Topic 1 Culturing Microorganisms Practical! Flashcards
How can bacteria be cultured
In a culture medium which contains carbohydrates, minerals, proteins and vitamins they need to grow
What can be used in a culture medium
Nutrient broth solution or agar jelly
What will bacteria on agar plates look like
Will form visible colonies on the surface of the jelly or spread out to give an even covering of bacteria
How to make Agar plate
Hot agar jelly is poured into Petri dish
When jelly is set Inoculating loop can be used to transfer micro organisms to the culture medium
Or a sterile dropping pet and spread it can be used to get an even covering of bacteria
The micro organisms then multiply
What temperature are cultures of micro organisms not kept above
Cultures of micro organisms are not kept above 25°C because half of pathogens are more likely to grow above this temperature
What is the temperature of cultures incubated at in industrial conditions
Are incubated at high temperatures so that they can grow a lot faster
Testing the effects of antibiotics and bacterial growth practical steps 1-2
1)Place paper discs certain different types or concentrations of antibiotics onto agar plate that has an even covering of bacteria, leave space between the discs
2) Antibiotics should diffuse into the agar jelly, antibiotic resistant bacteria will continue to grow but non-resistant strains will die
What is the inhibition zone
Clear area where the bacteria have died
What could affect your results of bacterial growth
Contamination by unwonted micro organisms affect your results
How to avoid contamination by one of micro organisms in your cultures
Petri dish and culture medium must be sterilised to kill any unwanted microorganisms
Sterilise inoculating loop by passing it through a hot flame
After transferring bacteria lead a petri dish should be lightly taped on
Petri dish should be stored upside down to stop drops of condensation falling onto the agar jelly
What does the inhibition zone say about the antibiotic
The larger the inhibition zone the more effective the antibiotic is against the bacteria
How to measure the inhibition zone or the area of a colony
Area= pi r^2
