A specific short dextrin-hydrolyzing extracellular glucosidase from the thermophilic fungus Thermoascus aurantiacus 179-5

• Autor(a) principal: Azevedo Carvalho, Ana Flávia [UNESP]
• Data de Publicação: 2006
• Outros Autores: Zorzetto Gonçalves, Aline [UNESP], Da Silva, Roberto [UNESP], Gomes, Eleni [UNESP]
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Institucional da UNESP
• Texto Completo: http://www.ncbi.nlm.nih.gov/pubmed/16820757; http://hdl.handle.net/11449/69425
• topic: Glucosidase; Solid-state fermentation; Submerged fermentation; Thermoascus; Thermophilic; Thermostable; Fungi; Manihot esculenta; Thermoascus aurantiacus; Triticum aestivum; dextrin; glucosidase; culture medium; enzyme specificity; enzyme stability; enzymology; Eurotiales; fermentation; growth, development and aging; heat; hydrolysis; metabolism; pH; Culture Media; Dextrins; Enzyme Stability; Fermentation; Glucosidases; Heat; Hydrogen-Ion Concentration; Hydrolysis; Substrate Specificity

The thermophilic fungus Thermoascus aurantiacus 179-5 produced large quantities of a glucosidase which preferentially hydrolyzed maltose over starch. Enzyme production was high in submerged fermentation, with a maximal activity of 30 U/ml after 336 h of fermentation. In solid-state fermentation, the activity of the enzyme was 22 U/ml at 144 h in medium containing wheat bran and 5.8 U/ml at 48 h when cassava pulp was used as the culture medium. The enzyme was specific for maltose, very slowly hydrolyzed starch, dextrins (2-7G) and the synthetic substrate (α-PNPG), and did not hydrolyze sucrose. These properties suggest that the enzyme is a type II α-glucosidase. The optimum temperature of the enzyme was 70°C. In addition, the enzyme was highly thermostable (100% stability for 10 h at 60°C and a half-life of 15 min at 80°C), and stable within a wide pH range. Copyright © 2006, The Microbiological Society of Korea.