Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Identifying a bacteria

  1. Feb 7, 2010 #1
    ok so I work in a chemistry lab but I am a microbiology major. Our lab works with endophytes. We have a positive result for one of them and I have to identify this thing by April. This task seems impossible to me. They did not keep track of where this sample came from or even which organism it was isolated from. All they have is that it is a white bacteria (like thats helpful). I did a gram stain and it is a gram positive cocci ( not a small category). Since it is a chemistry lab I am very limited in what tests I can actually do. I am only an undergrad and I have no idea where to go from here. My graduate student is also a chemistry person. So no help there.

    Please HELP!
  2. jcsd
  3. Feb 7, 2010 #2


    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    You are a microbiology major and you do not know how to identify a microorganism? That is very surprising. I don't know the English name for the test, but there is a series of tests that are done by growing the microorganism in test tubes on different media that helps in the identifications of microorganisms. The color of the tubes after incubation is dependent on the biochemistry and is used for the classification.

    I looked it up and apparently it is called an API test, you should look up the information on how to formulate the media for the tests yourself.
  4. Feb 7, 2010 #3
    As far as I know API is used only for gram negative rods, mine is a gram positive cocci. So I can't use API. We had to find unknowns in our microbiology class but we were given a list of 20 some bacteria so I had a strategy. Here there is no list, I don't have any information except that its a Gram positive cocci. I think I might end up having to use 16S sequence and PCR. However I don't know much about them not to mention our lab does not have the capability to do that since we are chemistry I'll have to ask a biology lab to help me with that.. Using phenotype as a way to identifying something that I have no idea. Its a very vague task?
  5. Feb 11, 2010 #4
    So you couldn't conclude further based on your gram stain? Just that it's a gram positive cocci? That's odd, judging from the size and shape you should be able to break it down even further... maybe even make a identification such as would be the case if it were pneumococcus.

    There are various systems however like the API system for specifically identifying gram-positive cocci. They hold similar ratings.
  6. Feb 13, 2010 #5
    Well this bacteria is a little different. Its def a bacteria but it exhibits fungal form of growth. Its an endophyte so a lot is not known about them specially since our sample is from somewhere very unusual. I got the permission to use another lab and I extracted the DNA Friday, I am planning on doing the PCR Monday and so hopefully we'll know what it is in 7-10 days! I don't know weather I want it to be something known or unknown. Of course I mean statistically its probably known but we do get our samples from an unusual place so it might be unknown.
  7. Feb 13, 2010 #6
    o when I say fungal form of growth I mean when we grow it over night in TSB first there is very low count and 2nd it looks fungal in strings and all, and I put it on BA to check for hemolysis but it looked like yeast on BA. I also got a positive for MSA and MYP agars.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook