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Electronic Journal of Biotechnology
Universidad Católica de Valparaíso
ISSN: 0717-3458
Vol. 15, No. 5, 2012
Bioline Code: ej12053
Full paper language: English
Document type: Research Article
Document available free of charge

Electronic Journal of Biotechnology, Vol. 15, No. 5, 2012

 en Characterization of a thermostable extracellular tannase produced under submerged fermentation by Aspergillus ochraceus check for this species in other resources
Gonçalves, Heloísa Bressan; Riul, Alana Jacomini; Quiapim, Andréa Carla; Jorge, João Atílio & Guimarães, Luis Henrique Souza

Abstract

Background: Tannases are enzymes that may be used in different industrial sectors as, for example, food and pharmaceutical. They are obtained mainly from microorganisms, as filamentous fungi. However, the diversity of fungi stays poorly explored for tannase production. In this article, Aspergillus ochraceus check for this species in other resources is presented as a new source of tannase with interesting features for biotechnological applications. Results: Extracellular tannase production was induced when the fungus was cultured in Khanna medium with tannic acid as carbon source. The extracellular tannase was purified 9-fold with 2% recovery and a single band corresponding to 85 kDa was observed in SDS-PAGE. The native apparent molecular mass was estimated as 112 kDa. Optima of temperature and pH were 40ºC and 5.0, respectively. The enzyme was fully stable from 40ºC to 60ºC during 1 hr. The activity was enhanced by Mn2+ (33-39%) and NH4 + (15%). The purified tannase hydrolyzed tannic acid and methyl gallate with Km of 0.76 mM and 0.72 mM, respectively, and Vmax of 0.92 U/mg protein and 0.68 U/mg protein, respectively. The analysis of a partial sequence of the tannase encoding gene showed an open read frame of 567 bp and a sequence of 199 amino acids were predicted. TLC analysis revealed the presence of gallic acid as a tannic acid hydrolysis product. Conclusion:The extracellular tannase produced by A. ochraceus showed distinctive characteristics such as monomeric structure and activation by Mn2+, suggesting a new kind of fungal tannases with biotechnological potential. Further, it was the first time that a partial gene sequence for A. ochraceus tannase was described.

Keywords
Aspergillus ochraceus; gallic acid; tannase; tannic acid; tannin acyl hydrolase

 
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