Microbiologia
URI permanente desta comunidadehttps://locus.ufv.br/handle/123456789/11840
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Resultados da Pesquisa
Item In vitro culture of Gigaspora decipiens and Glomus clarum in transformed roots of carrot: the influence of temperature and pH(Acta Scientiarum. Agronomy, 2013-07) Kasuya, Catarina Megumi; Costa, Francilina Araújo; Haddad, Lydice Sant'Anna Meira; Oton, Wagner Campos; Costa, Maurício Dutra; Borges, Arnaldo ChaerMonoxenic cultures of arbuscular mycorrhizal fungi (AMF) in transformed roots have been used to better understand the symbiosis with these fungi, but few species have been successfully established in vitro. The object was to establish monoxenic cultures of Gigaspora decipiens and Glomus clarum and to verify the effects of temperature and pH on spore formation. Cultures were established from superficially disinfested spores that were germinated on an agar and water. After germination, the spores were transferred to Petri dishes containing transformed carrot roots. After 4-6 days formed newly formed spores and structures typical. The effects of temperature (22, 25, 28 or 32ºC) and pH (4.0, 4.5, 5.5 or 6.5) on the production of spores were assessed over three months, resulting in sigmoidal growth curves. The spore increased from 22ºC, reaching higher values 28oC and 32oC there was a reduction in the production. The highest spore production of G. decipiens occurred in a pH of 6.5, whereas for G. clarum was pH of 4.0. The cultivation of other species is still necessary to elucidate particular aspects of the symbiosis that so far are unclear, including the effects of environmental factors on the production of spores of different AMF species.Item Levantamento fitossociológico de plantas daninhas em pastagens no município de Nova Olímpia-MT(Revista Agraria, 2013-11) Mendes, Kassio Ferreira; Inoue, Miriam Hiroko; Iskierski, Daiane; Ben, Ronei; Conciani, Paulo Alberto; Pereira, Rafael Luiz; Dallacort, RivanildoO objetivo do trabalho foi identificar a comunidade infestante de plantas daninhas em áreas de pastagens no município de Nova Olímpia, MT. O levantamento foi realizado nos meses de fevereiro e março de 2012, em que foram analisadas 10 propriedades, tendo cada uma 10 parcelas de 25 m2. Nas parcelas foram realizadas a contagem e identificação das espécies daninhas. Os dados foram analisados por meio de cálculo de densidade, frequência, abundância, densidade relativa, frequência relativa, abundância relativa, índice de valor de importância (IVI) e índice de similaridade. Foram encontradas 31 espécies de plantas daninhas distribuídas em 16 famílias botânicas, sendo, Asteraceae (4), Papilionoideae (4) Poaceae (4) e Malvaceae (3) as mais representativas em números de espécies. As espécies mais ocorrentes foram Sida carpinifolia (IVI = 38,50), Sida spp. (IVI = 36,26), Chenopodium ambrosiodies (IVI = 21,06) e Sida cordifolia (IVI = 19,71). Foi encontrada similaridade expressiva entre as propriedades sendo que as propriedades 6 e 8 se destacaram com índice de similaridade de 78,26%.Item Safety evaluation of the antimicrobial peptide bovicin HC5 orally administered to a murine model(BMC Microbiology, 2013) Paiva, Aline Dias; Fernandes, Kenner Morais; Dias, Roberto Sousa; Rocha, Alípio dos Santos; Oliveira, Leandro Licursi de; Neves, Clóvis Andrade; Paula, Sérgio Oliveira de; Mantovani, Hilário CuquettoBovicin HC5 is an antimicrobial peptide that shows a broad spectrum of activity and potential for biotechnological and therapeutic applications. To gain insight about the safety of bovicin HC5 application, the histological and immunostimulatory effects of orally administrated bovicin HC5 to BALB/c mice were evaluated. BALB/c mice were divided into three groups: negative control (NC group); mice given purified bovicin HC5 (Bov group); mice given ovalbumin (positive control, PC group; a murine model of enteropathy). The mice were initially pre-sensitized, and PBS, bovicin HC5 or ovalbumin were administered for 30 days by daily gavages. Histological and morphometric analysis were performed and the relative expression of cytokines was analyzed by real-time RT-PCR. The oral administration of bovicin HC5 to BALB/c mice reduced weight gain and caused alterations in the small intestine, although absorptive changes have not been detected. The number of total goblet cells and the mucopolysaccharides production were not affected by bovicin HC5 administration. A hypertrophy of Paneth cells and an increase in the number of mitotic cells were observed in Bov group, while the number of mast cells remained