Question

Starter interaction where one species is inhibited by the removal of essential nutrients or formation of toxic metabolites

• A. Amensalism
• B. Commensalism
• C. Competition
• D. Parasitism

Hint:

Microbial Interaction Models:
AMENSALISM (-, 0) = One species inhibited by toxic metabolites/bacteriocins of another.
COMMENSALISM (+, 0) = One benefits, other unaffected.
PROTO-COOPERATION (+, +) = Synergistic mutual benefit (Yoghurt culture).

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Microbial ecology in mixed dairy starter cultures: amensalism (antagonism) is an asymmetric biological interaction where one population is suppressed or killed by inhibitory metabolites (bacteriocins, organic acids, $ ext{H}_2 ext{O}_2$) synthesized by another species.
Key Formula or Approach:
\[ \text{Amensal Interaction } (-, 0): \text{Producer Organism (Unaffected / 0)} \xrightarrow{\text{Synthesizes Bacteriocins/H}_2\text{O}_2} \text{Target Organism (Inhibited / -)} \]

Step 2: Detailed Explanation:
In the microbial ecology and interspecific interactions of dairy starter consortia:
1. Amensalism (Antagonism) (A): An ecological interaction in which one microbial species is unfavorably affected, suppressed, or killed by the metabolic products (such as lactic acid, hydrogen peroxide, diacetyl, or bacteriocins like nisin) or by the aggressive depletion of growth-limiting trace amino acids/peptides by a co-cultured strain, while the producing organism remains unaffected (a $(-, 0)$ relationship).
2. Commensalism: One species benefits while the other is unaffected ($(+, 0)$, e.g., L. bulgaricus liberating valine/leucine for S. thermophilus in yoghurt proto-cooperation).
3. Competition: Mutually negative contest for identical nutrients ($(-, -)$).
4. Parasitism: One organism derives benefit at the direct expense of the host ($(+,-)$).

Step 3: Final Answer:
Therefore, the interaction described is Amensalism, corresponding to option (A).