Description
This criterion is linked to a Learning OutcomeIntroduction
5 pts
This criterion is linked to a Learning OutcomeMethodsMethods, photos & following of dichotomous key
10 pts
This criterion is linked to a Learning OutcomeResults and Interpretation of ResultsCorrect interpretations of Tests & Correct ID (4 pts). of Unknown organism
10 pts
This criterion is linked to a Learning OutcomeDiscussionDiscussion, including References w/in body of paper:
(including 3 points for one full page discussion)
12 pts
This criterion is linked to a Learning OutcomeConclusion
5 pts
This criterion is linked to a Learning OutcomeDichotomous Key/highlighting
2 pts
This criterion is linked to a Learning OutcomeReference pageShould be in APA formatting style
4 pts
This criterion is linked to a Learning OutcomeFormatting & Grammardouble-spaced, 12-pt. font, margins, gramma
2 pts( MY BACTIRA IS STAPHYLOCOCCUS AUREUS)
Unformatted Attachment Preview
Unknown Project(s) – BIO 203
Where do I start?!
1. Obtain an Unknown culture tube & record the # in your notebook.
2. Create stock cultures on nutrient agar using isolation streak plating. This
stock plate will be stored at 4oC and used to conduct further testing, so don’t
discard it! For both unknown projects, you will need to isolate to single
colonies; this is absolutely essential for your mixed unknown project in
which you will have two isolates, one Gram (+) & one Gram (-). For your
mixed unknown project: after you obtain single, isolated colonies, you
will then need to streak your different isolates on separate nutrient agar
stock plates & work directly from these latter plates for your
experiments.
3. Gram-stain the unknown organism(s), observe and photograph the Gramstained reaction(s), cell morphology, & arrangement under 1,000X
magnification using oil. Record results & photograph.
4. Using the Gram reaction & morphology, determine where to go using your
dichotomous key.
5. Follow your key, conduct the relevant tests, photograph results & use the
results/conclusions to determine the identity of your unknown(s).
Where do I obtain information?
Your guide for what tests to conduct is your very own dichotomous key!
All information that is needed to conduct tests should be in your lab manual.
You may consult textbooks, lab books, Internet, class notes, etc.
How long do I have to complete the Unknown project(s)?
Pure Unknown report is due October 31st. Mixed Unknowns report is
due November 28th. Five points will automatically be deducted if late!
How should I write the report? (See #1 – 7 below)
1. Use Word (or some other word processing format) & include color photos for
every test you’ve done, following your dichotomous key (mention the use of your
key that you developed in your reports)! Please make sure that you have a piece
of paper with your name on it, an image of our lab, etc. included with each
photo to show that you have not included photos from the Internet. I do realize
that this is impossible with photos taken through the ocular lens of a microscope.
2. Introduction – 1/3 to 1/2 page – Introduce and give background for this project. Why
is it important to be able to determine the identity of unknown microbe(s)? Mention the
1
number (and letters for mixed unknowns) of your unknown isolate at the end of this
section.
3. Methods/Tests, Photos, Results & Conclusions – Importantly, identify & document
the tests you conducted on your Unknown(s) with a brief description of each test.
*FOR EACH TEST:
i. State what a positive result looks like
ii. State what a negative result looks like
ii. State what your result is
*Elaborate a little regarding each test so that I know you understand it.
*Be descriptive regarding Gram staining, especially. State what a both a
positive & negative Gram stain would look like, then state the result you got.
Make sure you distinguish between results and conclusions:
Result = cells stain purple
Conclusion = cells are Gram-positive; the microbe has a thick peptidoglycan
layer in its cell wall and therefore retained the primary crystal violet dye following
decolorization.
