quiz 8 Flashcards
methyl red test
indicates mixed acid fermentation pathway, red is positive, yellow is negative, orange is inconclusive or negative
VP/acetoin test
butanediol fermentation pathway to ferment glucose, positive is red, no color is negative
citrate test
capability of utilizing citric acid as sole carbon source, visible growth is positive and sometimes blue
ornithine test
presence of enzyme ornithine decarboxylase. purple is positive, yellow is negative
What is the morphology of enterobacteria?
facultativ anaerobes, gram negative rods, oxidase negative, motile
What is the physical appearance of E.coli on EMB agar?
irregular, flat, almost black colonies with green sheen
Why use the lactose mineral salt?
To restrict streptococcus and micrococcus
Why were propionic bacteria able to survive our skin surface?
They’re aeroduric
On a sourdough TSY plate, what do yeast look like?
large, irregular, white colonies
What is the morphology of our LA bacteria?
gram positive, catalase negative
What does a cloudy/turbid plaque assume?
Incomplete lysis, temperate phage
what is the job of the repressor?
Deactivates sigma gene expression
How does sigma phage grow on E.coli?
partial growth bc no repressor of sigma genes
How does sigma phage grow on sigma E.coli?
No growth bc sigma phage repressor turns off sigma gene expression, lysogen immunity
What is lysogen immunity?
conferred protection against phage of same kinda as prophage
what is sigma vir?
Altered operator region where sigma repressor binds, no repression
Why is there no growth on lambda?
no phage receptors so cannot recognize the cell and grow
What is the ourpose of the K12 E.coli plate?
demonstrate the difference between turbid and clear plaque
what are the white micro colonies on clear plaques?
mutant e.coli strains that no longer express the lambda receptor protein, they are resistant to lambda infection because phage can no longer recognize and adsorb cell
with PNS bacteria, what do g neg rods and spills signify/
rods are rhodobacter and rhodopseudomonas, spirals are rhospirillium
