The principle microorganism for yogurt is:
The principle microorganism for yogurt is:
Select an option to attempt
Correct Answer: Option A
Explanation
Principal microorganism in yogurt production:Yogurt is produced by bacterial fermentation of milk. The two principal organisms used together:1. Streptococcus thermophilus: gram-positive, homofermentative; grows at 42–45°C; produces lactic acid and acetaldehyde.2. Lactobacillus delbrueckii subsp. bulgaricus: gram-positive, homofermentative; protease activity releases peptides that stimulate S. thermophilus.Synergistic relationship:• L. bulgaricus produces free amino acids (especially valine and histidine) from casein → stimulates growth of S. thermophilus.• S. thermophilus produces formate and CO₂ → stimulates L. bulgaricus.• Together they produce more lactic acid faster than either alone.Legal standard in many countries: yogurt MUST contain both organisms.Among the given options, Streptococcus thermophilus is identified as the principal organism in yogurt.Answer: Streptococcus thermophilus is the principal microorganism in yogurt production (synergistic with L. bulgaricus).