Microbiologia
URI permanente desta comunidadehttps://locus.ufv.br/handle/123456789/11840
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Resultados da Pesquisa
Item Padrão de integração de pAN7-1 em mutantes de Magnaporthe grisea com patogenicidade alterada em arroz(Summa Phytopathologica, 2010-01) Queiroz, Marisa Vieira de; Marchi, Carlos Eduardo; Brommonschenkel, Sérgio Hermínio; Borges, Mírian de Freitas; Mizubuti, Eduardo Seiti G.Ensaios foram conduzidos para verificar a presença, o número de cópias e de sítios de integração de pAN7-1 no genoma de mutantes de M. grisea I-22 com patogenicidade alterada em arroz. Foram analisados T41, T93, T251 (gerados por mutagênese REMI) e T108 (oriundo de mutagênese convencional), os quais exibiram diferentes fenótipos mutantes. O DNA total desses mutantes foi submetido à reação em cadeia de polimerase (PCR) e às análises de hibridização com o vetor (Southern blot). A presença de pAN7-1 no genoma de todos os mutantes foi confirmada por PCR. Segundo as análises de Southern blot, T41 exibiu duas integrações do vetor, ambas na forma de cópia única. No genoma de T93 também foram detectados dois sítios de inserção de pAN7-1, um dos quais envolvendo múltiplas cópias do vetor. Os resultados indicaram a presença de apenas uma cópia do vetor em um único sítio nos genomas de T108 e T251. O padrão de integração em T251 foi o único a sugerir a ocorrência de evento REMI. As diferenças quanto ao tamanho dos fragmentos com homologia a pAN7-1 refletiram a possível aleatoriedade dos eventos de integração no genoma de M. grisea. Os resultados evidenciaram o potencial de REMI para a mutagênese insercional de M. grisea, quando conduzida com pAN7-1 e HindIIIItem Características físico-químicas e microbiológicas de morango minimamente processado(Food Science and Technology, 2010-01) Ponce, Adriana dos Reis; Bastiani, Maria Inês Dantas; Minim, Valéria Paula; Vanetti, Maria Cristina DantasO presente trabalho teve como objetivo avaliar as alterações físico-químicas e microbiológicas de morangos submetidos ao processamento mínimo. Foram avaliados os efeitos da lavagem com cloreto de cálcio ou polietilenoglicol na microbiota contaminante e na textura dos morangos e da sanificação com ozônio gasoso ou clorado orgânico. Análises de textura, cor, perda de massa e microbiota contaminante foram feitas durante o armazenamento a 5 °C por 12 dias em embalagens envoltas com uma a quatro camadas de filme de cloreto de polivinil (PVC). A adição de até 1,5% de cloreto de cálcio ou de 0,5% de polietilenoglicol na água de lavagem não garantiu a manutenção da textura do morango ao final do período de armazenamento. A ozonização dos morangos por 60 minutos foi mais efetiva para reduzir (p < 0,05) a contagem de mesófilos aeróbios, fungos e leveduras e coliformes do que a ozonização por 30 minutos ou a imersão em solução de clorado orgânico. Os morangos armazenados em embalagens recobertas com três camadas de filme PVC apresentaram aumento na textura e na intensidade de escurecimento e redução na microbiota contaminante. Os principais fungos isolados de morangos minimamente processados durante o armazenamento pertenciam ao gênero Fusarium e à espécie Cladosporium cladosporioides.Item Antimicrobial activity and mineral composition of shiitake mushrooms cultivated on agricultural waste(Brazilian Archives of Biology and Technology, 2011-09) Kasuya, Maria Catarina Megumi; Casaril, Kérley Braga Pereira Bento; Vanetti, Maria Cristina DantasThe antimicrobial activity and mineral composition of shiitake mushrooms were evaluated in four isolates of Lentinula edodes. Mushrooms were cultivated on artificial logs, based on eucalyptus sawdust enriched with 20% rice, wheat, or soybean bran, or combination of 10% of two of these supplements. The substrates were humidified with a 0.1% mate tea extract or water. Logs of Eucalyptus grandis were also used to cultivate the shiitake mushrooms. The antimicrobial activity of an aqueous extract, corresponding to 40 mg of mushroom dry matter, was in some cases, depending on the isolate, able to inhibit both Bacillus subtilis and Escherichia coli K-12, independent of substrate composition or the growth stage of the mushrooms. Nitrogen, phosphorus, potassium, magnesium and calcium concentrations varied according to the substrate on which the mushrooms were cultivated, being, generally, higher with cultivation on artificial rather than natural eucalyptus logs. It could be concluded that, in addition to the fungal isolate, substrate composition and, processing methods must be considered during the production of antimicrobial substance(s) as well as in the mushroom nutritional compositionItem Production and regeneration of protoplasts from orchid Mycorrhizal Fungi Epulorhiza repens and Ceratorhiza sp.