Biology Unknown Organism Lab

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 Performed Result
Gram Stain +
Fluid Thioglycollate Strict aerobe
Catalase +
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 Aerococcus Genus Marinococcus Genus Saccharococcus
Genus Coprococcus Genus Melissococcus Genus Salinicoccus
Genus Deinobacter Genus Micrococcus Genus Sarcina
Genus Deinococcus Genus Pediococcus Genus Staphylococcus
Genus Enterococcus Genus Peptococcus Genus Stomatococcus
Genus Gemella Genus Peptostreptococcus Genus Streptococcus
Genus Lactococcus Genus Planococcus Genus Trichococcus
Genus Leuconostoc Genus Ruminococcus Genus Vagococcus

The unkonwn’s oxygen requirements in FTM determined it to be a strict aerobe, thus yielding the following possibilities:
Genus Deinobacter Genus Marinococcus Genus Planococcus
Genus Deinococcus Genus Micrococcus Genus Salinicoccus

Deinobacter, Planococcus, and Marinococcus were also deleted because they were either gram-negative or gram-variable, which left:
Genus Deinococcus Genus Micrococcus Genus 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 considered among Deinococcus and Micrococcus, collectively:
D. proteplyticus M. agilis M. lylae
D.radiodurans M. halobius M. nishinomiyaensis
D. radiophilus M. kristinae M.
roseus
D. radiopugnans M. luteus M. sedentarius M.
varitans

This list was shortened based on the Nitrate reduction test results. My unknown tested positive.
D.radiodurans M. nishinomiyaensis
D. radiopugnans M. roseus M. varitans

The organism’s colony color further narrowed the list, eliminating any species with a colony color other than red or red-orange leaving
D.radiodurans M. roseus
D. radiopugnans

Unfortunately this is as far as I can get using my test results as determining factors in my presumptive ID. The test results recorded in the Bergy’s Manual for D. radiodurans and D. radiopugnans do not give sufficient information to eliminate them as possibilities for my unknown. Further testing will have to be performed to definitively rule them out, despite the many indicators that the organism is that of M. roseus. The expected results of the three organisms, according to Bergy’s Manual, and the results of the tests performed in the Mesa lab are shown below.

Test Riley’s Toe Unknown M. roseus D. radiopugnans D. radiodurans
Glucose Fermentation + +
Nitrate Reduction + + + d
Gelatin Hydrolysis - -
Oxidase - -
Growth with 5% HaCl - - d
Growth with 7.5% NaCl + +
Colony Color Orange-red Pink or orange-red Orange-red
Red

Further research has brought to my attention that the Deinococcus was originally placed in the genus Micrococcus until, after further ribosomal evaluation, it was placed in Deinococcus. All species of the genus are radioresistant. It is this unique resistance that would be the determining test for the identity of my unknown organism as either genus Deinococcus or Micrococcus. However, despite the inconclusive testing, it can safely be presumed that the unknown organism is that of Micrococcus roseus, especially considering the culture of the unknown was taken from a puppy paw, an environment similar to the normal habitat for this species of Micrococcus – mammalian skin, soil, and water.