Which of the following soil bacterium produces a protein/chemical
that is toxic to insect pests?

Options

A. Proteobacteria
B. Bacillus thuringiensis
C. Spirochaetes
D. Trichoderma

Answer

To solve the question of which soil bacterium produces a protein or chemical that is toxic to insect pests, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Options**: The question provides four options:
- A) Proteobacteria
- B) Bacillus thuringiensis
- C) Pyroclites
- D) Trichoderma

2. **Analyze Each Option**:
- **Proteobacteria**: This is a large group of bacteria, but they are not specifically known for producing toxins that target insect pests.
- **Bacillus thuringiensis (Bt)**: This is a well-known soil bacterium that produces crystal proteins (also known as Cry proteins) which are toxic to various insect species. It is widely used as a biopesticide in agriculture, particularly in organic farming.
- **Pyroclites**: This is not a recognized group of bacteria known for any biopesticidal activity.
- **Trichoderma**: This is a genus of fungi, not bacteria, and while it has beneficial uses in agriculture, it does not produce toxins specifically targeting insect pests.

3. **Conclude the Correct Answer**: Based on the analysis, the only option that fits the criteria of producing a protein or chemical toxic to insect pests is **Bacillus thuringiensis**.

### Final Answer:
The correct answer is **B) Bacillus thuringiensis**.

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