***Important note: The result of a Gram stain is that it stains purple; the
conclusion is that it is Gram-positive. Stating both the result and conclusion for
each test tells me:
a. whether or not you got the correct result for that particular test for your
particular microbe
b. whether or not you are able to correctly interpret that result and arrive
at the right conclusion for that particular microbe. **AGAIN…PICTURES
OF ALL TESTS MUST BE INCLUDED
Another Example: “The next test performed was both selective and differential, using a
MSA plate containing high salt to look for growth and subsequently determine if the
microorganism could ferment the sugar mannitol. Growth of the organism would likely
confirm that the unknown microbe was Gram (+); little or no growth would indicate that it
was Gram (-). A positive result for mannitol fermentation would be indicated with
obvious growth on medium that turned yellow due to acid production and therefore a
decrease in pH. Pink agar with obvious growth would indicate that, although the
microbe was Gram (+), acid was not produced, the pH of the medium did not decrease,
and therefore fermentation of mannitol did not occur. Unknown #47 grew well on MSA
but the medium remained pink. Therefore, #47 was confirmed to be Gram (+), as
previously shown by Gram staining, but this microbe was not able to ferment mannitol.”
2
**Reminder: Obtaining single, pure, isolated colonies is part of your
Unknown determination, so make sure you write about it.
In addition, a Word or Excel table of tests performed & summarized results may also be
included (but is not required) in this section so that the reader (me) can easily follow
what you did.
Photos –
Your photos should be clearly labeled and mentioned throughout your text. (Ex: “An
isolation streak plate to obtain pure, single colonies was performed on nutrient agar
using Unknown #5 (see Fig. 1).” Then Fig. 1 should be clearly labeled as “Fig. 1”. Your
photos may appear throughout this section or may all be at the end of your paper,
whichever you prefer and whatever is easier for you. They must be in color so when I
am grading your papers, I can make sure you have interpreted your results correctly.
Dichotomous Key **Turn in a copy of your dichotomous key (including both Gram (+) and Gram (-)
microbes) with your report, with the name of your organism highlighted under every
test.
**Identify your unknown organism(s) by number, Genus & species at the END of
this section, AFTER writing about the results & conclusions of each test you
performed. Make sure the Genus & species are both written correctly and spelled
correctly throughout your manuscript.
Mixed Unknown (Methods/Tests/Photos/Results/Conclusions) –
For your mixed unknown project, you will write about the isolation streak plates and
Gram stain for both microbes first, identifying which number or letter is Gram (+) and
which is Gram (-). Following this, you will write about all additional biochemical tests for
your Gram (+) microbe first, and ID your Gram (+) microbe at the end of this section.
Following this, you will then write about all biochemical tests for your Gram (-) microbe,
and ID your Gram (-) isolate at the end of this section. In other words, do not switch
back and forth between writing about your your Gram (+) and Gram (-) organisms – this
becomes confusing.
4. Discussion (regarding your microbe) – **One (1) full page required for pure
unknown (the isolate you ID). For the mixed unknown project, two (2) full pages
are required.
3
Give researched background information on the organism you identified using citations
where necessary to avoid plagiarism (use APA or MLA – see below for more on
references).
**Options for mixed unknown, in the discussion you should predominantly be discussing
only 1 bacteria. You may choose either of the mixed unknown bacteria you identified to
write about OR if you are doing your class presentation on a bacteria you may discuss it
OR you may choose from the posted list of microorganisms in Canvas.
5. Conclusion –1/3 to 1/2 page – Draw everything together and finish the paper. Do
not just conclude the discussion. Conclude the entire project & DO NOT simply repeat
your results.
6. References – When using a reference, you must cite it to avoid plagiarism. No
shortcuts! If you use a website, do your best to track down the original source; don’t
just list the website. DO NOT use Wikipedia or MicrobeWiki as a cited source for this
paper!! You must use a minimum of three (3) references for each of your unknown
manuscripts (not including lab manual). References should be listed in alphabetical
order (see APA formatting instructions, websites below).
