BIOS242 W4 Lab Template
Ashley Williams
Week 4 Lab
CARBOHYDRATE TESTS
Introduction
To test for starches and simple sugars.
<brief summary of topic investigating and case studies >
<state major finding>
Procedure
The following tests will record positive (+) reactions or negative
(‐) reactions to fructose, sucrose, cellulose, starch, lactose and an unknown carbohydrate.
Observations and Results Report your test results in a tabular format
• Record the bacteria identified in each of the Four Media Tests.
Test Bacterium 1
Test Bacterium 2
Test Bacterium 3
Test Bacterium 4
Gram Stain
Gas from Glucose
Acid from Glucose
Sucrose
Lactose
Identification
Initial color of medium in Gas and Acid from Glucose test:
If you have a positive test, describe the changes seen in the medium. What is the purpose of the Durham tube? You use the Durham tube to trap gas.
Discussion o All four bacteria were able to metabolize glucose, but not all produced identical results. Predict the metabolic products expected for the four bacteria. A chemical energy is released when glucose is broken down. Glucose is broken down into CO2and H2O. A glucose test is screening the blood for signs of high blood glucose and low blood glucose. Not only not, but this test can help diagnose diabetes as well. o If all four bacteria were able to metabolize glucose, explain why all four were not able to metabolize lactose and sucrose. Consider the different chemical structure of each carbohydrate and what the bacteria would need to metabolize each carbohydrate. The bacteria quickly metabolized the glucose, initially producing an acid slant and an acid butt in a few hours. After further incubation glucose is consumed because the bacteria could not use lactose or sucrose. o Sugar fermentation tests are positive when the pH turns acidic. How are media for these tests modified to allow production of acids to be detected? The MR test employs the addition of the pH indicator methyl red, to
Week 4 Lab
CARBOHYDRATE TESTS
Introduction
To test for starches and simple sugars.
<brief summary of topic investigating and case studies >
<state major finding>
Procedure
The following tests will record positive (+) reactions or negative
(‐) reactions to fructose, sucrose, cellulose, starch, lactose and an unknown carbohydrate.
Observations and Results Report your test results in a tabular format
• Record the bacteria identified in each of the Four Media Tests.
Test Bacterium 1
Test Bacterium 2
Test Bacterium 3
Test Bacterium 4
Gram Stain
Gas from Glucose
Acid from Glucose
Sucrose
Lactose
Identification
Initial color of medium in Gas and Acid from Glucose test:
If you have a positive test, describe the changes seen in the medium. What is the purpose of the Durham tube? You use the Durham tube to trap gas.
Discussion o All four bacteria were able to metabolize glucose, but not all produced identical results. Predict the metabolic products expected for the four bacteria. A chemical energy is released when glucose is broken down. Glucose is broken down into CO2and H2O. A glucose test is screening the blood for signs of high blood glucose and low blood glucose. Not only not, but this test can help diagnose diabetes as well. o If all four bacteria were able to metabolize glucose, explain why all four were not able to metabolize lactose and sucrose. Consider the different chemical structure of each carbohydrate and what the bacteria would need to metabolize each carbohydrate. The bacteria quickly metabolized the glucose, initially producing an acid slant and an acid butt in a few hours. After further incubation glucose is consumed because the bacteria could not use lactose or sucrose. o Sugar fermentation tests are positive when the pH turns acidic. How are media for these tests modified to allow production of acids to be detected? The MR test employs the addition of the pH indicator methyl red, to