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gram negative cocci. please help

About microscopic forms of life, including Bacteria, Archea, protozoans, algae and fungi. Topics relating to viruses, viroids and prions also belong here.

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gram negative cocci. please help

Postby jenmae » Sun Sep 09, 2012 9:08 am

my professor asked me to identify 3 organism base on below result i already perform an acid fast staining and it shows that a gram negative cocci. the problem is, i cant enumerate the possible organism present in this test .. kindly help. it would really mean so much to me..

- indole
+motility
- methyl red
- voges proskauer
+ simmon nitrate
- ureas
- LIA
+ gas
- H2S
+ GLUCOSE AND MALTOSE
-LACTOSE
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Re: gram negative cocci. please help

Postby mamasewbusy » Sun Sep 09, 2012 3:39 pm

Your professor should have given you a dichotomous key or some other type of table(s) to help you identify your bacteria. At the very least I would think a list of bacteria would be provided, because only the professor knows what bacteria the students were given. When I had my unknown project in micro we were provided such information; I couldn't imagine not having it! Sorry I can't help you further, good luck!
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Postby jenmae » Sun Sep 09, 2012 4:02 pm

Thank you for trying :D my proffesor said we could reffer to any types of book of microbio since, the sample are from the water he said... I found some bacteria yet im not sure of it.
The bacteria are:
aeromonas hydrophila
s. arizonae
citrobacter freundii
and enterobacter cloacea.
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Re: gram negative cocci. please help

Postby mamasewbusy » Sun Sep 09, 2012 7:08 pm

Perhaps the colony morphology can help you narrow down your choices further? There are tons of images out there that might help you make some comparisons. Sometimes it isn't what you don't know but what you DO know that makes all the difference! :D
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Postby mamasewbusy » Sun Sep 09, 2012 7:09 pm

And also, Citrobacter freundi is H2S+
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Postby Cat » Sun Sep 09, 2012 9:41 pm

I don't understand.
1. If it's "gram negative cocci", why are you doing tests for enterics?
2. If it is a rod, repeat MR-VP. They usually opposites of each other (methyl red positive and VP -ve OR methyl red -ve and VP +ve). One of those tests is most likely wrong.
3. By " + simmon nitrate" you mean Simmon citrate OR Nitrate???
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Postby keetner » Mon Oct 08, 2012 12:23 am

You said you did an ACID FAST test to show you if it was GRAM NEGATIVE?
Did you do a Gram stain at all?

An acid-fast test doesn't tell you if it's Gram negative or Gram positive. Rather, it's an alternative test if your Gram stain doesn't work (of if you're unsure of results) to test if it has a crazy thick outer wall (eg. mycolic acids). But again, it won't tell you if it's Gram negative...

For determining your bacteria though, you should consider using "Bergey's Manual of Determinative Bacteriology". It's pretty helpful.
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Re: gram negative cocci. please help

Postby student2012 » Sun Nov 25, 2012 3:04 am

You might try Bergey's 7th, 8th or 9th edition manual and there you should see the lisitngs of the various bacteria and their results..Hope this helps! 8)
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Postby sampei » Tue May 28, 2013 2:46 pm

You should have done a gram stain ...
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