Descriptive Chart for our Unknown

Here is the culmination of every property we tested and identified for our Unknown:

Morphological Characteristics:

1. Cell Shape: Cocci
2. Arrangement: Staphylococcus (clusters)
3. Size: small
4. Spores: none
5. Gram Stain: Gram-positive bacteria
6. Motility: non-motile
7. Capsules: none
8. Special Stains: none

Cultural Characteristics

1. Colonies: circular, opaque, cream colored, entire, rigid, and flat
• Nutrient agar: growth
• Blood agar: N/A
2. Agar Slant: growth
3. Nutrient Broth: growth
4. Gelatin stab: non-motile, grows where pin is inserted
5. Oxygen requirements: facultative aerobe
6. Optimum temperature: 37 degrees Celsius

Physiological Characteristics

1. Fermentation
• Glucose: Fermentation
• Lactose: Fermentation
• Sucrose: negative; no fermentation
• Mannitol: growth occurs; no fermentation
• MacConkey: no growth 
• EMB: no growth
• Litmus: formation of an acid curd; litmus reduction
2. Hydrolysis
• Gelatin Liquefaction: negative
• Starch: negative
• Casein: negative
• Fat: positive
3. IMViC
• Indole: negative
• Methyl Red: positive for acid production and fermentation
• Voges-Proskauer: negative
• Citrate utilization: negative
• Nitrate reduction: positive
• Urease: positive
• Catalase: positive
• Oxidase: negative
• TSIA: acid slant with alkaline butt
4. Litmus Milk
• Acid: ferments lactose into an acid
• Alkaline: none
• Coagulation: acid curd
• Reduction: reduces litmus
• Peptonization: N/A
• No change: N/A

Using these characteristics we were able to narrow down the identity of our bacteria through use of a flow chart.  

1. First, we identified that the bacteria was "Gram-positive."
2. Then we identified it as cocci (not bacillus, etc.)
3. After, we referred to the Catalase test.  Because the test was positive, our bacteria is either from the Micrococcus spp. or Staphylococcus spp.
4. Next we referred to our Mannitol test and recalled that we tested negative for fermentation.  This narrowed the list to S. saprophyticus, S. epidermidis, M. luteus, and M. varians.
5. Because there was no pigment surrounding our bacteria in the Mannitol test, we limited our list to S. epidermidis and S. saprophyticus.
6. We are unable to identify our bacteria any further.  To completely identify our bacteria a fructose test needs to be completed.