Rhizobium Leguminosarum

Catherine Daymude

Gram Stain
This bacteria strain is a gram negative bacterium. Gram staining uses
R. Leguminosarum (SEM Image)
R. Leguminosarum (SEM Image)

two different stains that will show whether the bacteria is Gram Positive or Gram Negative. first stain used is Crystal violet and will be absorbed by Gram Positive bacteria which has a single layer cell wall. The second stain used is safranin Gram negative bacteria has a two-layer cell wall and will appear pink after staining.

Shape and Colony Type
Rhizobium Leguminosarum is a bacillus (rod) shaped bacteria. This bacteria makes random (staph) colonies.

Methyl Red Test
The Methyl Red test appeared positive for this bacteria. This test shows which type of waste product the bacteria produces: acid, neutral, or base. Positive bacteria produce an acid waste product such as Rhizobium Leguminosarum.

This bacteria is motile. The motility test uses ager gel in a test tube to see how the bacteria grows when stabbed down the center with an inoculating needle. If the bacteria grows throughout the test tube, the bacteria is motile.

R. Leguminosarum Hemolysis Plate (Beta)
R. Leguminosarum Hemolysis Plate (Beta)

Hemolysis tests to determine if the bacterium eats hemoglobin. Rhizobium Leguminosarum is Beta meaning it does digest hemoglobin. In order to test this, bacteria is streaked onto a sheep's blood ager plate and incubated. If area around the bacterium is clear, then the bacteria is Beta; if the bacteria only eats one protein in the quaternary structure of the hemoglobin and the area around the bacteria is brown in color, it is Alpha; and if it doesn't digest any hemoglobin it is Gamma.

Ideal Growth
Rhizobium Leguminosarum grows well at most temperatures but best at 25 degrees Celcius.
Rhizobium Leguminosarum is an aerobic bacterium which means it cannot grow without oxygen. To test this we grew bacteria in an incubator and in a large jar. To remove oxygen from the jar we lit a candle inside to use the oxygen. If the bacteria grew in both it was facultative, if it only grew in the pickle jar it was anaerobic.

Baur- Kirby Test
The Baur Kirby test determines which anti-biotics work best on a certain bacteria. To do this a circle of paper with the anti-biotic is placed on a plate streaked with the bacteria. Then after incubation affective antibiotics will leave a large circle around the disc with no bacterial growth. In the test on R. Leguminosarum, Ampicillin, Chloramphenicol, Tetracycline were used. The Cloramphenicol was the most effective with a ZOI (Zone of Inhibition) of 13mm. The Chloramphenicol uses protein synthesis to kill the bacteria. This process interferes with the ribosomes and stops the cell from creating more structural proteins or enzymes. Ampicillin works better on Gram positive strains because it uses cell wall synthesis instead of protein synthesis. Tetracycline also uses a protein synthesis method of action and had better results than the Ampicillin did with a 5mm ZOI.

This bacteria grows in soil and can adapt to many temperatures. It will grow on small root hairs of plants and cause root nodules to form.
Root nodules caused by R. Leguminosarum
Root nodules caused by R. Leguminosarum

Affects of Rhizobium Leguminosarum
Rhizobium Leguminosarum is a bacteria that causes root nodules to be formed on the roots of certain plants. This is a nitrogen fixing bacteria. Rhizobium Leguminosarum allows plants to receive oxygen in soil with low oxygen content. Rhizobium Leguminosarum is found growing on legumes such as peas, clover, lentils, and kidney beans. In a recent studie, it has been shown that Rhizobium Leguminosarum may increase the number of cytokines produces by human monocytes. Cytokines can cause a decrease in inflammation.