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If the area of inoculation turns dark-blue to maroon to almost black, then the result is positive. If a color change does not occur within three minutes, the result is negative. In alternative manner, live bacteria cultivated on trypticase soy agar plates may be prepared using sterile technique with a single-line streak inoculation. The ...
Before starting a test, one must confirm the cultured bacteria are Enterobacteriaceae, this is done by a quick oxidase test for cytochrome coxidase. Enterobacteriaceae are typically oxidase negative, meaning they either do not use oxygen as an electron acceptor in the electron transport chain , or they use a different cytochrome enzyme for ...
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.
In microbiology, the oxidase test is used as a phenotypic characteristic for the identification of bacterial strains; it determines whether a given bacterium produces cytochrome oxidases (and therefore utilizes oxygen with an electron transfer chain). The test is used to determine whether a bacterium is an aerobe or anaerobe. However a ...
To perform the OF-glucose test, two tubes of OF-glucose medium are inoculated with the test organism. A layer of mineral oil is added to the top of the deep in one of the tubes to create anaerobic conditions. Oil is not added to the other tube to allow for aerobic conditions. The tubes are then incubated for 24–48 hours.
The test tube on the right shows a negative result as no acidic products are formed by fermentation. The methyl red (MR) test can detect whether the mixed acid fermentation pathway occurs in microbes when given glucose. A pH indicator is used that turns the test solution red if the pH drops below 4.4. [12]
The TSI slant is a test tube that contains agar, a pH-sensitive dye , 1% lactose, 1% sucrose, 0.1% glucose, [2] and sodium thiosulfate and ferrous sulfate or ferrous ammonium sulfate. All of these ingredients are mixed together, heated to sterility, and allowed to solidify in the test tube at a slanted angle.
The test employs the Trinder reagent, and is a colour change test resulting from the Trinder reaction. The Trinder reagent, named after P. Trinder of the Biochemistry Department of the Royal Infirmary in Sunderland (see the article listed in further reading ), comprises an aminoantipyrine (such as 4-aminoantipyrine ) and phenol (p-hydroxybenzene).