporioides e Fusarium guttiforme são fungos fitopatogênicos causadores de diversas doenças pós-colheita em frutos. As substâncias "GRAS"-(Generally d Regarded As Safe), são uma alternativa no controle de microorganismos na fase pós-colheita, devido seus efeitos fungistáticos e fungicidas comprovados. O presente estudo observou os efeitos de cinco substâncias "GRAS" no controle de crescimento dos fungos fitopatogênicos C. gloeosporioides e F. guttiforme in vitro. GRAS substances in control of Colletotrichum gloeosporioides growth and Fusarium guttiforme vitroABSTRACT-Colletotrichum gloeosporioides and Fusarium guttiforme are phytopathogenic fungi causing various post-harvest diseases in fruits. Substances "GRAS" -(Generally Regarded Ase Safe), they are an alternative for the control of microorganisms in the post-harvest phase, due to their fungistatic and fungicide effects. The objective of this study was to evaluate the inhibitory effects of five "GRAS" substances over the growth of pathogenic fungi C. gloeosporioides and F. guttiforme in vitro. Culture media (PDA) were supplemented with 1%, 3% and 5% sodium bicarbonate, sodium carbonate, calcium carbonate, calcium chloride and 0.1% 0.5% 1% potassium chloride. 10μl spore solution was inoculated at a concentration of 5x10 3 ml/spore. From the five substances used in the tests, sodium bicarbonate and sodium carbonate inhibited 100% of C. gloeosporioides growth, the others were not limiting to the development of the fungus when compared to control. Sodium carbonate inhibited 100% of F. guttiforme growth at all concentrations. Were also positive, sodium bicarbonate in concentrations of 3% and 5%. The treatment with 5% calcium chloride at 51% reduced the growth this phytopatogen. Other substances not reduced or inhibited the mycelial growth of the pathogen when compared to the control. From the five substances "GRAS" tested in this work, sodium carbonate and sodium bicarbonate, were effective in inhibiting the mycelial growth of C. gloeosporioides. Sodium carbonate, sodium bicarbonate and calcium chloride were able in to reduce the growth of F. guttiforme.
ResumoNeste estudo, verificou-se a utilização de um filme de quitosana para o controle do crescimento e produção de aflatoxinas por A. parasiticus em amendoim. Os filmes foram aplicados sobre os grãos por meio de duas metodologias (aspersão e imersão). Os grãos recobertos foram inoculados com 2,5 ml de uma suspensão contendo 1,0×106 esporos/ml e incubados a 25 o C por 7 dias. A concentração de aflatoxinas foi determinada por cromatografia em camada delgada, utilizando a técnica de densitometria. A verificação da inibição do crescimento fúngico foi realizada por meio da inoculação do patógeno em placas de Petri contendo GYEP suplementado com quitosana a 2% e incubadas por 7 dias a 25 ºC. Após incubação, o diâmetro da colônia do patógeno foi estimado e comparado com o controle. Todos os testes foram realizados com cinco repetições. Para a verificação de alterações morfológicas, uma suspensão de esporos ou hifas incubados na presença de quitosana foi submetida à microscopia eletrônica de varredura. Foi observado que tanto o método de imersão quanto o de aspersão reduziram a produção de aflatoxina significativamente, 84,3% e 86,7% respectivamente. A presença de quitosana no meio de cultura reduziu o diâmetro das colônias e promoveu modificações morfológicas nos esporos de A. parasiticus. Com esse procedimento foi verificado que a utilização de quitosana a 2% na forma de filme, principalmente por aspersão, pode reduzir a concentração de esporos e aflatoxinas de A. parasiticus em amendoim, o que confere a essa substância uma grande perspectiva de utilização no controle de fungos aflatoxigênicos.Palavras-chave: Arachis hypogaea, Aspergillus parasiticus, micotoxinas, pós-colheita, substância GRAS. Use of chitosan film to control aflatoxins in peanuts AbstractIn this study, we evaluate the utilization on chitosan film to control the growth and aflatoxin production by A. parasiticus in peanut. The films were inoculated over the grains by aspersion or immersion methods. The chitosan coated grains were inoculated with 2.5 ml solution with 1.0×10 6 spores/ml and incubated at 25 °C for 7 days. The aflatoxin concentration was estimated by thin layer chromatography and densitometry. The fungus growth inhibition was observed by pathogen inoculation in Petri dishes with GYEP media plus 2% chitosan and incubated by 7 days at 25 °C. After incubation the colony diameter was measured and compared with the control. All assays were repeated five times. To verify morphological alterations, a spore/hypha suspension was incubated in media with chitosan and observed in scanning electron microscopy.Both methods (immersion and aspersion) were able to reduce the aflatoxin production significantly, 84.3% and 86.7%, respectively. The chitosan reduced the colonies diameters and promoted morphological alterations in A. parasiticus spores. With this, was observed that a 2% chitosan film, specially inoculated by aspersion, can to reduce A. parasiticus spores and aflatoxins concentrations in peanuts. This characteristic gives to this substance an ex...
