Dropbox Assignment #2 for Week 6: Nitrate reduction phenol red Nitrate Test 1. Explain why "zinc to pink" is a negative result. What happened in the tube? 2. Complete the table by including your observations and interpretations of the following three cultures. All are pure cultures inoculated into the nitrate reduction broth and incubated for at least 48hrs until the culture was turbid. Be sure to read under the 'organism' column what reagents (= chemicals), if any, have been added to the culture post incubation. Organism Nitrite reduction Observations and interpretations broth culture Pseudomonas Observations (what do you seeot see) aeruginosa *no reagents have been Interpretations (what do the observations indicate added to the about the organism? culture Escherichia coli Observations (what do you seeot see) * only naphthalamine sulfanilic acid Interpretations (what do the observations indicate added about the organism? Alcaligenes Observations (what do you seeot see) faecalis naphthalamine sulfanilic acid Interpretations (what do the observations indicate added (no color about the organism? change). Then powdered zinc added Phenol Red Broths/Glucose Fermentation Test 1. Explain how the phenol red broth test is differential. *more on next page2. List the two most common general types of byproducts and then list what key ingredient in the phenol red broth allows for their detection. 3. A student inoculated a phenol red (PR) glucose broth with an unknown organism and after 24 hours the broth was a distinct hot pink. Explain (1) why the broth is pink and (2) why this ts a negative result for glucose fermentation