Page 65 - Enzymes in Tropical Soils

Enzymes in Tropical Soils 53

1982; Tabatabai and Fu, 1992). Some modification are used; for example the
modification in the incubation temperature (Salam et al.,1998d). The analysis of
enzymatic activities in general follows the procedure shown in Fig. 4.11 and involve
nine components, i.e. soil sample, microbial stopping solution, substrate, buffer
solution, temperature controller (incubator), enzyme stopper, exctracting solution,
standard solution, and measuring equipment. For the case of phosphatase
analysis, the substrate is p-nitrophenyl phosphate (p-NPP), the microbial stopper is
toluene, the enzyme stopper is NaOH solution, the buffer is the modified universal
buffer, the extracting solution is CaCl 2 , and the standard is p-nitrophenol.

Steps Notes
1 Usually 1 g 105 C oven-dry equivalent
o
Soil Sample

2 + Microbial Stopper To stop the activity of microorganisms producing
the related enzyme; for particular enzyme analysis
such as urease, added after incubation

3
+ Substrate

4 To buffer the system at a particular pH value;
+ Buffer Solution particularly for those that are pH-dependent

After a gentle mixing, the system is incubated for 1
hour at a particular value of temperature using
incubator

5 To stop the work of enzyme in catalyzing the
+ Enzyme Stopper reaction

6 To extract the enzyme adsorbed on the soil
+ Extracting Solution adsorptive sites

7 To separate the liquid from the soil solid
+ Filtrate

8 To indirectly measure the concentration of enzyme
+ Measurement by measuring a particular compound such as p-
nitrophenol in phosphatase analysis

Fig.4.11. The general procedure of enzymatic analyses.

Abdul Kadir Salam - 2014