Microbiology P1 Flashcards
What are you investigating in microbiology?
Investigate the effect of antiseptics or antibiotics on bacterial growth using agar plates and measuring zones of inhibition.
What materials do you need for microbiology?
Materials For the basic method • a nutrient agar plate that has been inoculated with bacteria • a heatproof mat • filter paper discs • three antiseptics (such as mouthwash, TCP, and antiseptic cream) • disinfectant bench spray • 1% Virkon disinfectant • forceps • clear tape • hand wash • a wax pencil or permanent marker • access to an incubator (set to 25 °C).
How can time be saved during microbiology?
- commercially produced antibiotics discs rather than self prepared ones
What is a culture medium?
bacteria grown containing carbohydrates, minerals, proteins and vitamins.
It can be a nutrient broth solution or a solid agar jelly
How can you avoid contaminating cultures?
- petri dishes and culture medium are sterilised before use to kill unwanted microorganisms
- Sterilise inoculating loop by passing through a hot flame
- Lightly tape Petri dish together
- Store upside down to stop condensation falling onto the agar surface.
How do you investigate the effects of antibiotics?
Bacterial Growth
- place paper discs soaked in antibiotics on agar plate with an even covering of bacteria leaving space between discs
- Antibiotics diffuse into agar jelly. Antibiotic- resistant bacteria continues to grow around discs and non-resistant stains will die. so clear area will be left.
- You should use a control paper disk which is soaked in sterile water.
- Leave plates for 48 hours at 25 degrees (so harmful pathogens can’t grow)
The more effective antibiotic has the largest inhibition zone.
What is an inhibition zone?
A clear area will be left where the bacteria have died.
How should you measure the inhibition area?
area of the circles.
measure diameter from both right angle directions and then use pi r^2
