The ability of organisms such as E. coli to ferment via the mixed acids pathway can be tested by the methyl-red test, which detects O the low pH resulting from the acidic end products O Gram-negative rod shaped bacteria O obligate fermenters O all members of the Enterobacteriaceae family
Added by Brian C.
Close
Step 1
Step 1: The methyl-red test is used to detect the production of mixed acids during fermentation. Show more…
Show all steps
Your feedback will help us improve your experience
Dominador Tan and 70 other Biology educators are ready to help you.
Ask a new question
Labs
Want to see this concept in action?
Explore this concept interactively to see how it behaves as you change inputs.
Key Concepts
Recommended Videos
Methyl Red: This test determines the presence of acidic byproducts of glucose fermentation, specifically mixed acid fermentation. The test organism is inoculated into a tube of MRVP broth (Methyl Red, Voges-Proskauer broth), allowed to grow, and then tested for pH below 4.4 by adding the pH indicator Methyl Red. A bright red color indicates a positive result (pH below 4.4), whereas a negative result shows yellow (pH above 4.4). Voges-Proskauer: This test determines the ability of bacteria to produce acidic byproducts from glucose, specifically the presence of acetoin, an intermediate of 2,3 butanedio fermentation. The test organism is inoculated into a tube of MRVP broth, allowed to grow, and then tested for the presence of acetoin by adding 10 drops each of alpha naphthol and 40% KOH. A dull brick red color indicates a positive result. This result may require vigorous agitation and application of heat (placing the tube in the incubator) and may take up to 1 hour to develop. No change in the color of the tube indicates a negative result.
Dominador T.
MRVP (7 points) Organism Color After Methyl Red Color after MR (+/-) VP (+/-) and VP B coli E aerogenes Do you think it's possible that an organism is both MR positive and VP positive? Why or why not? What is the purpose of the methyl red test? What are two types of organisms that use the mixed-acid pathway? What is the purpose of the Voges Proskauer test? What are two types of organisms that use the butylene glycol pathway? What types of fermentation products can be released via the breakdown of pyruvic acid?
Adi S.
The methyl red test detects a microbe's ability to: - perform mixed-acid fermentation - perform butanediol fermentation - respire aerobically - All of the above
Recommended Textbooks
Biology for AP Courses
Objective Biology for NEET
Introduction to General, Organic and Biochemistry
Transcript
Watch the video solution with this free unlock.
EMAIL
PASSWORD