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- https://bio.libretexts.org/Learning_Objects/Laboratory_Experiments/Microbiology_Labs/Microbiology_for_Allied_Health_Students%3A_Lab_Manual/3.04%3A_CatalaseCatalase is an enzyme that breaks hydrogen peroxide into water and oxygen. Hydrogen peroxide is a common byproduct of metabolic reactions occurring in an environment where water and oxygen are present...Catalase is an enzyme that breaks hydrogen peroxide into water and oxygen. Hydrogen peroxide is a common byproduct of metabolic reactions occurring in an environment where water and oxygen are present, but it is toxic to cells. Therefore, most organisms that survive in the presence of oxygen contain enzymes to degrade the hydrogen peroxide.
- https://bio.libretexts.org/Learning_Objects/Laboratory_Experiments/Microbiology_Labs/Microbiology_for_Allied_Health_Students%3A_Lab_Manual/3.01%3A_Carbohydrate_FermentationDuring fermentation most bacteria convert carbohydrates into organic acids, with or without the production of gas. One can test for this by adding a pH indicator and an inverted tube (a Durham tube) t...During fermentation most bacteria convert carbohydrates into organic acids, with or without the production of gas. One can test for this by adding a pH indicator and an inverted tube (a Durham tube) to the culture medium. We will use phenol red as the pH indicator. If acid is produced the phenol red will turn yellow (pH below 6.8). Any gas produced will form a bubble in the inverted tube.
- https://bio.libretexts.org/Learning_Objects/Laboratory_Experiments/Microbiology_Labs/Microbiology_for_Allied_Health_Students%3A_Lab_Manual/3.05%3A_Motility_AgarBecause the flagellar staining procedure often produces poor results in the hands of novices, other tests for motility (and the presence of flagella) have been developed. One type of test involves usi...Because the flagellar staining procedure often produces poor results in the hands of novices, other tests for motility (and the presence of flagella) have been developed. One type of test involves using a semi-solid medium that allows motile bacteria to penetrate.
- https://bio.libretexts.org/Learning_Objects/Laboratory_Experiments/Microbiology_Labs/Microbiology_for_Allied_Health_Students%3A_Lab_Manual/3.13%3A_Levine_EMB_AgarLevine EMB (eosin methylene blue) agar is an example of a selective and differential medium. This means that only some bacteria will grow on this agar and that the appearance of those that do grow wil...Levine EMB (eosin methylene blue) agar is an example of a selective and differential medium. This means that only some bacteria will grow on this agar and that the appearance of those that do grow will be different. In particular, EMB agar inhibits the growth of Gram-positive bacteria and helps differentiate some of the Gram-negative rods.
- https://bio.libretexts.org/Learning_Objects/Laboratory_Experiments/Microbiology_Labs/Microbiology_for_Allied_Health_Students%3A_Lab_Manual/3.03%3A_Gelatin_AgarGelatinase is an exoenzyme that digests the protein gelatin into amino acids and shortchain peptides. There are two ways to test for the production of gelatinase. One method, the gelatin liquefaction ...Gelatinase is an exoenzyme that digests the protein gelatin into amino acids and shortchain peptides. There are two ways to test for the production of gelatinase. One method, the gelatin liquefaction test, examines the ability of gelatinase to liquefy nutrient gelatin. However, the tubes need to be incubated for up to 7 days. However, the test that we will use takes advantage of the ability of strong acids to denature proteins and form a visible precipitate.
- https://bio.libretexts.org/Learning_Objects/Laboratory_Experiments/Microbiology_Labs/Microbiology_for_Allied_Health_Students%3A_Lab_Manual/3.11%3A_Phenylalanine_AgarBacteria that produce phenylalanine deaminase are able to remove the amino group from the amino acid phenylalanine yielding ammonia and phenylpyruvic acid
- https://bio.libretexts.org/Learning_Objects/Laboratory_Experiments/Microbiology_Labs/Microbiology_for_Allied_Health_Students%3A_Lab_ManualThis lab manual was created to support a microbiology course for allied health students. While many traditional lab manuals are lengthy and comprehensive, descriptions of the labs in this manual are k...This lab manual was created to support a microbiology course for allied health students. While many traditional lab manuals are lengthy and comprehensive, descriptions of the labs in this manual are kept minimal to encourage students to further research the procedures and results on their own.
- https://bio.libretexts.org/Learning_Objects/Laboratory_Experiments/Microbiology_Labs/Microbiology_for_Allied_Health_Students%3A_Lab_Manual/3.08%3A_Methyl_Red_-_Voges-Proskauer_(MR-VP)_BrothWhen glucose is fermented, a variety of products are possible. This is a test used to determine some of those products. Most organisms differentiated by this test convert the glucose to acids. Some ba...When glucose is fermented, a variety of products are possible. This is a test used to determine some of those products. Most organisms differentiated by this test convert the glucose to acids. Some bacteria continue to produce more acid in ‘mixed acid fermentation.’ Some genera use the glucose but produce end products with a more neutral pH like those that result from ‘butanediol fermentation.’
- https://bio.libretexts.org/Learning_Objects/Laboratory_Experiments/Microbiology_Labs/Microbiology_for_Allied_Health_Students%3A_Lab_Manual/2.3%3A_Acid-fast_Stain_ProcedureAcid-fast organisms like Mycobacterium contain large amounts of lipid substances within their cell walls called mycolic acids. These acids resist staining by ordinary methods such as a Gram stain. It ...Acid-fast organisms like Mycobacterium contain large amounts of lipid substances within their cell walls called mycolic acids. These acids resist staining by ordinary methods such as a Gram stain. It can also be used to stain a few other bacteria, such as Nocardia.
- https://bio.libretexts.org/Learning_Objects/Laboratory_Experiments/Microbiology_Labs/Microbiology_for_Allied_Health_Students%3A_Lab_Manual/3.07%3A_Tryptone_BrothBacterial tryptophanase coverts the amino acid tryptophan into pyruvate, ammonia, and indole. The medium used to test for this enzyme is 1% tryptone in water.
- https://bio.libretexts.org/Learning_Objects/Laboratory_Experiments/Microbiology_Labs/Microbiology_for_Allied_Health_Students%3A_Lab_Manual/2.1%3A_Gram_Stain_ProcedureThe Gram stain procedure is a differential staining procedure that involves multiple steps. It was developed by Danish microbiologist Hans Christian Gram in 1884 as an effective method to distinguish ...The Gram stain procedure is a differential staining procedure that involves multiple steps. It was developed by Danish microbiologist Hans Christian Gram in 1884 as an effective method to distinguish between bacteria with different types of cell walls, and even today it remains one of the most frequently used staining techniques.
