Microbial linamarases for the detoxification of vegetable products

Fifty-eight strains of Penicillium, known to produce interesting concentrat ions of pectolytic activities, were screened for linamarase and amygdalase activity in culture broths. Seven strains were active at a level of interes t for further investigations. Penicillium aurantiogriseum (P35) was selecte d for optimization of enzyme production. Likewise, 75 strains of food-grade organisms (lactic acid bacteria, yeasts, and filamentous fungi) were inves tigated for their ability to degrade amygdalin. Among 16 effective degrader s Mucor circinelloides (M40) proved to also degrade linamarin effectively. The enzymes from P. aurantiogriseum (called PGI and PGII) were characterize d with respect to molecular weight, temperature and H optimum and stability , substrate affinities, and inhibitors. The molecular weights were estimate d to be approximately 247 and 147 kDa, respectively. Both enzymes showed pH optimum at 6.0; the optimum temperature (60 degrees C) of PGII was higher than that of PGI (55 degrees C). A wide ra of cyanogenic glycosides were hy drolyzed bs both of these enzymes. The apparent K-m, values for prunasin, a mygdalin, 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 P-glycosidases, and for the detoxification of food and feeds that contain toxic glycosides, such as linamarin in cassava.