Which of the following act as decomposers in an ecosystem ?

Options

A. Lactobacillus bacteria
B. Cyanobacteria
C. Purifying bacteria
D. Rhizobium bacteria

Answer

To determine which of the following acts as decomposers in an ecosystem, we need to analyze each option provided.

### Step-by-Step Solution:

1. **Understand the Role of Decomposers**:
Decomposers are organisms that break down dead or decaying organic matter, returning essential nutrients to the ecosystem.

2. **Evaluate the First Option - Lactobacillus Bacteria**:
- Lactobacillus is primarily known for its role in fermentation, particularly in converting milk into yogurt.
- **Conclusion**: Lactobacillus does not act as a decomposer.

3. **Evaluate the Second Option - Cyanobacteria**:
- Cyanobacteria, also known as blue-green algae, are primarily involved in photosynthesis and nitrogen fixation in certain plants.
- They do not decompose organic matter but rather contribute to nutrient cycling by fixing nitrogen.
- **Conclusion**: Cyanobacteria do not act as decomposers.

4. **Evaluate the Third Option - Purifying Bacteria**:
- Purifying bacteria are involved in the decomposition of organic waste, especially in sewage treatment processes.
- They break down organic materials and help purify water by decomposing waste.
- **Conclusion**: Purifying bacteria act as decomposers.

5. **Final Answer**:
- Among the options provided, **Purifying bacteria** are the ones that act as decomposers in an ecosystem.