Aseptic techniques Flashcards
(12 cards)
Why open the Petri dish as little as possible?
To prevent bacteria in the dish getting out and bacteria in the air getting in to contaminate the plate
Why use a sterile pipette?
To maintain a pure culture of bacteria
Why use a Bunsen burner to flame the inoculating loop, bottle of the neck and the spreader?
To maintain a pure culture of bacteria
By killing microbes here
Why wash hands with soap?
To prevent contamination from bacteria on hands
Why disinfect the surfaces?
To kill bacteria on surfaces so contamination doesn’t occur
Why work close to a Bunsen burner flame?
To allow for upward convection currents to sterilise air
2 types of cultured bacteria
Streak plate = investigate different colonies of bacteria
ANtibiotic discs = investigate effectiveness against bacteria
Streak plate method
Use inocculating loop dipped in bacteria solution ONCE to spread on agar jelly in petri dish and tape shut
Spread thinner and thinner to identify individual colonies
Antibiotic disk method
Use spreader to create layer of bacteria colony in petri dish then place disks of bacteria inside
Incubation
Leave in fairly warm environment for a week
Why can incubation not be done at high temperatures?
Leads to excessive growth - dangerous
ANalysis of inhibition zones
Measure diameter around each antibiotic disk
