Myrosinase immobilized by plant root-mucigel: effect of soil water status on the enzyme efficiency

Water plays an important role in the native conformation and activity of myrosinase. At the rhizosphere level, water exists in three phases namely, that associated with mucigel, free water in soil solution, and water adsorbed on soil particles. The activity of myrosinase was investigated as a function of soil water status by adding the enzyme to soil either in water solution form or immobilized in the hydrogel of one of the most important root mucigel polysaccharides. At high soil moisture, water and hydrogel-delivered myrosinase activities were comparable whereas in water stressed soil, the activity of myrosinase immobilized on hydrogel was twice as high as that allowed by water delivery. The mucigel-related increase in myrosinase activity could be ascribed to the polarization of water molecules within the hydrogel system, which prevents them from being adsorbed on soil particles and hence available to preserve the enzyme active conformation.