Which organism must be present for a bacti sample to fluoresce?

The presence of Escherichia coli in a bacti sample is crucial for fluorescence because this organism contains a specific enzyme called glucuronidase. When E. coli is present and is acted upon by fluorogenic substrates, it breaks these substrates down, leading to the production of fluorescence. This property is often used in various testing methods to identify and quantify E. coli, especially in water and wastewater samples.

In contrast, the other organisms listed do not typically show this specific fluorescence response. While they are important pathogens in different contexts, they lack the specific enzymatic activity necessary for the fluorescence reaction associated with the substrates used in these assays. Therefore, the detection of E. coli through fluorescence is a valuable method in wastewater analysis for indicating contamination levels and potential health risks.