Which bacterium can not grown on synthetic media

Options

A. E.coli
B. Lactobacillus
C. Rhizobium
D. Mycobacterium leprae

Answer

To answer the question "Which bacterium cannot grow on synthetic media?" we will analyze the options provided: E. coli, Lactobacillus, Rhizobium, and Mycobacterium leprae.

### Step-by-Step Solution:

1. **Understanding Synthetic Media**:
- Synthetic media is a type of culture medium that is artificially prepared in a laboratory. It does not contain any living cells or tissues.

2. **Identifying Bacterial Types**:
- Bacteria can be categorized based on their growth requirements:
- **Intercellular Parasites**: These bacteria can grow outside of host cells. They can survive and proliferate in the extracellular environment.
- **Obligate Intracellular Parasites**: These bacteria can only survive and reproduce inside host cells. They cannot grow outside of a living host.

3. **Analyzing Each Option**:
- **E. coli**: This bacterium is an intercellular parasite and can grow on synthetic media. It thrives in the gastrointestinal tract of animals.
- **Lactobacillus**: Also an intercellular parasite, Lactobacillus can grow on synthetic media and is found in the oral and intestinal tracts.
- **Rhizobium**: This bacterium is an intercellular parasite found in the root nodules of legumes and can also be cultured on synthetic media.
- **Mycobacterium leprae**: This bacterium is an obligate intracellular parasite. It cannot survive outside of host cells and therefore cannot be cultured on synthetic media. It requires live animal inoculation for growth.

4. **Conclusion**:
- Based on the analysis, the bacterium that cannot grow on synthetic media is **Mycobacterium leprae**.

### Final Answer:
**Mycobacterium leprae**