Essay On Microbiology Lab

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Collection and Identification of an Environmental Bacteria to the Genus level

Introduction: Bacteria can be found virtually anywhere, and interaction with these organisms occurs daily (Fitzpatrick & Allison, 2014). However, though the interaction between human and bacterium is continual, it is not always known what type of bacteria a person is coming into contact with. Therefore it is important to understand, and to have knowledge about, the characteristics of bacteria in our environment. As part of a microbiology lab course, students were assigned to collect and identify an environmental sample down to the genus level. For this particular experiment a skin bacterial sample, taken from the arm, was selected and put through different differential
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Using controls and tables within the Microbiology lab manual, observations were then interpreted. Through the gram staining procedure purple spherical cells were observed, and thus it is interpreted that the bacterium is not only a gram positive organism but that it is has a tetrad cell arrangement and cell morphology of a cocci. Through the oxygen tolerance test it was found that the bacterium grew predominately within the pink oxidized zone, but it also had strings of growth within the anaerobic zone. Due to this observation it was interpreted that the bacterium was indeed a facultative anaerobe. Finally through the catalase test, due to the fact that the organism caused the hydrogen peroxide to bubble immediately, it was interpreted to have the enzyme catalase and therefore is said to be catalase positive.
Test Purpose Observations Result

Gram Staining The purpose of this test is to determine the shape as well as the nature of the bacteria’s cell wall by distinguishing between Gram negative and Gram positive cells The bacterium retained the crystal violet stain and appeared purple. The shape of the cell was spherical and they cells are arranged in a tetrad
The organism is a Gram positive
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To understand just what kind of organism can live on the human body with ease and with little knowledge of its existence by the host, several differential tests were conducted on the isolated skin sample to discover the genus. Through these tests it was found, as observed through Table 1, that the environmental sample was, gram positive, a cocci, a facultative anaerobe, and produced the enzyme catalase . By referring to the bacterial flowchart (Holt et al., 2000), it was found that the genus of the bacterium collected from the skin, was Staphylococcus. Staphylococcus is a gram positive bacteria which are spherical in shape, can grow in areas with or without oxygen, and is able to produce the catalase enzyme (Holt et al., 2000). Therefore as the environmental unknown holds all of these characteristics as well, it is determined that the environmental unknown is in fact

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