The organisms you will use are: (1) G+ and (1) G- *
Staphylococcus aureus(G+), Escherichia coli, (G-)
Here are the tests you will use to identify the organisms and whether they are for G+ or G- or both:
MSA Mannitol salt agar
PRG Phenol red glucose
EMB Eosin methylene Blue Agar
MRVP Methyl red Voges-Proskauer
Nitrate Reduction Test
After you pick your organisms, pick the series (G+ or G+/-) of tests you would perform to identify each organism. Use all the tests in that series, e.g. there are 14 tests for just G+ and 8 tests for G-, so G+ will take 14 tests for identification and G- will be 8 tests for identification. Altogether you will have 22 test results to write about and give me the results for. You don’t need to give me pictures just describe what the test results would be for your 2 organisms, using the appropriate tests.
Put your findings in a paper with a title, introduction (abstract), the tests and the results (you can do this in table form or just an organized word description), a descriptive summary of your results including diseases caused by the organisms and the history of each organism. Then send it to me via an attachment to an email as you have been doing for the assignments.
Good luck, and I am here for any questions you may have.
The “Unknown” Report! The most common question I am getting is, “where do I start?” In previous emails, I gave you some guidelines. Please review them.
If we were doing this face-to-face, I would give you an Unknown organism and then each week you would do a series of tests (ones we previously performed in the lab). You would then record your test results and from those test results, you would use deductive reasoning, along with resources like: your lab book (charts in the back and tests you preformed, which is why I required you to fill out the tables and record your results for future reference); Bergey’s Manual (the bible of the microbiologist) from the library (because it’s over $100 to purchase); and the internet, to come up with the identity of your Unknown. I would give you an outline to follow and then you would write a report with tables, pictures, materials used, methods used and a summary of your findings, along with the history of your bacterium. You would put this into a binder, folder, report sleeve or whatever and submit it by the Final Lab Exam. All that I would be allowed to do is confirm your first Gram stain findings, that’s it, the rest would be up to you (using my outline, as a guide, of course).
Since we can not perform those tests, thanks to the Wuhan virus restrictions, I had to come up with a different format so that it would be a meaningful exercise but still challenge your critical thinking and deductive reasoning ability, which is one of the paramount goals (and one of the reasons you are required to take this course in the first place) of this microbiology course.
Okay, that said, here is where you begin!
1. Pick your organisms from the list I gave you: 1 G+ and 1 G-
2. Go to the correct flow chart (dichotomous chart) in the back of the book. Find your organism (I picked them from the labs we performed) and using the chart, give the expected results you should find from the list of tests I sent you (all ones we performed or you were given as an assignment). IF YOU CAN’T FIND your test listed for your organism in the back of the book, then look at the actual tests we performed and see if your organism was one we used. If you did the test in lab, then you should have the (correct) results for your organism. But, if it’s from the assignments I gave you, then look at the “Application” section just before the “In This Exercise” section of that lab, it will give you a hint to your organism or organism class like Enterobacteriacea, (Gelatinase + or Gelatinase -, for instance).
3. Outline your results on a separate piece of paper. So, for instance; You pick E.coli, so first G- or G+? Then; Indole – or Indole +, Citrate – or Citrate +, etc. After you have done all the tests or at least, all the ones you could find results for in the book or online or in Bergey’s Manual, then put it either in Tables with an explanation of the result OR your own dichotomous chart (flow chart) like the ones in the back of the book ( OR if you want the top grade, do both!)
4. After you are happy with the organization of your tables or charts, then write your results up in a paper using the table method, if you are handy with this technology on your computer or you can write it manually as; Citrate + or Citrate -, underline, bold italicize, different color or whatever you come up with, indicate the correct expected result. In either one, explain why your organism was Citrate – (because it doesn’t use the citric acid cycle for respiration, for instance). Do this for each test for that organism.
5. Write a summary of your results. If one of the tests defines your organism like; my organism is definitely E.coli because it was the one that gave a positive (or negative) result in motility for instance.
6. Write a brief history about your organism, for example: E. coli was discovered by Kermit the Frog in 1893 when he isolated this bacterium after examining Oscar the Grouch (which attests to why he is such a grouch!) for an unknown chronic gastrointestinal infection. It is a ubiquitous organism found in our normal microbiome but can mutate and cause outbreaks like the one in 1993 at Jack-in-the-Box, etc., etc. blah, blah, blah.
7. Put a cover on your report, write an introduction (abstract in science) and include a reference page.
8. And, finally, attach it to an email to me. That’s it!
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