Manipulation of Microbial Growth
Year 12 Nutrition Stage 2 SACE: Practical – Manipulation of Microbial Growth | August 25
2013
Hypothesis:
The hypothesis for this particular practical experiment is that, as the pH decreases or increases from neutral pH of approximately 7, the amount of microbial growth on the agar solution will decrease
Materials:
Agar Solution Preparation:
*hand sanitizer/ hand wash soap
*small container
*1g of agar powder
*0.25g of beef extract stock
*60mL of heated water
*electronic balance
*small spoons (2x)
*teaspoons (2x)
*0.2M Acetic Acid Solution (pH of 3)
*0.2M Sodium Hydroxide Solution (pH of a 11)
*100mL beaker (3 x)
*Bunsen burner
*lighter
*heat-proof mat
*tripod
*gauze mat
*stirring rod
*Petri dishes (6x)
*small wooden blocks
*fine black marker
Agar Plate Inoculation:
*fine black marker
*ruler
*sticky tape
*sterilized cotton bud (6x)
*paper towels
*meat extract stock
*pipette dropper
*50mL conical flask
Method:
Agar Solution Preparation: 1. Hands were first washed with soap or sanitizer. 2. Then using a small spoon, 1g of agar powder was measured onto the small container provided using the electronic balance. 3. With the use of another spoon, 0.25g of beef extract broth was then measured into same small container containing agar powder. 4. 60mL of heated water was then added into a 100mL beaker. Exactly one teaspoon of the water was then removed from the beaker. 5. Teaspoon of water removed is then replaced with exactly one teaspoon of Acetic Acid solution which was added directly into the beaker. 6. Contents of the small container (agar powder and beef broth) were then emptied into the 100mL beaker containing 60mL of solution. 7. Apparatus required for heating the contents of the 100mL beaker was set up afterwards. This included the Bunsen burner, tripod, gauze mat and heat-proof mat. 8. Beaker was then placed on top of tripod and gauze mat apparatus; lighter was used to ignite Bunsen
2013
Hypothesis:
The hypothesis for this particular practical experiment is that, as the pH decreases or increases from neutral pH of approximately 7, the amount of microbial growth on the agar solution will decrease
Materials:
Agar Solution Preparation:
*hand sanitizer/ hand wash soap
*small container
*1g of agar powder
*0.25g of beef extract stock
*60mL of heated water
*electronic balance
*small spoons (2x)
*teaspoons (2x)
*0.2M Acetic Acid Solution (pH of 3)
*0.2M Sodium Hydroxide Solution (pH of a 11)
*100mL beaker (3 x)
*Bunsen burner
*lighter
*heat-proof mat
*tripod
*gauze mat
*stirring rod
*Petri dishes (6x)
*small wooden blocks
*fine black marker
Agar Plate Inoculation:
*fine black marker
*ruler
*sticky tape
*sterilized cotton bud (6x)
*paper towels
*meat extract stock
*pipette dropper
*50mL conical flask
Method:
Agar Solution Preparation: 1. Hands were first washed with soap or sanitizer. 2. Then using a small spoon, 1g of agar powder was measured onto the small container provided using the electronic balance. 3. With the use of another spoon, 0.25g of beef extract broth was then measured into same small container containing agar powder. 4. 60mL of heated water was then added into a 100mL beaker. Exactly one teaspoon of the water was then removed from the beaker. 5. Teaspoon of water removed is then replaced with exactly one teaspoon of Acetic Acid solution which was added directly into the beaker. 6. Contents of the small container (agar powder and beef broth) were then emptied into the 100mL beaker containing 60mL of solution. 7. Apparatus required for heating the contents of the 100mL beaker was set up afterwards. This included the Bunsen burner, tripod, gauze mat and heat-proof mat. 8. Beaker was then placed on top of tripod and gauze mat apparatus; lighter was used to ignite Bunsen