Which organism is commonly used as an indicator in water quality assessment?

Escherichia coli (E. coli) is commonly used as an indicator organism in water quality assessments due to its significant role in identifying fecal contamination in water. E. coli is a type of coliform bacteria that is normally found in the intestines of warm-blooded organisms, including humans. The presence of E. coli in water samples is a strong indicator that fecal matter may be present, which can carry pathogens causing waterborne diseases.

This makes E. coli an effective measure for assessing the microbiological safety of water, as it is relatively easy to test for and its detection indicates a potential risk to human health from other pathogens that are much harder to detect directly. Moreover, E. coli is consistently present in high numbers in feces, making it a reliable indicator of the degree of fecal contamination.

While other organisms listed may have their roles in microbiology and health, they do not serve the same purpose or provide the same level of assurance for fecal contamination in water quality assessments. For instance, Salmonella typically indicates a specific type of infection and does not serve as a general indicator for fecal pollution, while Staphylococcus and Lactobacillus are not associated with fecal contamination or water quality assessments in the