Coliform Bacteria Testing Procedures

The video tutorial discusses the role of E. coli in public health and ecosystems, highlighting its presence in the digestive systems of endotherms and its use as an indicator species. It explains the process of collecting and testing water samples for bacterial contamination, focusing on the membrane filter technique to detect coliform bacteria. The tutorial provides detailed instructions on preparing samples and plates for analysis, incubating them, and counting bacterial colonies to assess water quality.

What is the primary role of E. coli in the intestines of endotherms?

• To cause digestive distress

• To produce toxins

• To aid in food digestion

• To act as a pathogen

Which strain of E. coli is known to be pathogenic and can cause severe health issues?

• B2

• K12

• C600

• O157:H7

Why is E. coli used as an indicator species in water testing?

• It is the only bacterium found in water

• It is the least harmful bacterium

• It is the most dangerous bacterium

• It is easy to detect and indicates the presence of other pathogens

What is the purpose of the membrane filter technique in water testing?

• To purify water

• To measure water temperature

• To detect the presence of coliform bacteria

• To remove all bacteria from water

What color do total coliform bacteria colonies appear after incubation?

• Yellow

• Green

• White

• Blue or red with a metallic sheen

What is the first step in preparing samples for coliform analysis?

• Incubating the samples

• Labeling the petri plates

• Counting bacterial colonies

• Pouring nutrient broth

Why is it important to not turn on the suction pump before pouring the sample into the filter?

• It will contaminate the sample

• It will make the sample too cold

• It will result in clumps of bacteria instead of individual colonies

• It will cause the filter to break

At what temperature should the total coliform plate be incubated?

• 25°C

• 35°C

• 45°C

• 55°C

How should you calculate the number of bacteria per 100 mL if you used 50 mL of sample?

• Multiply by 5

• Multiply by 10

• Multiply by 20

• Multiply by 2

What should you do before leaving the lab after completing the water testing process?

• Turn off the incubator

• Re-label the petri plates

• Wash your hands

• Count the bacterial colonies again