Dehydrogenase activity is a good index of biological activity of soil because it plays a role in:
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Dehydrogenase activity cannot exist in dead cells or as an extracellular enzyme.
This makes it a highly sensitive indicator of live, active microbial biomass in the soil, unlike enzymes like urease which can exist outside of cells.
Step 1: Understanding the Concept:
Soil enzymes serve as key indicators of soil health and microbiological activity.
Dehydrogenase is an intracellular enzyme found only within viable, active microbial cells.
Unlike other extracellular soil enzymes, it does not persist in a free state in the soil matrix after cell death. Step 2: Detailed Explanation:
Dehydrogenase enzymes catalyze the oxidation of organic substances by transferring protons and electrons from organic substrates to acceptors.
This transfer is a core biochemical step in the respiratory pathways (electron transport chain) of all aerobic and facultative anaerobic soil microorganisms.
Because dehydrogenase is directly involved in microbial respiration (B), its activity correlates with the rate of oxygen consumption, carbon dioxide release, and active microbial biomass in the soil.
Consequently, measuring dehydrogenase activity in a laboratory provides an accurate, reliable index of the total living, breathing microbial population and overall biological activity of the soil.
While respiration is linked to carbon metabolism (A), the specific biological role of dehydrogenase is in the electron transfer chain of respiration.
It does not play a direct role in macromolecule synthesis (C) or cell division (D). Step 2: Final Answer:
Dehydrogenase activity is a good index of soil biological activity because it plays a key role in respiration.
