Microbiologia
URI permanente desta comunidadehttps://locus.ufv.br/handle/123456789/11840
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Resultados da Pesquisa
Item Production of pectin lyase by Penicillium griseoroseum in bioreactors in the absence of inducer(Brazilian Journal of Microbiology, 2001-04) Passos, Flávia Maria Lopes; Passos, Frederico José Vieira; Silva, Daison Olzany; Piccoli-Valle, Roberta HilsdorfPenicillium griseoroseum was grown in bioreactors on mineral medium supplemented with yeast extract and sucrose. The influence of inoculum and carbon source concentrations, aeration and pH on pectin lyase (PL) production, as well as the capacity of P. griseoroseum to produce PL when grown on sugar cane syrup as carbon source were evaluated. Inoculum concentration did not influence PL production. Production was higher in non-aerated than in aerated medium. The best results were obtained using 60 mM sucrose at pH 6.3-7.2. Production using cane syrup 25% (v/v), without yeast extract supplement, was equal to that obtained under the conditions cited above.Item Structural organization of polygalacturonase-encoding genes from Penicillium griseoroseum(Genetics and Molecular Biology, 2002) Ribon, Andréa O. B.; Queiroz, Marisa V.; Araújo, Elza F. deThe pectinolytic system of Penicillium griseoroseum has been studied as a model to investigate aspects of gene organization in filamentous fungi. Here we show that the endopolygalacturonase-coding genes previously isolated exist as single copies in the fungus genome. DNA blot analysis revealed the presence of corresponding genes in other Penicillium species, although only one or two genes were found in opposition to the endoPG gene family reported for other filamentous fungi. The nucleotide and amino acid sequences of Penicillium PG genes of retrieved from data banks were compared for intron length and number, codon usage, and consensus sequences for translation initiation sites. The introns are conserved in the same position, although there was no conservation of their nucleotide sequences. Other sequence features resemble those seen in Aspergillus and Neurospora genesItem Fermentation of sweet whey by recombinant Escherichia coli KO11(Brazilian Journal of Microbiology, 2000-07) Leite, Amarildo Ricardo; Guimarães, Walter Vieira; Araújo, Elza Fernandes de; Silva, Daison OlzanyThe production of ethanol from sweet whey using the recombinant Escherichia coli KO11, in batch fermentation, was tested. The maximum ethanol yield was reached after 96h, representing only 38% of the theoretical yield. The supplementation of whey with components of LB broth increased the maximum yield to 96% in 72h. The addition of 0.5% yeast extract to whey resulted in maximum yield of 74% at 36h and it increased to over 100% when yeast extract and trace metals solution (Fe++, Mn++ and Zn++) were added.Item Polymorphism in the internal transcribed spacer (ITS) of the ribosomal DNA of 26 isolates of ectomycorrhizal fungi(Genetics and Molecular Biology, 2002) Gomes, Eliane A.; Kasuya, Maria Catarina M.; Barros, Everaldo G. de; Borges, Arnaldo C.; Araújo, Elza F.Inter- and intraspecific variation among 26 isolates of ectomycorrhizal fungi belonging to 8 genera and 19 species were evaluated by analysis of the internal transcribed sequence (ITS) of the rDNA region using restriction fragment length polymorphism (RFLP). The ITS region was first amplified by polymerase chain reaction (PCR) with specific primers and then cleaved with different restriction enzymes. Amplification products, which ranged between 560 and 750 base pairs (bp), were obtained for all the isolates analyzed. The degree of polymorphism observed did not allow proper identification of most of the isolates. Cleavage of amplified fragments with the restriction enzymes Alu I, Hae III, Hinf I, and Hpa II revealed extensive polymorphism. All eight genera and most species presented specific restriction patterns. Species not identifiable by a specific pattern belonged to two