An Explanation Of An Unknown Bacterium Essay

1466 Words Feb 18th, 2015 null Page
This experiment pertained to identifying an unknown bacterium. This bacterium was retrieved from a member of our group’s hand. Bacteria are prokaryotic, but like all other living organism there are many genus and species. Through experimentation these unknowns can be found can be brought to light. Bacteria can be classified either gram-positive or gram-negative. These groups differ by the composition of their cell walls. In particular, the difference in the composition pertains to amount of peptidoglycan, a polymer of amino acids and sugars, present. A Gram test is most commonly used for this classification, and pertains to using a dye to determine the classification of the bacteria. The peptidoglycan that is found in gram-positive bacteria retains the dye, and gram-negative bacteria, that lack peptidoglycan and have a thin cell wall, will not retain the dye. This test however, is quite complicated and there are simpler methods to determine if the bacterium is gram-positive or gram-negative. A KOH string test is one of these methods. In this method, the bacteria is mixed with KOH, and while mixing the sample will either become viscous somewhat quickly (Positive String) or it will not (Negative String). This reaction correlates with gram-positive or gram-negative classification in a somewhat opposite manner. A positive string test indicates a gram-negative bacteria and a negative string test indicates a gram-positive bacteria. Another method that…

Related Documents