RESUMO
A thermotolerant and halotolerant strain of Pycnoporus sanguineus was isolated from an oil-polluted site in a tropical area located in Veracruz, Mexico. This strain was able to grow at 47 degrees C and in culture medium containing 500 mM NaCl. The strain was also tolerant to the presence of 30,000 ppm of crude Maya oil. A 68-kDa protein purified from submerged cultures exhibited laccase activity towards 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS), guaiacol, syringaldazine, and o-dianisidine, for which it presented the highest affinity (Km = 43 microM). Two-dimensional gel electrophoresis analysis showed that, unusual for laccases, the enzyme has two active isoforms, with isoelectric points of 7.00 and 7.08. The purified enzyme showed high thermostability, retaining 40% of its original activity after 3 h at 60 degrees C. This property seems to correlate with a long "shelf-life," given that at 40 degrees C enzyme activity was only gradually lost over a 5-day period incubation. Both the fungus and its laccase are likely to have high potential for biotechnological applications.
Assuntos
Poluição Ambiental , Temperatura Alta , Lacase/biossíntese , Petróleo , Casca de Planta/microbiologia , Polyporaceae/enzimologia , Ecossistema , Estabilidade Enzimática , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Isoenzimas/biossíntese , Isoenzimas/química , Isoenzimas/isolamento & purificação , Lacase/química , Lacase/isolamento & purificação , México , Polyporaceae/genética , Polyporaceae/isolamento & purificação , Polyporaceae/fisiologia , Cloreto de Sódio/farmacologia , Especificidade por Substrato , Clima TropicalRESUMO
Seventy-five fungal strains from different groups of basidiomycetes, newly isolated from rotten wood, were screened for pectinolytic activity. Despite the fact that basidiomycetes are scarcely referred to as pectinase producers, the polygalacturonase (PG) activity was detected in 76% of the strains; 16% with activity higher than 40 nkat/g, 40% between 13.3 and 40 nkat/g, and 44% with activity lower than 13.3 nkat/g. The highest productions were obtained among the fungi from order Aphyllophorales, family Polyporaceae. The characterization of the enzymes from the highest PG producers (Lentinus sp., Gloeophyllum striatum, Pycnoporus sanguineus, Schizophyllum commune) showed optimum temperature for catalytic activity at 60-70 degrees C and two peaks of pH optimum (3.5-4.5 and 8.5-9.5). The enzymes exhibited high pH stability (3.0-11.0) but after incubation at 40 degrees C for 1 h their activity dropped by 18-73%.
Assuntos
Basidiomycota/enzimologia , Basidiomycota/metabolismo , Pectinas/metabolismo , Poligalacturonase/metabolismo , Madeira , Basidiomycota/isolamento & purificação , Microbiologia Ambiental , Estabilidade Enzimática , Concentração de Íons de Hidrogênio , Lentinula/enzimologia , Lentinula/isolamento & purificação , Lentinula/metabolismo , Polyporaceae/enzimologia , Polyporaceae/isolamento & purificação , Polyporaceae/metabolismo , Schizophyllum/enzimologia , Schizophyllum/isolamento & purificação , Schizophyllum/metabolismo , TemperaturaRESUMO
Foi observado que na cultura de Pycnoporus sanguineus MIP 89007, a síntese de substâncias com atividade antimicrobiana ocorreu principalmente entre o 18§. e o 23§. dia de incubaçäo. Além disso, foi também constatado que a substância produzida foi rapidamente degradada quando permaneceu no caldo de cultura após ter cessado a síntese e que os extratos obtidos a partir do fungo somente retiveram a atividade quando mantidos à vácuo