genera: Rhizopogon (R. nigrescens, R. reaii, R. roseolus, R. rubescens and Rhizopogon sp.), and Laccaria (L. bicolor and L. amethystea). Our data confirm the potential of ITS region PCR-RFLP for the molecular characterization of ectomycorrhizal fungi and their identification and monitoring in artificial inoculation programs.Item Electrophoretic characterization ofaspergillus nidulans strains with chromosomal duplications(Genetics and Molecular Biology, 2000-06) Queiroz, Marisa V. de; Pizzirani-Kleiner, Aline Aparecida; Azevedo, João LúcioPulsed-field gel electrophoresis was used to characterize strains ofAspergillus nidulans with a chromosomal duplication Dp(I-II). Morphologically deteriorated and improved variants of these strains were also analyzed. The electrophoretic karyotype demonstrated that in two duplicated strains (A and B) the 4.2 Mb band, which corresponds to chromosome II, was absent and a new band was observed. Hybridization studies using the uapA (chromosome I) and wA (chromosome II) genes demonstrated that the new band corresponded to chromosome II plus the duplicated segment of chromosome I. The size of the chromosomal duplication was approximately 1.0 Mb. Analysis of the chromosomal bands of a morphologically improved strain showed that the duplicated segment of chromosome I was completely lost. The morphologically deteriorated variants V9 and V17 had the same karyotype as the duplicated strains. However, the deteriorated variant V5 lost part of chromosome I and had a rearrangement involving chromosome V. This rearrangement may have resulted from the mutagenic treatment used to obtain the genetic markers. Pulsed-field gel electrophoresis was found to be an excellent tool for locating chromosomal rearrangements.Item Influência de doses de calcário com diferentes relações cálcio: magnésio na produção de matéria seca e na composição mineral da alfafa(Pesquisa Agropecuária Brasileira, 2002-12) Gomes, Fernando Teixeira; Borges, Arnaldo Chaer; Neves, Júlio César Lima; Fontes, Paulo Cezar RezendeA acidez dos solos brasileiros, com alumínio em níveis tóxicos e baixa disponibilidade de elementos essenciais, principalmente o fósforo, exige aplicações de calcário e fertilizantes para a adequada utilização agrícola. Este trabalho objetivou avaliar o efeito de quatro doses de calcário calculadas com base no teor de Al3+ trocável do solo e em cinco relações molares de Ca:Mg, na produção de matéria seca e na composição mineral da alfafa. Duas cultivares de alfafa, Flórida 77 e Crioula, foram cultivadas em Latossolo Vermelho-Amarelo álico, textura argilosa, em casa de vegetação, em esquema fatorial disposto no delineamento inteiramente casualizado, com quatro repetições. A produção de matéria seca da parte aérea das duas cultivares aumentou em razão do aumento das doses de calcário, e somente a cultivar Flórida 77 apresentou diferenças significativas entre as relações molares Ca:Mg. Os teores de Ca, Mg e N na matéria seca da parte aérea, de modo geral, aumentaram em razão do aumento na quantidade de calcário, sendo somente os teores de Ca e Mg alterados pelas diferentes relações molares de Ca:Mg. Os teores de P e K, de modo geral, apresentaram pequenos decréscimos com a elevação das doses de calcário, embora considerados satisfatórios para a nutrição da alfafa.Item Molecular characterization and evaluation of pectinase and cellulase production of Penicillium spp.