RP: Growing microbes Flashcards
what do most microbes need to grow?
warmth
food
oxygen
why can we not incubate at a temperature higher than 25 *C
pathogenic bacteria can grow above 25*C
why do bacteria need oxygen?
to respire
what is the optimum temperature for bacteria?
30-40*C
where do the bacteria receive food from in this experiment?
agar jelly has a nutrient broth that contains minerals vitamins carbs and proteins
(its also sterile)
if you have a bacteria that divides every 20 mins how many divisions are there after 12 hours?
how many 20 minutes go into 12 hours? =36
so the answer is 2^36
what are some aseptic techniques used in this experiment?
bunsen burner on - creates convection currents that move bacteria away
disinfect surface- kills baceria on surface
flaming the neck of the bottle
only opening the lid when ready- reducing number of bacteria that can enter the petri dish
sellotape lid- to stop the lid from falling off/ someone touching the bacteria
what is the method testing the eficacy of antibiotics?
1: disinfect surface
2: turn bunsen burner on on to push away bacteria
3: label petri dish dicreetly
4: flame bottle of bateria
5: put a 1/2 ml of bacteria in to the agar plate with a pipette
6: put pipette in virkon and flame again
7: put some agar in the petri dish as well making sure to flame the bottle before and after use
8: mix/swirl slightly and leave to set
9: flame forceps and put the antibiotic disks in also flaming forceps after each use (make sure to leave space for zone of inhibition)
10: tape the lid onto the base
11: disinfect surface
what are some risks and hazards for this experiment?
hot water and bunsen- can burn you so wear heat proof gloves and a safety flame
glass equipment-could cut you so make sure ther lids on and dont put near the edges of tables
ecoli (biohazard)- could make you ill so keep the lids on
