Determinative Bacteriology

Topics: Bacteria, Gram staining, Microbiology Pages: 3 (602 words) Published: June 7, 2012
Phelps, Biology 205
MW 2:10pm.
Unknown Organism Paper

The unknown organism tested in the Mesa lab was collected from in between the toes of my puppy, Riley. The original culture grown consisted of dozens of visibly different organisms of varying colony colors and growth patterns. I chose to test a smaller, red colony for my experiments. Based on its gram reaction and oxygen requirements, the following tests were performed to reach my presumptive ID: Test PerformedResult

Gram Stain+
Fluid ThioglycollateStrict aerobe
Nitrate Reduction+
Growth 5% NaCl-
Growth 7.5% NaCl+
Gelatin Hydrolysis-
Glucose Fermentation+

My organism appeared to consist of gram-positive cocci, making it a member of Group 17 in Bergy’s Manual of Determinative Bacteriology. Genus AerococcusGenus MarinococcusGenus Saccharococcus
Genus CoprococcusGenus MelissococcusGenus Salinicoccus
Genus DeinobacterGenus MicrococcusGenus Sarcina
Genus DeinococcusGenus PediococcusGenus Staphylococcus
Genus EnterococcusGenus PeptococcusGenus Stomatococcus
Genus GemellaGenus PeptostreptococcusGenus Streptococcus
Genus LactococcusGenus PlanococcusGenus Trichococcus
Genus LeuconostocGenus RuminococcusGenus Vagococcus

The unkonwn’s oxygen requirements in FTM determined it to be a strict aerobe, thus yielding the following possibilities: Genus DeinobacterGenus MarinococcusGenus Planococcus
Genus DeinococcusGenus MicrococcusGenus Salinicoccus

Deinobacter, Planococcus, and Marinococcus were also deleted because they were either gram-negative or gram-variable, which left: Genus DeinococcusGenus MicrococcusGenus Salinicoccus

However, Salinicoccus requires 7.5% NaCl for growth. Although the unknown tested positive for growth in 7.5% NaCl, it grows fine without it. This narrows any following tests to be performed to those that would differentiate between Genus Micrococcus and Genus Deinococcus. The following is a list of species to be...
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