A specific short dextrin-hydrolyzing extracellular glucosidase from the thermophilic fungus Thermoascus aurantiacus 179-5.
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 (alpha-PNPG), and did not hydrolyze sucrose. These properties suggest that the enzyme is a type II alpha-glucosidase. The optimum temperature of the enzyme was 70 degrees . In addition, the enzyme was highly thermostable (100% stability for 10 h at 60 degrees and a half-life of 15 min at 80 degrees), and stable within a wide pH range.
Carvalho
Ana Flávia Azevedo
AF
Laboratory of Biochemistry and Applied Microbiology, IBILCE, Sao Paulo State University, Brazil.
Gonçalves
Aline Zorzetto
AZ
da Silva
Roberto
R
Gomes
Eleni
E
D003470:Culture Media; D003912:Dextrins / Q000378:metabolism*; D004795:Enzyme Stability; D032641:Eurotiales / Q000201:enzymology* / Q000254:growth & development; D005285:Fermentation; D005959:Glucosidases / Q000378:metabolism*; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D013379:Substrate Specificity
D003470:Culture Media; D003912:Dextrins; D005959:Glucosidases