Microbiology Unknown Paper.

Words: 1352
Pages: 6

Lahela Correa
Microbiology 140
Matthew Tuthill
Unknown Lab Report

There are many reasons for knowing the identity of microorganisms. The reasons range from knowing the causative agent of a disease in a patient, so as to know how it can be treated, to knowing the correct microorganism to be used for making certain foods or antibiotics. This study was done by applying all of the methods that I have been learned so far in the microbiology laboratory class for the identification of an unknown bacterium.
The purpose of this lab was to identify two unknown bacteria cultures using various differential tests. The identification of these unknown cultures was accomplished by separating and differentiating possible
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Production of this compound will cause a reaction to occur with ferrous sulfate and will result in the production of a black precipitate. Thus, the culture is positive for H2S production if a black precipitate is seen and negative if one is not observed. The yielding results after incubation was (A/A) for gram (-) bacteria and (K/K) for gram (+) bacteria, there were no black precipitate present in either tubes.

Flow chart

Unknown 126

Gram Stain (G+ Coccus)

Catalase (positive)

Positive Negative

Staph. aureus Strep. pyogenes
Staph. epidermidis Strep. aglactea
Staph. saprophyticus Enterococcus faecalis
Micrococcus roseus Strep. pneumonia


Gamma Other
Staph. Saprophyticus Staph. Aureus
Micrococcus roseus Staph. Epidermidis

TSI (k/k)

Negative Positive

Micrococcus roseus Staph. Saprphyticus

Urease (Negative) / Bacitracin (S)

Micrococcus roseus

Unknown 126- Micrococcus roseus

With multiple differential and biochemical test runned on the unknown 126 I was able to single out the bacteria which lead to Micrococcus roseus. After running the test and observing the results I believe