BIOS 242 Week 4 iLab: Carbohydrate Tests
BIOS 242 Week 4 iLab
BIOS 242 Week 4
BIOS 242
BIOS 242 Week 4 iLab: Carbohydrate Tests
CARBOHYDRATE
... [Show More] TESTS
Introduction:
The purpose of this lab was to determine which carbohydrates a bacterium can use on three different specimens. The acid from glucose test is done to see if the microbe can ferment the glucose a carbon source. The lactose fermentation test was performed to see if the microbe can ferment lactose as a carbon source and the sucrose fermentation test was performed to see if the microbe can ferment sucrose as a carbon source. I tested each of the bacterium for glucose, lactose and sucrose as carbon sources. In the first case study I was presented with water from the Baker ranch that was provided from a pond that they used to give the cattle to drink as the earthquake had opened up a natural spring. The tests I conducted came back positive for glucose, sucrose, and lactose. It was negative for gas, and contained a gram negative rod stain. The second case was a boy dropped a slice of watermelon on the ground of the barn and rinsed it off with water then proceeded to try to eat it when the nurse in charge took it away from him because it was not good to eat it and wanted to test it to prove that fact. The tests I conducted came back positive for glucose, sucrose, and lactose. It was negative for gas, and contained a gram negative rod stain. The third case was a flight attendant who presented with a cold, followed by fever and joint paint the following day. The tests I conducted came back positive for glucose. It was negative for lactose, sucrose, and gas. It was also a gram negative rod stain. The fourth case I was given was a cow who had red, swollen udders. The tests I performed were positive for glucose, negative for sucrose, lactose, and gas. It was also a gram negative rod stain.
Procedure: Part 1 –
Conduct four biochemical tests on bacterium sample, TestBacterium1.
Conduct Acid from Glucose and Gas from Glucose Tests:
1. Click on the New Unknown button and type TestBacterium1 in the “enter a label” field. Select
Media Tests 1 from the Subgroup dropdown menu. Select the box allowing autoinoculation.
2. Record your Case Study.
3. The Gram Stain window will open. Record the results of the Gram Stain.
4. Open the Biochemical Tests Reference Book. (You can find this resource in two way; you can
click on the T? button or select the Reference Books from the Help dropdown menu.)
5. Open the Acid from Glucose test. Review the steps of the test and determination of test results
before you begin your experiment.
6. From the Media dropdown menu, select Phenol Red Glucose Broth Durham Tube. The Media
dropdown menu is to the far right of the New Unknown button.
7. Enter Phenol Red Glucose in the Medium Label window to label your sample. Click OK. Two
tubes will appear on your workbench. Take a careful look at the sample tube (the one on the
right.) Is there media in the Durham Tube (this is the tube that is upside down in the medium.)
8. Turn on Bunsen burner by right clicking on the Bunsen burner and hitting on. You will see the
flame of the Bunsen burner.
9. Select Loop from the Tool dropdown menu. Flame the wire in the flame of the Bunsen burner
until it glows red.
10. Bring wire over to Inoculum sample (the sample on the left). Right click on sample and
select Inoculate.
11. Check the Traffic Signals in the upper right hand corner of the lab. Check to see that you
have successfully inoculated your sample and that no contamination was introduced.
12. Turn off Bunsen burner.
13. Select Pointer tool from Tool menu.
14. Put cursor, with your Pointer tool, over your inoculated sample, drag it, and place it in the 37
degree incubator. You will also see that your inoculum sample will “disappear” from the
workbench.
15. Click the New Day button. Notice that the Virtual Days counter now reads 2.
16. Put cursor over the incubator. Right click and select your sample, Phenol Red Glucose. Your
sample tube will appear on your workspace.
17. Right click on tube and select Record Results. NOTE: You will record results for two tests –
Acid from Glucose and Gas from Glucose. NOTE: Is there media in the Durham Tube?
Making note of this is important in recording the correct results. Refer to the Gas from
Glucose Test in the Biochemical Test Reference Book.
18. After you record your results, the sample tubes are automatically disposed of in the
Biohazard bag.
Conduct the Lactose Fermentation Test:
NOTE – you will be using the same bacteria sample as you did in the Acid from Glucose and Gas from Glucose tests.
1. Open the Lactose Fermentation Test from the Biochemical Tests Reference book. Review the
steps of the test and determination of test results before you begin your experiment.
2. From the Media dropdown menu, select Phenol Red Lactose Broth.
3. Enter Phenol Red Lactose in the Medium Label window to label your sample. Click OK. Two
tubes will appear on your workbench.
4. You will now inoculate your sample. You will follow the same steps as above.
These have been repeated below.
Turn on Bunsen Burner.
Select Loop from the Tool dropdown menu. Flame the wire in the flame of the Bunsen burner
until it glows red.
Bring wire over to Inoculum sample (the sample on the left). Right click on sample and select
Inoculate.
Click the New Day button. Notice that the Virtual Days counter now reads 3. Put cursor over
the incubator. Right click and select your sample, Phenol Red Lactose. Your sample tube will
appear on your workspace.
Right click on the tube and Record Results. Make sure to refer to the Lactose Fermentation Test
information in order to determine if you have a positive or negative result.
