Reazurine Lab Report

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FTM: The fluid thioglycollate medium is a semi solid, in which the thioglycollate is used as a reducing agent to protect anaerobes and determine the organism’s oxygen requirements. Reazurin is used as an indicator for the medium’s aerobic region, as it is only pink when O2 is present or oxidized1. If there is growth throughout the tube it would be positive as a facultative aerobe; however, if there is only growth within the reazurin region, the organism is an aerobe. Gas Pack: the gas pack will indicate the organism’s ability to grow under anaerobic conditions. A gas pack is used to contain an inoculated brewers plate enhanced with a reazurin indicator and protective thioglycollate reducing agent. If there is growth present on the plate, then the organism would …show more content…

If agar were to turn bright blue, it would signify that the organism was able to utilize the citrate carbon source. The reagent bromthymal blue will turn from green to blue when combined with the ammonium salts5. This reaction will then raise the pH and cause the positive color transformation. Methyl Red: One can identify an organism’s ability to conduct the mixed acid fermentation of glucose in a positive test. The fermentation of glucose will lower the pH to less than 5 by overcoming the phosphate buffer that is in the medium6. The lowered pH will allow the indicator, methyl red, to turn the medium red. Voges Proskauer: An organism that is positive for the VP test would indicate that it is capable of the 2, 3 butandiol and the fermentation of glucose. The reagent Barrits is added and, after a short period of time, will turn red. The reaction will be indicative that acetonin is present, as it is a product of the said fermentation. When the reagent is in contact with the acetonin it triggers a series of chemical reactions that will turn red and provide a positive test

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