Lab Exercise 14: Replica Plating Flashcards
Describe the basic technique
You have some sterile velvet, block, and something to tie around the sterile velvet to hold in place (metal thing)
Set the sterile velvet onto block and then set master plate onto it to get bacteria on velvet. Make sure to note which side is the top. Then you continue with the rest of the plate (MSA, MAC,TRY-7,EMB,NA) NA going last b/c it is the control
Why would you do this? (What’s the alternative? What advantages does this technique have over the alternative?)
Replica plating is a method to transfer a pattern of colonies from one plate to another. this has an advantage because you aren’t wasting as much plates and time as if you were to do an individual type of bacteria on a single plate in lab we did 5 different bacteria in one plate onto 5 different plates.
How do you know if your technique worked? (What’s your control?)
Control is a N.A plate it shows that there was enough colonies/bacteria on the replica plates done. The control plate goes last.
What is Selective media?
only some organisms will grow; prevents the growth of some organisms
ex: MacConkey’s agar → only gram neg. will grow
MSA salt prevents growth of organisms that cannot grow w/salt
What is Differential media?
Different organism will appear differentially based on physiology
ex: MacConkey’s Agar→ lactose ferments= pink
MSA Mannitol ferments to acid (phenol red)
What is Enriched media?
promotes the growth of FASTIDIOUS (organisms w/speaiacl nutritional requirements)
-higher organisms usually contain TISSUES
ex: blood agar
heart agar
Type: Mannitol Salt Agar
o What type is it? (selective, differential, enriched, none of the above?)
o If it is selective: Who can grow on it? Who can’t? Why? (What’s in it that prevents something from growing?)
o If it is differential, what do different types of organisms look like on it, and what does that mean? (What’s in it that makes different organisms look different?)
o You may encounter a plate with colonies on it – be able to say what type of organism is likely growing (based on what you know about the medium)
Selective & differential media
Selective: salt prevents growth of organisms that can’t grow w/salt
Differential:
YELLOW—organism can ferment mannitol
NOT YELLOW— organism can’t ferment mannitol
1) Can the organism tolerate 7.5% salt? (growth- yes)
2) Can the organism ferment mannitol?
KEY INGREDIENTS: 7.5% salt, mannitol, phenol red
Type: MacConkey Agar
o What type is it? (selective, differential, enriched, none of the above?)
o If it is selective: Who can grow on it? Who can’t? Why? (What’s in it that
prevents something from growing?)
o If it is differential, what do different types of organisms look like on it, and what does that mean? (What’s in it that makes different organisms look different?)
o You may encounter a plate with colonies on it – be able to say what type of organism is likely growing (based on what you know about the medium)
Selective & Differential Media
Selective: only gram-negative will grow
Differential:
PINK— Yes Lactose-ferment
NOT PINK—Can’t ferment lactose
1) Is the organism Gram- Negative? GROWTH—Gram-NEG
2) Can the organism ferment lactose?
KEY INGREDIENTS: crystal violet, Lactose, neutral red
Type: Eosin Methylene Blue Agar
o What type is it? (selective, differential, enriched, none of the above?)
o If it is selective: Who can grow on it? Who can’t? Why? (What’s in it that
prevents something from growing?)
o If it is differential, what do different types of organisms look like on it, and what does that mean? (What’s in it that makes different organisms look different?)
o You may encounter a plate with colonies on it – be able to say what type of organism is likely growing (based on what you know about the medium)
Selective & Differential Media
Selective: only gram-negative will grow
Differential:
NO BLACK OR GREEN— Not ferment lactose
BLACK— Ferments lactose
METALLIC GREEN—Makes lots of acid from fermentation (E.coli)
1) Is the organism Gram- Negative?
2) Can the organism ferment lactose?
KEY INGREDIENTS: eosin, methylene blue, lactose
Type: Tergitol-7 Agar
o What type is it? (selective, differential, enriched, none of the above?)
o If it is selective: Who can grow on it? Who can’t? Why? (What’s in it that
prevents something from growing?)
o If it is differential, what do different types of organisms look like on it, and what does that mean? (What’s in it that makes different organisms look different?)
o You may encounter a plate with colonies on it – be able to say what type of organism is likely growing (based on what you know about the medium)
Selective & Differential Media
Selective: only gram-negative will grow
Differential:
YELLOW—Ferments lactose
NOT YELLOW—Does not ferment lactose
1) Is the organism Gram- Negative?
2) Can the organism ferment lactose?
KEY INGREDIENTS: tergitol-7, Lactose, bromothymol blue
Type: Blood agar
o What type is it? (selective, differential, enriched, none of the above?)
o If it is selective: Who can grow on it? Who can’t? Why? (What’s in it that
prevents something from growing?)
o If it is differential, what do different types of organisms look like on it, and what does that mean? (What’s in it that makes different organisms look different?)
o You may encounter a plate with colonies on it – be able to say what type of organism is likely growing (based on what you know about the medium)
enriched media
Type: Tryptic Soy Agar
o What type is it? (selective, differential, enriched, none of the above?)
o If it is selective: Who can grow on it? Who can’t? Why? (What’s in it that
prevents something from growing?)
o If it is differential, what do different types of organisms look like on it, and what does that mean? (What’s in it that makes different organisms look different?)
o You may encounter a plate with colonies on it – be able to say what type of organism is likely growing (based on what you know about the medium)