After you record your results, the sample tubes are automatically disposed of in the Biohazard
bag.
Conduct the Sucrose Fermentation Test:
NOTE – you will be using the same bacteria sample as you did in the Acid from Glucose test,
Gas from Glucose test and Lactose Fermentation test.
1. Open the Sucrose Fermentation Test from the Biochemical Tests Reference book. Review the steps of the test and determination of test results before you begin your experiment.
2. From the Media dropdown menu, select Phenol Red Sucrose Broth.
3. Enter Phenol Red Sucrose in the Medium Label window to label your sample. Click OK. Two tubes will appear on your workbench.
4. You will now inoculate your sample. You will follow the same steps as above.
5. These have been repeated below.
These have been repeated below.
Turn on Bunsen Burner.
Select Loop from the Tool dropdown menu. Flame the wire in the flame of the Bunsen burner until it glows red.
Bring wire over to Inoculum sample (the sample on the left). Right click on sample and select Inoculate.
Click the New Day button. Notice that the Virtual Days counter now reads 4.
Put cursor over the incubator. Right click and select your sample, PhenolRedSucrose.
Your sample tube will appear on your workspace.
Right click on the tube and Record Results. Make sure to refer to the Sucrose Fermentation Test information in order to determine if you have a positive or negative result.
After you record your results, the sample tubes are automatically disposed of in the
Biohazard bag.
Viewing Results for Test Bacterium 1:
1. Select “Lab Report” from the View item on the top menu bar.
2. You can copy and paste the contents of this lab report to a Word document and save.
3. Note the following:
At the top of the page, it identifies your unknown as, TestBacterium1.
Under the Identification Information section, the report will note that “Identification not
yet complete” and that the “Identified Unknown” is TBD.
Under Test Detail, the tests that were conducted are listed, along with the results. It tells
you how many bacteria were eliminated as a result of each test and how many bacteria
remain. Note that as you conduct a series of tests that the number of bacteria that remain
is smaller.
4. Note that the lab report records the results of each of the four tests that you conducted
on your sample. The lab report identifies the number of bacteria that were eliminated
after each test. You will want to include this information in your lab report.
Determine Identity of TestBacterium1:
1. Open the Identification Matrix from the View Command. You will find that only
possible bacteria that remain after conducting this series of tests will be shown on the
Identification Matrix. Make note of the possible bacteria that might cause this infection.
2. From the Unknown command, select Identify. From the drop down menu, select a
bacterium that is likely the cause of the agent (based upon the information you have from
your tests and by viewing the Identification Matrix.
3. Click OK. Then, click Yes when the Confirm Identification Window opens. A window
will open letting you know if you chose the correct bacterium.
4. Now, open up the Lab report. Under the Identification Information of the lab report,
you will see the bacterium that you selected and the bacterium that was assigned. You
will also want to record this information in your final lab report.
5. Include your guess and the correct organism in the results section of your lab report.
Repeat these steps for Test Bacterium 2, 3, and 4.
Observations and Results: Please review table for results.
Bacterium Acid from Glucose Gas from Glucose Lactose Fermentation Sucrose Fermentation
TestBacteruim1 Positive Negative Positive Positive
TestBacterium2 Positive Negative Positive Positive
TestBacterium3 Positive Negative Negative Negative
TestBacterium4 Positive Negative Negative Positive
During these experiments most of my guesses were correct except for one. I felt like I came close with the one that I missed but ended up selected the wrong microbe. In the acid from glucose and gas from glucose test the initial color was a brick red. After inoculating the sample and placing it in the incubator for the 24 hours it changed to a cloudy yellow and that indicated a positive reaction. The purpose of the Durham tube was to trap the gas bubbles created during fermentation.
Discussion:
All four of the bacterium were able to produce acid from glucose. But no gas was able to be produced from the glucose. However some were able to produce lactose and sucrose, and some were able to produce one but not the other. The reason behind this is because glucose is used up first so when it can continue on to produce sucrose and lactose it is indicating the sugars are higher in that specific microbe than in the others. The media during these tests are modified by the lactic acid which is produced during fermentation. This byproduct changes the color of the media dependent upon the decreasing pH from the lactic acid production. The changes in color indicate a positive or negative reaction. When the sugar is not metabolized in a carbohydrate test medium it may still detect another growth. This can be determined by using a different indicator.
Conclusion:
Glucose and Fructose are monosaccharides which means that they are made up of one sugar. The molecular formula for monosaccharides is C6H12O6. Sucrose is a disaccharide which means it is made up of two sugars. The molecular formula for disaccharides is: C12H22O11 = 2 C6H12O6 − H2O. During this experiment I feel as if I learned more about carbohydrates and how they are used to tests for different diseases which I didn’t know before. I was unsuccessful at identifying the correct microbes as often as I should have but I assume that guessing more consistently will come with time. I typically use to the identification matrix then I research each remaining possible bacterium and guess by eliminating what each one does. I feel I am getting better at learning and identifying the microbes but still need more practice on identifying them that is for sure. Overall I am really enjoying the labs because the hands on helps to bring the lessons to life. [Show Less]