The poisonous substances comonly produced by bacteria are known as

Options

A. Antibiotics
B. Toxins
C. Antigens
D. Allergens.

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks for the poisonous substances that are commonly produced by bacteria.

2. **Analyzing the Options**: The options provided are:
- Antibiotics
- Toxins
- Antigens
- Allergens

3. **Identifying the Correct Answer**:
- **Antibiotics**: These are substances used to kill or inhibit the growth of bacteria, not produced by bacteria as poisons.
- **Toxins**: These are poisonous substances produced by bacteria. This is a strong candidate.
- **Antigens**: These are substances that induce an immune response, not necessarily poisonous.
- **Allergens**: These are substances that cause allergic reactions, not specifically produced by bacteria as poisons.

4. **Confirming the Correct Answer**: The correct answer is **Toxins**. Toxins are indeed the poisonous substances produced by bacteria.

5. **Understanding Types of Toxins**:
- **Exotoxins**: These are toxins secreted by both gram-positive and gram-negative bacteria. They are heat-sensitive and can be destroyed by heat. An example is the toxin from the bacterium that causes tetanus.
- **Endotoxins**: These are found in the outer membrane of gram-negative bacteria and are released when the bacteria die. They are heat-stable and less toxic compared to exotoxins. An example is the toxin from meningococcinia.

6. **Conclusion**: The answer to the question is **Toxins**, as they are the poisonous substances produced by bacteria.

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