Indole Test Lab Report
Citrate Test:
Some bacteria can use citrate as a source of carbon. To test if the unknown bacteria uses citrate as a source of carbon, Simmon’s citrate agar was used as the medium on which the bacteria was grown. The Simmon’s citrate agar consists of sodium citrate as the source of carbon, ammonium dihydrogen phosphate as the source of nitrogen along with pH indicator such as bromothymol blue.
Procedure:
The Citratase activity was detected by inoculating the unknown bacteria on the slant surface of Simmon’s citrate agar. Followed by overnight incubation at 37°C. Day after the slant was observed for a change in color.
Results:
Two results can be acquired in the citrate test, positive and negative. The positive result indicate growth with the …show more content…
Indole Test:
Procedure:
We obtained a tube of tryptic soy broth (tsb) and inoculated it with our unknown bacteria. Then placed our tube in the incubator at 37 oC and allowed for it to grow overnight; the following day we came back to finish our confirmatory test. To do so, we added 10 drops of Kovac’s reagent to the tube and watched for a color change.
Results:
A positive test, indicated by a red/pink layer, is due to the tryptophan being hydrolyzed producing indole, pyruvic acid, and ammonia. The Kovac’s reagent indicates solely the presence of indole because the bacteria will use the pyruvic acid and ammonia for nutritional needs. A negative test is indicated by the lack of a red/pink color; this indicates that the bacteria does not contain the enzyme tryptophanase, therefore, they cannot hydrolyze tryptophan resulting in the lack of indole production. Once we added the Kovac’s reagent we observed the formation of a red/pink layer indicating that indole was produced.
Confirmatory …show more content…
Growth indicated that the bacteria grown was gram-negative, whereas no growth indicated that the bacteria grown was gram-positive. Whereas no color change inferred that the bacteria grown can’t ferment lactose whereas color change to pink inferred that the bacteria grown can ferment lactose. The results acquired by our test was positive with color change to pink. Hence the unknown bacteria was gram-negative and can ferment lactose. Amongst Escherichia coli and Proteus vulgaris, the result MacConkey agar confirmed that the unknown bacteria was Escherichia
Some bacteria can use citrate as a source of carbon. To test if the unknown bacteria uses citrate as a source of carbon, Simmon’s citrate agar was used as the medium on which the bacteria was grown. The Simmon’s citrate agar consists of sodium citrate as the source of carbon, ammonium dihydrogen phosphate as the source of nitrogen along with pH indicator such as bromothymol blue.
Procedure:
The Citratase activity was detected by inoculating the unknown bacteria on the slant surface of Simmon’s citrate agar. Followed by overnight incubation at 37°C. Day after the slant was observed for a change in color.
Results:
Two results can be acquired in the citrate test, positive and negative. The positive result indicate growth with the …show more content…
Indole Test:
Procedure:
We obtained a tube of tryptic soy broth (tsb) and inoculated it with our unknown bacteria. Then placed our tube in the incubator at 37 oC and allowed for it to grow overnight; the following day we came back to finish our confirmatory test. To do so, we added 10 drops of Kovac’s reagent to the tube and watched for a color change.
Results:
A positive test, indicated by a red/pink layer, is due to the tryptophan being hydrolyzed producing indole, pyruvic acid, and ammonia. The Kovac’s reagent indicates solely the presence of indole because the bacteria will use the pyruvic acid and ammonia for nutritional needs. A negative test is indicated by the lack of a red/pink color; this indicates that the bacteria does not contain the enzyme tryptophanase, therefore, they cannot hydrolyze tryptophan resulting in the lack of indole production. Once we added the Kovac’s reagent we observed the formation of a red/pink layer indicating that indole was produced.
Confirmatory …show more content…
Growth indicated that the bacteria grown was gram-negative, whereas no growth indicated that the bacteria grown was gram-positive. Whereas no color change inferred that the bacteria grown can’t ferment lactose whereas color change to pink inferred that the bacteria grown can ferment lactose. The results acquired by our test was positive with color change to pink. Hence the unknown bacteria was gram-negative and can ferment lactose. Amongst Escherichia coli and Proteus vulgaris, the result MacConkey agar confirmed that the unknown bacteria was Escherichia