Lab 3 Flashcards
(13 cards)
What type of plate is the Mac plates?
Differential and Selective
What is the MAC plate composed of (3 things)
Bile Salts, Indicator Dye, Lactos
What is the purpose of bile salts in MAC plate?
Firmicutes can not grow in the presence of bile salts so this gives it the differential capability to only grow protobacteria (gram +)
What is the purpose of Indicator Dye and lactose in MAC plate?
The inicator dye tell if the pH is acidic or basic and the lactose is present to determine fermentation ability
What color does the MAC plate turn if the cells CAN ferment lactose and why?
Pink because organic acids are produced which interact with the bile salts and cause the acidic pH
What color does MAC plate turn if cells CAN NOT ferment lactose and why?
yello because NH3 is produced which makes pH basic
What test can be performed to determine if a bacteria is a facultative anaerobe?
Glucose Fermentation test
How does glucose fermentation test work?
Inoculate cells in broth. If able to ferment glucose=yello
If not able to ferment but can grow=red (turbid)
IF not able to grow at all= no change
How to tell if bacteria is facultative aneorobe for sure?
Using a oxidase test
How does oxidase test work?
It tests for the presence of cytochrome C. If bacteria has it, the paper turns blue and shows that it is a facultative aneorobe.
What morphology and gram stain type cell most likely has spores?
gram positive rods
What is the problem with using gram staining on bacteria containing spores?
The spores do not stain correctly (they stain pink even when the organism is gram positive)
Does salmonella ferment lactose?
NO
