![]() Nitrate was not reduced by the organism, it was reduced by zinc. Red color = Negative (Nitrate was not reduced by the bacteria) Nitrate Reduction Test After Adding Sulfanilic Acid, Alpha-Naphthylamine, and Zinc. ![]() No color = Positive (Nitrate was reduced to Nitrogen gas) ![]() Red color = Positive (Nitrate was reduced to Nitrite) Record your reaction and results on the worksheet.Īfter adding sulfanilic acid & alpha-naphthylamine This is considered a positive result since the organism reduced nitrate to nitrogen gas. If a red color does not occur after the addition of zinc, there was no nitrate for zinc to reduce. A red color after the addition of zinc is a negative test result. The zinc powder reduces nitrate to nitrite. If no red color occurs: Dip a wooden applicator stick in zinc powder (just enough to get the stick “dirty”) and drop it into the nitrate broth. ![]() The organism used the nitrate reductase enzyme to reduce nitrate to nitrite. Nitrate Reduction Test After Adding Sulfanilic Acid and Alpha-Naphthylamine. Record your reaction and results on the worksheet. This is a positive test result, and no further testing is required. IMMEDIATELY look for a dark red color which indicates the organism used the nitrate reductase enzyme to reduce nitrate to nitrite. Add 10 drops of 0.8% sulfanilic acid and then add 10 drops of 0.6% N, N-Dimethyl-alpha-naphthylamine. Incubate the nitrate broth in the class test tube rack.ĪFTER INCUBATION –Add reagents to the incubated nitrate broth. Using a sterile inoculating loop, obtain a small amount of bacteria and inoculate the nitrate broth.ģ. Make a tape label writing your name, your assigned culture and the name of the media.Ģ. Other organisms do not have the ability to reduce nitrate at all.ġ. Other bacteria can reduce nitrate to nitrogen gas by also producing the enzyme nitrite reductase which reduces nitrite to nitrogen gas. Some bacteria can reduce nitrate (NO 3) to nitrite (NO 2) by producing the enzyme nitrate reductase. Nitrate broth is used to determine if an organism can reduce nitrate. Each person in the group will work with one of the color dot cultures. Many (but not all) are oxidase positiveįor this exercise: Work in groups of 4.The Non- Enterobacteriaceae also have three common characteristics: The Enterobacteriaceae have four common characteristics: These bacteria are mostly found in the environment, yet some of these organisms can cause wound infections and serious life-threatening infections in immunocompromised patients. Several of the bacteria in this group include bacteria such as Pseudomonas aeruginosa, Alcaligenes faecalis and Acinetobacter baumanii. The Gram-negative bacilli that are not in the Enterobacteriaceae family are composed of several families but are collectively called Non- Enterobacteriaceae or Nonfermenters (of glucose) to differentiate them from the Enterobacteriaceae. These Gram-negative, facultative anaerobes are frequently called “enterics” since they are normally found in the intestinal tract of humans and other animals. coli, Klebsiella, Enterobacter and Proteus. One major group of Gram-negative bacilli is the Family Enterobacteriaceae which contain many genera of organisms such as E. Gram negative bacilli comprise a vast array of bacteria, yet most clinically significant Gram-negative bacilli can be divided into two groups.
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