Base de dados : LILACS
Pesquisa : D08.811.520.241.300.050 [Categoria DeCS]
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Fotocópia
Id: lil-333171
Autor: Majolli, M. V; Aguirre, S. N.
Título: Efecto de metales traza sobre la morfología celular, actividad enzimßtica y producción de ácido cítrico en una cepa de Aspergillus wentii / Effect of trace metals on cell morphology, enzyme activation, and production of citric acid in a strain of Aspergillus wentii
Fonte: Rev. argent. microbiol;31(2):65-71, abr.-jun. 1999.
Idioma: es.
Resumo: Data concerning the effect of very low concentrations of metals on citric acid production by microorganisms, as well as on the activity of enzymes presumptively involved in the process, are confuse. The bulk of information was obtained mainly studying selected strains of Aspergillus niger. Information concerning other citric acid producer filamentous fungi, such as A. wentii, is scanty. In the present article we report the effect of different cations on the growth pattern of A. wentii P1 as well as on the related citric acid production and the activity of several enzymes. It was found that without any addition to the culture medium the fungus developed a pelleted form of growth, pellets being about 1.5 mm in diameter. The citric acid yield was about 90. The addition of Cu2+ impaired the sugar uptake, as well as the production of citric acid and biomass. The uptake of sugar increased in the presence of Zn2+, and there was a marked increase of the biomass production, which could account for the low citric acid production. The addition of Fe2+ impaired the citric acid production and, as sulfate, the sugar uptake. The presence of Fe3+ markedly impaired the citric acid production and increased the sugar uptake. There is no agreement about the enzymes involved in the accumulation of citric acid by microorganisms. In spite of this, aconitase (Ac), isocitrate lyase (IL), isocitrate dehydrogenase NAD(+)-dependent (ICDH- NAD+) and isocitrate dehydrogenase NADP(+)-dependent (ICDH-NADP+) are often postulated as key enzymes. In our case, these enzymes were active during the standard fermentation, although with variations, particularly concerning Ac and IL. The behavior of enzymes might be different when tested in vivo or in vitro, mainly from the quantitative point of view. Nevertheless, the activity determined in vitro might give some indication concerning the effect on fermentation of substances present in the medium. It was found that all the enzymes tested increased their activity in the presence of Fe2+ and Fe3+. The addition of Cu2+ improved the activity of Ac, IL and ICDH-NADP+, while that of ICDH-NAD+ was impaired. The presence of Zn2+ decreased the activity of the enzymes excepting that of ICDH-NADP+ which increased. It must be pointed out that according to these results there are differences concerning the behavior of ICDH-NAD+ and ICDH-NADP+ in the presence of Cu2+ or Zn2+.
Descritores: Ácido Cítrico/metabolismo
Aspergillus
Oligoelementos
-Aconitato Hidratase
Aspergillus
Carboidratos
Cobre
Fermentação/efeitos dos fármacos
Ferro
Isocitrato Desidrogenase
Isocitrato Liase
Isoenzimas
Proteínas de Bactérias/análise
Zinco
Tipo de Publ: Estudo Comparativo
Research Support, Non-U.S. Gov't
Responsável: BR1.1 - BIREME


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Fotocópia
Azevêdo, Eliane S
Silva, Maria Christina B. O
Id: lil-33710
Autor: Azevêdo, Eliane S; Souza, Maria das Graças de F; Silva, Maria Christina B. O.
Título: Estudos genéticos e fisiopatológicos da placenta humana e mola hidatiforme / Genetic and physiopathological studies of human placenta and hydatidiform mole
Fonte: Rev. bras. genét = Braz. j. genet;8(2):405-19, Jun. 1985.
Idioma: pt.
Resumo: Apresenta-se uma revisäo das diversas linhas de pesquisa em genética e fisiopatologia da placenta humana e mola hidatiforme. Enfase especial é dada à revisäo dos trabalhos sobre polimorfismos genéticos placentários e aspectos genéticos da mola hidatiforme. Além das consideraçöes sobre o conhecimento atual em placenta humana säo também apresentados resultados de trabalhos pertinentes desenvolvidos no Brasil
Descritores: Aconitato Hidratase/metabolismo
Fosfatase Alcalina/metabolismo
Mola Hidatiforme/genética
Placenta/enzimologia
Polimorfismo Genético
Limites: Gravidez
Humanos
Feminino
Responsável: BR1.1 - BIREME



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