Hi all, I had to choose two unknown microorganisms at lab. one, pertaining to a

Question

Hi all, I had to choose two unknown microorganisms at lab. one, pertaining to a number, and the other pertaining to a letter. in this case, my organisms are "3" and letter "o". i did several tests. six on plates and six on test tubes (broth and slants). To make things easy, I have attached the picture files that i have taken which I have observed in the lab along with their descriptions of what I saw. please find the attached copy. Please save the copy and zoom in the description details.

After incubation, my test results on plates and testtubes are as follows.
plates:
1)PEA - 3 grew, o was clear.
2)EMB - 3 was clear, o grew.
3)MSA - 3 grew and yellowish, o clear but reddish on side.
4)TSA - 3 grew, o grew. after catalase test, both bubbled but 3 faster and stayed longer whereas o slower but faded soon.
5)MAC - 3 clear, o grew.
6)Starch - 3 grew, o grew. Iodine test proved negative since none had clear zone of hydrolysis.
testtubes:
7)TSA slant - 3 showed pigmentation, o was clear.
8)Gelatin - 3 showed no change except for liquification, o had thin pink layer on surface and butt.
9)Citrate slant - 3 remained green -ve, o turned blue +ve.
10)Urea - 3 was orange -ve, o was orange -ve.
11)SIM - 3 very blackish and motile, o normal or no change in color but motile.
12)Phenol red fermentation broths - 3 luctose, sucrose and glucose all turned yellow and showed no presence of gas on durham tube, o had only one tube red (same color), rest yellow and no presence of gas in durham tube.

One out of the two microorganims can be mine which is a gram negative and the other is a gram positive. Here are the list of microorganims that can be mine for "3" and "o":
1)E.coli and L.lactis
2)E.aerogenes and P.mirabilis
3)Pseudomonas and S.epi
4)Klebsiella and S.aureus
5)Serratia and S.pyogenes
6)Citrobacter freundii and B.subtilis
7)Alcaligenes faecalis and M.luteus
8)P.vulgaris and E.faecalis

Help needed desperately. Will rate lifesaver. Its worth a 100 points and I really need to get this done. If you are not able to see my attached copy. Please let me know then I can email it to you.

Thank You and a Happy Easter to you all.

Note: I have concluded that "o" is gram -ve and "3" is gram +ve with EMB and PEA plates. I cannot conlude the same with gram stain though. My gram stain for "o" shows -ve because it is purple dots in color but I also saw red/pinkish inside those blue dots. And as for shape and arrangement it shows cluster and cocci. In contrast, "3" did not show anything. I think iwill have to do it again.

Explanation / Answer

I got 6)Citrobacter freundii and B.subtilis OR 4)Klebsiella and S.aureus. I go with the first over the second, but your tests are conflicting, this is normal microbiology tests are often contaminated.

 

I feel your pain on the blue culture for gram stainig, mine did that originally, soo irritating.

Also your 3 and O appear to be switched because all the 3 choices are gram negative but you said it was gram postive and O choices are all gram positive but you said it was gram negative, unless it doesn't matter and those are just the possible pairs you can get. 

So you can rule out E.coli because the EMB plate would have metallic green growth making your life so much easier because its so easy to distinguish and identify.

if you compare your tests to this you can see its true.

  Microscopic Techniques   Various Agar plates   Sugar Fermentation Enysmatic Tests Motility   Full name Shape Gram Stain Pigmentation EMB Blood Agar MacConkey Mannitol Salt Agar Glucose test +/- Lipase Amylase Caseinase Catalase Urease Cysteine (H2S) SIM deeps   B. Subtilis Cocci Positive                   Positive         Enterococcus faecalis Cocci Postive     alpha, can show pseudocatalase reaction if grow on blood agar     Ferments wihout gas       negative         L. lactis Cocci Positive Lactic acid postive     lactic acid positive                     Micrococcus luteus Cocci Postive Yellow       Yellow                   Staphyloccus aureus Cocci Positive Orange No growth Golden Yellow Turns yellow                     Staphylococcus epidermidis Cocci Positive     non Hemolytic         Negative   +         Streptococcus pyogenes Cocci Positive                     Negative       Alcaligenes faecalis Rod Negative                 Positive         citrate positive Citrobacter freundii Rod Negative       lactose fermenting     Postive               Enterobacter aerogenes Rod Negative   Purple Colony                         Escherichia coli Rod Negative   Metalic Green                     Black   Klebsiella Rod Negative       Lactose fermenting   maybe positive       Negative?     positive   P. mirabilis Rod Negative       Negative     Negative Negative Negative Positive Positive Postive Indole Negative/Nitrate Reductase Positive, no gas bubble   Proteus vulgaris Rod Negative       Negative   Positive with Gas     Postive       Film at top   Pseudomonas aeruginosa Rod Negative       Negative     Positive     Positive         Pseudomonas fragi Rod Negative                   postive         Serratia Rod Negative Red pigment         O/F+: can produce lactic acid via oxidative and fermentaive metabolism Positive   Positive Hydrolysis       Motile  

(I can send this to you can excel form if you give me your email, cause reading it like that is kindof hard)

So this is what I looked at and the results aren't pretty. Most of the results indicate Klebsiella and S. aureus, except for you motility tests, which indicates Citrobacter freundii and B.subtilis, which could work, because thats correct for all the tests I have answers for except for Urea negative, I have b. subtilis being positive for that. So if I was you I'd google the results and focus on checking those two. Here was my line of thought, along with the tests I didn't check for:

 

1)PEA - 3 grew, o was clear.             I've never used this test so I can't tell you                                                   3)MSA - 3 grew and yellowish, o clear but reddish on side.         Indicates S. Aureus, and Klebsiella which is red pigmenations Includes- S. Aureus, and Klebsiella           4)TSA - 3 grew, o grew. after catalase test, both bubbled but 3 faster and stayed longer whereas o slower but faded soon. Rules out P. mirabilis                 5)MAC - 3 clear, o grew.             rules out l lactis, p mirabilis, p vulgars, p aerginos Includes-C. freundii, Klebsiella           6)Starch - 3 grew, o grew. Iodine test proved negative since none had clear zone of hydrolysis.   Uknown, I don't have pertinent info on this                 testtubes:                                 7)TSA slant - 3 showed pigmentation, o was clear.         Didn't use this can't tell you, you'd have to google it                 8)Gelatin - 3 showed no change except for liquification, o had thin pink layer on surface and butt.   Didn't use this can't tell you, you'd have to google it                 9)Citrate slant - 3 remained green -ve, o turned blue +ve.         Didn't use this can't tell you, you'd have to google it                 10)Urea - 3 was orange -ve, o was orange -ve.           Rules out P. mirabilis, P. aeroginos, P. fragi and B. subtilis                 11)SIM - 3 very blackish and motile, o normal or no change in color but motile.     The only motile cocci you have is B subtillis which is ruled out by the urea positive test, the only non motile rod is Klebsiella        

 

(Again I have this in excel if you want it.

 

Hope it helps. 

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