Exercise 5-2 Micro Lab: Oxidation-Fermentation Test
The oxidation fermentation test is designed to:
differentiate bacteria on the basis of fermentative or oxidative metabolism of carbohydrates
What does Hugh and Leifson's OF test include to reduce the possibility that alkaline products from peptone ulitization will neutralize weak acids produced by oxidation of the carbohydrate?
a high sugar to peptone ratio
What is the pH indicator in the OF test?
bromthymol blue dye
the bromthymol blue dye is ____ at pH of 6 and ____ at pH of 7
How is the OF medium prepared?
with glucose, lactose, sucrose, maltose, mannitol, or xylose and is not slanted
After innoculation, what happens to one of the tubes of OF and why?
it is sealed with a layer of mineral oil to promote anaerobic growth and fermentation
Organisms that are able to ferment the carbohydrate or ferment and oxidize the carbohydrate will do what?
turn the sealed and unsealed media yellow throughout
Organisms that are able to oxidize only will do what?
turn the unsealed medium yellow and leave the sealed medium green or blue
Slow or weak fermenters will do what?
turn both tubes slightly yellow at the top
Organisms that are not able to metabolize sugar will do what?
produce no color change or turn the medium blue because of alkaline products from amino acid degredation