Natural genetic engineer is: Bacillus subtills Pseudomonas sp. Escherichia coli Agrobacterium tumefaciens

Options

A. Bacillus subtills
B. Pseudomonas sp.
C. Escherichia coli
D. Agrobacterium tumegaciens

Answer

To determine which organism is referred to as the "natural genetic engineer," we can analyze the options provided:

1. **Bacillus subtilis**: This is a gram-positive bacterium that can cause diseases in humans but is not primarily known for its role in genetic engineering.

2. **Pseudomonas sp.**: This group of gram-negative bacteria is also associated with various diseases in humans and other organisms. They are not typically used in genetic engineering or gene transfer methods.

3. **Escherichia coli (E. coli)**: While E. coli is a beneficial bacterium found in the human gut and is used in laboratory settings for cloning and genetic engineering, it is not considered a natural genetic engineer.

4. **Agrobacterium tumefaciens**: This is a soil-borne pathogen known for its unique ability to transfer a segment of its DNA (tDNA) from its Ti-plasmid into the host plant cells. This process leads to the formation of tumors (crown gall disease) in plants. Because of its ability to naturally transfer genetic material into plant cells, it is referred to as a "natural genetic engineer."

**Conclusion**: The correct answer is **Agrobacterium tumefaciens**.

### Step-by-Step Solution:
1. **Identify the organisms listed**: Look at each of the four options provided.
2. **Analyze the role of each organism**: Determine if they are involved in genetic engineering or gene transfer.
3. **Evaluate Agrobacterium tumefaciens**: Recognize its unique ability to transfer DNA into plant cells.
4. **Conclude**: Based on the analysis, conclude that Agrobacterium tumefaciens is the natural genetic engineer.