World Bank assisted National Agricultural Research Project (NARP) - University of Port Harcourt
Abstract
For evaluating the relative effects of some polluting salts on the
measurement of cellulase activity assayed by 3,5-dinitrosalicylate
(DNS) this study was done. Glucose and cellulase solutions have been
treated with salts. Exoglucanase and endoglucanase were assayed by
3,5-dinitrosalicylate reagent. Measurement of reducing sugar by DNS
indicator in the presence of Ca+2, Ba+2, Fe+3, Mn+2, Pb+2, Fe+2, Ag+1,
Zn+2, Co+2, and Al+3 salts overestimated and in the presence of Mg+2,
Cu+2, Cd+2, and Hg+2 salts underestimated the real contents. The
intensity of DNS color and/or the reducing power of glucose increased
by decreasing radius of hydrated cation of alkaline-earth elements
(from Mg+2 to Ba+2) in glucose solution. Exoglucanase and endoglucanase
activities increased in the presence of Na+, K+, Ca+2, Ba+2 and Mn+2
salts and decreased in the presence of NH4+ and Mg+2 salts. Among the
trace elements studied, Fe+3, Pb+2, Fe+2, Ag+1, Zn+2, Co+2, and Al+3
were the most effective inhibitors of cellulase activity. These ions
inhibited exoglucanase more than endoglucanase. The effect of most ions
on cellulase activity may be related to negative or positive effect of
them on the method of cellulase assessment. So, for a better data
interpretation in the study of ion effects on the soil enzyme activity,
both the effects of ions on the method of enzyme assay, and the effects
of ions on the enzyme activity should be studied