Question

Methyl Red and Voges-Proskauer Tests OBSERVATIONS AND INTERPRETATIONS 5-3 1 Refer to Tables 5-3 and 5-4, page 290, as you record your results (color) and interpretations in the table below Organism Uninoculated control MR Result VP Result Interpretation QUESTIONS Some protocols call for a shorter incubation time for the MR and VP tests. Other protocols alloue for up to 10 days incubation with virtually no risk of producing a false positive. a. Which of the two tests would likely produce more false negatives with a shorter incubation timet Why b. Which test would likely benefit most from a longer incubation timet Why? SECTION5 Differential Tests 293

Answer 1

Ans-1 the MR test will give false negative result from short incubation period because it requires minimum 48 hours of incubation for a proper result.

Ans-2 it is also MR test because four different acid are formed by bacteria from glucose , so a proper time is needed by bacteria to ferment this ,that is why a longer incubation period is given to the MR test and it is beneficial in proper characterisation.