This is the observed results and conclusion for my bacterial motility experiment.
Observed Results:
For the motility agar test the agar inoculated with P. mirabilis was entirely purple. This demonstrated that tetrazolium salt had been reduced by bacterial cells, in order for this to happen the bacteria must be motile showing that P. mirabilis is motile. For the motility agar inoculated with S. aureus only the area of inoculation was purple meaning only S. aureus was only able to reduce the tetrazolium salt in its immediate vicinity showing that it is non-motile. The results for the chemotaxis plates were not as expected. The plates inoculated with E. faecalis (plated by Liam Potter) showed no growth on either the control or test plate. The plates inoculated with S. marcescens (plated by Christina Fruciano) showed growth but not motility. On the control plate colonies of S. marcescens grew on both halves of the GYE agar. On the test plate S. marcescens grew on the GYE agar but not on the water agar, it did not move from the inoculated water agar to GYE agar as expected.
Conclusion:
The organisms tested on motility agar behaved as expected. S. aureus did not reduce all of the tetrazolium salt in the agar because it is non-motile. P. mirabilis did reduce all of the tetrazolium salt in the agar because it is motile. The organisms tested on the chemotaxis plates did not behave as expected. E. faecalis did not grow on either the test plate or control plate. This may have been due to cells in the inoculum being dead or due to a plating error. The results couldn’t confirm that E. faecalis was either motile or non-motile because there was no cell growth. S. marcescens did not travel across the filter paper after being inoculated on the water agar, nor did it form any colony on the water agar. This may have been due to nutrients not being properly absorbed by the filter paper causing no chemical signal to be present for S. marcescens. Another possibility is that the inoculated cells may have died on the water agar due to lack of nutrients. Based of the observed results S. marcescens is non-motile contrary to the expected results.
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