Catalase Test Lab Report

Mixtures of microorganisms are normally present in the natural environment (Intrieri, 19) and microorganisms are found everywhere including the human body and the air (25). As a result, in different laboratory settings from food to clinical the microbiologists in those laboratories follow experimental tests to identify unknown microorganisms in a sample (111). Our goal in this laboratory was to perform the types of testing microbiologist do every day to isolate and identify unknown bacteria in a mixture sample. Also, throughout the project learn about the morphological and physiological characteristics of the bacteria that distinguish them from each other.

The methods and testing procedures performed included: T-streak, Gram Stain, Oxidase Test, Catalase Test, and EnteroPluri-Test . Highlighted in the experimental flow chart it states the tests performed and the results that led to the identification of isolate A and isolate B in sample 4-24. Each test …show more content…
Then, a gram stain differentiated the isolates into two groups (gram-positive and gram-negative) based on the cell envelope structure. Isolate A was gram positive and coccus shaped and as a result a catalase test was done. The catalase test for isolate A was negative, which identified isolate A as E. faecalis due to the fact that the various test results describe the morphological and physiological traits of E. faecalis. As for isolate B, it was gram negative so an oxidase test was performed which gave a negative result. An EnteroPluri-Test was done since the oxidase test was negative and a lactose test was needed to identify the bacteria. Isolate B did not ferment lactose and for that reason it was identified as S. enterica based on the fact that the results from the test are specific to S. enterica. Based on the previous statements, there were no conflicting results with the identification of the