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help identifying unknown bacteria

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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help identifying unknown bacteria

Postby Nancy » Sun Sep 30, 2007 2:36 am

Hello everyone. I am enrolled in a Microbiology course and am working on a project. I was given an unknown bacteria in a test tube. So far, this is what I have:

unknown in test tube appeared as white/tan sediment floting at the top of the light yellow liquid agar broth (NO sediment at the bottom)

optimum temp to grow bacteria is 37C

Thioglycolate test = obligate aerobe

Gram Positive Streptobacillus with what appear to be spores

Oxidase Production = Negative

I have narrowed my choices down (from a list of 25 possibilities) to:

Bacillus cereus
Bacillus megaterium
Bacillus subtilis
Cornybacterium pseudodiptheriticum (Cornyebacterium hofmannii)
Cornyebacterium xerosis
Lactobacillus plantarum
Mycobacterium phlei
Mycobacterium smegmatis

I have researched the web to find as much as I could. Tomorrow, I will go into lab to get the results of the following tests I have performed:

Glucose, Lactose, Maltose, Manitol Fermentation
Methyl Red
Voges Proskaur
Catalase
Oxidase
Nitrate Reduction
Starch Hydrolysis
Tryptophan Hydrolysis
Urea Hydrolysis
H2s Productrion
Citrate Utilization

(And finally, my question)

Does any one know a source where I can plug in my results to find out what the bacteria could be?

Also, if any of the bacteria listed above are highly pathogenic, I doubt they would be given to us in lab. Does anyone know if any of these are?

Thank you for any help.
Nanc
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Unknown Bacillus

Postby Ania » Mon Oct 08, 2007 4:38 pm

Hi Nancy,

I think I am doing an identification on the exact same bacteria. I have identified it as a Bacillus, but that's about it. Streptobaclli, Gram +, some endospores present. Scores on the following tests:
Gelatinase producing neg
Strach Hydrolysis pos
Lipid hydrolysis neg
Casein hydrolysis (produces caesase) pos
Carbohydrate Fermentation
Lactose pos w/o gas
Glucose pos w/o gas
Sucrose pos w/ gas
Mannitol neg
Triple Sugar Fe Agar Test
Lactose neg
Dextrose pos
Sucrose neg
Hydrogen Sulfide neg
Methyl Red neg



Still have many tests to do, but do those mesh with you?

I'm a teacher in Yuma, AZ.
Good luck

Ania Mathews
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Postby BDeis » Tue Oct 09, 2007 5:12 pm

Check out this link. It may help.

http://www.som.soton.ac.uk/staff/tnb/pib.htm
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Postby Nancy » Wed Oct 10, 2007 12:04 am

Hi Ania,
I didn't run as many tests as you did, but can tell you some information for three types of Bacillus -- you definetly have either Bacillus or Clostridium if you have endospores. (I didn't try the link from BDeis but will use it when we do our next project to identify many bacteria from one sample).
I referenced "Bergey's Manual of Systematic Bacteriology" and another Microbiology book in the reference section of my college library.

Here are what results would be for Baccillus cereus for the tests I ran:
Gram Positive
Glucose: Acid
Lactose: Acid
Manitol: negative
Maltose: Acid
MR: +
VP: +
Urea -
Catalase +
Nitrate -
Starch +
Oxidase -
Citric -
Hydrogen Sulfide -
Indole -

Results for Bacillus megaterium
Gram Positive
Glucose -
Lactose: Acid
Manitol: Acid
Maltose: -
MR -
VP -
Urea -
Catalase -
Nitrate +
Starch -
Oxidase -
Citrate -
Hydrogen Sulfide -
Indole -

Bacillus subtilis
Gram Positive
Glucose: Acid
Lactose : acid (slight)
Manitol : acid (slight)
Maltose : Acid
MR -
VP +
Urea -
Catalase +
Nitrate +
Starch +
Oxidase -
Citrate +
Hydrogen Sulfide -
Indole -

I hope this helps you.
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Postby Nancy » Wed Oct 10, 2007 12:09 am

I forgot to add that my bacteria ended up being Bacillus subtilis. From the informaiton above, I was able to eliminate the other two Bacillus bacteria.
My sugar tests were a little off. I didn't get a slight positive for Lactose and my maltose was a slight positive. This could have been from not inoculating enough bacteria into the Methyl Red broth. Also, sugar tests can change very quickly. I think they should be checked in two days - but don't quote me on that. I also got a negative result fo rthe Nitrate test when it should have been positive. I was only off on two tests for subtilis but more on the others. We were told to expect one or two variations.
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Postby creidesca » Sat Dec 01, 2007 7:20 pm

Nancy, at least you managed to determine what your unknown was.

I, on the other hand, have less than a week left to determine the identity of my Gram positive unknown.

I received confirmation of endospores from my teacher, so I had narrowed it down to those in the Bacillus spp.

These were the results of the tests I performed:

Catalase +
Mannitol -
Voges-Proskauer -
Arabinose -
Citrate -

I thought I had Bacillus cereus, but my confirmation test (Citrate) was negative. Not to mention that streak and incubation on a BA plate gave me nonhemolysis.

I did test for acid from glucose, but I had to redo it (and am currently waiting on the results) since after a 2-day period, the indicator turned an a uniform orangish color, instead of yellow (positive for acid).

I questioned whether I really had endospores, so I did another stain, and will be looking at the slide this coming Tuesday.

Suppose my unknown did not produce endospores, that would leave me with the Corynebacterium spp.

At the Microbiology lab of the hospital where I volunteer, urea hydrolysis was positive, which would narrow my unknown to Corynebacterium pseudodiptheriticum or Corynebacterium pseudotuberculosis. The reason why I included Corynebacterium pseudotuberculosis on my list is because my colonies look yellowish-white. Corynebacterium xerosis would have been negative for urea hydrolysis.

I am hopeful results from the glucose acid test will pinpoint my unknown. I likely will do a maltose acid test to determine whether it is pseudodiptheriticum or pseudotuberculosis, as results should be negative for acid in all major carbohydrates should it be pseudodiptheriticum.
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Postby jeonkjc » Fri Jul 22, 2011 5:20 pm

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