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From left to right solutions of 0.1 M HCl, 3 buffer solutions of pH 3.78, 3 of pH 4.00, 3 of pH 4.62 and NaOH 0.1 M after adding different amounts of bromocresol green (more in darker solutions) In aqueous solution , bromocresol green will ionize to give the monoanionic form (yellow), that further deprotonates at higher pH to give the dianionic ...
Bromocresol purple (BCP) or 5′,5″-dibromo-o-cresolsulfophthalein, is a dye of the triphenylmethane family (triarylmethane dyes) and a pH indicator. It is colored yellow below pH 5.2, and violet above pH 6.8. In its cyclic sulfonate ester form, it has a pK a value of 6.3, and is usually prepared as a 0.04% aqueous solution. [1]
The increase in pH then causes color change in the bromothymol blue indicator, turning it blue. Under neutral conditions the medium remains a green color. The color change to blue is useful because growth on Simmons' citrate agar is often limited and would be hard to observe if it were not for the color change.
Inoculating from a broth culture is not recommended because the inoculum would be too heavy. If the organism has the ability to use citrate, the medium usually changes its color from green to blue, though growth on the medium even without colour change is considered a positive result. [1] An observation of no growth is a negative result.
Phenol red, 40 μM: colors in cell culture medium at a pH range from 6.0 to 8.0. Most living tissues prosper at a near-neutral pH—that is, a pH close to 7. The pH of blood ranges from 7.35 to 7.45, for instance. When cells are grown in tissue culture, the medium in which they grow is held close to this physiological pH. A small amount of ...
Agar plates may also be indicator plates, in which the organisms are not selected based on growth, but are instead distinguished by a color change in some colonies, typically caused by the action of an enzyme on some compound added to the medium. [6] The plates are incubated for 12 hours up to several days, depending on the test that is performed.
As CO 2 is absorbed from the breath into the solution, carbonic acid forms and change the solution color from green to yellow. Thus, BTB is commonly used in science classes to demonstrate that the more that muscles are used, the greater the CO 2 output.
Hemolysis is the breakdown of red blood cells. The ability of bacterial colonies to induce hemolysis when grown on blood agar is used to classify certain microorganisms. This is particularly useful in classifying streptococcal species. A substance that causes hemolysis is called a hemolysin.