unaltered. Increased expression of TNF-α, INF-γ and IL-12 was observed in the small intestine upon bovicin HC5 administration. Bovicin HC5 has only minor effects on intestinal permeability and did not elicit an allergenic response upon oral administration to animal models. Considering the low in vivo toxicity of bovicin HC5, it might be a good candidate for enteral applications.Item Morphological and molecular characterization of Tulasnella spp. fungi isolated from the roots of Epidendrum secundum, a widespread Brazilian orchid(Symbiosis, 2014-02) Pereira, Marlon Corrêa; Coelho, Irene da Silva; Valadares, Rafael Borges da Silva; Oliveira, Sabrina Feliciano; Bocayuva, Melissa; Pereira, Olinto Liparini; Araújo, Elza Fernandes; Kasuya, Maria Catarina MegumiTulasnella spp. are the main fungal symbionts of Brazilian Epidendrum orchids. The taxonomy of these fungi is largely based on ITS rDNA similarity, but culture dependent techniques are still essential to establish the true biological entity of the mycobiont. The aim of this study was to characterize morphologically and molecularly 16 Tulasnella spp. fungi isolated from three different populations of E. secundum and to test the coincidences between morphological and molecular characterization. Two uninucleate rhizoctonia fungi, obtained from Oncidium barbaceniae, and two phytopathogenic isolates were included as outgroups. Qualitative and quantitative morphological characteristics were analyzed using multivariate statistics and were able to distinguish Ceratobasidium, Tulasnella and Thanatephorus genera and separate the isolates of Tulasnella spp. into two groups. Analysis of RAPD (Random Amplified Polymorphic DNA) and ITS rDNA sequences validated the morphological data. Symbionts of O. barbaceniae presented identity to ITS sequences of Ceratobasidium genus, while E. secundum isolates presented identity to two species of Tulasnella. We observed homogeneity among Tulasnella spp. obtained from a single population and from neighboring populations, but there was higher variability among isolates obtained from populations of regions that were farther apart. Morphological data associated with multivariate statistics proved to be a useful tool in the multi-level taxonomy of these orchid-associated fungi and in estimating the diversity of orchid mycorrhizal fungi.Item Endophytic microbial diversity in coffee cherries of Coffea arabica from southeastern Brazil(Canadian Journal of Microbiology, 2013-01-22) Oliveira, Marcelo N. V.; Santos, Thiago M. A.; Vale, Helson M. M.; Delvaux, Júlio C.; Cordero, Alexander P.; Ferreira, Alessandra B.; Miguel, Paulo S. B.; Tótola, Marcos R.; Costa, Maurício D.; Moraes, Célia A.; Moraes, Célia A.The microbiota associated with coffee plants may play a critical role in the final expression of coffee quality. However, the microbial diversity in coffee cherries is still poorly characterized. Here, we investigated the endophytic diversity in cherries of Coffea arabica by using culture-independent approaches to identify the associated microbes, ultimately to better understand their ecology and potential role in determining coffee quality. Group-specific 16S rRNA and 26S rRNA genes polymerase chain reaction – denaturing gradient gel electrophoresis and clone library sequencing showed that the endophytic community is composed of members of the 3 domains of life. Bacterial sequences showing high similarity with cultured and uncultured bacteria belonged to the Betaproteobacteria, Gammaproteobacteria, and Firmicutes phyla. Phylogenetic analyses of cloned sequences from Firmicutes revealed that most sequences fell into 3 major genera: Bacillus, Staphylococcus, and Paenibacillus. Archaeal sequences revealed the presence of operational taxonomic units belonging to Euryarchaeota and Crenarchaeota phyla. Sequences from endophytic yeast were not recovered, but various distinct sequences showing high identity with filamentous fungi were found. There was no obvious correlation between the microbial composition and cultivar or geographic location of the coffee plant. To the best of our knowledge, this is the first report demonstrating internal tissue colonization of plant fruits by members of the Archaea domain. The finding of archaeal small-subunit rRNA in coffee cherries, although not sufficient to indicate their role as active endophytes, certainly expands our perspectives toward considering members of this domain as potential endophytic microbes.Item Endophytic microbial diversity in coffee cherries of Coffea arabica from southeastern Brazil(Canadian Journal of Microbiology, 2013) Oliveira, Marcelo