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1.
Rev. iberoam. micol ; 23(3): 189-191, sept. 2006. tab, ilus
Artigo em Inglês | IBECS | ID: ibc-75388

RESUMO

Several microorganisms are reported to have transfructosylation activity due to fructosyltransferase and/or fructofuranosidase activities. However, the search for other fungi with higher transfructosylation activity remains a challenge. So, a presumptive and indirect colorimetric plate assay for the evaluation of transfructosylation activity in fungi was developed which involved the simultaneous determination in the same plate of glucose and fructose released from sucrose. The method entailed the (a) glucose oxidase-peroxidase coupled reaction using phenol and 4-aminoantipyrine for determination of glucose; and (b) fructose dehydrogenase oxidation in the presence of a tetrazolium salt for determination of fructose. The presence of enzymes with transfructosylation activity was identified by the formation of pink (presence of glucose) and blue (presence of fructose) halos around the fungal colony. In conclusion, the results showed that the method is suitable for screening a large number of fungi due to its simplicity, reproducibility and rapidity and also gives a relative quantitative idea of the transfructosylation activity of different fungi species(AU)


Assuntos
Colorimetria/métodos , Proteínas Fúngicas/análise , Fungos/enzimologia , Hexosiltransferases/análise , Microbiologia Industrial/métodos , Micologia/métodos , Ampirona , Ascomicetos/enzimologia , Desidrogenases de Carboidrato/metabolismo , Compostos Cromogênicos/análise , Frutose/metabolismo , Fungos/isolamento & purificação , Especificidade da Espécie , Tiazóis , Fenol , Oligossacarídeos/biossíntese
3.
Int. microbiol ; 4(4): 217-222, dic. 2001. ilus, tab
Artigo em Inglês | IBECS | ID: ibc-163516

RESUMO

A total of 12 non-epidemiologically related clinical isolates of Streptococcus mitis that showed different levels of resistance to penicillin were studied. Membrane-protein profiles and penicillin-binding protein (PBP) patterns showed a great polymorphism; and patterns of 4-7 PBPs, with sizes that ranged from approximately 101 kDa to approximately 40 kDa, were detected in each strain. No association could be found between PBP pattern and resistance level to penicillin among these isolates. Arbitrarily primed PCR confirmed the genetic diversity among this group of streptococci. One of the isolates of intermediate level of resistance to penicillin, which showed a PBP pattern similar to that of the high-resistance strains, was used as a laboratory model to analyse the mechanism underlying high-resistance acquisition by these strains. A 14-fold increase in penicillin resistance was obtained after a single selection step, which resulted in a decrease in penicillin affinity for PBP1. The size of this PBP (92 kDa) and the differences in PBP profiles of the penicillin-resistant clinical isolates suggest the existence in S. mitis of PBP-mediated mechanisms to acquire high-level resistance to penicillin, among which alterations in PBP1 seem to play a main role, in contrast to the PBP2X mediated mechanism described for other streptococci (AU)


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Assuntos
Humanos , Hexosiltransferases , Proteínas de Bactérias , Penicilinas/farmacologia , Resistência às Penicilinas , Peptidil Transferases , Muramilpentapeptídeo Carboxipeptidase/análise , Mutação , Proteínas de Membrana/análise , Polimorfismo Genético , Testes de Sensibilidade Microbiana , Eletroforese em Gel de Poliacrilamida , Proteínas de Ligação às Penicilinas
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