Week of 3/4

Introduction


Due to the Gibson assembly falling through, we have decided instead to make our project on the characterization of Deinococcus xinjiangensis through biochemical testing. The following tests will be done:


  1. Urease test: tests for presence of enzyme urease through observing for the breakdown of urea into carbon dioxide and ammonia byproducts.

  2. Indole test: tests for the presence of enzyme tryptophanase through observing for the breakdown of tryptophan into indole and pyruvate byproducts.

  3. Starch test: tests for the presence of enzyme amylase through observing for the breakdown of starch into glucose and maltose byproducts.

  4. Catalase test: Tests for the presence of enzyme catalase through observing for the breakdown of hydrogen peroxide into water and oxygen gas.

  5. Oxidase test: tests for the presence of enzyme cytochrome oxidase through observing for the breakdown of oxidase solution into water and hydrogen peroxide byproducts.

  6. Hydrogen sulfide test: tests for a bacteria’s ability to break down sulfur-containing molecules into hydrogen sulfide. This is typically done either by the enzyme cysteine desulfurase or by anaerobic respiration.

  7. Citrate test: tests for the bacteria’s ability to break citrate down into pyruvate and carbon dioxide byproducts.


Procedure


I have been placed in charge of performing the indole test. The procedure is as follows:

  • Create SIM agar using premade SIM mix and deionized water.

  • Prepare and autoclave six test tubes for the experimental and control.

  • Inoculate the negative control bacteria into two of the tubes, the positive control bacteria into two of the tubes, and the experimental into two of the tubes. Label and incubate.

  • Within a day or two maximum, there will be enough growth for the test. In a fume hood, squeeze three drops of kovak’s reagent into each tube, on the surface of the agar. 

  • A negative result stays the yellow of the reagent, while a positive result turns red. 

Results

Biochemical tests of D. xinjiangensis:

  • Sulfur: negative

  • Catalase: positive

  • Oxidase: negative

  • Starch: positive

  • Urease: negative

  • Indole: negative





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