B3.12 Flashcards
What does aseptic mean
It means without microorganisms
What is aseptic technique
It prevents cross-contamination from unwanted microorganisms. It ensures that the apparatus and environment remain sterile.
What is technique 1 and the reason
Wash working areas with alcohol before and after working
To ensure that no microorganisms are present in the working area
What is technique 2 and the reason
Wear gloves if at risk of working with pathogens
To prevent microorganisms passing from a sample to the skin
What is technique 3 and the reason
Autoclave glassware and apparatus before and after use
To sterilise the apparatus, preventing unwanted contamination of a sample
What is technique 4 and the reason
Work close to a bunsen burner flame
To prevent unwanted micro-organisms falling into an open sample.
How are microorganisms transferred
They are transferred from one medium to another using a wire loop.
How is the loop sterilised
It’s sterilised by heating it in a bunsen burner flame until the loop flows red.
What are the steps for identifying bacteria
The characteristics of the colony allow you to identify the bacteria from the sample. Colonies differ in characteristics such as shape, colour etc.
Steps to grow bacteria
1) Dip sterilised wire loop into the sample of bacteria
2) Make four streaks across one edge of agar plate
3) Flame and cool the loop
4) Make a second series of streaks by crossing over the first set picking up some of the cells and spreading them out across a new section of the plate
5) Repeat steps 3 & 4 making a third set of streaks
6) Repeat steps 3 & 4 making a fourth set of streaks. Fix the lid with four short lengths of tape. Can’t seal all the way as it needs to promote growth of bacteria
7) Label and incubate the plate upside down, allowing bacteria to grow into colonies.
