if an organism can breakdown carbohydrates by fermentation what is produced?
acid
In phenol red carbohydrate tests what indicates the presence of acid
a color change in the pH indicator, phenol red, from red at alkaline pH values to yellow at acidic pH values
what do you use to determine whether an organism actually 1. produces acid through fermentation or 2. only through oxidation?
O/F carbohydrate tubes are used
in phenol red carbohydrate tubes What carbohydrates can be added to the O/F medium?
any carbohydrate
What is the difference between phenol red tubes and O/F carbohydrate tubes?
carbohydrate tubes contain a semisolid agar rather than liquid
What is the difference in O and F carbohydrate tubes?
sterile mineral oil is added to top of tube in F and no oil is added to O
what happens if acid is produced in O/F carbohydrate tubes?
the medium changes from green to yellow
What is the purpose of carbohydrate metabolism or O/F carbohydrate tests
to see if an organism can breakdown carbohydrates by oxidation or fermentation
organisms that turn both O and F tubes yellow
carry out fermentation of carbohydrates
organisms that turn only the O tube yellow
cannot carry out fermentation and produce acid only through the oxidative pathway (respiration)
in the Methyl red test/ MR test escherichia, salmonella, and proteus ferment glucose to produce organic acids such as
lactic, acetic, succinic, formic acids, and CO2, H2, and ethanol
the amount of acid produced in methyl red test is sufficient to lower what
pH of the MRVP broth to 5.0 or less
what is the pH indicator in methyl red test?
methyl red
a positive methyl test indicates what
organism has carried out mixed acid fermentation