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What are the indole test principles?
The indole test is based on the ability of certain bacteria to produce the enzyme tryptophanase, which converts tryptophan into indole. This indole is then detected by adding a reagent such as Kovac's reagent, which reacts with indole to produce a red color. A positive test indicates the presence of tryptophanase enzyme in the bacteria.
What is borsch reagent?
Borsch reagent is a chemical solution commonly used in microbiology to detect the presence of indole. It is composed of hydrochloric acid, dimethylaminobenzaldehyde, and amyl alcohol. When added to a bacterial culture, the reagent reacts with indole produced by certain bacteria, resulting in a color change from yellow to red.
Why determine motility and h2s before adding kovac's reagent?
You will do this regardless since Indole is part of the SIM media....this media will turn black if H2S is present and you read it for motility just like standard motility media. It must incubate for 24-28 hrs before doing the indole portion. Hope this helps.
What is the component in the SIM deep tubes that makes the medium suitable to detect the production of indole by bacteria?
The component in SIM deep tubes that makes the medium suitable to detect the production of indole by bacteria is tryptophan. Bacteria that possess the enzyme tryptophanase can break down tryptophan to produce indole, which can be detected by the addition of Kovac's reagent that reacts with indole to form a red color.
What is the component in the SIM deep tubes that makes this medium suitable to detect the production of indole?
The ingredients in SIM Medium enable the determination of three activities by which enteric bacteria can be differentiated. Sodium thiosulfate and ferrous ammonium sulfate are indicators of hydrogen sulfide production. The ferrous ammonium sulfate reacts with H2S gas to produce ferrous sulfide, a black precipitate.1 The casein peptone is rich in tryptophan, which is attacked by certain microorganisms resulting in the production of indole. The indole is detected by the addition of chemical reagents following the incubation period. Motility detection is possible due to the semisolid nature of the medium. Growth radiating out from the central stab line indicates that the test organism is motile.
What is the use of concentrated HCL in Ehrlichs reagent?
You must take 88,8 mL concentrated HCL and fill up to 1000 mL with distilated water. (REMEMBER: ALWAYS ADD ACID TO WATER! - add 88.8mL to 900mL water and dilute to final volume = 1L) The simplest...
What are the indole test principles?
The indole test is based on the ability of certain bacteria to produce the enzyme tryptophanase, which converts tryptophan into indole. This indole is then detected by adding a reagent such as Kovac's reagent, which reacts with indole to produce a red color. A positive test indicates the presence of tryptophanase enzyme in the bacteria.
What does kovac's reagent do in a reaction?
Used to test prescece of Indole in medium
Explain the chemical mechanism for detecting indole in a bacterial culture?
Indole is extracted from the medium and into the reagent layer (Kovac's) by the acidified butyl alcohol component and forms a complex with the p-dimethylaminobenzaldehyde, yielding the cherry red color seen when the culture is indole positive.
What is the reagent of Pauly?
The reagent used in Pauly's reaction is α-naphthol and concentrated hydrochloric acid. This reagent system is used to test for the presence of indole-like compounds in organic molecules.
What is borsch reagent?
Borsch reagent is a chemical solution commonly used in microbiology to detect the presence of indole. It is composed of hydrochloric acid, dimethylaminobenzaldehyde, and amyl alcohol. When added to a bacterial culture, the reagent reacts with indole produced by certain bacteria, resulting in a color change from yellow to red.
Why determine motility and h2s before adding kovac's reagent?
You will do this regardless since Indole is part of the SIM media....this media will turn black if H2S is present and you read it for motility just like standard motility media. It must incubate for 24-28 hrs before doing the indole portion. Hope this helps.
What is the substrate for the Indole test?
The indole test is a biochemical test performed on bacterial species to determine the ability of the organism to split indole from the amino acid tryptophan. This division is performed by a chain of a number of different intracellular enzymes, a system generally referred to as "tryptophanase."
What is the component in the SIM deep tubes that makes the medium suitable to detect the production of indole by bacteria?
The component in SIM deep tubes that makes the medium suitable to detect the production of indole by bacteria is tryptophan. Bacteria that possess the enzyme tryptophanase can break down tryptophan to produce indole, which can be detected by the addition of Kovac's reagent that reacts with indole to form a red color.
Indole positive gram negative bacteria rods?
Indole positive gram negative rod-shaped bacteria include members of the Enterobacteriaceae family such as Escherichia coli and Klebsiella pneumoniae. These bacteria produce indole from the amino acid tryptophan as a metabolic byproduct, which can be detected using the Kovac's reagent test. Indole production is a characteristic used in the identification and differentiation of these bacteria in the laboratory.
How do you prepare Salkowski reagent?
Mix 2 ml 0.5M FeCl3 and 48 ml water and 50 ml 70% perchloric acid.
What amino acids give positive Ehrlich test?
Amino acids that contain an indole group, such as tryptophan, give a positive Ehrlich test. The Ehrlich test is a colorimetric test that detects compounds containing indole or phenolic groups by producing a pink or red color when reacted with p-dimethylaminobenzaldehyde reagent.
