Fermentation: Phenol Red Tubes, methyl red test, vogues-proskauer test, citrate test Flashcards
what is the chemical reaction for the breakdown of lactose (substrate, enzyme, product)?
substrate: lactose
enzyme: lacatase
product: glucose
what is the chemical reaction for the breakdown of sucrose (substrate, enzyme, product)?
substrate: sucrose
enzyme: sucrase
product: glucose
what is the indicator dye in phenol red tubes
and what color is it when alkaline or acidic
phenol red
acidic: yellow
basic: red
what causes reversion?
ammonia is produced if left inoculating for too long
how to prevent reversion?
inoculate for only 24 hours
what color is a positive methyl red test
RED
in the methyl red test e coli will turn the broth what color ?
RED and it will be positive for mixed acid fermentation
what about Enterobacter aerogenes in the methyl red test?
YELLOW and negative indicating no acid production
what is the reagent used in the methyl red test ?
methyl red
during the methyl red test the color is ___when negative
yellow
during the methyl red test the color is ___when postive?
red
a postive VP test is inidicated by the color
red for a alkaline end product
why cant you get a postive MR and VP test
you cant get both pathways can only metabolize one or the other
in the VP test a negative test result (yellow) identifies which organism?
Esherichia col
in the VP test a postive test result (red) identifies which organism?
enterobacter aerogenes
what is the indicator dye used in citrate test
Bromthymol blue
citrate test postive result?
blue when medium is alkalized
citrate test negative result ?
yellow
citrate test substrate enyzme product
substrate: citrate
enzyme: citrase
product: ammonia
citrate neutral result
green
VP Test
product for positive test ?
alkaline
methyl red positive test product?
acid
