Abstract: Through incubation test, the kinetic characteristics of catalase and dehydrogenase in Black soil (Phaeozem, FAO), albic soil (albic luvisols, FAO), brown soil (Cambisols, FAO) and cinnamon soil (Haplic Greyxems, FAO) were studied under 3 installed soil moisture conditions, i.e., wilting point, 60% of field capacity and saturated water content. The study showed that the kinetics of both catalase and dehydrogenase in test soils exhibited typical Michaelis-Menten kinetic behaviors. The 2 soil intracellular enzymes had larger Km values than corresponding pure enzymes, indicating their weaker enzyme-substrate affinity in soil. For catalase, its Km value was much smaller in black soil and albic soil than in brown soil and cinnamon soil, due to the greater differences of soil organic matter content among the soils and possibly, different origins. The Km and Vmax values of the catalase decreased with increasing soil moisture content and its catalytic ability (Vmax/Km value) was the largest at 60% of field capacity in black soil, albic soil and brown soil and at saturated water content in cinnamon soil. As for dehydrogenase, its Km value had smaller differences under different soil moisture conditions, but its Vmax and Vmax/Km increased with increasing soil moisture content, showing that soil moisture content had less effect on its enzyme-substrate affinity but affected its catalytic ability. There was a significant positive correlation between dehydrogenase Vmax/Km and soil organic matter content, showing that organic soil exhibited a higher dehydrogenase catalytic ability than mineral soil.
Lili Zhang , W.U. Zhijie , Lijun Chen , Yong Jiang and L.I. Dongpo , 2009. Kinetics of Catalase and Dehydrogenase in Main Soils of Northeast China under Different Soil Moisture Conditions. Agricultural Journal, 4: 113-120.