1. Conclusions References
“Bacillus cereus.” Bacillus cereus. Department
Unknown
The first step in determining the identity of the un-
known organism began with the completion and of Vet. Microbiology, KVL. n.d. Web. Retrieved, Microbiology
24 April 2011, from
analysis of the gram stain. It was determined that
http://www.microbiologyatlas.kvl.dk/biologi/en
Organism Report
the organism was gram positive, which immediately
glish/showmorf.asp?articleid=2
eliminated Enterobacter aerogenes, Proteus mirabi-
lis and Proteus vulgaris. Next, morphology was used Unknown #: 15
to narrow down the list of prospective gram positive Black, Jacquelyn G. Microbiology: Principles Unknown Name: Bacillus cereus
bacteria. Of the five remaining gram positive bacte- and Explorations. 5th ed. Hoboken, NJ: John
ria, only two were rod shaped, or bacillus, further Wiley & Sons, Inc, 2002. Print.
narrowing the search to either Bacillus subtilis or
Bacillus cereus. B. subtilis and B. cereus share
Cowan, Marjorie K. and Kathleen P. Talaro.
many characteristics. In addition to being gram
Microbiology: A Systems Approach. 2nd ed.
positive and sharing the rod morphology, both are
New York, NY: McGraw-Hill, 2009. Print.
motile, facultative anaerobes, catalase positive, and
β-hemolytic. The determinative factors that were
able to finally and definitively classify the unknown Health Protection Agency (2007). Identification
organism as Bacillus cereus included: the arrange- of Bacillus species. National Standard Method
ment of the bacteria, the colony morphology, and BSOP ID 9 Issue 2.1. http://www.hpa-
the glucose fermentation test. The arrangement of standardmethods.org.uk/pdf_sops.asp.
the bacteria is predominantly streptobacillus com-
pared to the clusters formations of B. subtilis. The
“Microbiology Education Series – Bacteriology
colony morphology consists of flat, irregular clusters
No. 8: Bacillus cereus.” Cosmos Biomedical.
with undulate margins, while the colonies of B. sub- cosmosbiomedical.com. n.d. Web. Retrieved,
tilis displays a circular form. Finally, the glucose 24 April 2011, from http://
Bacillus cereus Gram Stain
fermentation test yielded a positive result which is www.cosmosbiomedical.com/education/
Magnification: 1000x
indicative only of B. cereus. All testing completed in bacteriology/8-B.Cereus.shtml
the laboratory directly correlates with verified scien-
BIO 204 - Section 104
tific results and does not deviate from the norm.
None of the tests completed yielded results con-
“Typical Results for Biochemical Tests.” Microbiology
Microbiology: Microbes Everywhere. University
trary to the typical results for the Bacillus cereus For Dr. Lisa Davis
of Wisconsin: Department of Bacteriology. n.d.
bacteria solidifying the organism’s identity. Given By Brittany Morgan
Web. Retrieved, 24 April 2011, from http://
the information outlined above as well as the labo- inst.bact.wisc.edu/inst/index.php?
ratory testing completed, unknown organism #15 is module=book&func=displayarticle&art_id=123
also known as Bacillus cereus.

2. Table of Results Decision Tree
Test Result
Gram Stain +
Morphology Rod
Colony Morphology Large, irregular, flat
Arrangement Variable:
Diplobacillus
Streptobacillus
Motility Motile
Anaerobic Jar Facultative Anaerobe
Hemolysis β-hemolysis
Gelatinase +
Nitrate Reduction +1
Catalase +
Oxidase +
Glucose +
Fermentation
Citrase +
Indole —
Starch Hydrolysis +