Which of the following is not used to transfer the recombinant `DNA` into the host ?

Options

A. 1) Micro-injection method
B. 2) Gene gun method
C. 3) Bioreactor
D. 4) Disarmed pathogen vectors

Explanation

To determine which of the following options is not used to transfer recombinant DNA into a host, we will analyze each option provided:

1. **Microinjection Method**:
- This method involves directly injecting recombinant DNA into the nucleus of the host cell using a fine glass needle.
- Since this method is specifically designed for transferring DNA into cells, it is indeed used for this purpose.

2. **Gene Gun Method**:
- In this technique, high-velocity microparticles coated with recombinant DNA are shot into the host cells.
- This method is also effective for transferring DNA into cells, making it a valid method for recombinant DNA transfer.

3. **Bioreactor**:
- A bioreactor is a vessel where biological reactions occur, often used for culturing cells or microorganisms.
- It does not involve the direct transfer of recombinant DNA into host cells. Instead, it is a controlled environment for growing cells or producing biological products. Therefore, this method is not used for transferring recombinant DNA.

4. **Disarmed Pathogen Vectors**:
- This method utilizes modified pathogens that cannot cause disease but can still deliver recombinant DNA into host cells through infection.
- This is a recognized method for transferring recombinant DNA into hosts.

Based on the analysis, the option that is **not used** to transfer recombinant DNA into the host is:

**Answer: Option 3 - Bioreactor**