(Biotechnology Letters, 2002-05) Pereira, Jorge Fernando; Queiroz, Marisa Vieira de; Gomes, Eliane Aparecida; Muro-Abad, Júpiter Israel; Araújo, Elza Fernandes dePenicillium species were analyzed with molecular markers and for pectinase and cellulase production. RAPD and PCR-RFLP analysis indicated high polymorphism among at least 5 of 10 Penicillium species. Five species were chosen for pectinase and cellulase production in liquid medium and four of which appeared similar based on molecular analyses. P. brevicompactum and P. griseoroseum gave the highest pectinase production and were highly divergent by molecular techniques.Item Differential expression of polygalacturonase-encoding genes from Penicillium griseoroseum in different carbon sources(Journal of Industrial Microbiology and Biotechnology, 2002-06-14) Ribon, A. O. B.; Queiroz, M. V.; Coelho, J. L. C.; Araújo, E. F deA second polygalacturonase - encoding gene ( pgg2 ) of Penicillium griseoroseum was cloned and consists of an opening reading frame of 1107 bp after removal of two introns. The gene encodes a protein of 369 amino acids with a predicted molecular mass of 38.3 kDa. The deduced protein sequence exhibited high homology with other fungal endopolygalacturonases. A polymerase chain reaction ( PCR ) - based strategy was used to study the expression patterns of pgg1 and pgg2 genes under different culture conditions and our results show that both genes are regulated by the carbon source at the transcriptional level. The pgg1 transcript was detected at 76 h of fungal growth in pectin while the pgg2 transcript was also induced by sucrose. The addition of yeast extract to glucose medium abolished the repressive effect of glucose, suggesting that the transcription of these genes is controlled by different mechanisms.Item Development of a transformation system for Crinipellis perniciosa, the causal agent of witches' broom in cocoa plants(Current Genetics, 2002-12-17) Lima, Juliana Oliveira; Santos, Jildete Karla dos; Pereira, Jorge Fernando; Resende, Mário Lúcio Vilela de; Araújo, Elza Fernandes de; Queiroz, Marisa Vieira deProtoplasts of the pathogenic plant fungus, Crinipellis perniciosa, were transformed to hygromycin B resistance using the pAN7-1 plasmid, which contains the Escherichia coli hph gene under the control of Aspergillus nidulans regulatory sequences. The pAN7-1 plasmid was introduced by PEG/CaCl2 treatment. Transformation frequencies of 1.6–2.5 transformants/μg of DNA were achieved. About 54% of the transformants were abortive and 40 analyzed transformants were mitotically stable and showed different hygromycin B resistance levels. The presence of the hph gene was checked by PCR in five transformants and the integration of multiple plasmid copies into different genome sites was observed by Southern analysis. This is the first report of a C. perniciosa transformation system and represents an important step for further research into genetic manipulation of this fungal plant pathogen.Item The high fermentative metabolism of Kluyveromyces marxianus UFV-3 relies on the increased expression of key lactose metabolic enzymes(Antonie van Leeuwenhoek, 2001-11-09) Diniz, Raphael H. S.; Silveira, Wendel B.; Fietto, Luciano G.; Passos, Flávia M. L.The aim of this work was to obtain insights about the factors that determine the lactose fermentative metabolism of Kluyveromyces marxianus UFV-3. K. marxianus UFV-3 and Kluyveromyces lactis JA6 were cultured in a minimal medium containing different lactose concentrations (ranging from 0.25 to 64 mmol l−1) under aerobic and hypoxic conditions to evaluate their growth kinetics, gene expression and enzymatic activity. The increase in lactose concentration and the decrease in oxygen level favoured ethanol yield for both yeasts but in K. marxianus UFV-3 the effect was more pronounced. Under hypoxic conditions, the activities of β-galactosidase and pyruvate decarboxylase from K. marxianus UFV-3 were significantly higher than those in K. lactis JA6. The expression of the LAC4 (β-galactosidase), RAG6 (pyruvate decarboxylase), GAL7 (galactose-1-phosphate uridylyltransferase) and GAL10 (epimerase) genes in K. marxianus UFV-3 was higher under hypoxic conditions than under aerobic conditions. The high expression of genes of the Leloir pathway, LAC4 and RAG6, associated with the high activity of β-galactosidase and pyruvate decarboxylase contribute to the high fermentative flux in K. marxianus UFV-3. These data on the fermentative metabolism of K. marxianus UFV-3 will be useful for optimising the conversion of cheese whey lactose to ethanol.