197. Commercial production of citric acid is done by fermentation using:
A. Aspergillus niger
B. Clostridium butyricum
C. Saccharomyces cerevisiae
D. Lactobacillus acidophilus

Explanation:

Citric acid is an important organic acid widely used in the food, pharmaceutical, and cosmetic industries. The commercial production of citric acid is mainly achieved by fermentation, and Aspergillus niger, a type of fungus, plays a central role in this process.

✅ Why Aspergillus niger?

• Aspergillus niger is a mold that is known for its ability to produce citric acid efficiently.

• The fungus ferments sugars (such as glucose or sucrose) to produce citric acid as a metabolic product.

• It is particularly effective in large-scale fermentation due to its high yield and adaptability to industrial conditions.

• The fermentation process with A. niger typically occurs in a controlled environment using carbohydrate-rich substrates, resulting in citric acid production.

❌ Why Not the Other Organisms?

• Clostridium butyricum: This bacterium is involved in butyric acid production, not citric acid.

• Saccharomyces cerevisiae: Yeast like S. cerevisiae is primarily used in the production of ethanol and other byproducts like bread and beer, not citric acid.

• Lactobacillus acidophilus: This bacterium is known for its role in dairy fermentation (e.g., yogurt production), but it does not produce citric acid.

Conclusion:

The most widely used organism in the commercial production of citric acid is Aspergillus niger, making it the key player in this fermentation process.