Unit 9 Carbohydrate Fermentation Durham Tubes
Summary
TLDRThe video explains the process of testing carbohydrate fermentation in microorganisms using Durham tubes. These tubes contain phenol red as an indicator, which turns yellow when acid is produced during fermentation, signaling the presence of specific enzymes. The inverted glass tube inside the Durham tube is used to detect gas production. The video demonstrates how different colors indicate whether an organism can ferment sugars like lactose or sucrose, and how this test can be used alongside others like TSI to identify an organism's metabolic capabilities.
Takeaways
- 🔬 The video discusses the fermentation of simple sugars using Durham tubes, a method to test an organism's ability to ferment specific sugars.
- 🌡️ Durham tubes contain an inverted glass tube to capture air bubbles, indicating gas production during fermentation.
- 🍬 The presence of different sugars in separate tubes allows for testing an organism's ability to ferment various simple sugars.
- 🧬 An organism's ability to ferment a sugar suggests it possesses the necessary enzymes, such as lactase for lactose or sucrase for sucrose.
- 🌈 Phenol red is used as an indicator in the broth; it turns yellow if the pH drops due to acid production from fermentation.
- 🟡 A yellow color in the Durham tube indicates a positive result, showing that the organism can ferment the sugar and produce acid.
- 🔴 A red or orange color suggests a negative result, meaning the organism lacks the enzyme to ferment the specific sugar.
- 💨 The clearing of the inverted glass tube indicates the production of CO2, which is associated with acid production and fermentation.
- 🔍 Observing air bubbles in the inverted tube is crucial, as a significant amount of clearing (at least a third of the tube) is needed to confirm gas production.
- 📚 Using Durham tubes in conjunction with other tests like TSI can provide comprehensive information about an organism's carbohydrate fermentation capabilities.
Q & A
What is the purpose of the Durham tube in microbiology?
-The Durham tube is used to test the fermentation of simple sugars by microorganisms. It contains an inverted glass tube to catch air bubbles, indicating gas production during fermentation.
How does the inverted glass tube inside the Durham tube function?
-The inverted glass tube is used to capture air bubbles produced during fermentation. If the tube is cleared by at least a third, it indicates that the organism can produce CO2 as a byproduct of fermentation.
What role does phenol red play in the Durham tube?
-Phenol red is an indicator in the Durham tube that changes color based on pH. It starts red and turns yellow if the pH drops due to acid production, indicating fermentation.
What color change in phenol red indicates acid production during fermentation?
-A color change from red to yellow in phenol red indicates acid production, suggesting that the organism can ferment the sugar and produce an acidic byproduct.
What color of phenol red suggests that the organism does not ferment a particular sugar?
-If phenol red remains orange or red, it indicates that the organism does not have the enzyme necessary to ferment the sugar, and no acid production has occurred.
How can you determine if an organism has the enzyme to ferment lactose based on the Durham tube test?
-If the phenol red in the lactose tube turns yellow and the inverted tube is cleared, it indicates that the organism has the enzyme lactase to ferment lactose.
What does the absence of air bubbles in the inverted tube signify?
-The absence of air bubbles in the inverted tube suggests that the organism does not produce CO2 during fermentation of the sugar being tested.
Can the Durham tube test be used with a variety of simple sugars?
-Yes, the Durham tube can be used with different simple sugars to determine which ones an organism can ferment, as indicated by color change and gas production.
What is the significance of using the Durham tube in conjunction with a TSI tube?
-Using the Durham tube with a TSI tube can provide additional supporting information about which sugars are fermented by an organism, as TSI contains multiple sugars.
What does a cleared inverted tube in a sucrose Durham tube indicate?
-A cleared inverted tube in a sucrose Durham tube indicates that the organism has fermented sucrose, producing acid and CO2, and possesses the sucrase enzyme.
How can you interpret a red result in a Durham tube test for a simple sugar?
-A red result in a Durham tube test for a simple sugar indicates a negative test, meaning the organism did not ferment the sugar and no acid production occurred.
