Culturing Microorganisms

Question 1

What does bacteria need to grow in a cultured medium and what forms can they be in?

Answer 1

Carbohydrates, minerals, proteins and vitamins. They can either be a nutrient broth solution or a solid agar jelly.

Question 2

What can be observed when bacteria is grown on agar plates (relating to spacing)?

Answer 2

They will either form visible colonies or will spread out evenly on the surface of the jelly

Question 3

What are the steps in making an agar plate?

Answer 3

1. Pour hot jelly into a shallow, round, plastic Petri dish.
2. Allow jelly to cool, then use an inoculating loop to transfer microorganisms.

Question 4

What is an alternative for an inoculating loop?

Answer 4

A sterile dropping pipette and a spreader.

Question 5

Compare the conditions for this in schools vs industrial production.

Answer 5

School- not kept above 25 degrees in a lab because any higher can cause harmful pathogens.
Industrial production- higher temperatures to speed up growth

Question 6

Why should we make sure our environment is not contaminated?

Answer 6

This could cause unwanted microorganisms to affect the results of the experiment. It can also potentially result in growth of pathogens.

Question 7

How should you sterilise a Petri dish, an inoculating loop and how should it be stored? Why?

Answer 7

Petri dish- Heated to high temperature to kill unwanted microorganisms
Inoculating loop- Passed through hot flame
Storage- Tape the lid on to keep unwanted microorganisms from the air getting in. Store upside down to stop condensation from falling on to the agar surface.

Question 8

What does PAISTE stand for in terms of testing antibiotics?

Answer 8

P- Paper disks with different concentrations of antibiotics or different antibiotics.
A- Antibiotic resistant bacteria will continue to grow. Non- resistant bacteria will die.
I- Inhibition zone is a clear area where bacteria has died.
S- Soak one paper disk in sterile water as a control disk
T- Temperature and Time should be 25 degrees for 48 hours
E- The more Effective the bacteria, the larger the inhibition zone will be.

Question 9

How can you measure the inhibition sone and the area of a colony?

Answer 9

Inhibition zone- Pi x r^2
Colony- just measure diameter