4.2 Agar Plates Part 4 Flashcards
How do non-pathogenic strains of E coli appear on SMAC plates?
red colonies; acidic conditions
How do pathogenic strains of E coli appear on SMAC plates?
white colonies; neutral to basic conditions
What is an EMB agar?
eosin methylene blue agar
What color is an EMB?
red color
What type of media is an EMB?
selective and differential
How are microorganisms differentiated in EMB?
ability to ferment lactose present in the media
What does the media contain in EMB?
eosin and methylene blue
How do non-fermenting microbes appear on an EMB?
white/tan colonies
How do lactose-fermenting microbes appear on an EMB?
dark purple or black colonies on the surface of the agar
What do E coli look like on an EMB?
metallic green shade
What is an MSA agar?
mannitol salt agar
What color is an MSA agar?
red
What type of media is an MSA agar?
selective and differential
What is the function of an MSA agar?
selective for Gram positive bacteria and can differentiate members of the Stahylcocci family
What does the media for MSA contain?
high concentration of sodium chloride
mannitol
pH indicator dye phenol red
What is the purpose of the sodium chloride in an MSA?
prevents the growth of certain microorganisms
What is the purpose of the mannitol and pH indicator dye in the MSA?
differentiate pathogenic from non-pathogenic strains of Staph
What is the pathogenic strain of Staph?
staph aureus
Which type if Staph can ferment the mannitol in an MSA?
pathogenic strain
What does the MSA with pathogenic staph look like?
lowers the pH changing the dye color from red to yellow