Voges-Proskauer (VP) test is used to identify Gram negative bacteria that produce 2,3-butanediol (acetoin) from the fermentation of glucose. The Voges–Proskauer test determines the capability of some organisms to produce non acidic or neutral end products, such as acetyl methyl carbinol from glucose or sugar fermentation. VP is a test used to detect acetoin in […]
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Biochemical Tests in Microbiology Lab
Sugar (glucose) utilization test or carbohydrate fermentation test is used to detect bacteria that ferment various sugars (e.g. glucose) as well as convert pyruvate (the end product of glycolysis) into gaseous by-products (e.g. hydrogen and CO2). Bacteria in an effort to generate energy can ferment various simple sugars including glucose, sucrose, mannitol, and lactose, and
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Biochemical Tests in Microbiology Lab
Citrate test is used to identify Enterobacteriaceae that utilize citrate or citric acid as their sole carbon and energy source. Simmon’s citrate agar or citrate tablet is used in performing this test but only the Simmon’s citrate agar method is expanded in this book. The Simmons citrate agar tests the ability of organisms to utilize
Urease test is used to detect and differentiate Enterobacteriaceae that produce urease enzymes from those that do not. The urease test is used to determine the ability of an organism to split urea, through the production of the enzyme urease. Urease is an exoenzyme that hydrolyzes urea to produce ammonia and carbondioxide. Urease positive enterobacteria
Indole test (Tryptophan hydrolysis) is used to identify Enterobacteria that breakdown tryptophan (an amino acid) to produce indole. The indole test is a biochemical test performed on bacterial species to determine the ability of the organism to convert tryptophan into the indole. Tryptophan hydrolysis is catalyzed by the enzyme tryptophanase to produce indole and pyruvic
Oxidase test is used to identify microorganisms that produce the enzyme, cytochrome-c oxidase. Cytochrome-c oxidase, a respiratory enzyme is an important enzyme of the electron transport chain (ETC), where it catalyzes the transport of electrons from a donor compound (e.g. NADH) to oxygen, the final electron acceptor. If cytochrome-c oxidase is present, it will oxidize
Catalase test is used to identify microorganisms that produce catalase enzyme. It is used to differentiate catalase-producing organisms (e.g. Staphylococcus species) from non-catalase producing bacteria (e.g. Streptococcus species). Catalase enzyme breakdown hydrogen peroxide (H2O2) to water and oxygen; and this leads to the release or production of bubbles – which indicates a positive test result
Coagulase test is used to distinguish pathogenic Staphylococcus aureus (which is coagulase positive) from nonpathogenic strains of S. aureus (which is coagulase negative). This test is used to differentiate Staphylococcus aureus (positive) from Coagulase Negative Staphylococcus (CONS). Coagulase is an enzyme produced by S. aureus that converts (soluble) fibrinogen in plasma to (insoluble) fibrin. Staphylococcus
Biochemical tests are series of experiments that can be used to differentiate bacteria based on their metabolic activity or ability to utilize a given substrate such as glucose. These tests are generally useful in characterizing bacteria in the Microbiology Laboratory, and they take advantage of the organism’s physiological, osmotic, and nutritional requirements. The identification of
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Biochemical Tests in Microbiology Lab