blue/positive
The result is the initial green color of the Simmons Citrate Agar turning blue; generating a positive indication that the organism does indeed utilize citrate as the sole source of carbon and energy.
No, it is present/positive. • Cocci* • Gram-Positive* • Non-motile* • No Capsules* • No Spores* • Facultative Aerobe* • No Glucose, Lactose*, Mannitol* Fermentation • No Urease*, Catalase*, Oxidase*, Ligase*, Protease* Production • Production of Indole*, tryptophonase*
Yes, Serratia marcescens typically tests negative for citrate utilization in citrate utilization tests. This bacterium lacks the enzyme citrate-permease needed to import citrate into the cell, resulting in a negative citrate test.
An organism that possesses the citrate lyase enzyme may not test positive on Simmon's citrate agar if it does not effectively utilize citrate under the specific conditions of the test, such as pH or temperature. Additionally, the organism might not be able to grow on the agar due to other metabolic limitations or competition with other microorganisms. This situation is not strictly a false negative, as the test specifically measures the ability to utilize citrate as the sole carbon source, rather than merely the presence of the enzyme. Thus, a negative result could reflect the organism's inability to metabolize citrate in that particular environment.
si
blue/positive
Pseudomonas aeruginosa typically demonstrates a negative result on the citrate test, as it is unable to utilize citrate as its sole carbon source for growth. This bacterium lacks the enzyme citrate-permease needed to transport citrate into the cell for metabolism, leading to a lack of growth on citrate agar and a lack of color change from green to blue.
The positive organism for citrate utilization test is usually Escherichia coli. When this bacterium is able to grow on a citrate-containing medium, it will produce alkaline byproducts that change the pH of the medium, turning it from green to blue. This color change indicates a positive result for citrate utilization.
The result is the initial green color of the Simmons Citrate Agar turning blue; generating a positive indication that the organism does indeed utilize citrate as the sole source of carbon and energy.
No, it is present/positive. • Cocci* • Gram-Positive* • Non-motile* • No Capsules* • No Spores* • Facultative Aerobe* • No Glucose, Lactose*, Mannitol* Fermentation • No Urease*, Catalase*, Oxidase*, Ligase*, Protease* Production • Production of Indole*, tryptophonase*
Yes, Serratia marcescens typically tests negative for citrate utilization in citrate utilization tests. This bacterium lacks the enzyme citrate-permease needed to import citrate into the cell, resulting in a negative citrate test.
Optochin is a test used only for determining if an isolate of alpha-hemolytic streptococcus is Streptococcus pneumoniae. In the clinical laboratory, it is not used for testing of gram negative rods such as E. coli.
Based on my own test, Shigella flexneri tests negative for the citrate test.
An organism that possesses the citrate lyase enzyme may not test positive on Simmon's citrate agar if it does not effectively utilize citrate under the specific conditions of the test, such as pH or temperature. Additionally, the organism might not be able to grow on the agar due to other metabolic limitations or competition with other microorganisms. This situation is not strictly a false negative, as the test specifically measures the ability to utilize citrate as the sole carbon source, rather than merely the presence of the enzyme. Thus, a negative result could reflect the organism's inability to metabolize citrate in that particular environment.
assay test of sodium acid citrate
Klebsiella pneumoniae is typically citrate negative, meaning it does not utilize citrate as a carbon source in the citrate utilization test. This bacterium lacks the enzyme citrate permease needed for citrate utilization.