Search results
Results from the WOW.Com Content Network
The IMViC tests are a group of individual tests used in microbiology lab testing to identify an organism in the coliform group. A coliform is a gram negative , aerobic, or facultative anaerobic rod, which produces gas from lactose within 48 hours.
The positive control should give a large amount of enzyme activity, while the negative control should give very low to no activity. If the positive control does not produce the expected result, there may be something wrong with the experimental procedure, and the experiment is repeated.
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 a sample, E. coli, which is citrate-negative, can be distinguished from non-fecal, citrate-positive coliforms that are often found in water, soil, and on plants using Simmons’ agar. Additionally, Simmons’ agar is commonly used as part of the IMViC tests to identify coliforms. [4]
If stronger with the sera adsorbed with guinea-pig kidney, the test is positive. If stronger with the sera adsorbed with ox red cell stroma, the test is negative. If agglutination is absent in both mixtures, the test is negative. A known 'positive' and 'negative' control serum is tested with each batch of test sera. [citation needed]
Klebsiella oxytoca on agar plate. Klebsiella oxytoca is a Gram-negative, rod-shaped bacterium that is closely related to K. pneumoniae, from which it is distinguished by being indole-positive; it also has slightly different growth characteristics in that it is able to grow on melezitose, but not 3-hydroxybutyrate.
A. faecalis is a Gram-negative bacterium which appears rod-shaped and motile under a microscope. It is positive by the oxidase test and catalase test, but negative by the nitrate reductase test. It is alpha-hemolytic and requires oxygen. A. faecalis can be grown at 37 °C, and forms colonies that lack pigmentation. [1]
Klebsiella aerogenes, [2] previously known as Enterobacter aerogenes, is a Gram-negative, oxidase-negative, catalase-positive, citrate-positive, indole-negative, rod-shaped bacterium. [3] Capable of motility via peritrichous flagella, [ 4 ] it is approximately one to three microns in length.