Question

In an experiment to examine the role of exopolymetric substances (EPS) on bacterial growth, a wild-type strain (S⁺) and a mutant strain deficient in EPS production (S⁻) were grown in monocultures as well as in co-culture (in equal proportion of S⁺ and S⁻). The CFU (colony forming units) of these cultures measured after 24 hours are shown in the following figure. 

Which one of the following phenomena best describes the interaction between the wild-type strain (S⁺) and mutant strain (S⁻)? 
 

• A. Amensalism
• B. Cooperation
• C. Commensalism
• D. Mutualism

Hint:

In cooperative interactions, both organisms benefit from the relationship, unlike in mutualism where both gain benefits, or amensalism where one organism is harmed.

Answer 1

The Correct Option is B

Step 1: Understanding the interaction.
In the context of the interaction between the two strains, Cooperation refers to a relationship where both organisms benefit, potentially by producing substances like EPS that aid in growth.
Step 2: Analyzing the figure.
In co-culture, the growth of both the wild-type (S⁺) and mutant (S⁻) strains is enhanced compared to monoculture growth, suggesting a cooperative interaction where the EPS produced by the wild-type strain benefits the mutant strain.
Step 3: Conclusion.
Therefore, the best description of the interaction is Cooperation (B).