Question

What is the most common technique used to test the present of coliforms (fecal pollution) in water system!!!

Answer 1

The most commonly used fecal contamination indicators are total and thermotolerant coliforms, Escherichia coli and enterococci. That is, use as indicator microorganisms those that have a behavior similar to pathogens in terms of concentration in water and reaction to environmental factors, but are easier, faster and cheaper to identify. Once the presence of these indicator groups has been demonstrated, it can be inferred which pathogenic microorganisms are present and their behavior against different factors such as pH, temperature, presence of nutrients and water retention time.

The group of coliform microorganisms is suitable as an indicator of fecal contamination because they are part of the normal microbiota of the gastrointestinal tract, both of the human being and of the homoeothermic animals and are present in large quantities in it.

Thermotolerant coliforms, so called because they withstand temperatures up to 45 ° C, comprise a very small number of microorganisms, which are indicators of quality by origin. They are mostly represented by E. coli, but the species Citrobacter freundii and Klebsiella pneumoniae can be found. They are better hygiene indicators in food and water. The presence of these microorganisms indicates the existence of fecal contamination of human or animal origin, since the feces contain thermotolerant coliforms that are present in the intestinal microbiota, with E. coli being the most representative.

The technique of membrane filtration can be used to get the phage content and subsequently through the methodology of single layer using tryptic soy agar modified.