Identifying an Unknown Bacteria
Introduction
Knowing the identity of a microorganism is extremely beneficial. Knowing what you are dealing with can allow one to knowing the causative agent of a disease and how it can be treated. The purpose of this lab was to identify an unknown microorganism by using various differential tests. These experiments separated and differentiated bacteria based upon specific characteristics. The experiments included identifying shape and motility, gram staining, endospores, oxygen, glucose, lactose, mannitol, VP, MR, citrate, nitrate, catalase, and oxidase. If I perform theses experiments correctly and accurately then I will be able to identify my unknown bacteria. Materials/Methods
The different tests performed on the bacteria were all done in order to determine the identity if an unknown bacteria. Identifying the shape of a bacteria allows one to not only determine how a bacteria looks physically, but can also be applicable in naming a bacteria. Motility is if a bacteria is mobile or immobile. Motility is determined to find if one’s bacteria is alive or not; if bacteria is moving then that means it is alive and if the bacteria is not moving that indicates the bacteria is dead. gram staining indicates if there is peptidoglycan in the cell walls of the bacteria or not. In gram staining the reagents use where crystal violet for the primary stain, Gram’s iodine for the mordant, 95% ethyl alcohol for the decolorizing agent, and safranin for the counter stain.
The Term Paper on Identifying Unknown Bacteria
Abstract. One of the most fundamental differential staining techniques used in the study of bacteriology is gram staining. There are two main types of bacteria, gram negative and gram-positive. The purpose of this experiment was to perform a variety of tests to identify the bacteria contained in the unknown sample labeled number 15. The following are the tests that were used to identify the two ...
If a bacteria contains peptidoglycan in their cell walls then that bacteria is considered to be gram positive and will turn purple. If the cell does not contain peptidoglycan in their cell walls then the bacteria is gram negative and will turn purple. “Endospores are formed by a few genera of gram positive bacteria. Endospores are specialized for survival in unfavorable growth conditions, including heat and drying” (Lammert, 2007, p. 112).
In the endosporee test reagents used were the staining with the malachite green and heating, washing with water to remove malachite green from cells, but not from endospores, and safranin as a counter stain to visualize vegetative cells. For the oxygen test……… (Lammert, 2007)
Results

Discussion:
Determining the unknown was somewhat of a challenge because all of my tests turned out incorrectly. However, I did determine the shape and motility correctly as well as gram staining and endospores. Consequently, I believed my unknown to be Micrococcus luteus, Micrococcus roseus, Staphylococcus aureus, Staphylococcus epidermis, Streptococcus lactis, Streptococcus mutans, or Streptococcus pneumoniae. If I were to have based my conclusion on my results from my tests I would determine my unknown to be Micrococcus roseus. I am aware that my unknown is Staphylococcus aureus though.
A majority of my tests did not turn out correctly. I think this is due to contamination of the bacteria within the first two weeks. When I was transferring my unknown using the inoculating loop I was not properly sterilizing it. I was not allowing the loop to completely turn orange and as a result I believe that my unknown was getting contaminated from the unspecialized loop. Therefore, the tests I performed after the first couple of weeks were inaccurate.
Literature Cited:
Lammert, J. (2007).
Techniques in microbiology a student handbook. San Fransisco: Pearson Benjamin Cummings.
Unknown 42
Staphylococcus aureus
Shape
C
C
GramRx
+
+
Spores
–
–
Motility
–
–
The Essay on Gram Positive And Gram Negative Bacteria
Gram Positive and Gram Negative Bacteria It is a well-known fact that bacterial cells, like plant cells, are surrounded by a cell wall. However, few people know that their cell walls are quite different. Bacterial cell walls are made up of polysaccharide chains linked to amino acids. At the same time, plant cell walls are made up of cellulose, which contains no amino acids. In the same way, ...
Oxygen
A
F
Glucose
+
+
Lactose
–
d
Mannitol
–
d
MR
N/A
d
VP
N/A
d
Citrate
–
d
Nitrate
+
d
Catalase
+
+
Oxidase
–