*Use APA of MLA reference style, please! Please see one of these examples:
https://guides.libraries.psu.edu/apaquickguide/intext
https://sites.umuc.edu/library/libhow/apa_examples.cfm
*NOTE ON PLAGIARISM: If I discover that you’ve directly lifted sentences from
another source, I will give you a ZERO (0) on the Discussion (at least) and perhaps on
the entire paper. Plagiarism is SERIOUS! ***When in doubt, REFERENCE (or check
with me)!
How much is this assignment worth?
Pure Unknown project = 50 pts.
Mixed Unknown project = 100 points
Grading rubric for Pure Unknown paper will be as follows:
I. Introduction – (1/3 to1/2 page) – Make sure to include # of your Unknown (and
letter(s) for the mixed unknown project) at end of this section = 5 pts.
II. Description of Methods/Tests, Photos, following of Dichotomous Key = 10 pts.
III. Results & Conclusions (including clear documentation with photos) = 10 pts.
(including 4 points for correct ID)
4
IV. Discussion of your Unknown microbe –
**Required one full page for Pure Unknown = 12 pts. (including 3 pts. for length
for Pure Unknown project; margins must be < 1.5 inches)
**Minimum of three references must be cited in body of discussion.
V. Conclusion = 5 pts. (1/3 to1/2 page)
VI. Dichotomous Key = 2 pts.
VII. Reference page = 4 pts. - References may be included on the same page with
text, following your conclusion, in order not to waste paper. ***Minimum of 3
references required (not including your lab manual)! *Don’t forget to write the
names of microbes correctly on this page as well.
VIII. Format & grammar = 2 pts.
o Must be double-spaced
o 12-point font (note: this is 12-point font)
o < 1.5-inch margins
o Grammar & spelling, including correctly written Genus & species
Tips:
o Read these directions and follow them; most students lose points because they
do not follow directions (especially in regards to the discussion, color figures, and
attaching both dichotomous keys).
o You used 1,000X magnification under an oil immersion lens to determine your
Gram stain and morphology; make sure you mention that in your paper.
o You do not need to list every single detail regarding the Gram stain and other
tests but do give enough information so that I know you understand each test
and why and how it works as it does.
5
Gram + organisms
*Colony color refers to growth on nutrient agar at room temperature. White, cream, yellow, and ‘yellowish’ are very difficult to
distinguish from one another and should not be used to ID bacteria. However, gold and rose are very distinctive and therefore can
and should be used to confirm identification!
REVISED FEB. 2018
Organism
Gram
Shape
Colony
color
Fermentation
Mannitol
Maltose
Galactose
Lactose
Glucose
Gelatinase
Catalase
Amylase
Urease
Methyl
red
Nitrate
reductase
Bacillus subtilis
+
Bac
Cream
-
-
-
-
Acid
-
+
+
-
-
+
Bacillus cereus
+
Bac
Cream
-
Acid
-
-
Acid
-
+
+
-
+
+
Staphylococcus
aureus
+
Coc
Yellowish
Acid
Acid
Acid
Acid
Acid
-
+
-
-
+
+
Staphylococcus
epidermidis
+
Coc
Cream/
white
-
-
Acid
Acid
Acid
-
+/-
-
+
+
-
Enterococcus
faecalis
+
Coc
Cream
Acid
Acid
Acid
Acid
Acid
-
-
-
-
+
-
Sarcina
aurantiaca
+
Coc
Gold
-
-
-
-
-
-
+
-
-
-
-
Sarcina lutea
+
Coc
Yellow
-
-
-
-
-
-
+
-
+
-
-
Micrococcus
roseus
+
Coc
Rose
-
-
-
-
-
-
+/-
-
-
-
+
Streptococcus
salivarius
+
Coc
Cream/
white
-
Acid
Acid
Acid
Acid
-
-
-
-
+
-
Sporosarcina
ureae
+
Coc
Yellowish
-
-
-
-
-
-
+/-
-
+
-
+
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