Zusammenfassung der Ressource
Culturing Microorganisms
- You can grow bacteria in the lab
- Bacteria are cultured in a culture medium
- This contains the carbohydrates, minerals, proteins and vitamins they need to grow
- Can be a nutrient broth solution or solid agar
jelly
- Bacteria grown on agar plates will form visible colonies on the surface of the jelly, or will spread out to give an even covering of bacteria
- To make an agar plate, hot agar jelly is poured into shallow round plastic dishes called Petri dishes
- When the jelly's cooled and set, inoculating loops can be used to transfer microorganisms to the culture medium
- The microorganisms then
multiply
- In the lab at school, cultures of microorganisms are not kept above 25 C
- Because harmful pathogens are more likely to grow above this temperature
- In industrial conditions, cultures are incubated at higher temperatures so that they can grow a lot
faster
- You need to use uncontaminated cultures
- Contamination by unwanted microorganisms will affect the results
- It can also potentially result in the growth of pathogens
- The Petri dishes and culture medium must be sterilised before use to kill any unwanted microorganisms that may be lurking on them
- If an inoculating loop is used to transfer the bacteria to the culture medium, it should be sterilised first by passing it through a hot flame
- After transferring the bacteria, the lid of the Petri dish should be lightly taped on
- To stop microorganisms from the air getting in