why do we need to identify unknown bacteria

According to the European Molecular Biology Organization, approximately only one percent of all estimated amounts of bacteria has currently been discovered and fully studied. This shockingly minimal percentage lends credence to the idea that increasing humankindвs knowledge of unknown bacteria could have great future benefits. Bacteria are mostly known for causing disease or harming the health of humans. But not all bacteria should be viewed this way; some are essential to our existence and keep our food chain from collapsing. Others prove beneficial to humans, such as those that are found naturally in some of our favorite foods. Discovering and studying new bacteria can lead to new innovations and possible cures for existing or future diseases. The investigation of these new bacteria can also help incubate ourselves or act quickly in response to an invasive strain. One of the great disasters in human history was caused by bacteria--the Plague. During the Middle Ages and again in the 19th century, millions of people succumbed to infection by the bacteria Yersinia Petis.
P Microbiology Unknown Lab Report P Samantha Moellenhoff Microbiology,P Fall 2012 P INTRODUCTION With the constant debate in society about microorganisms, it is important to distinguish their identities. (There are many reasons as to why this is important such as knowing what agent is causing a disease and the correct treatment is determined, to knowing which microbes are beneficial to a person and important to body functioning. ) The purpose of this study was to identify an unknown bacterium by applying all methods that were previously conducted and learned in the microbiology laboratory class.


MATERIALS AND METHODS An unknown test tube labeled 120 was given out by the lab instructor. The goal at this point was to determine two separate unknown bacterium, one Gram positive and one Gram negative. The procedures performed consisted of sterile technique in addition to being followed as stated in the referenced course laboratory manual, unless otherwise noted. The first procedure performed was an isolation of the unknown bacteria with the goal of obtaining a pure culture.


This was conducted by streaking the unknown out on a Trypticase Soy Agar (TSA) plate using the T streak method described in the manual. From that, the plates were incubated for two days and the bacterium grew. The bacteria were studied based on their physical characteristics and recorded. Two distinct different colonies grew. Each colony was isolated to grow purely on its own TSA plate. One TSA was labeled culture A and the other culture B. Gram stains were performed on each culture. It was critical to follow each step correctly while using sterile technique because from this test not only is the stain determined but also the shape of the cells. Culture A was determined to be a Gram positive cocci and culture B was determined to be a Gram negative rod. After the Gram stain was determined, specific biochemical tests were performed. The biochemical tests performed were chosen based on the identification table that was given from the lab instructor. The flow charts on the following page list these tests and results for the Gram positive and Gram negative bacteria.


RESULTS (this section contains flowcharts) P P P P P P P P P P P P DISCUSSION/CONCLUSION After several different biochemical tests, it was concluded that the Gram positive in unknown 120 was Staphylococcus aureus. The bacterium was grown on a TSA agar plate for use of additional tests, gram stain reaction determined that the unknown was a gram positive cocci. The culture was then inoculated onto a Mannitol Salt Agar plate. The growth and color change to yellow indicated Mannitol fermentation because acid was produced. This indicated that the unknown was either Staphylococcus aureus Enterococcus faecalis. Acid fermentation is a characteristic of pathogenic Staphylococci. Then, a Nitrate broth test was performed. This test had a positive reaction meaning the reduction to nitrites occurred. This indication meant the unknown was Staphylococcus aureus. A Catalase test was the performed for clearification. The Catalase test had a positive reaction meaning the bacteria produced the enzyme catalase confirming that the unknown bacterium was Staphylococcus aureus.


P Staphylococcus aureus is in the Staphylococcaceae family. It is usually found in nasal passageways but can also be found on skin, in the oral cavity and gastrointestinal tract. It can be carried as part of the normal bacterial flora. Staphylococcus aureus (methicillin-resistant Staphylococcus aureus ) which is an epidemic in the medical world because of its antibiotic resistance. S aureus can become pathogenic through tissue invasion and toxin pollution. Vancomycin is the usually prescribed because of resistance to penicillin. PP P P References P McDonald, V. , Thoele, M. , Salagiver, B. , Gero, S. (2011). Lab Manual for General Microbiology: Bio 203. N. p. : St. Louis Community College at Meramec. Tolan Jr. , R. W. (2012, July 9). Staphylococcus Aureus Infection. In Medscape Reference. Retrieved December 2, 2012, from http://emedicine. medscape. com/article/971358-overview#a0101 Todar, K. (n. d. ). Staphylococcus aureus and Staphylococcal Disease. In Todar s Online Textbook of Bacteriology. Retrieved December 3, 2012

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