Navegando por Autor "Pereira, Júlia Santos"

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Genomic identification, gene expression and enzyme activity of CAZymes from biotrophic fungus Hemileia vastatrix during coffee leaf infection
(Universidade Federal de Minas Gerais, 2021-02-25) Pereira, Júlia Santos; Mendes, Tiago Antônio de Oliveira
Coffee leaf rust, caused by the fungus Hemileia vastatrix, is a major disease that affects many coffee producers around the world, causing a huge economic loss. H. vastatrix is a biotrophic fungus, hence, its growth and reproduction are totally dependent on the cells of the living host. Because of that, they infect the tissue without causing necrosis. Nevertheless, it is known that some fungi during plant interaction can express genes involved in the formation of infectious structures, as well as synthesize enzymes responsible for the degradation of the host cell wall. However, little is known about the importance of cell wall degrading enzymes (CWDE) for biotrophic phytopathogens. In this work, we performed genomic analysis to identify CAZymes (Carbohydrate Active EnZymes) from H. vastatrix and the analysis of expression and enzyme activity during experimental coffee infection. The first step was the ab initio prediction of H. vastatrix genome, using AUGUSTUS program, which was adjusted with H. vastatrix RNA-Seq for model determination. Functional annotation to identify CAZymes was performed using dbCAN2 meta server. Among the 345 CAZymes found, 162 belong to Glycoside Hydrolases (GH) including 34 endoglucanases, xylanases and polygalacturonases from families GH 5, 9, 10, 12 and 28 - which may act during fungal infection degrading the highest prevalent components of cell wall, represented by cellulose, xylan and pectin, respectively. Physico-chemical parameters of these enzymes were checked, including identification of catalytic residues and standard CAZymes motifs. The enzyme structures were also modelled. Moreover, analysis of expression of enzymes were performed using RNA-seq data from a genotype of C. arabica susceptible to infection, therefore presenting compatible interaction with the pathogen, after 0, 12, 24 and 96 hours after inoculation (hai). Enzyme activity assays were carried out in order to verify if these enzymes were also active during the fungal infection. The enzymes showed typical physico-chemical characteristics and structures of active enzymes including conservation of the catalytic sites. Genes encoding endoglucanases and xylanases were expressed during different times of H. vastatrix infection, being the first more expressed at 12 hai and the other at 24 hai. In agreement with expression data, endoglucanases started to be produced early, and were more active at 24 hai, whereas xylanases had greater activity at 96 hai. The results suggest that biotrophic fungus also use active enzymes on carbohydrates during the infection. In relation to H. vastatrix, these enzymes start being produced at the pre-haustorial phase of the fungal infection, but are more active at the post-haustorial phase, when the haustorium begins to be formed in the host membranes and in the plant cell wall.
Produção de bioplástico a partir de resíduos de café e seu uso como matriz de liberação de antimicrobianos
(Embrapa Café, 2019-10) Paulino, Graziela dos Santos; Pereira, Júlia Santos; Ribon, Andréa de Oliveira Barros; Caixeta, Eveline Teixeira; Mendes, Tiago Antônio de Oliveira
Cada vez mais tem-se buscado desenvolver produtos sustentáveis, dada a grande preocupação com a disposição de rejeitos no meio ambiente. O objetivo desse trabalho foi desenvolver um bioplástico de amido reforçado com microfibras de celulose extraídas do café e incorporado com ampicilina, para avaliação do mesmo como matriz de liberação de ampicilina. Para a fabricação do bioplástico, utilizou-se uma mistura de frutos cereja, boia e verde e o antibiótico testado para liberação controlada foi a ampicilina. Foram utilizados dois protocolos diferentes para a extração das microfibras de celulose, os resultados preliminares mostraram que o protocolo 1 foi mais eficiente. Além disso, todos os biofilmes foram capazes de liberar ampicilina, resultando na inibição do crescimento de Escherichia Coli BL21 em placa. Em estudos futuros pretende-se obter nanocelulose a partir da hidrólise ácida das microfibras para a criação de um bioplástico de celulose pura, que posteriormente será funcionalizado para aplicação na indústria de alimentos.