Abstract-This study aimed to propose a safe methodology for the control anthracnose caused by the fungus Colletotrichum gloeosporioides in the papaya (Carica papaya L.). In addition, yeast present in epiphytic microbiota associated with this fruit were isolated and selected as biocontrol agents, its use in classical and integrated biological control protocols with GRAS substances. For selection as biocontrol agents, the obtained isolates were tested for their ability to: produce antagonistic substances against C. gloeosporioides, not grow at 37ºC and subsequently tested for their potential control. Considering the total of 85 isolated yeasts, only UFT 5852 was selected in the above mentioned tests and due to this it was used in biological control tests in vivo. It was identified molecularly belonging to species Anthracocystis grodzinskae by the sequencing the D1/ D2 domain. The results of the biocontrol had showed that the yeast presented a reduction of the disease severity by 93.7%, the sodium bicarbonate 100%, and the biological control integrated with sodium bicarbonate showed a decrease of 84.4%. The treatments did not differ 5% by Tukey test. However, the sodium bicarbonate at 1% showed the best strategy for the control of Anthracnose produced by the phytopathogenic fungus C. gloeosporioides in papaya due accessible strategy. Index terms: epiphytic yeasts, Anthracocystis grodzinskae, Colletotrichum gloeosporioides, GRAS substances, biological control. Método seguro para controle da antracnose em mamãoResumo -Este estudo teve como objetivo propor uma metodologia segura para o controle da antracnose causada pelo fungo Colletotrichum gloeosporioides em mamão (Carica papaya L.), além de isolar leveduras presentes, a microbiota epifítica associada a este fruto e selecioná-las como agentes de biocontrole, avaliando seu uso em protocolos de controle biológico clássico e integrado a substâncias GRAS. Para a seleção como agentes biocontroladores, os isolados obtidos foram testados quanto à capacidade de produzirem substâncias antagônicas contra C. gloeosporioides, não crescerem à temperatura de 37ºC e, posteriormente, testados quanto a seu potencial de controle. Do total de 85 isolados de leveduras obtidos, apenas o isolado UFT 5852 foi selecionado nos testes acima citados e, com isto, utilizado nos testes de controle biológico in vivo. O isolado selecionado foi identificado molecularmente por meio do domínio D1/D2, como pertencente à espécie Anthracocystis grodzinskae. Os resultados do controle biológico demonstraram que a levedura apresentou redução de severidade da doença em 93,7%, o bicarbonato de sódio em 100%, e o controle biológico integrado ao bicarbonato de sódio demonstrou redução de 84,4%. Embora a eficiência dos tratamentos com levedura e bicarbonato não tenha diferido entre si (p<0.05), bicarbonato de sódio a 1% apresentou ser a melhor estratégia observada para o controle da Antracnose produzida pelo fungo fitopatogênico C. gloeosporioides em mamão, devido ser uma estratégia acessível e de baixo custo. ...
Plants commonly interact with microorganisms that may influence their physiology and performance. Epiphytic yeasts are microorganisms that can be found in the phylosphere, in significantly larger numbers in fruits than in other plant tissues due to their higher nutritional content. The present study aimed to contribute to knowledge of epiphytic yeasts associated with Eugenia dysenterica DC. fruits and to evaluate their antimicrobial activity against phytopathogens. E. dysenterica fruits were collected, washed in saline solution, and sonicated. Each fruit solution was plated in three Petri dishes with NYDA medium. Yeast identification was performed through morphological and physiological criteria, and richness evaluation was performed using the Jackknife 1 estimator. All isolated yeasts were tested for diffusible substances against three phytopathogenic fungi. Only four of 42 isolates were inhibited sporulation of Aspergillus parasiticus, but none was able to inhibit or diminish mycelium growth of any tested phytopathogen. The present study contributes to the characterization of the E. dysenterica microbiome, presenting the first report of in vitro A. parasiticus sporulation inhibition by epiphytic yeasts and suggesting their promising use in biological control of this phytopathogen.
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