| Abstrakt: |
The effects of medium composition on the production of β-glucosidase (amygdalase and linamarase) by Penicillium aurantiogriseumP35 were studied and the medium optimized as follows (g/l of deionized water): pectin, 10.0; (NH4)2SO4, 8.0; KH2PO4, 8.0; Na2HPO4, 2.8; MgSO4•7H2O, 0.5; yeast extract, 4.0; initial pH 6.0. When grown in a bench fermenter on this medium, the fungus produced 50.5 mU of amygdalase and 9.4 mU of linamarase per ml of culture broth. Two β-glucosidases (PGI and PGII), each having amygdalase and linamarase activities, were recovered from the culture broth and purified; their relative molecular weights, as native enzymes, were estimated to be about 247000 and 147000, respectively. Both enzymes showed the same optimum pH (6.0) but different optimum temperatures (55 and 60°C for PGI and PGII, respectively). Thermostability (10 min at 60°C) and half-life of enzyme activity (7 hours at 60°C) of PGII were higher than those of PGI (10 min at 50°C and 2 hours at 55°C, respectively). A wide range of cyanogenic glycosides (such as tetraphyllin B, epivolkenin, gynocardin, passibiflorin, prunasin, taxiphyllin, amygdalin, lucumin, sambunigrin, dhurrin, linamarin and cardiospermin sulfate) were hydrolyzed by both enzymes. |
