1st Successful Dilution of Plain Yogurt
From the previous experiment of diluting four different brands of the plain yogurts, professor Murthi and I set new dilution factors for each brand, hoping that we can finally count the bacterial colonies with that dilution factors for all brands.
Procedure:
1. Obtain sterile test tubes, petri dishes with LB media, liquid LB media, a micropipette, and spreader. Label the test tubes and petri dishes.
2. Add 4.5mL of liquid LB media to each test tube.
3. Extract 500 μL of yogurt to test tube 1 (Labeled as 10x) and shake it.
4. Extract 500 μL from test tube 1 (10x) to test tube 2 (100x) and shake it.
5. Repeat step (3)-(4) for other three brands of plain yogurt.
- Dannon: up to 103x
- Stonyfield: up to 102x
- Siggi's: up to 106x
- Chobani: up to 106x
6. Extract 100 μL from each of yogurt cultures with different dilution factors and place it in the center of the respective plate. Plate 3 plates for each one.
- Dannon: 102x + 103x
- Stonyfield: 10x + 102x
- Siggi's: 105x + 106x
- Chobani: 105x + 106x
8. Using the L-shape spreader, spread the solution on the plate while rotating it in a circular motion.
9. Incubate the plates at 37.0 degrees Celsius. Observe the bacterial growth after the plates remain in the incubator for 48 hours.
Results:
Dannon:
- 102x: couldn't count
- 103x:
CFU's = [109 x 103] / 0.1mL = 1.09 x 106
Stonyfield:
- 10x: couldn't count
- 102x:
CFU's = [50.3 x 102] / 0.1mL = 5.03 x 104
Siggi's:
CFU's = [165 x 105] /0.1mL = 1.65 x 108
- 106x:
CFU's = [17 x 106] /0.1mL = 17 x 108
Chobani:
- 105x:
CFU's = [94.7 x 105] /0.1mL = 9.47 x 107
- 106x:
CFU's = [12.3 x 106] / 0.1mL = 12.3 x 107
Procedure:
1. Obtain sterile test tubes, petri dishes with LB media, liquid LB media, a micropipette, and spreader. Label the test tubes and petri dishes.
2. Add 4.5mL of liquid LB media to each test tube.
3. Extract 500 μL of yogurt to test tube 1 (Labeled as 10x) and shake it.
4. Extract 500 μL from test tube 1 (10x) to test tube 2 (100x) and shake it.
5. Repeat step (3)-(4) for other three brands of plain yogurt.
- Dannon: up to 103x
- Stonyfield: up to 102x
- Siggi's: up to 106x
- Chobani: up to 106x
6. Extract 100 μL from each of yogurt cultures with different dilution factors and place it in the center of the respective plate. Plate 3 plates for each one.
- Dannon: 102x + 103x
- Stonyfield: 10x + 102x
- Siggi's: 105x + 106x
- Chobani: 105x + 106x
8. Using the L-shape spreader, spread the solution on the plate while rotating it in a circular motion.
9. Incubate the plates at 37.0 degrees Celsius. Observe the bacterial growth after the plates remain in the incubator for 48 hours.
Results:
Dannon:
- 102x: couldn't count
- 103x:
a
|
108
|
b
|
115
|
c
|
105
|
Average
|
109
|
Stonyfield:
- 10x: couldn't count
- 102x:
a
|
53
|
b
|
48
|
c
|
50
|
Average
|
50.3
|
Siggi's:
- 105x:
a
|
168
|
b
|
189
|
c
|
138
|
Average
|
165
|
- 106x:
a
|
14
|
b
|
12
|
c
|
25
|
Average
|
17
|
Chobani:
a
|
104
|
b
|
80
|
c
|
100
|
Average
|
94.7
|
- 106x:
a
|
6
|
b
|
15
|
c
|
16
|
Average
|
12.3
|
Comments
Post a Comment