Attack of the Superbugs
Lab Introduction
Mrs. Stewart
Medical Interventions
Superbugs
• What is a
“superbug”?
– Bacteria that
have become
stronger and
less
responsive to
antibiotic
treatment
How can bacteria share resistance?
Genetic Transfer
Method
Conjugation
Description
The one-way transfer of DNA
(plasmid) between bacteria in close
cellular contact
Transformation
The genetic modification of a
bacterium by incorporation of free
DNA from the surrounding
environment (usually caused by
another ruptured bacterial cell)
Transduction
The transfer of genetic material from
one bacterium to another by a genetic
vector (bacteriophage virus)
This lab uses 2 types of Bacteria:
• E. coli I
– contains a gene found on the chromosomal DNA
coding for streptomycin resistance
• E. coli II
– contains a gene found on the plasmid DNA coding
for ampicillin resistance.
Predict
• What will happen when the E. coli I
strain is mixed with the E. coli II strain?
Lab Materials: 4 growth plates
LB Agar
LB + Amp
LB + Str
LB /Str /Amp
*LB Agar = growth medium for bacterial cells
Lab Day 1: Confirmation Plates
• Obtain 1 of each type of growth plate – 4
plates total
• Streak E. coli I on 4 plates
• Streak E. coli II on 4 plates
• Incubate overnight
How to label the plates
I
II
Group Name
I
II
Group Name
Evaluate
• What are we confirming?
These plates will
confirm that our
strains of E. coli
are correctly
labeled
Data Table
E. coli I
E. coli II
LB agar
LB + Str
LB + Amp
LB + Str + Amp
+ = Growth /
-- = No Growth
Prediction
• Predict the results from your confirmation
plates that you will expect to record
Lab Day 2:
• Observe confirmation plate results
• Prepare “mix” plate
– You will literally be mixing the two types of
bacteria together onto one plate
• Incubate overnight
Evaluate
• Specifically, what will happen when we
mix them together?
Lab Day 3:
• Use new “mixed” bacterial cultures and
spread onto the 3 types of antibiotic plates
Predict
• What would you expect to see on
these growth plates?
• Why?
Lab Day 4
• Observe and record your results
• Remember: Pictures of lab results will be
required in your lab reports
*Growth plates will be discarded after today.
Any results not recorded will be lost.
Day:
Lab
Day 1
Time
Needed:
~ 30
minutes
Lab
Day 2
~ 30
minutes
Lab
Day 3
~ 30
minutes
Lab
Day 4
~ 10
minutes
Student Lab Schedule
Activity:
How to Store:
Students prepare
confirmation
plates.
Students observe
confirmation plates
and prepare “Mix
Plate.”
Students streak
cultures from “Mix
Plate” onto
antibiotic plates.
Students observe
& record results
Invert the plates,
label, and incubate
at 37˚C for 24 hours.
Invert the plates,
label, and incubate
at 37˚C for 24 hours.
Invert the plates,
label, and incubate
at 37˚C for 24 hours.
Clean-up all
materials.