lab_22_major_unknown_TTh

lab_22_major_unknown_TTh - Miramar College Biology 205...

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Lab Exercise 22: The Major Unknown Page 1 of 5 Miramar College Biology 205 Microbiology Lab Exercise 22: The Major Unknown Background Throughout the semester you have learned to successfully isolate bacteria from mixed cultures. From there you learned to apply differential staining techniques to learn the Gram reaction, Acid-fastness and/or spore forming capabilities of a given organism. You have learned to use various differential and selective media to determine the biochemical attributes of microorganisms and have put several of those techniques into practice in order to identify staphylococcal, streptococcal and enteric bacteria. During previous lab exercises, you have been directed, to varying degrees, while isolating and identifying your organisms. While that is true for a few of the inoculations to be done during the Major Unknown , the amount of guidance will be noticeably less. You will now work to isolate and identify two organisms from a mixed broth culture. These organisms comprise your Major Unknowns . Your work on these two organisms will culminate in a written report for each, wherein you discuss your isolation and identification strategy as well as provide information on the habitat, lifestyle, clinical significance and/or special characteristics of these organisms. Details of this report can be found at the end of this lab handout. Introduction The isolation of your Major Unknown organisms is your chance to put into practice the experience that you have worked during the last several weeks to acquire. No doubt, you will find the information you collected during previous labs to be useful. In addition, you may find pertinent information elsewhere in your photographic lab atlas, lab manual and/or lab notebook, depending on the organisms you have been given. The Major Unknowns are an individual project. You are required to perform and interpret your own staining and inoculations. You may ask your fellow students for their opinions, but you are responsible for the conclusions reached. Additionally, you will not be given assistance from your instructor or laboratory staff in the interpretation of or isolation strategy for these organisms. You will research and request media that will aid in your organism identification. Media are requested using M edia Request Forms , which can be found on the course website. These will need to be turned in as part of your assignment, so please do not discard them. Your use of media will be monitored and media waste will result in a loss of points. You will begin your identification by isolating your organisms from a mixed culture. Because there are major points of distinction for the identification of Gram negative organisms from one another, your search will begin along a route in common with your classmates. The use of the dichotomous key found in Figure 1 will allow you to narrow your search to a bacterial grouping found in Bergey’s Manual of Determinative Bacteriology . Once you have identified the genus or
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lab_22_major_unknown_TTh - Miramar College Biology 205...

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