Plasmid used to construct the first recombinant DNA was isolated from which bacterium species?

Options

A. Escherichia coli
B. Salmonella typhimurium
C. Agrobacterium tumefacines
D. Thermus aquaicus

Explanation

To answer the question about which bacterium species the plasmid used to construct the first recombinant DNA was isolated from, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Context**: The question asks about the source of the plasmid used to create the first recombinant DNA. This is a historical question related to biotechnology.

2. **Identify Key Figures**: The first recombinant DNA technology was developed by scientists Stanley Cohen and Herbert Boyer. They are crucial to this question.

3. **Recall the Bacterial Species**: The options provided are:
- Acerciacoli
- Salmonella Typhimurium
- Agrobacterium Tumefaciens
- Thermus Aquaticus

4. **Research Historical Context**: The first recombinant DNA was created using the plasmid from a specific bacterium. In this case, it is important to remember that Cohen and Boyer used a plasmid from *Salmonella Typhimurium*.

5. **Confirm the Answer**: Based on historical records, the correct answer is that the plasmid used to construct the first recombinant DNA was isolated from *Salmonella Typhimurium*.

### Final Answer:
The plasmid used to construct the first recombinant DNA was isolated from *Salmonella Typhimurium*.