Outlines
🔬 Carbohydrate Fermentation Test with Durham Tubes
This paragraph describes the process of testing an organism's ability to ferment simple sugars using Durham tubes. The Durham tubes contain a broth medium with an inverted glass tube to collect air bubbles, indicating gas production. Phenol red is used as an indicator; it turns yellow when the pH drops due to acid production during fermentation. The presence of yellow color signifies the production of acid, suggesting the organism has the necessary enzymes to ferment the sugar. The absence of yellow color (remaining red or orange) indicates a negative result, meaning the organism lacks the specific enzyme to ferment that sugar. The inverted tube also helps to determine if CO2 is produced during fermentation. The paragraph also mentions the use of different sugars in separate tubes and the possibility of using these results in conjunction with TSI tubes for further analysis.
Mindmap
Keywords
💡Fermentation
💡Durham Tube
💡Simple Sugars
💡Phenol Red
💡Acid Production
💡Gas Production
💡Lactose
💡Sucrose
💡Enzymes
💡TSI Tube
Highlights
Fermentation of simple sugars can be tested using Durham tubes.
Durham tubes contain an inverted glass tube to catch air bubbles.
Organisms with enzymes to ferment sugars can be identified through this method.
Phenol red is used as an indicator; it turns yellow if acid is produced during fermentation.
A yellow color in the Durham tube indicates acid production from fermentation.
A red or orange color suggests the organism lacks the enzyme to ferment the sugar.
The inverted glass tube can indicate gas production during fermentation.
Clearing of the inverted tube by at least a third indicates CO2 production.
Acid and gas production are consistent indicators of successful fermentation.
Sucrose fermentation results in a yellow color indicating a positive test.
No air bubbles in the inverted tube suggest no gas production during sucrose fermentation.
Different simple sugars can be tested in separate Durham tubes.
Durham tubes can be used alongside TSI tubes for additional information on sugar fermentation.
TSI tubes contain multiple sugars and can support Durham tube findings.
The process helps to determine which sugars are fermented by an organism.
Carbohydrate fermentation using Durham tubes is a valuable method in microbiology.
Transcripts
This video outlines
Fermentation of simple sugars testing this with the Durham, or what's often called the carbohydrate - this is a broth
medium so in the tube you'll notice that you have
an additional inverted tube inside which is a glass tube and that is there to catch air bubbles.
So we can test for the ability of an organism to ferment a particular simple sugar and we can have different sugars in different tubes
If the organism can ferment that particular sugar we say it has the enzymes with which to do so
We also can look to see if the organism produces gas in the course of
fermentation and that's what that inverted glass tube is for inside.
Now the indicator here is phenol red. Phenol red starts out red
which you actually see here on the left that looks almost like a uninoculated tube even though it's not. And
phenol red will turn yellow if the pH drops when an acid is produced.
So here on my lactose tubes on the left. I've got the yellow
which indicates acid is produced, the phenol red turned yellow
Any other color, orange, red
that we call that a negative that the organism does not have the particular enzyme in this case lactase to ferment lactose.
On the left here
We can see that this remained red so the phenol red did not react with an acid because there was not
Fermentation of lactose that produced an acid end product. Another thing to note here is that
inverted tube. So if that is cleared out at least a third of the way
Not just a little bit at the tip because sometimes that can happen during the manufacturing of the tube
But if there are enough air bubbles to clear out about a third of the tube
We say that the organism can also produce CO2 in the course of
fermentation. You would only see this with an acid production because that's going to be in line with the acid production and the fermentation.
On the right here, you've got the sucrose tubes the same idea again
If an acid is produced you get a yellow color. Now on this one you don't get the air bubbles produced at the top
Put that little bit closer to see
Yeah, you can see that
There's no air bubbles produced there
As opposed to one that does have the air bubbles you can see the clearing pretty well there I think.
So the yellow product acid production phenol red, which is our indicator turns yellow
So that in this case, since sucrose is a simple sugar
that's used
we can say that the organism is positive for the fermentation of sucrose or we can say has the
sucrase enzyme and
Right next to it here in the red
The red results that is a negative because again
We didn't get that acid production. And we can put a variety of
simple sugars in different tubes. One nice thing to do with these is to use them in conjunction with a TSI tube in particular.
A TSI slant, because TSI has multiple sugars in there. So this can help narrow down or give us additional
Supporting information as to which sugars are fermented and that is the carbohydrate
fermentation with Durham tube
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