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Mucor circinelloides LU M40 produced 12·2 mU ml−1 of linamarase activity when grown in a 3 l fermenter in the following optimized medium (g l−1 deionized water): pectin, 10·0; (NH4)2SO4, 1·0; KH2PO4, 2·0; Na2HPO4, 0·7; MgSO4.7H2O, 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 molecular mass of 210 kDa; the enzyme showed optimum catalytic activity at pH 5·5 and 40 °C and had a wide range (3·0–7·0) of pH stability. The enzyme substrate specificity on plant cyanogenic glycosides was wide; the Km value for linamarin was 2·93 mmol l−1. The addition, before processing, of the fungal crude enzyme to cassava roots facilitated and shortened detoxification; after 24 h of fermentation, all cyanogenic glycosides were hydrolysed.

Mucor circinelloides LU M40 and Penicillium aurantiogriseum P 35 produce extracellular beta-glycosidases that are active on the cyanogenic glycoside amygdalin. From the culture broths of M. circinelloides, only one beta-glycosidase could be identified, while two different enzymes - both having amygdalase activity - were found in culture broths of P. aurantiogriseum. The study of the mechanism of hydrolysis of the beta-bis-glycoside amygdalin with purified enzymes from the two organisms indicated a possible sequential (two-step) reaction. In all cases, the first step of hydrolysis from amygdalin to prunasin was very rapid, while the second step from prunasin to cyanohydrin was much slower. No cyanohydrin lyase activity was found in the culture broths of either fungus.