Question

The organisms involved in yoghurt production are:

• A. Streptococcus thermophilus
• B. Lactobacillus bulgaricus
• C. Streptococcus thermophilus & Lactobacillus bulgaricus
• D. Serratia

Hint:

For the best quality yoghurt, these two bacteria should be present in a 1:1 ratio. If one dominates, the yoghurt may become too sour or lose its characteristic aroma.

Answer 1

The Correct Option is C

Concept: Yoghurt is a fermented milk product produced by a specific symbiotic blend of bacteria.

• Fermentation: The conversion of lactose (milk sugar) into lactic acid.

• Symbiosis: Two organisms working together to grow faster than they would alone.

• Acidity: The resulting acid coagulates the milk proteins, forming a thick gel.

Step 1: Identifying the starter culture.
Yoghurt production requires a thermophilic starter culture. The two essential bacteria are S. thermophilus and L. bulgaricus.

Step 2: Understanding the symbiotic relationship.
S. thermophilus grows first and produces $CO_2$ and formic acid. These products stimulate the growth of L. bulgaricus. In return, L. bulgaricus breaks down proteins to provide amino acids for S. thermophilus.

Step 3: Conclusion.
Since both organisms are necessary to develop the correct flavor and texture: The correct answer is the combination of both bacteria. Final Answer: (C)