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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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Microbiology help in identifying Gram + rod for my unknown

Thu May 03, 2012 5:21 am

This unknown is extremely hard narrowing down, with that said I was wondering if anyone could point me in the right direction. I have narrowed down my Genus based on the fact that it forms spores and is gram positive rod to Bacillus.
However when approaching my proffessor she did say I could have inoculated some of the tubes wrong or the tests did not come out as accurate as I would have liked. These are all the tests and the results I ran. What do you think?
Cell shape= rod
gram reaction= positive
Size when done with a mixed gram stain with . aereus is seen to be much larger.
Spores= +
capsules= -
motility= ? seemed to be nonmotile in the wet mount, and slight red formation towards top of gelatinase, but I thought that was only due to introduction of oxygen. I dont know.
Acid fast stains were shown to form chains with rods and spores
optimum temperature ranges from 20- 45 and mostly likes 37
Growth was seen mostly at the top of the tube
The TSA plate shows a creamy white with a slight tint of yellow, the colonies formed slightly, raised, circular bumps.
Blood plate= I thought was beta hemolytic because it was a green greyish color but I dont know exactly could be alpha
TSB= showed slight growth at the bottom a kind of hazeyness to it, but still not a lot.
Oxidation/Fermentation= -/- for both tests
Glucose=-
Lactose=-
Sucrose=-
Mannitol=-
Nitrate= red=- N/C= +
Methyl red=-
Voges= -it wouldnt turn totally red so it stayed a brown but we could have not done it right, that was a little iffy
citrate= -
oxidase= -
catalase= +
Gelatin liquefaction= -
starch=-
casein=+
urease= +
Indole= -
Dnase= +
ornithine decarboxylase= -
Lysine decarboxylase= +
Arginine decarboxylase= -
Any help would be great I have been racking my brain over the bacillus and nothing seems to fit
Thank you
Cara Capelouto

Thu May 03, 2012 6:48 am

Any special reason, why is it in Evolution or is it OK, if I move it into Micro?

Re: Microbiology help in identifying Gram + rod for my unknown

Sat May 05, 2012 2:17 am

No my bad you can move iti to micro, thank you

Re: Microbiology help in identifying Gram + rod for my unknown

Sun May 06, 2012 9:34 am

Identification of Gram + spore formers is fairly complicated and not very useful as a teaching lab excercise. The positive catalase probably points toward Bacillus spp. but taking it to species will be tough. Are you sure you aren't working with a contaminant? The tests you've run seem more relevant to an enteric id excercise.

Re: Microbiology help in identifying Gram + rod for my unknown

Wed May 09, 2012 12:09 am

JorgeLobo wrote:Identification of Gram + spore formers is fairly complicated and not very useful as a teaching lab excercise. The positive catalase probably points toward Bacillus spp. but taking it to species will be tough. Are you sure you aren't working with a contaminant? The tests you've run seem more relevant to an enteric id excercise.

no this is my unknown, it may have been contaminatied, but still I have to write this paper regardless. Any suggestions as to where to start?

Re: Microbiology help in identifying Gram + rod for my unknown

Wed May 09, 2012 11:36 am

Curious - is this beginning micro lab?

You can rule out some species but a specific ID is probably not readily obtained. I'd start with Bergey's Determinative
( http://www.uiweb.uidaho.edu/micro_biolo ... charts.pdf ). You'll see some of it's pretty subjective and for many species, you can only arrive at a group.

Wed May 09, 2012 3:06 pm

Ok thank you ill try I have looked over bergeys systematic manual to no avail, and yes this is an intro class.

Thu May 10, 2012 3:37 am

Could it possibly be B. sphaericus, everything matches on all the results except the motility!!!! its the closest on eI have found yet, should I go for it????

Re: Microbiology help in identifying Gram + rod for my unknown

Thu May 10, 2012 12:02 pm

Could be but the data you have aren't very convincing. Was any context offered for the excercise such as food micro?

Have to say that this backward approach to teaching microbial identification is pretty poor on the part of your prof. You should have had appropriate keys that would have led to a plan of identification rather than throwing every test available into the effort and then looking for an answer.

Re: Microbiology help in identifying Gram + rod for my unknown

Tue Jun 26, 2012 1:02 pm

I am so confused... My unknown is due tomorrow and I want to make sure I am correct before I turn it in..

Cell Shape: Bacilli
Arrangement: Diplibacilli
Size: 2mm X .5mm
Gram Stain: Negative
Motility: Yes

Glucose Fermanation: yes acid/gas
Lactose " ": yes acid/gas
Mannitol " ": yes acid/gas
Sucrose " ": negative
Menthyl Red: positive
Butanediol (VP): negative
Nitrate Reduction: +NO2
Catalase: positive

Hydrolysis
Indole: positive
Starch: positive
Casein: negative
Urea: negative
Citrate: negative
Hydrogen Sulfide: negative
phenylalanase: negative

I got for my genus: Escherichia
and my species: Fergusonii

Please help me determine if I am correct? Thank you!!! Lisa

Wed Aug 22, 2012 10:43 am

Why you guys perform such amount of time consuming tests? Simply amplify 16S rDNA, sequence it and compare with the database via BLAST tool at NCBI website....

Wed Aug 22, 2012 1:42 pm

My guess would be they have it for some school labs, where it is the purpose to try all these tests and identify the bacteria.
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