What are ways to determine a bacteria? using gram positive and negative?

Gram positive/negative staining is one possible outlet to shine some light on your specimen. Being gram positive you will know that it contains a cell wall comprised of high levels of peptidoglycan, however, bacterium such as cocci and bacillus can be gram negative as well.

You will be better off learning relative shape and formation of broader scale bacterium and from that you should be able to narrow your search down.

Take for instance: Coccus is a spherical bacteria and it is arranged in a line. Streptococci has these qualities.

OR

Bacillus is a rod shaped bacteria and it is arranged in a line. Streptobacilli has these qualities.

This.

Perhaps of a more general nature, I'd recommend you design a flowchart. Here is one example illustrating a process of identification:



Obviously a diverse grid o DNA probes would work even better.

This post was edited by Dmon_Hunter on Feb 15 2012 08:26am

Chart above is great example of what you should be doing^

The three main ways are a gram stain with crystal violet/acid alcohol/safranin, selective plates with abnormal food sources/salinity/chemicals, and differential plates and dyes as indicators of specific traits.

examples are MSA plate, HEA plate, PEA plate, Blood Agar, Coagulase test, etc. google em up

Edit: I'd start with a streak plate to make sure its a pure culture first

This post was edited by EndlessSky on Feb 15 2012 05:25pm

thanks guys!