Culturing Microorganisms

Question 1

What are two ways in which bacteria can be cultured?

Answer 1

Using** agar jelly plate **or nutrient broth solution

Question 2

Your method should include 5 steps

What are the steps for culturing bacteria?

- Using agar jelly plate

Include terms: Sterilisation, Petri dish, Agar jelly, Inoculating loop, Bunsen Burner, Medium, Tape, Condensation, Incubator

Answer 2

1. Sterilise petri dish, bacteria nutrient broth and agar to kill microorganisms and prevent contamination.
2. Pour agar jelly onto petri dish and leave to cool and set
3. Sterilise inoculating loop in bunsen burner flame and transfer bacteria to medium (agar jelly on petri dish)
4. Attach lid using adhesive tape to prevent contamination and lid coming off.
5. Agar plate placed upside down in incubatorat 25 degree celcius to **reduce chance of harmful bacteria growth **and to prevent condensation disrupting bacterial growth.

Question 3

Also includes 5 steps which are similar to other practical

What are the steps to find the effects of antibiotics on bacterial growth?

Include terms: Disinfectant, Sterilise, Inoculating Loop, Bunsen Burner, Agar Jelly Plate, Filter Paper disks, Antibiotics, Incubation

Answer 3

1. Clean bench with disinfectant solution to kill unwanted microorganims.
2. Sterilise inoculating loop (with bunsen burner)
   3.** Open sterile agar jelly plate near bunsen burne**r (flames heat will kill any nearby bacteria in air to prevent cross contamination)
3. Spread bacteria evenly over plate using loop.
4. Place sterile filter paper disks containing antibiotics on plate and incubate at 25 degrees celcius.

Question 4

What is the zone of inhibition?

Answer 4

Area where bacteria haven’t grown.
π * radius^2 = area