Effects of trace elements on β-glucosaminidase activity in soils

The enzyme β-glucosaminidase (N-acetyl-β-d-glucosaminidase, EC 3.2.1.30) hydrolyzes N-acetyl-β-d-glucosamine residues from the terminal non-reducing ends of chitooligosaccharides in soils. This is one of the enzymes that play a major role in N mineralization in soils. Studies to evaluate the effects of salts of 23 trace elements on the activity of β-glucosaminidase in three Iowa surface (0–15 cm) soils showed that at 5 mmol kg−1 soil, the activity of β-glucosaminidase was inhibited by 18 and activated by five of the trace elements tested. The inhibition values ranged from 0 to 73%, depending on the trace element and the soil used. In general, Ag(I) and Hg(II) were the most effective inhibitors. Other metals that inhibited the β-glucosaminidase activity in soils were Cu(I), Ba(II), Cu(II), Ni(II), Pb(II), Sn(II), Zn(II), As(III), Cr(III), Se(IV), Ti(IV), V(IV), W(VI) and Mo(VI). At the concentration tested, Al(III), Fe(II), and Fe(III) also inhibited the activity of this enzyme. The elements Co(II), Mg(II), Mn(II), B(III) and As(V) activated this enzyme by values ranging from 4 to 68% in three soils.