Isolates Lab Report PDF

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This document contains the lab report or answers to questions in the corresponding lab manual for MCB 2610 laboratory for the specific lab. Course taken with Dr. Patricia Rossi....

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Introduction: Microorganisms are everywhere and share the environment we live in. They even are found in our bodies functioning through a symbiosis relationship. Although only some strains of bacteria and other microorganisms are shown to be pathogenic, the diseases they can cause and the outcome can be fatal (Fundamentals of Microbiology Laboratory Manual, 2019). Moreover, since we cannot view these microorganisms with the naked eye, it is essential that we learn how to use equipment like microscopes and perform techniques like the T-streak to learn as much as we can about these organisms (Fundamentals of Microbiology Laboratory Manual, 2019). Each day microbiologists, clinicians, and other healthcare professionals are presented with the issue of identifying unknown microorganisms that may be pathogenic and find a potential treatment for it (Fundamentals of Microbiology Laboratory Manual, 2019). According to the Center for Disease Control (CDC), Campylobacter infection has been identified as the most common infection caused by poultry in humans followed by Salmonella infection (CDC, 2018) since 2013. The incidences of these reports and other diseases continue to grow each year despite all our research and clinical trials with different organisms (CDC, 2018). It is increasingly becoming difficult to limit the spread of such diseases and it is even harder to find a cure once an outbreak has begun. Thus, it is crucial for students to learn the techniques for proper handling and experimenting with such microorganisms so that once we enter the real world we can aid in finding a treatment or antibiotic if an outbreak occurs. Moreover, the significance of this project lies in the skill set we developed when attempting to identify the bacteria such as creating pure cultures and understanding how to navigate through different tests to find the correct bacteria.

Isolation/Experimental Plan: This section according to the lab manual was already graded previously but the morphological characteristics of the isolates chart and the flow chart are handed in lab (Fundamentals of Microbiology Laboratory Manual, 2019). The experimental plan for this project was a flowchart that consisted of breaking down the list of bacteria by different characteristics and groups. For instance, the first test is a gram stain and the bacteria were divided up based on the results yielded by that test and so on. The flow chart can be found on page 113 that was handed in.

Results: The data tables have been handed in lab. Figure 16.1 contains data regarding the morphological characteristics of the two isolates, A and B. Table 17.1 is composed of data regarding all eight of the possible bacteria and their colony morphology as well as the morphology of the two isolates. Table 17.2 also includes data for all eight possible bacteria and the two isolates but it lists their physical properties such as gram stain information, cell shape, arrangement, spores, and presence of a flagella (Fundamentals of Microbiology Laboratory Manual, 2019). Table 17.3 contains results from the catalase and oxidase tests for the eight bacteria as well as the isolates. Lastly, 17.4 contains the results from the fermentation and EnteroPluri-Test for the eight organisms and the isolates. All this data as well as background information gathered from different labs throughout the semester was utilized to make a prediction regarding the identity of the two isolates (A & B). Not all data was gathered at one time. Data tables were filled throughout the semester as the tests were done for several microorganisms in different labs as we progressed through the semester. The positive sing (+) in

the data tables indicates either a positive result or growth was observed for the specific bacteria. The negative sign (-) implies either negative result or a no growth was observed for the specific bacteria. In table 17.4, in the EnteroPluri-Test result section, I chose to observe the results from three tests, the Citrate, Lactose, and Sorbitol as I felt those would be the most important tests to identify my isolates and since we cannot include all twelve test results (Fundamentals of Microbiology Laboratory Manual, 2019). Moreover, according to me, the most important data table would be 16.1 which holds the results from the gram stains of our isolates as well as their physical properties. These results allowed us to create our experimental plan and proceed to the next step, eventually leading us to our findings.

Discussion: The purpose behind this project was to expose students interested in the field of microbiology to different lab techniques, gain an understanding and appreciation for different types of microbes as well as independently carry out an experiment with knowledge from multiple labs. Taking an organized approach to identity the unknown bacteria in sample number 25-4 allowed students to be certain of the tests they are doing and eliminate the first round of possible bacteria right away. By having an organized approach and a plan, we can perform the necessary tests to efficiently find the bacteria instead of performing multiple test after test getting us nowhere. Some microorganisms are positive or show growth for one test and may be negative for another, but without knowing where you start it becomes very difficult to find an unknown. Being organized and planning gives us direction and enables us to be confident in each test and saves us time as well as resources. The rationale behind the experimental plan was basically to start off with a broad test that would split up majority of the eight bacteria into two sets and we

did that using a gram stain test (Fundamentals of Microbiology Laboratory Manual, 2019). Having found a positive and a negative gram stain for each isolate was helpful as now we were able to perform tests specific to those results. The basis of the rationale is to perform the least number of tests to identify the bacteria and the best way to do that is to eliminate the ones we can and then predict from the ones that are left (Fundamentals of Microbiology Laboratory Manual, 2019). Our first test, the gram stain indicated that our isolate A was gram negative and our isolate B was gram positive. Moreover, viewing the specimen under the microscope during the gram stain allowed us to determine the shape of each isolate. We found isolate A to be rods and isolate B to be coccus while enabled us to select the next set of tests for isolate B specifically. Since B was gram positive and coccus, the only test left was a catalase test according to the flow chart that would allow us to find the bacteria. For isolate A we performed the oxidase test next (-), followed by the lactose test (+), followed by the citrate test (+) which all was done through the EnteroPluri tube. We ultimately took the results from previous tests to perform and guide us to the next one based on the flowchart. Our isolate A ended up being Klebsiella aerogenes and our isolate B was Enterococcus faecalis. Our results did not conflict with one another as we were able to identify two different species of bacteria from our sample, thus we did not experience any isolation issues. I personally would not do anything differently other than viewing the specimen with greater accuracy under the microscope when redoing it.

Conclusion: Overall, the “Differentiation of microorganisms” lab was essential to the success of this project as it exposed us to differential types of selective and differential media as well as the importance of bacterial enzymes and their role in determining unknown species. It also

illustrated the efficiency of using an EnteroPluri test to test of different enzymes which was huge for our isolate A as it involved the testing of multiple enzymes and the bacterium’s niche. Moreover, this project contributed greatly to my thought process and assisted me in preparing for any other course that requires lab techniques and work with microbes. The planning, the experimental map, the exercises, and the execution of the tests all improved my laboratory skills and developed my problem-solving strategies. In the real world this type of preparation and execution occurs on a daily basis in research labs all over the world who are attempting to identity unknown pathogens and microbes that may cause human death or an epidemic. They utilize the same basic skills of performing numerous tests base tests to eliminate all the obvious choices first and then performing the intricate tests to determine the identity. When an endemic occurs anywhere, a sample of the strain of bacteria is sent all over the world to countless labs who focus on finding a cure right away. They take in the sample and perform numerous tests using different assays, medias, and techniques that will ultimately yield an agent in the bacteria that we can target with an antibiotic or other drug. This way we can quickly and efficiently put an end to fatal diseases before they spread to more prevalent areas that don’t have easy access to innovative and modernized healthcare (Fundamentals of Microbiology Laboratory Manual, 2019). Lastly, this project assisted and prepared me greatly for a future in a laboratory or microbiology related fields.

References Center for Disease Control and Prevention. (2018). Foodborne Diseases Active Surveillance Network (FoodNet). Center for Disease Control and Prevention. Retrieved from https://www.cdc.gov/foodnet/reports/prelim-data-intro-2018.html Intrieri, G. (2019). Fundamentals of Microbiology: Fall 2019 Laboratory Manual. Plymouth, MI: Hayden-McNeil....