Enrichment and Isolation of Rhizobium



Results

Test/Technique
Result
Interpretation
Streak Plate
white mucilaginous colonies
yellow slimy colonies
Two different strains of Rhizobia
Gram Stain
pink rod shaped cells
Gram Negative Bacilli
Capsule Stain
negative
Does not produce capusles but extracellular polysaccharide slime
Catalase Test
positive
Undergoes aerobic respiration
Oxidase Test
white colonies - positive
yellow colonies - negative
Further confirms the presence of two different organisms
Wet Mount
yes
Motile organisms
Dextrose Tubes
white colonies - change in color (from red to yellow)
yellow colonies - change in color (from red to yellow)
Two different bacterial strins possible
Anaerobic Chamber
white colonies - growth
yellow colonies - growth
Inconclusive (Free living Rhizobium cannot grow in anaerobic conditions; the anaerobic chamber was probably not sealed properly)
* white colonies isolated from the soy bean sample
* yellow colonies isolated from the clover sample



Movie: Flagellated motion of Rhizobium from the clover sample.
Click here to download/watch movie.
[AVI file: 3.38Mb]



Soybean Plate
Rhizobium from the Soybean sample grown on the the YMA plate.


Clover Plate
Rhizobium from the clover sample grown on the the YMA plate.


Soybean gram stain
Gram stain of soybean samples showing the gram negative rods.


Clover gram stain
Gram stain of clover samples showing the gram negative rods.


Polysaccharide slime
Capsule stain of the sample showing the extra cellular polysaccharide slime.


No capsule
Capsule stain of the soybean sample proving that it capsules are not present.


Dextrose tubes
Acid production in the dextrose tubes confirming that the samples are capable of utilizing dextrose.