As we have learned, bacteria are ubiquitously found throughout our environment and possess different properties that allow them to flourish in different environments. One instance of exploring bacteria more in depth is by looking at their biochemical reactions, a identification test often used alongside differential media samples. Exploring a bacteria’s biochemical reaction involves observing the nutritional and metabolic abilities of a bacteria (Isaguirre, 2013). These enzymatic capabilities allow microbiologists to determine where the bacteria belongs – in which genus and species of the organism (Isaguirre, 2013). One specific example of a differential media test used alongside these biochemical reactions is pH indicator. Because pH is related to the concentration of H+ within an organism, pH can be used to determine how much H+ ion are within the organism (Escobar, Blosse, & Nakajima, 2014). Typically, it is easier to observe pH with a color indicator which tells the microbiologist the general range of the organism under investigation (Escobar et. al, 2014). Likewise, metabolic assays is another way of studying how bacteria gain energy or a process of metabolism (Biocat, n.d.). In the current experiment, we used oxidase assay for respiration and catalase assay tests to explores bacterial samples taken from a sneaker, a kitchen sink, a phone screen, and a control. Oxidase assay analysis involves identifying bacteria that produce a specific type of enzyme known as Cytochrome C Oxidase (Acharya, 2012). This specific enzyme is found within the bacterial electron transport chain and plays an important role in glucose respiration (Acharya, 2012). Bacteria that change color during the Oxidase Assay are considered oxidase positive or aerobic (Acharya, 2012). On the other hand, bacteria that do not change color during the Oxidase Assay are considered oxidase negative and can be anaerobic, aerobic or facultative (Acharya, 2012).In the first experiment, I predict that both the Sink and Shoe bacterial samples will be oxidase positive while the Phone and Control bacterial samples will be oxidase negative. In the next experiment, Catalase Assay entails testing for other types of molecules within the electron transport chain, such as flavoproteins, catalase, and like objects (Michigan State University, 2010). In this test, the presence of oxygen or oxidase positive individuals is determined by the bubbling, which indicates that the catalase has converted the peroxide into water and oxygen (Michigan State University, 2010). In the current experiment, I predicted that the shoe, sink and phone samples will be considered oxidase positive while the control sample will be oxidase negative. In Experiment One, only the sink bacterial sample was oxidase positive, meaning this specific bacterial sample contained the molecules needed for respiration energy conversion. On the other hand, the shoe, phone and control bacterial samples were all oxidase negative. When placed on the Oxidase Assay Cassette, the sink bacterial sample turned to a dark purple or blue, which indicates the presence of cytochrome C Oxidase achieved through a reduction-oxidation reaction (Austin Community College, n.d.). On the other hand, the shoe, phone and control samples did not change colors. This indicates that these bacteria samples have a different molecule on the end of their electron transport chain. Examples of bacteria found within a kitchen sink include Salmonella, Campylobacter jejuni, Escherichia coli, or Staphylococcus aureus (Richards-Gustafson, 2017). These bacteria can thrive in the skin environment, given its typically wet nature (Richards-Gustafson, 2017). Ideas for future research could explore different samples of bacteria, such as a kitchen sponge, toilet seat, or other types of surfaces that could harbor a variety of other microorganisms. The Oxidase Test is useful to see if a microorganism is aerobic or anaerobic (Austin Community College, n.d.). After investigation of this topic, it is interesting to learn more about bacteria that use such forms of aerobic respiration. This indicates that instead of another molecule or element, oxygen is at the terminal end of the ECT (Basit, 2015). Bacteria engage in aerobic respiration in three specific stages: Glycolysis, Krebs Cycle and Electron Transport Chain (Basit, 2015). Focusing on ECT, bacteria use aerobic respiration to release energy and eventually generate ATP (Basit, 2015). The Oxidase Assay for Respiration is an important test because it helps microbiologists identify if the unknown bacteria contains cytochrome c oxidase (Michigan State University, 2010). It also allows them more information into classifying bacteria into a genus or species (Michigan State University, 2010). For instance, an example oxidase positive bacteria include Neisseria and Pseudomonas while oxidase negative bacteria include the Enterobacteriaceae family (Michigan State University, 2010). In Experiment Two, all colonies from the shoe, sink and phone petri dish sections were considered oxidase positive, according to the Catalase Assay test. This identification stemmed from the bubbling, which all colonies showed the same reaction. None of the plates contained catalase negative bacteria. The bubbling provides microbiologists an easily observable way of assessing the presence of catalase within a bacterial sample. The bubbling indicates that the catalase has converted the hydrogen peroxide into water and oxygen (Michigan State University, 2010). Although oxygen plays an important role in our bodies, oxygen can also cause serious side effects but the presence of catalase can protect us from such reactive molecules (Goodsell, 2004). The conversion of hydrogen peroxide into water and oxygen gas is important because catalase helps oversee the cell, making sure to keep the hydrogen peroxide at a healthy level (Goodsell, 2004). These catalase are extremely efficient and beneficial enzymes which serve to rapidly destroy excess hydrogen peroxide and help the body return to homeostasis (Goodsell, 2004). If the catalase is not present to rid of the peroxide, oxygen can cause damage which is why it is important the hydrogen peroxide is degraded into non-toxic components – water and oxygen (Lohner, 2016).