Which one of the following pairs is not correctly matched

Options

A. Streptomyces Antibiotic
B. Serratia Drug addiction
C. Spirulina Single cell protein
D. Rhizobium Biofertilizer.

Explanation

To solve the question "Which one of the following pairs is not correctly matched?", we need to analyze each option provided:

1. **Streptomyces - Antibiotic**
- **Analysis**: Streptomyces is a genus of bacteria known for its ability to produce a wide variety of bioactive secondary metabolites, including antibiotics. Therefore, this pair is correctly matched.

2. **Serratia - Drug Addiction**
- **Analysis**: Serratia is a genus of bacteria that can cause nosocomial infections (hospital-acquired infections). It is not associated with drug addiction. Therefore, this pair is not correctly matched.

3. **Spirulina - Single Cell Protein**
- **Analysis**: Spirulina is a type of cyanobacteria that is rich in proteins and is often used as a dietary supplement, making it a source of single-cell protein. Thus, this pair is correctly matched.

4. **Rhizobium - Biofertilizer**
- **Analysis**: Rhizobium is a genus of bacteria that forms symbiotic relationships with legumes, fixing nitrogen in root nodules. This makes it an important biofertilizer. Hence, this pair is also correctly matched.

**Conclusion**: The pair that is not correctly matched is **Serratia - Drug Addiction**.

### Final Answer:
**Serratia - Drug Addiction** is the pair that is not correctly matched.

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