Selective Mediums Flashcards
What Temperature does the Autoclave reach?
121 C
How does the Autoclave increase temp?
Hot Steam and Increased Pressure
What does CFU stand for?
Colony Forming Unit
What all should you label on a plate?
Medium Type, Date, Organism, Group Number, Section Number, Initials
What does it mean for a medium to be Undefined?
Unknown exact recipe. Includes “digests”, “peptone”, “extracts”
What does it mean for a medium to be Selective?
Medium will encourage some bacteria to grow and discourage/inhibit other bacterial growth. Can only tell you if an organism possesses a certain quality, can not identify an unknown organism.
What does it mean for a medium to be Differential?
Medium can differentiate between two different organisms, can tell you what an unknown bacteria actually is.
What does it mean for a medium to be Defined?
All chemical ingredients are known
What are the 6 fundamental features of selective media?
- Selective/Differential, Defined/Undefined
- Nutritional Components
- Inhibitors–make it selective
- Substrates–make it differential
- Indicators
- Agar
What kind of media is Phenylethyl Alcohol (PEA)?
Selective, Undefined
What kind of organisms does PEA Media inhibit?
Inhibits Gram -
Selects for Gram +
What part of PEA Media inhibits Gram - growth?
B-Phenylethyl Alcohol
What kind of media is Mannitol Salt Agar (MSA)?
Selective, Differential, Undefined
What kind of organisms does MSA Media grow?
Selects for Staphylococcus genus
How is MSA Media selective?
High salt concentrations (Sodium Chloride). Staphylococcus is the only species that can survive in high salt concentration.
How is MSA Media differential?
D-Mannitol is a Substrate. Staphylococcus aureus reacts with D-Mannitol and makes environment more acidic. The Phenol Red Indicator turns Yellow in Acidic environments. The Phenol Red Indicator stays Red in Basic environments.
What kind of media is MaConkey Again (MAC)?
Selective, Differential, Undefined
How is MAC Media Selective?
Bile Salts and Crystal Violet Dye Inhibit Gram + growth
Selects for Gram -
How is MAC Media Differential?
Lactose is a Substrate. Lactose Fermentors will make the environment more Acidic. The Neutral Red Indicator is Colorless in Basic environments and Red in Acidic Environments.
What kind of media is Eosin Methylene Blue Agar (EMB)?
Selective, Differential, Undefined
What makes EMB Media Selective?
Eosin and Methylene Blue dyes encourage Gram - growth.
What makes EMB Media Differential?
Lactose and Sucrose are Substrates. Fermentation makes environment more acidic, which changes color of Eosin and Methylene Blue. Shows Degree of Lactose use. How efficiently it ferments Lactose or Sucrose.
Esherichia coli, Salmonella typhimurium, Enterobacter aerogenes
Gram -
Staphylococcus aureus, Staphlococcus epidermitis, Enterococcus faecalis
Gram +
