What is the Difference Between Autochthonous and Zymogenous Bacteria?

Autochthonous and zymogenous bacteria are two categories of soil bacteria based on their nutritional differences, distribution, and growth patterns. The main differences between them are as follows:

• Distribution: Autochthonous bacteria are native or indigenous bacteria that are uniformly spread and relatively constant throughout the soil. In contrast, zymogenous bacteria require an external source of energy and are present in the soil in lower numbers than autochthonous bacteria. Their population fluctuates and increases when an external energy source is introduced into the soil.
• Growth: Autochthonous bacteria can grow in soil with a limited source of energy and are generally found in high numbers in the soil. Zymogenous bacteria, on the other hand, need external energy resources or easily oxidizable organic substrates for their growth.
• Population Dynamics: Autochthonous bacteria exhibit the growth kinetics of population Z, with a low ^max but relatively low Ks (i.e., a high substrate affinity). Zymogenous bacteria are typically dominant in soil microenvironments such as the early rhizosphere, where they grow rapidly on simple C substrates (primarily glucose).

Examples of autochthonous bacteria include Arthrobacter spp., which derive their food from native soil organic matter. Pseudomonas spp. bacteria are an example of zymogenous bacteria, as they are present in the soil in lower numbers and fluctuate in response to nutrient availability.

Comparative Table: Autochthonous vs Zymogenous Bacteria

The main differences between autochthonous and zymogenous bacteria are their nutritional requirements and growth characteristics. Here is a table summarizing these differences:

In summary, autochthonous bacteria are native soil bacteria that grow and metabolize under scarce nutrient resources, while zymogenous bacteria require easily oxidizable organic materials for growth and show rapid growth when high energy-containing nutrients are added.