QUESTIONS Name DATA SHEET 5-2 (continued) ate ab Section as present and performe

Question

QUESTIONS Name DATA SHEET 5-2 (continued) ate ab Section as present and performed this exercise (initials) 4 Assuming you tested an organism using the three carbohydrate broths and a base broth, which of the combinations of results in the following table would be reliable? Interpret each of the combinations and explain why the results are reliable or not. Assume all tubes in a series were inoculated with the same amount of organism and were incubated for 24 hours. Base PR Glucose PR Lactose PR Sucrose Reliable? Y/N (explain why, if not) Interpretation A/G A/G A/G A/G A/G

Explanation / Answer

This question is based on carbon fermentation. When the base medium is supplemented with carbohydrate source, bacteria utilize the carbohydrate and produce acidic byproducts. The presence of pH indicator in the broth changes the color of the medium and based on this change we can interpret the results.

Bacteria which utilize carbohydrate and produce acidic byproduct and gas are designated as A/G. Those bacteria which produce only acidic byproduct are designated as A/- and those which are non-fermentors and non-gas producers are designated as -/-.

Now let us interpret the given data:

PR glucose PR lactose PR sucrose Interpretation Reliable? Y/N A/G A/G A/G The organism was able to utilize glucose, lactose, and sucrose. It produced acidic byproduct and gas. This organism can grow in anaerobic condition. Yes A/- A/- -/- The organism was able to utilize glucose and lactose. But, it failed to utilize sucrose. It did not produce acidic byproduct and gas. In presence of glucose and lactose, the organism produced an acidic byproduct No. The same organism was used for the experiment and it was incubated for 24 hours. In the first and third set, same results were obtained. In this set, the results were not matching. There might be an experimental error while performing the experiment. So, this result is not reliable. A/G A/G A/G The organism was able to utilize glucose, lactose, and sucrose. It produced acidic byproduct and gas. Yes

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