| Autor: |
Masui DC; Departamento de Biologia, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, 14040-901, Brazil. dcmasui@usp.br, Zimbardi AL, Souza FH, Guimarães LH, Furriel RP, Jorge JA |
| Jazyk: |
angličtina |
| Zdroj: |
World journal of microbiology & biotechnology [World J Microbiol Biotechnol] 2012 Aug; Vol. 28 (8), pp. 2689-701. Date of Electronic Publication: 2012 May 29. |
| DOI: |
10.1007/s11274-012-1079-1 |
| Abstrakt: |
Humicola brevis var. thermoidea cultivated under solid state fermentation in wheat bran and water (1:2 w/v) was a good producer of β-glucosidase and xylanase. After optimization using response surface methodology the level of xylanase reached 5,791.2 ± 411.2 U g(-1), while β-glucosidase production was increased about 2.6-fold, reaching 20.7 ± 1.5 U g(-1). Cellulase levels were negligible. Biochemical characterization of H. brevis β-glucosidase and xylanase activities showed that they were stable in a wide pH range. Optimum pH for β-glucosidase and xylanase activities were 5.0 and 5.5, respectively, but the xylanase showed 80 % of maximal activity when assayed at pH 8.0. Both enzymes presented high thermal stability. The β-glucosidase maintained about 95 % of its activity after 26 h in water at 55 °C, with half-lives of 15.7 h at 60 °C and 5.1 h at 65 °C. The presence of xylose during heat treatment at 65 °C protected β-glucosidase against thermal inactivation. Xylanase maintained about 80 % of its activity after 200 h in water at 60 °C. Xylose stimulated β-glucosidase activity up to 1.7-fold, at 200 mmol L(-1). The notable features of both xylanase and β-glucosidase suggest that H. brevis crude culture extract may be useful to compose efficient enzymatic cocktails for lignocellulosic materials treatment or paper pulp biobleaching. |
| Databáze: |
MEDLINE |
| Externí odkaz: |
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