N. V.; Santos, Thiago M. A.; Vale, Helson M. M.; Delvaux, Júlio C.; Cordero, Alexander P.; Ferreira, Alessandra B.; Miguel, Paulo S. B.; Tótola, Marcos R.; Costa, Maurício D.; Moraes, Célia A.; Borges, Arnaldo C.The microbiota associated with coffee plants may play a critical role in the final expression of coffee quality. However, the microbial diversity in coffee cherries is still poorly characterized. Here, we investigated the endophytic diversity in cherries of Coffea arabica by using culture-independent approaches to identify the associated microbes, ultimately to better understand their ecology and potential role in determining coffee quality. Group-specific 16S rRNA and 26S rRNA genes polymerase chain reaction – denaturing gradient gel electrophoresis and clone library sequencing showed that the endophytic community is composed of members of the 3 domains of life. Bacterial sequences showing high similarity with cultured and uncultured bacteria belonged to the Betaproteobacteria, Gammaproteobacteria, and Firmicutes phyla. Phylogenetic analyses of cloned sequences from Firmicutes revealed that most sequences fell into 3 major genera: Bacillus, Staphylococcus, and Paenibacillus. Archaeal sequences revealed the presence of operational taxonomic units belonging to Euryarchaeota and Crenarchaeota phyla. Sequences from endophytic yeast were not recovered, but various distinct sequences showing high identity with filamentous fungi were found. There was no obvious correlation between the microbial composition and cultivar or geographic location of the coffee plant. To the best of our knowledge, this is the first report demonstrating internal tissue colonization of plant fruits by members of the Archaea domain. The finding of archaeal small-subunit rRNA in coffee cherries, although not sufficient to indicate their role as active endophytes, certainly expands our perspectives toward considering members of this domain as potential endophytic microbes.Item Mechanisms of phosphate solubilization by fungal isolates when exposed to different P sources(Annals of Microbiology, 2014-03) Mendes, Gilberto de Oliveira; Freitas, André Luiz Moreira de; Pereira, Olinto Liparini; Silva, Ivo Ribeiro da; Vassilev, Nikolay Bojkov; Costa, Maurício DutraThe use of phosphate-solubilizing fungi is a promising biotechnological strategy in the management of phosphorus (P) fertilization, as it enables the utilization of rock phosphates (RP) or the recovery of P fixed in soil particles. The objective of our study was to evaluate fungal isolates for mechanisms of solubilization of P-bearing compounds, such as AlPO4, FePO4, Ca3(PO4)2, Araxá RP, and Catalão RP. Four fungal isolates obtained from Brazilian soils were characterized in liquid media: Aspergillus niger FS1, Penicillium canescens FS23, Eupenicillium ludwigii FS27, and Penicillium islandicum FS30. A. niger FS1 was the only isolate able to solubilize all of the P sources, solubilizing 71, 36, 100, and 14 % of the P from AlPO4, FePO4, Ca3(PO4)2, and RPs, respectively. Medium acidification was an effective solubilization mechanism, particularly for Ca3(PO4)2. The other P sources were mainly solubilized through organic acids produced by the fungi. Oxalic acid, produced exclusively by A. niger FS1, and citric acid were decisive factors in the solubilization of AlPO4 and FePO4. Penicillium isolates produced more gluconic acid than A. niger FS1 in all treatments. However, this higher production did not result in higher solubilization for any of the P sources, showing that gluconic acid contributes little to the solubilization of the P sources evaluated. The higher capacity of medium acidification and the production of organic acids with stronger metal-complexation activity are characteristics that confer to A. niger FS1 a wider action on insoluble P sources. Consequently, this isolate qualifies as a promising candidate for application in the management of P fertilization.Item Production of Panus strigellus spawn using the internal sheath of Peach Palm (Bactris gasipaes) as a substrate(Interciencia, 2013-10) Vargas- Isla, Ruby; Yuyama, Lucia Kiyoko Ozaki; Aguiar, Jaime Paiva Lopes; Ishikawa, Noemia KazueMycelial growth takes place at elevated temperatures in Panus strigellus, which makes it a promising species for cultivation in tropical regions. The use of locally available substrates is the first step in cost-effective mushroom production. Peach alm, Bactris gasipaes is grown in palm agribusinesses in Amazonas State, Brazil; one of the waste products of this crop is its protective internal sheath (PPIS). The potential use of PPIS for