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How to identify an unknown microbe?

  1. Jan 22, 2005 #1
    :cry: :cry: :cry: please help, how to identify an unknown microbe? :confused: :confused:
  2. jcsd
  3. Jan 22, 2005 #2

    host type
    gram stain (+ve, -ve)
    morphology (size, shape, other fixtures)
    proteins (western blot?)
    dna (PCR)

    and that's all i can remember.. never did do microbiology.
  4. Jan 22, 2005 #3


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    Are you starting from a mixed culture, tissue sample or sample from environment.

    The type of culture will influence the steps required to identify your organism.
    For mixed culture, tissue and environmental sample, first streak for isolation of rich non specific media. Use the temperature that is most appropriate. Tissue sample comming from a mammal should be grown at 37C whereas an environmental sample should be grown between 15C and 20C
    Once you have isolated the organism you do a gram stain and also do a wet mount. The gram strain will help you identified the morphology of the organims and how it colonies are formed. For example, a gram positive cocci that forms line will be a streptococcus. The wet mount will tell you if your organism is mobile or not.
    You also need to do catalse and peroxidase test. This guide you towards are more specific group.
    You can then do more group specific stain such as spore stain.
    Once you have this information look in the Bergey's. Bergey's is the bible of bacteriologist. It has all classified bacteria. If it is not a bacteria than use another taxonomy book.
    Bergey's or the other taxonomy book will help you to find the biochemical test required to identify the organism.
    You also do not have to carry the biochemical test. There is strips that are sold that included all the test for a specific organims.

    To support your identification and to have a more specific results, you will need do isolated DNA from you pure culture and amplifed and sequence the small ribosmal unit gene.

    Strain/serotype/species specific test will also be required for additional and better classification. You will again refered to the bergey or any litterature that is specific for that organism.
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