Phenol red - be a bubble in the Durham tube where the broth...

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Travis Copple Micro Lab 005 Phenol Red and Purple Broth Phenol Red Broth is a differential test medium, which is prepared as a base and a carbohydrate is added. Peptone and a pH indicator phenol red is included in the broth as well. Below a pH of 6.8 the broth is yellow, if it is above 7.4, the broth will be pink to magenta, and red in between. The pH is adjusted at 7.3, so the broth is red. There is also a Durham tube inserted as an indicator of gas production. If the medium turns yellow, that means there was acid production from fermentation of the carbohydrate, which lowers the pH below the neutral range. If the broth of the medium turns pink, then deanimation of the peptone amino acid produces ammonia. If there is gas production, then there will
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Unformatted text preview: be a bubble in the Durham tube where the broth was displaced. Purple Broth is also a differential test medium that is made up of a basal recipe where a carbohydrate is added. This allows fermentation characteristics for a variety of carbohydrates. The base formulation contains peptone and the pH indicator bromcresol purple. If the pH is below 6.8 then the medium is yellow, and purple above 6.8. This medium is ideal for testing enteric bacteria because the final medium is more acidic than Phenol Red. A Durham tube is also inserted into this medium to test for gas production....
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This note was uploaded on 04/07/2008 for the course MICRO LAB ??? taught by Professor Mulacny during the Spring '08 term at Johnson County Community College.

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