Which one of the following is used in industrial preparation of ethanol ?

Options

A. Lactobacillus
B. Azotobacter
C. Penicillium
D. Saccharomyces

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks which organism is used in the industrial preparation of ethanol. Ethanol is commonly produced through fermentation processes.

2. **Analyzing the Options**:
- **Option A: Lactobacillus**: This is a type of bacteria that ferments lactose in milk to produce lactic acid. It is not used for ethanol production.
- **Option B: Azotobacter**: This is a free-living nitrogen-fixing bacterium. It helps in fixing atmospheric nitrogen but does not play a role in ethanol production.
- **Option C: Penicillium**: This is a mold known for producing the antibiotic penicillin. It does not contribute to the fermentation process for ethanol.
- **Option D: Saccharomyces**: This is a genus of yeast, specifically Saccharomyces cerevisiae, which is widely used in the fermentation process to convert sugars into ethanol and carbon dioxide.

3. **Identifying the Correct Answer**: Based on the analysis, Saccharomyces cerevisiae is the organism used in the industrial preparation of ethanol through fermentation.

4. **Conclusion**: The correct answer to the question is **Option D: Saccharomyces**.

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