Labmr Vp

Could an organism be both MR and VP positive? Explain. (6 pts)

Answer below:

The MRVP test is able to distinguish among organism that produce large amount of acid from glucose and the others in which that produce the neutral acetoin product. The MR test turns red if the organism creates acid from glucose when the methyl red is added. The VP test is used to detect neutral products specifically acetoin. If there is acetoin present, the upper part of the medium will turn a yellowish copper color. No, an organism can not be both MR and VP positive. For something to be MR positive, converts all the glucose available into acidic products. It will produce a large amount of acid, which will be enough to change the color of the methyl red pH indicator from yellow to red. For an organism to be VP positive, the organism turns red if there is some of the glucose being converted into the neutral product. If all of glucose available for the acidic product, there can’t be any used for the neutral product conversion because there wouldn’t be enough glucose converted into the acid for a positive MR test.

Online lab #7: Biochemical Tests Lab (n.d.). Rio Salado College. Retrieved from:

https://www.riolearn.org/content/bio/bio205/BIO205_INTER_0000_v1/labs/lab07.shtml?encrypted-sectionid=bEJyZnJlV1VacHU1RXlUOTdvM2hXZz09

What is the name of each of the three tests (A, B, and C) seen above? What is the result of each test (positive or negative)? Name one organism that can have all of these results (i.e. taken as a combination of the results shown). (6 pts)

Answer below:

Test A is a methyl red test. Test B is a carbohydrate fermentation test. Test C is a phenylalanine deaminase test. Test A is a positive result, Test B is a positive result, and Test C is a negative result. One organism that can have all these results from each test would be E. Coli.

Online lab #7: Biochemical Tests Lab (n.d.). Rio Salado College. Retrieved from:...