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Indole test positive: appearance of pink layer at top (e.g. Escherichia coli) Like many biochemical tests on bacteria, results of an indole test are indicated by a change in color following a reaction with an added reagent. Pure bacterial culture must be grown in sterile tryptophan or peptone broth for 24–48 hours before performing the test.
The species C. amalonaticus, C. koseri, and C. freundii can use citrate as a sole carbon source. Citrobacter species are differentiated by their ability to convert tryptophan to indole (C. koseri is the only citrobacter to be commonly indole-positive), ferment lactose (C. koseri is a lactose fermentor), and use malonate.
Proteus vulgaris is a rod-shaped, nitrate-reducing, indole-positive and catalase-positive, hydrogen sulfide-producing, Gram-negative bacterium that inhabits the intestinal tracts of humans and animals. It can be found in soil, water, and fecal matter.
Morganella morganii is a species of Gram-negative bacteria. [2] It has a commensal relationship within the intestinal tracts of humans, mammals, and reptiles as normal flora. [ 2 ] Although M. morganii has a wide distribution, it is considered an uncommon cause of community-acquired infection, and it is most often encountered in postoperative ...
Proteus is a genus of Gram-negative bacteria. It is a rod shaped, aerobic and motile bacteria, which is able to migrate across surfaces due its “swarming” characteristic in temperatures between 20 and 37 °C. [1] Their size generally ranges from 0.4 to 0.8 μm in diameter and 1.0–3.0 μm in length. They tend to have an ammonia smell. [2]
P. hauseri is ONPG negative and PDA positive [citation needed]. Unlike the more commonly seen species of Proteus, P. hauseri is also able to convert tryptophan into indole, resulting in a positive indole test. P. hauseri shares a similar biochemical profile with Proteus vulgaris but can be differentiated by its ability to produce acid from ...
To test the broth for indole production, Kovac's reagent. Kovac's reagent consist of amyl alcohol and para-dimethylaminobenzaldehyde and concentrated hydrochloric acid . Kovac's reagent is actually used to determine ability of an organism to separate indole from amino acid tryptophan and it is added after incubation.
P. canis is positive for catalase, oxidase, and ornithine decarboxylase, but negative for lysine decarboxylase, V-factor (nicotinamide adenine dinucleotide), D-mannitol, dulcitol, D-sorbitol, urease, maltose, and L-arabinose. [1] [8] [10] It can also be indole positive or negative depending on the biotype. [10]