The linamarase of Mucor circinelloides LU M40 and its detoxifying activityon cassava

Mucor circinelloides LU M40 produced 12.2 mU ml(-1) of linamarase activity when grown in a 3 1 fermenter in the following optimized medium (g l(-1) de ionized water): pectin, 10.0; (NH4)(2)SO4, 1.0; KH2PO4, 2.0; Na2HPO4, 0.7; MgSO4. 7H(2)O, 0.5; yeast extract, 1.0; Tween-80, 1.0, added after 48 h of fermentation. The purified linamarase was a dimeric protein with a molecula r mass of 210 Kda; the enzyme showed optimum catalytic activity at pH 5.5 a nd 40 degrees C and had a wide range (3.0-7.0) of pH stability. The enzyme substrate specificity on plant cyanogenic glycosides was wied; the K-m valu e for linamarin was 2.93 mmol l(-1). The addition, before processing, of th e fungal crude enzyme to cassava roots facilitated and shortened detoxifica tion; after 24 h of fermentation, all cyanogenic glycosides were hydrolysed .