Which of the following bacteria is used as an indicator of water pollution?

Question

Accepted Answer

The correct answer is **4. Coliform**.

**Explanation:**

Coliform bacteria are a group of microorganisms that are commonly found in the environment, including in soil, vegetation, and the intestines of warm-blooded animals. They are used as an indicator of water quality and pollution because their presence in water suggests that there may be contamination by fecal matter, which can carry harmful pathogens.

**Reasoning:**

1. **Coliform Bacteria:**
   - Coliforms, particularly **Escherichia coli (E. coli)**, are the primary indicators of fecal contamination in water. Their presence indicates that the water may contain harmful pathogens that can cause diseases in humans and animals. Testing for coliforms is a standard practice in water quality assessments.

2. **Other Options:**
   - **1. Staphylococcus:** While Staphylococcus bacteria can be found in various environments, they are not typically used as indicators of water pollution. They are more associated with skin infections and food poisoning.
   - **2. Streptococcus:** Similar to Staphylococcus, Streptococcus bacteria are not commonly used as indicators of water pollution. Some species can be pathogenic, but they are not the standard indicators for water quality.
   - **3. Diplococcus:** This term refers to bacteria that occur in pairs, and while some species can cause disease, they are not used as indicators for water pollution.

In summary, coliform bacteria are specifically monitored in water quality testing because they provide a reliable indication of potential contamination and the presence of harmful pathogens, making them the correct answer to the question.