P. strigellus spawn production was evaluated through the analysis in Petri dishes of the effects of substrate moisture and sawdust supplementation levels. Mycelial growth was evaluated by measuring the growth (cm/day) and vigor of the colony. A humidity of 60% and supplementation of Simarouba amara sawdust with PPIS in a 10:1 ratio was considered the most suitable combination. This formulation was applied for spawn preparation in polypropylene bags. Spawn production of P. strigellus was successfully achieved after 25 days of incubation at 35°C.Item Signals of aging associated with lower growth rates in Kluyveromyces lactis cultures under nitrogen limitation(Canadian Journal of Microbiology, 2014) Corrêa, Lygia Fátima da Mata; Passos, Frederico José Vieira; Viloria, Marlene Isabel Vargas; Martins Filho, Olindo Assis; Carvalho, Andréa Teixeira de; Passos, Flávia Maria LopesThe effects of aging on the specific growth rate of Kluyveromyces lactis cultures, as a function of (NH4)2SO4 concentration, were evaluated. The growth kinetic parameters maximum specific growth rate and saturation constant for (NH4)2SO4 were calculated to be 0.44 h−1 and 0.15 mmol·L−1, respectively. Batch cultures were allowed to age for 16 days without influence of cell density or starvation. The specific growth rates of these cultures were determined each day and decreased as the population aged at different nitrogen concentrations. Aging signals (N-acetylglucosamine content of the cell wall, cell dimensions, and apoptosis markers) were measured. Apoptosis markers were detected after 5 days at limiting (NH4)2SO4 concentrations (0.57, 3.80, and 7.60 mmol·L−1) but only after 8 days at a nonlimiting (NH4)2SO4 concentration (38.0 mmol·L−1). Similarly, continuous cultures of K. lactis performed under nitrogen limitation and, at lower dilution rates, accumulated cells exhibiting aging signals. The results demonstrate that aging affects growth rate and raise the question of whether nitrogen limitation accelerates aging. Because aging is correlated with growth rate, and each dilution rate of the continuous cultures tends to select and accumulate cells with a respective age, cultures growing at lower growth rates can be useful to investigate yeast physiological responses, including aging.Item Analysis of Tc1-Mariner elements in Sclerotinia sclerotiorum suggests recent activity and flexible transposases(BMC Microbiology, 2014) Santana, Mateus F.; Silva, José C. F.; Mizubuti, Eduardo S. G.; Araújo, Elza F.; Queiroz, Marisa V.Sclerotinia sclerotiorum is a necrotrophic fungus that is pathogenic to many plants. Genomic analysis of its revealed transposable element expansion that has strongly influenced the evolutionary trajectory of several species. Transposons from the Tc1-Mariner superfamily are thought to be ubiquitous components of fungal genomes and are generally found in low copy numbers with large numbers of deleterious mutations in their transposase coding sequence.This study shows that the genome of S. sclerotiorum has a large number of copies of Tc1-Mariner transposons, and in silico analysis shows evidence that they were recently active. This finding was confirmed by expressed sequence tag (EST) analysis. Fourteen new Tc1-Mariner transposon families that were distributed throughout the genome were identified, and in some cases, due to the excision/retention of introns, different transcripts were observed for the same family, which might be the result of an efficient strategy to circumvent mutations that generate premature stop codons in the RNA sequence. In addition, the presence of these introns shows that the transposase protein has a flexible coding sequence and, consequently, conformation. No evidence for RIP-like gene silencing mechanisms, which are commonly found in fungi, was found in the identified Tc1-Mariner elements, and analysis of the genomic insertion sites of these elements showed that they were widely distributed throughout the genome with some copies located near the 3′ regions of genes. In particular, EST analysis demonstrated that one of these copies was co-expressed with a gene, which showed the potential for these elements to undergo exaptation.Fourteen novel Tc1-Mariner families were characterized. Some families had evidence of introns, which might or might not be excised depending on the family or element in question, and this finding demonstrates a possible strategy for overcoming possible mutations that generate premature stop codons in a RNA sequence. Tc1-Mariner elements likely play an important role in the structure and evolution of the S. sclerotiorum genome.