The following organism because of its easy culture methods is widely used as bacteriology indicator of water pollution –
**Core Concept**
The question is testing the student's knowledge of bacteriological indicators of water pollution, specifically the use of an organism that is easily cultured and serves as an indicator of water quality.
**Why the Correct Answer is Right**
The organism in question is likely E. coli, which is a common indicator of fecal contamination in water. E. coli is easily cultured on agar plates and is a reliable indicator of water pollution because its presence suggests the presence of other pathogens. The presence of E. coli in water is often used as a proxy for the presence of other enteric pathogens.
**Why Each Wrong Option is Incorrect**
* **Option A:** Some organisms, like Salmonella, can also be used as indicators of water pollution, but they are not as easily cultured as E. coli and are not as commonly used.
* **Option B:** Pseudomonas aeruginosa is a common opportunistic pathogen, but it is not typically used as an indicator of water pollution.
* **Option C:** Staphylococcus aureus is a common skin commensal and can be found in water, but it is not a reliable indicator of water pollution.
**Clinical Pearl / High-Yield Fact**
It's worth noting that E. coli is a gram-negative, facultative anaerobe that is commonly found in the human gut, and its presence in water is often used as a proxy for fecal contamination.
**Correct Answer: D. E. coli**