Vouges-Proskaur Test Is The Presence Of Acetylmethylcarbinol After Glucose Infection

The following tests according to the lab manual were performed: gram stain, fermentation tubes, methyl red, vogues proskauer, sulfur, indole, motility and growing it up on MacConkey agar. The gram stain was performed incorrectly the first time. This is because the decolorizer was not on the bacterium slide for long enough, giving a false outcome.

The Voges-Proskauer test to detect organisms that are able to ferment glucose, but convert the products to acetoin and 2,3-butanediol. This is deduced by the addition of Reagent A and Reagent B, and the observation of the color change thereafter. Reagent A is a solution of -naphthol and alcohol. Reagent A catalyzes the conversion of acetoin to diacetyl. Diacetyl thens react with guanidine-containing compounds from the peptone to form a red color in the presence of -naphthol. Reagent B is a solution of potassium hydroxide and water. It

The null hypothesis will be that the test tubes with an increase in temperature, pH values, enzyme concentrations, and substrate concentration will have a very small color change or no color change at all. The alternate hypothesis is that the test tubes containing an increase in temperature, pH values, enzyme concentrations, and substrate concentration will all have an intense color change; the more the change, the more intense the color change will be.

After carefully taking them out, observe each test tubes color and then fill Table 2 with the results.

This test is used to detect if the bacteria contains any deoxyribonuclease activity. Because no color change was observed from blue to clear my unknown bacteria displayed a negative result.

To perform this test, a tube of broth rich with glucose is acquired. In this tube is phenol red, a pH indicator. Initially, the tube appeared pink in color, indicating a normal pH level. Next, a sample of unknown #44 is introduced into this medium using the aseptic technique, and this is allowed to sit for several days. If the organism is able to ferment glucose, the pH in the medium would decrease and cause the phenol red to exhibit a yellow color. In addition to the straw color, gas can also be produced and trapped inside the Durham tube placed in the medium. This production of acid and gas is a direct result of the fermentation of glucose, as seen with unknown

For the Urease test, I incoluated my Urea test tube with my unkown bacteria from a TSA plate using and inoculating loop. The Urea tube was then incubated at 37 degrees Celsius for 8 days to observe for a color change. The Urea tests for the ability of a bacteria grown in urea broth produces urease. This medium contains the pH indicator phenol red. If urease is produced the pH of the media will raise thus causing the phenol red to change from yellow to a pink color.

The bases of this experiment was to discover the identify of the unknown from three possible specimens: Klebsiella pneumonia, Escherichia coli, and Enterobacter aerogenes. Utilizaing the T streak technique, the bacteria was isolated into pure colonies for further study. The Gram Stain method was used to identity the morhphology of the bacteria such as the shape and whether the bacteria was Gram positive or Gram negative. Biochemical test were also used to help identify the unknown bacteria. The biochemical test used was the Triple Sugar Iron Agar, Sulfur Indole Motility test, Methyl Red test, Voges-Proskauer test, Citrate test, Urease test, and the Gelatin test. After observing the morphology of the bacteria using the Gram Stain method and utilizing all the possible biochemical test, the bacteria was identified to be Enterobacter aerogenes.

The purpose of this assignment was to correctly identify an unknown bacterium, labeled #76, which was provided by the lab instructor. After a series of experiments and lab techniques were performed, the unknown sample was classified as Citrobacter Freundii (C. freundii). C. freundii was first discovered in 1932 by Werkman and Gillen (Collier, Balows, & Sussman, 1998). It is a facultative anaerobic gram-negative bacilli identified in the Enterbacteriaceae family (Holt, Kreig, Sneath, Staley, & WIlliams, 1994).

Citrate positive: growth will be visible on the slant surface and the medium will be an intense Prussian blue. The alkaline carbonates and bicarbonates produced as by-products of citrate catabolism raise the pH of the medium to above 7.6, causing the bromothymol blue to change from the original green colour to

The pH indicator in this medium is phenol red, and as mannitol sugar is used, the acid produced changes the pH indicator to yellow around the individual colonies. [2]

Incubate the bacteria for about 24 hours and then begin testing. If hydrogen sulfide is present, it will react with the sodium thiosulfate in the medium and the indicator, ferric ammonium citrate, to produce ferrous sulfide which falls out of solution as a blackish precipitate. The presence of hydrogen sulfide typically means that the bacteria produces the enzyme cysteine desulfanase which breaks up the cysteine in the medium into hydrogen sulfide. A positive result will turn the medium black. If the result is negative then the medium will stay semi-clear.

After the 30 minutes, the color was observed and recorded on the data sheet. The dialysis tubing was removed from the beaker and a small slice was made, we then used a glucose indicator strip to test for the presence of glucose, along with the solution in the beaker. The results were then recorded in table 1on the data sheet.

With the results of the Starch Hydrolysis Test I preceded to the final test which is the Citrate Test. Using aseptic technique, I streaked the organism onto the surface of the Simmons’ citrate slant and let it incubate overnight at 37°C. The Citrate Test determines if the organism is able to

VP test (a.k.a. butanediol fermentation test) contains peptone, glucose, and a phosphate buffer in its media, which is the same media as the MR test (Stout et al, 47). To perform the VP test, I used the stabbing technique to inoculate the VP media. I