Required Practical 6- Effect of antimicrobial substances Flashcards
Control experiment?
Well with no amylase solution (distilled water instead)
Why is sample incubated at 25°C
Because incubating at 37°C (human body temperature) could enable pathogens to grow that are harmful to humans
Inhibition zone
Clear circle around antibiotics
What does zone tell you?
Larger inhibition zone= killed more bacteria= antibiotic works better
Little/ no inhibition zone= bacteria are resistant, antibiotic not killed by it= not effective
What are the control variables?
-size of holes: use same cork borer to cut holes
-volume of enzyme: add exactly 2 drops in each well, using pipette
Aspetic techniques?
-wipe surfaces down with antibacterial wipes before & after experiment
-use Bunsen burner in work space so convection currents draw microbes away from culture
-flame wire hoop
-flame neck of bottle- prevent bacteria entering
-keep vessels containing bacteria open for minimum amount of time
How can you spread bacteria evenly?
Using sterileinoculating loop
How should you tape the lid on?
Lightly- taping the entire dish prevents oxygen entering so promotes growth of more harmful anaerobic bacteria
Why are agar plates upside down?
-clearer observation of inhibition zones due to condensation on lid- measure zones
-prevents drops of moisture formed during incubation dropping on culture
Why are aseptic techniques necessary?
-prevent contamination of cultures from environment
-Environment not contaminated by potentially hazardous microorganisms
Potential risk of using non-pathogenic bacteria?
-could mutate into disease-causing strain