Introduction
Medical microbiology is an aspect of microbiology sciences. Microbiological systems play a vital role in people’s everyday life. Specifically, bacteria maintain processes within and on the body. Bacteria can also cause disease from an infection of the opportunistic bacteria living symbiotically with people or foreign bacteria introduced from various plausible sources.
The identification of the unknown bacteria was accomplished by an independent study of numerous biochemical tests. The tests gave physiological information about the morphology, type of respiration, energy sources, and metabolic processes. The test results indicated the bacteria was Escherichia coli.
Materials & Methods
Unknown microorganism (#33) was obtained
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It also provided a differential media for non-lactose fermenters producing colorless colonies while lactose ferments create an acidic environment producing reddish, dark- colored colonies. The blood agar is a differential media for similar Steptococcaceae and Enterococcaceae growing on the media with varying hemolytic growth patterns. Some streptococci and enterococci produce alpha-hemolysis by partial lysis of the cell by breaking down the hemoglobin in the red blood cells in the agar producing a dark-greenish color around the colonies. The beta-hemolysis growth pattern of some of the others release endotoxins resulting in complete lysis of the red blood cells giving a clear zone around the colonies. The bacteria that do not carry out any kind of hemolysis of blood agar have a growth pattern called gamma-hemolysis with colorless colonies on the agar.
Oxidation and fermentation
MR-VP test
Methyl Red - Voges Proskauer (MR-VP) is a media that contains glucose with buffering agents, peptone and dipotassium phosphate. In a methyl red test, three drops of the pH indicator, methyl red, is added to the broth that will immediately indicate if mixed acid fermentation has taken place. Methyl red test is to examine if the bacterium’s fermentation of glucose results in mixed products of lactic, acetic, succinic, and formic acids
Voges-Proskauer test indicates whether the bacterium ferments glucose into some organic acids and 2,3-butanediol by adding six drops of
The following tests according to the lab manual were performed: gram stain, fermentation tubes, methyl red, vogues proskauer, sulfur, indole, motility and growing it up on MacConkey agar. The gram stain was performed incorrectly the first time. This is because the decolorizer was not on the bacterium slide for long enough, giving a false outcome.
The Voges-Proskauer test to detect organisms that are able to ferment glucose, but convert the products to acetoin and 2,3-butanediol. This is deduced by the addition of Reagent A and Reagent B, and the observation of the color change thereafter. Reagent A is a solution of -naphthol and alcohol. Reagent A catalyzes the conversion of acetoin to diacetyl. Diacetyl thens react with guanidine-containing compounds from the peptone to form a red color in the presence of -naphthol. Reagent B is a solution of potassium hydroxide and water. It
One of my areas of interest is microbiology, particularly the mechanisms by which pathogens evade host defense systems and cause disease. Since I currently work in a microbiology lab I have read a few papers dealing with these issues and as such I would like to investigate the clinical aspects of bacterial infections.
Fermentation is a metabolic pathway that produce ATP molecules under anaerobic conditions (only undergoes glycolysis), NAD+ is used directly in glycolysis to form ATP molecules, which is not as efficient as cellular respiration because only 2ATP molecules are formed during the glycolysis. One type of fermentation is alcohol fermentation, it produces pyruvate molecules made by glycolysis and the yeast will break it down to give off carbon dioxide, the reactant is glucose and the byproducts are ethanol and carbon dioxide. In this lab, the purpose is to measure whether the changes of
The purpose of this lab was to identify two unknown bacteria from a mixed culture. The reason for identification of unknown bacteria was to help students recognize different bacteria through different biochemical tests and characteristics. This is important in the medical field because identification of unknown bacteria can help treat a patient by knowing the contributing source of a disease. Also knowledge of different bacteria helped others make antibiotics used today. This lab was completed by using the methods learned thus far in identification of bacteria.
