aseptic techniques practical

Question 1

detailed method

Answer 1

• spray the bench with the disinfectant and wipe down with clean paper towels
• place bunsen burner on heat proof mat and light it
• place agar plate, the mccartney bottle and spreader next to bunsen burner
• write name and date and name of bacteria on underside of agar plate
• wash hands
• remove a sterile 1cm3 pipette from foil and place the filler onto it
• flame the neck of the bottle again and replace the lid
• lift the lid of agar plate and place pipette into beaker of disinfectant
• take the sterile plastic spreader in your right hand. facing the bunsen, lift the lid of the agar plate and use the spreader to make sure that the bacteria are evenly spread around the surface of the agar

placing antibiotic ring:
- use forceps
- carefully flatten the multodisk onto the surface of the plate, using the forceps
- hold the lid in place with two pieces of tape
- place it upside down in an incubator at 25 degrees for 48 hours
- wash hands

Question 2

aseptic techniques

Answer 2

wiping down surface with antibacterial cleaner
bunsen burner to draw away unwanted microorganisms
flame neck of bottles before using
keep lid over plate during transfer
use pipette to transfer culture

Question 3

what is a bacterial lawn

Answer 3

when the whole dish is covered in bacteria

Question 4

what temperature do you incubate it at and why

Answer 4

room temperature- non pathogenic for humans

Question 5

why dont you fully seal the petri dish

Answer 5

allows oxygen in to prevent growth of anaerobic bacteria

Question 6

what happened in clear zone

Answer 6

bacteria killed

Question 7

what does larger inhibition zone mean

Answer 7

more bacteria killed
more effective antibiotic

Question 8

no inhibition zone

Answer 8

bacteria resistant to that antibiotic

Question 9

hazards

Answer 9

naked flame- keep away when possible, tie hair up and wear goggles
disinfectant- flammable, keep away from naked flame
bacteria- biohazard, wash hands

Question 10

factors that affect diffusion of antibiotic through agar

Answer 10

size of molecule
temperature