(Brazilian Archives of Biology and Technology, 2010-01) Coelho, Irene da Silva; Queiroz, Marisa Vieira de; Costa, Maurício Dutra; Kasuya, Maria Catarina Megumi; Araújo, Elza Fernandes deThe aim of this work was to study the standardization of conditions to obtain and regenerate Epulorhiza repens and Ceratorhiza sp. protoplasts. For E. repens, the largest number of protoplasts (8.0 × 106 protoplasts/mL) was obtained in 0.6 M KCl, using 15 mg/mL of Lysing Enzymes, and 2-day-old fungal mycelium. When 0.5 M sucrose was used as osmotic stabilizer, the highest frequency of regeneration was achieved (8.5 %); 80.0 % of protoplasts were nucleated, and 20.0 % anucleated. For Ceratorhiza sp., the largest number of protoplasts (4.0 × 107 protoplasts/mL) was achieved in 0.6 M NaCl, when 15 mg/mL of Lysing Enzymes and 15mg/mL of Glucanex, with 2-day-old fungal mycelium were used. The highest frequency of regeneration was 6.7 % using 0.5 M sucrose as osmotic stabilizer; 88.8 % of protoplasts were nucleated, and 11.2 % anucleated.Item Aumento da disponibilidade de N via deposição atmosférica e fenologia reprodutiva de Habenaria caldensis Kraenzl. (Orchidaceae) no Parque Estadual do Itacolomi (PEIT) – MG, Brasil(Biota Neotropica, 2011-04) Pylro, Victor Satler; Cruz, Eduardo dos Santos; Duarte, Gabriela Frois; Kozovits, Alessandra RodriguesAlong with the increased concentration of CO 2 , the atmospheric deposition of nitrogen is currently considered one of the most important factors of change in the functioning of native ecosystems and has caused drastic changes in their floristic composition and nutrient cycling in the northern hemisphere. In tropical and subtropical systems, however, the largest holders of the plants diversity, little is known about the effects of the nitrogen enrichment via deposition on their performance. Understanding the magnitude and direction of the responses of the orchids to the increase of the concentration of available nitrogen might be helpful to modeling of rock outcrops population dynamics in response to global changes. We evaluated the responses of flowering and fruiting in plants of Habenaria caldensis Kraenzl. (Orchidaceae), a species widely distributed in Minas Gerais, as a result of increased nitrogen availability through fertilization with ammonium nitrate, in situ, by spraying. In response to the addition of N, anthesis occurred about 15 days earlier compared to individuals of the control group. The results of this study demonstrated that the increased availability of N via atmospheric deposition can affect in a short term the ecology of orchids and possibly other plants from rock outcrops by changing their phenological and allometric patterns. In a medium and long term, such changes can have an important impact on the dynamics of populations and communities of this vegetation type.Item Mycovirus in Pseudocercospora griseola, the causal agent of angular leaf spot in common bean(Canadian Journal of Microbiology, 2010) Lima, Swiany Silveira; Abadio, Ana Karina Rodrigues; Araújo, Elza Fernandes; Kitajima, Elliot Watanabe; Watanabe, Elliot; Queiroz, Marisa Vieira dePseudocercospora griseola (Sacc.) Crous & Braun is a widespread fungal phytopathogen that is responsible for angular leaf spot in the common bean (Phaseolus vulgaris L.). A number of fungal phytopathogens have been shown to harbour mycoviruses, and this possibility was investigated in populations of Pseudocercospora griseola. The total nucleic acid extracts of 61 fungal isolates were subjected to agarose gel electrophoresis. Small fragments (800–4800 bp) could be identified in 42 of the samples. The presence of dsRNA in isolate Ig838 was confirmed by treatment of total nucleic acid with DNase, RNase A, and nuclease S1. Transmission electron microscopy revealed the presence of viral-like particles 40 nm in diameter in the mycelia of 2 fungal isolates, namely 29-3 and Ig838. The transmission of dsRNA by means of conidia was 100% for isolate 29-3, but there was loss of 1–6 fragments of dsRNA in monosporic colonies of isolate Ig848. Cycloheximide treatment failed to inhibit the mycovirus in isolate 29-3, but proved efficient in the elimination of the 2.2, 2.0, 1.8, 1.2 and 1.0 kb fragments in 2 colonies of isolate Ig848. The occurrence of a mycovirus in Pseudocercospora griseola was demonstrated for the first time in the present study.Item Pectin lyase production by recombinant Penicillium griseoroseum strain 105(Canadian Journal of Microbiology, 2010) Teixeira, Janaina Aparecida; Queiroz, Marisa Vieira de; Araújo, Elza Fernandes de; Cardoso, Patrícia GomesRecombinant Penicillium griseoroseum strain 105 overproduces an extracellular pectin lyase (PL) under the transcriptional control of the strong gpdA promoter of Aspergillus nidulans. Our aim was to evaluate PL production by recombinant P. griseoroseum strain 105 in submerged fermentation system bioreactors BioFloIII and BioFloIV using 2 or 10 L working volumes under different growth conditions and to analyze the production of cellulase, polygalacturonase, pectin methylesterase, and protease. PL overproduction by recombinant P. griseoroseum strain 105 was 112 times higher than that of P. griseoroseum PG63 grown in sugarcane juice. Cellulases and proteases were not