I began by running the starch test, which tests for the presence of starch hydrolyzing enzymes. After doing a one-line inoculation of the organism, the plate had to be incubated. Once I received an appropriate amount of growth I added the reagent iodine. The iodine turned the plate purple, formed no clear zone, and lifted the organism off of the plate, which revealed that the starch was not degraded and the enzyme was not present. The organism being lifted off the plate is unique to the bacteria Corynebacterium xerosis indicating that it was my gram positive rod. For reassurance, I ran the Phenol Red Glucose test, which tests if the organism contains various enzymes that determine if the bacteria can ferment glucose. After incubation, the broth turned orange, but this did not provide a clear positive or negative result so I ran the Nitrate Broth Reduction test. The Nitrate Broth Reduction test detects if the organism utilizes nitrate. After incubation for forty-eight hours I added Nitrate A and Nitrate B indicators. However, there was no color change indicating that the test was inconclusive. Since the test was inconclusive, I proceeded to the following step, which included adding a small amount of zinc to the broth, and this turned the broth a red color. The red color indicated that
The purpose of this study project was to carefully isolate and identify two unknown bacteria from a mixed culture. The ability to properly evaluate biochemical test results is also necessary for the identification to be successful. The goal was to apply all of the methods and techniques that have been learned in the microbiology laboratory course for the proper identification of unknown bacteria. A certain amount of bacteria that were used throughout the course were possible bacteria that could be found in a mixed culture. The bacteria that were identified in the mixed culture were Staphylococcus Aureus and Kocuria Rhizophila.
The first result of importance was the result of the Gram stain. The observations of the unknown bacteria from the slant culture after Gram staining showed that the unknown bacteria were Gram negative bacilli (Image 1). After determining the unknown bacteria was Gram negative, an oxidase test was conducted on a sample from the slant culture. The cotton swap with the sample of bacteria did not change color when the oxidase reagent was applied, thus providing a negative result. With a negative oxidase test, further tests were conducted to determine various characteristics of the unknown bacteria. A MR-VP broth was inoculated with a sample from a slant culture of unknown bacteria. After incubation, the methyl red reagent was added to the broth, and the broth turned red, providing a positive result (Image 2). An EMB agar streak plate was inoculated with a sample from a slant culture of the unknown bacteria, and after incubation, growth was found on the plate, providing a positive result (Image 3). A Citrate agar slant was inoculated, and after incubation, growth was found on the media, providing a positive result (Image 4). A Urea agar slant was inoculated, and after incubation, the agar had changed from a peach color to a bright pink color, providing a positive result (Image 5). Using the flowchart (Figure 1) developed from the Table of Expected Results, the lab partners started at the oxidase test. Given the negative result of the oxidase test, the flowchart is
Triple Sugar Iron agar slant (TSI) was used to test for the fermentation of glucose and lactose, as well as the production of H2S. Gas production was also monitored, looking for fissures produced by production of gas during fermentation. The conversion of the originally red slant and butt of the agar to yellow indicates that
|EMB Agar | |Distinguishes bacteria that ferment |Dark blue colonies with|E. coli and P. |
Citrobacter Freundii is a species of bacteria that can be potentially harmful to humans. It is known to cause meningitis by protruding into the brain and replicating itself (1). The Citrobacter species has also been found as a cause of some urinary tract infections, diarrhea, and even gastrointestinal diseases and symptoms (3). C. Freundii can be located in a wide variety of soils and water (3). Lastly, it is also the cause of many nosocomial infections due to its presence in water (1).
The main idea of this experiment was to correctly identify the unknown bacteria, #3. Identification of unknown bacteria yields multiple benefits in many different areas in the research of microorganisms. In this experiment I performed many different test dealing with things such as the presence of enzymes, fermentation abilities and different chemical reactions. Observations made from the tests were then compared to a gram negative unknown chart in order to identify the bacteria. Based off of my results and the chart, I concluded the bacteria #3 was the bacteria Escherichia coli. E. coli is most commonly found in the intestines of warm blooded organisms. Most E. coli strands are non pathogenic however, there are strands
The purpose of this study was to identify the unknown bacterium using biochemical tests and various methods that had been learned from previous the microbiology laboratory class. Identifying the unknown bacterium was determined by separating and differentiating possible
Microbiology is a subject dealing with microbes and related concepts. Microbiology has come a long way since discovery of microbes and is presently of great help to mankind. It is used in health care, food production, diagnosis, production of alcohol, maintenance of sterility and cleanliness etc.
They study the microorganisms that lead to illness in humans and animals. They perform tests and analyze viruses, bacteria, funguses and pathogens in order to gain knowledge about fighting and preventing diseases. They work and manage in research labs in hospitals and medical schools, however some work for pharmaceutical companies also. They research and investigate the origin of contagious diseases and they explore and investigate new treatments for these infections. The clinical microbiologists also carry out trials and tests to try find cures to certain diseases, viruses, pathogens etc. They do this by collecting samples from various sources or locations and they then record and analyse any data they find as a result. Therefore they then might be able to recommend some