Abstract
Fifty-eight strains of Penicillium, known to produce interesting concentrations of pectolytic activities, were screened for linamarase and amygdalase activity in culture broths. Seven strains were active at a level of interest for further investigations. Penicillium aurantiogriseum (P35) was selected for optimization of enzyme production. Likewise, 75 strains of food-grade organisms (lactic acid bacteria, yeasts, and filamentous fungi) were investigated for their ability to degrade amygdalin. Among 16 effective degraders Mucor circinelloides (M40) proved to also degrade linamarin effectively. The enzymes from P. aurantiogriseum (called PGI and PGII) were characterized with respect to molecular weight, temperature and H optimum and stability, substrate affinities, and inhibitors. The molecular weights were estimated to be approximately 247 and 147 kDa, respectively. Both enzymes showed pH optimum at 6.0; the optimum temperature (60°C) of PGII was higher than that of PGI (55°C). A wide range of cyanogenic glycosides were hydrolyzed by both of these enzymes. The apparent Km values for prunasin, amygdalin, and linamarin of PGI were approximately 0.43, 0.47, and 2.41 mM, respectively, and those of PGII were 0.13, 0.11, and 2.32 mM, respectively. Thus, filamentous fungi, [among which are P. aurantiogriseum (P35) and M. circinelloides (M40)] are candidates for the production of ?-glycosidases, and for the detoxification of food and feeds that contain toxic glycosides, such as linamarin in cassava.
