The microbe used for the commercial production of ethanol is

Options

A. Clostridium butylicum , a bacterium
B. Aspergillus niger , a fungus
C. Lactobacillus , a bacterium
D. Saccharomyces cerevisiae , a fungus

Answer

To solve the question regarding the microbe used for the commercial production of ethanol, we will analyze each option provided:

1. **Option A: Clostridium butylicum**
- This is a bacterium that is primarily involved in the production of butyric acid. It does not play a significant role in the production of ethanol.

**Hint:** Remember that Clostridium butylicum is associated with butyric acid, not ethanol.

2. **Option B: Aspergillus niger**
- This is a fungus known for its role in the production of citric acid. It is not used for the commercial production of ethanol.

**Hint:** Aspergillus niger is linked to citric acid production, not ethanol.

3. **Option C: Lactobacillus**
- This is a bacterium that ferments lactose into lactic acid, which is essential in the process of curdling milk. It does not produce ethanol.

**Hint:** Lactobacillus is important for lactic acid production in dairy, not for ethanol.

4. **Option D: Saccharomyces cerevisiae**
- This is a fungus that is widely used in the commercial production of ethanol. It ferments sugars (like glucose) into ethanol under anaerobic conditions (absence of oxygen).

**Hint:** Saccharomyces cerevisiae is the key organism for ethanol production through fermentation.

**Conclusion:**
The correct answer is **D. Saccharomyces cerevisiae**, as it is the microbe used for the commercial production of ethanol.

### Summary of Steps:
1. Analyze each option provided.
2. Identify the primary products associated with each microbe.
3. Determine which microbe is specifically known for ethanol production.
4. Conclude with the correct answer based on the analysis.