Serratia Liquefaciens


Shape: Bacillus
Colony: Staph
Gram Stain: Negative
Methyl Red Test: Negative
Motility Test: Positive
Hemolysis Test: Gamma
Aerobic or Anaerobic: Facultative
Serratia Liquifaciens
Serratia Liquifaciens
Notes: White

Gram Stains:

Results: Gram Negative
A Gram Stain is when you put your bacteria on a slide, heat fix it and stain it with two different types of stain. The first stain is Crystal Violet, it makes the bacteria appear purple or blue under the microscope. The Stain will be soaked in if the bacteria is gram positive. Which means that the bacteria has one thick cell wall made of peptidoglycan. The second stain is Safranin, this stain will not soak into the cell wall but it will stay on gram negative bacteria making the bacteria appear red or pink under the microscope. The cell wall of Gram Negative bacteria has two layers; a thin layer of peptidoglycan is covered by a layer of lipid.

Methyl Red Test:

Results: - (Negative)
A Methyl Red Test is conducted to see what kind of waste the bacteria produces. Serratia Liquifaciens made the tube turn yellow, showing negative test results. This means that Serratia Liquifaciens does not produce acidic waste. The test is done by putting some of the bacteria in a test tube of glucose broth. Mix up the contents of the test tube and incubate the mixture for 48 hours. After 48 hours lace 5 drops of Methyl Red into the tube. If the bacteria digested glucose produced acidic waste the tube will turn red, but if it produced neutral waste the tube will turn orange or yellow.
Motility Test:

S. Liquifaciens Motility Test results
S. Liquifaciens Motility Test results

Results: + (positive)
This means that Serratia Liquifaciens can move. The test was conducted using a Test Tube of Motility Test Agar. A sample of the bacteria was taken on an Inoculating Loop and stabbed into the center of the Agar Test Tube. Incubate the test tube. If bacteria has grown only along the stab line the bacteria is non-motile, you obtained negative results. If the Agar appears cloudy or you see definite trails of growth the bacteria is motile, you have obtained positive results.

Hemolysis Test:

Results: Gamma
The Hemolysis Test was used to tell if the bacteria was Alpha, Beta or Gamma. If the bacteria is Alpha it only ate 1 protein in the quaternary structure the Agar turns a brownish-green color. If the bacteria is Beta, the Hemoglobin is completely digested. If the bacteria is Gamma, the bacteria does not digest hemoglobin at all. To conduct the test you place a sample of the bacteria on a plate of Sheep's Blood Agar and incubate it for 48 hours.

Aerobic or Anaerobic Test:

Results: F (facultative)
Serratia Liquifaciens is facultative, meaning that it can grow in both an aerobic or anaerobic environment. This test w
Example of a plant where S. Liquifaciens can be found
Example of a plant where S. Liquifaciens can be found
as performed by putting a Nutrient Agar plate in a big glass pickle jar and placing a burning candle in the jar before putting on the lid. The candle burned up all the oxygen in the jar so if the bacteria is anaerobic it could not grow.

Bauer-Kirby Test:

Penicillin: 0 mm
Chloramphenicol: 0 mm
Ampicillin: 16mm
Hand Sanitizer: 0 mm
Ampicillin kills bacteria by preventing the growth of cell membrane, therefore the cell wall eventually breaks down because the peptidoglycan in the cell wall can not replace itself. This only works on negative bacteria such as Serratia Liquefaciens. Penicilin prevents the cell from dividing but S. Liquifaciens is resistant to penicillin so it does not work. Lots of Gram Negative bacteria are developing resistance towards anti-bacterials which you can see by the fact that 3 of the 4 antibiotics tested had no effect on the Serratia Liquifaciens.

Serratia Liquefaciens can be found on certain plants (such as the one to the right) and the digestive tracts of certain rodents. It is associated with blood infections, sometimes severe ones. S. Liquefaciens is associated with wound infections and/or urinary tract infections.

Ashley Fellers