LAB REPORT

Name:____________Abigail Glass, Jenn _______________ Lab section: _____14L_

Score: ______ / 27

Section 1: Based on experiments/ procedures completed in the laboratory.

Directions: Answer the short answer questions completely in phrases, sentences or with a drawing. Various point values, 15 pts total.

1. Answer the following pertaining to the TSI (Triple sugar iron) test: (3 pts)

a. Color of slant: pink

b. Color of butt: yellow

c. Was there gas present? no

2. Answer the following pertaining to the SIM (Sulfur, Indole, Motility) test: (3 pts)

a. Was there sulfur reduction? yes

b. Was there indole production?yes

c. Was there motility? no

3. Describe the result on EMB (Eosin methylene blue) agar. (1 pt)

agar colored colonies (no firmentation of lactose)

4. Describe the result on HEK (Hektoen enteric) agar. (1 pt)

yellow and orange growth (fermentation of lactose/sucrose)

5. What color was your inoculated Glucose Phenol Red broth?

a. Red

b. Yellow

c. Other ________________ (write color)

6. What color was your inoculated Sucrose Phenol Red broth?

a. Red

b. Yellow

c. Other ________________ (write color)

7. What color was your inoculated Lactose Phenol Red broth?

a. Red

b. Yellow

c. Other ________________ (write color)

8. What was the result of your catalase test?

a. Bubbles

b. No bubbles

9. What color was your inoculated urease test?

a. Pink/ red

b. Orange/ yellow

c. Other ________________ (write color)

10. What color was your inoculated Simmons citrate slant?

a. Blue

b. Green

11. What color was your inoculated MRVP?

a. Red

b. Yellow

Section 2: Based on lab exercise, videos and research using credible sources. (12pts)

12. All Enteric bacteria have the ability to ferment glucose

a. True

b. False

13. All Enteric bacteria are Gram negative.

a. True

b. False

14. Why must the Simmons citrate tube be incubated for 7 days?

a. All citrate utilizing microbes take 5-6 days to express citrate permease transporter.

b. Citrate diffuses through the medium incredibly slowly which requires a longer incubation period to see the utilization.

c. Some microbes that use citrate have much slower growth rates than what would occur with a carbon source like glucose.

d. The bacteria need time to move through the agar to reach the citrate at the bottom of the tube.

15. If a TSI tube displays a yellow butt and red slant after inoculation, what is the interpretation of this result?

a. Glucose only fermentation

b. Lactose/Sucrose only fermentation

c. Glucose/Lactose/Sucrose fermentation

d. No fermentation

16. If a TSI tube displays a yellow butt and yellow slant after inoculation, what is the interpretation of this result?

a. Glucose only fermentation

b. Lactose/Sucrose only fermentation

c. Glucose/Lactose/Sucrose fermentation

d. No fermentation

17. What is the function of the Durham tube in phenol red broths?

a. Release the carbon source (i.e. lactose, glucose, sucrose) slowly into the medium.

b. Capture the CO2 that some species produce as a byproduct of fermentation.

c. Release the phenol red indicator into the medium.

d. Capture the acids that some species produce as a byproduct of fermentation.

18. Which of the following is a correct interpretation of a MR-VP tube that turns red in color after the addition of methyl red to a tube that has been incubated with an enteric.

a. The microbe produced weak, unstable acids as a byproduct of fermentation, which were buffered by the phosphate buffer, keeping the pH at or above 6.2.

b. The microbe produced strong, stable acids as a byproduct of fermentation, which were buffered by the phosphate buffer, keeping the pH at or above 6.2.

c. The microbe produced weak, unstable acids as a byproduct of fermentation, which were not buffered by the phosphate buffer, allowing the pH to drop to a pH of 4.4 or below.

d. The microbe produced strong, stable acids as a byproduct of fermentation, which were not buffered by the phosphate buffer, allowing the pH to drop to a pH of 4.4 or below.

19. The color changes observed in most of these media occur due to similar biochemical processes. Explain in general why these similar processes and why it is useful to base tests on the observation of a color change. (Hint: think about the HEK, EMB, urease, citrate, TSI and phenol red broths) (3pts)

20. Why must a SIM tube be inoculated with an inoculating needle instead of an inoculating loop. (1pts)

21. As demonstrated with in your flow chart, you used 3 or 4 tests to identify your microbe. Why did we do all of the biochemical tests when 3 or 4 tests can lead to an identification? (2pts)