detected in the culture filtrate, and evaluation for extracellular proteins in the culture medium by SDS–PAGE showed the presence of a 36 kDa predominant band, similar to the molecular mass estimated from the nucleotide sequence of plg1 gene for PL of P. griseoroseum strain 105. This recombinant strain provides the advantage of PL production, which predominates over other extracellular proteins usually present in most commercial pectinase preparations, using sugarcane juice as a substrate of low cost.Item Development of molecular markers based on retrotransposons for the analysis of genetic variability in Moniliophthora perniciosa(European Journal of Plant Pathology, 2012-11) Santana, Mateus Ferreira; Araújo, Elza Fernandes de; Queiroz, Marisa Vieira de; Souza, Jorge Teodoro de; Mizubuti, Eduardo Seiti GomideMoniliophthora perniciosa is a fungus that causes witches’ broom disease (WBD) in the cacao tree (Theobroma cacao). The M. perniciosa genome contains different transposable elements; this prompted an evaluation of the use of its retrotransposons as molecular markers for population studies. The inter-retrotransposon amplified polymorphism (IRAP) and retrotransposon-microsatellite amplified polymorphism (REMAP) techniques were used to study the variability of 70 M. perniciosa isolates from different geographic origins and biotypes. A total of 43 loci was amplified. Cluster analysis of different geographical regions of C biotype revealed two large groups in the state of Bahia, Brazil. Techniques using retrotransposon-based molecular markers showed advantages over previously used molecular techniques for the study of genetic variability in M. perniciosa.Item Basidiosporogenesis, meiosis, and post-meiotic mitosis in the ectomycorrhizal fungus Pisolithusmicrocarpus(Fungal Genetics and Biology, 2010-03-03) Campos, André Narvaes da Rocha; Costa, Maurício DutraPisolithus microcarpus (Cooke and Massee) G. Cunn. is a model organism for the studies on the ecology, physiology, and genetics of the ectomycorrhizal associations. However, little is known about the basidiosporogenesis in this species and, in particular, the nuclear behavior after karyogamy. In this work, the events involved in basidiosporogenesis and meiosis in P. microcarpus were analyzed using fluorescence and scanning electron microscopy. The basidia are formed inside peridioles by the differentiation of the cells along the whole hyphae. Basidial cells measure 12–18 μm in length and 6–7 μm in diameter. P. microcarpus produces eight basidiospores per basidium imbibed in a gelatinous matrix in the basidiocarp. The basidiospores are globose, equinate, with blunt spines, and measure 6–8 μm. Karyogamy can take place inside basidia as well as in undifferentiated hyphal cells followed by nuclear migration to a newly developed basidium where meiosis takes place. After the formation of the meiotic tetrad, one round of post-meiotic mitosis occurs, resulting in the production of eight nuclei per basidium. The newly-formed nuclei migrate into the basidiospores asynchronously, resulting in the production of eight uninucleate spores. This corresponds to pattern A of post-meiotic mitosis. This work is the first report on meiosis and post-meiotic mitosis during basidiosporogenesis in P. microcarpus and contributes to clarify some aspects of the biology and genetics of this ectomycorrhizal species.Item Kinetics of growth and ethanol formation from a mix of glucose/xylose substrate by Kluyveromyces marxianus UFV-3(Antonie van Leeuwenhoek, 2012-09-11) Passos, Flávia Maria Lopes; Santos, Valdilene Canazart dos; Bragança, Caio Roberto Soares; Passos, Frederico José VieiraThe fermentation of both glucose and xylose is important to maximize ethanol yield from renewable biomass feedstocks. In this article, we analyze growth, sugar consumption, and ethanol formation by the yeast Kluyveromyces marxianus UFV-3 using various glucose and xylose concentrations and also under conditions of reduced respiratory activity. In almost all the conditions analyzed, glucose repressed xylose assimilation and xylose consumption began after glucose had been exhausted. A remarkable difference was observed when mixtures of 5 g L^−1 glucose/20 g L^−1 xylose and 20 g L^−1 glucose/20 g L^−1 xylose were used. In the former, the xylose consumption began immediately after the glucose depletion. Indeed, there was no striking diauxic phase, as observed in the latter condition, in which there was an interval of 30 h between glucose depletion and the beginning of xylose consumption. Ethanol production was always higher in a mixture of glucose and xylose than in glucose alone. The highest ethanol concentration (8.65 g L^−1) and cell mass concentration (4.42 g L^−1) were achieved after 8 and 74 h, respectively, in a mixture of 20 g L^−1 glucose/20 g L^−1 xylose. When inhibitors of respiration were added to the medium, glucose repression of xylose consumption was alleviated completely and K. marxianus was able to consume xylose and glucose simultaneously.