Introduction The purpose of this experiment was to identify an unknown microbe with the knowledge we have obtained from previous experiments. We used our knowledge of staining properties, cell morphology, cell arrangement, and biochemical tests to identify the microbe. Our professor provided us with a flowchart to guide us through the elimination process of this experiment. Methods We began the experiment with conducting a Gram Stain to be able to differentiate if our organism is gram negative or gram positive. The Gram Stain also allows to determine the size of the cell, the cell’s morphology, and arrangement of the cell. Gram negative cells have a LPS outer layer and an inner thin peptidoglycan layer and the gram-positive cells have a …show more content…
The enzyme also can catalyze the reduction of cytochrome c by tetramethyl-p-phenylenediamine, which is a chromogenic reducing agent. This agent is a chemical that changes color as they become oxidized. I inoculated the unknown organism onto a petri dish the day of the Gram Stain test. The following day of the Oxidase test the organism had grown on the petri dish ready for testing. I added five drops of oxidase reagent over the growth and saw the results after 20 seconds. The next experiment from the flowchart is the Acid and Gas from Lactose, but in our lab manual it is call Phenol Red Fermentation Broth test. This experiment allows for us to see if the microbe ferments a sugar with a distinctive color change. A special test tube called Durham tube is used to detect if they are also gas producers. Final experiment is to test if the microbe had a red pigment at 25ºC. At the beginning of this experiment, we had inoculated the microbe to have more than one pure culture. Therefore, I inoculated a clean petri dish, allowed it to grow and saw the results. …show more content…
There are currently 14 species of Serratia although 8 are associated with human infection. Of the Serratia species, S. marcescens is common in clinical settings and most important human pathogen. It is also one of the easiest to identify in the Enterobacteriaceae family. Although it is a community-acquired infection, there is frequent outbreaks in the hospitals. It is ranked 5th of Gram-negative infections found in Intensive Care Units. S. marcescens is involved in infections including pneumonia, lower respiratory tract infections, urinary tract infections, bloodstream infections, wound related infections, ocular infections and meningitis. It also can rarely be a cause of endocarditis. There have been traces of S. marcescens on medical equipment such as nebulizers, electrocardiogram leads, bronchoscopes, laryngoscopes. It is also found contaminated in solutions such as saline solutions, prefilled syringes, antiseptics and parenteral nutrition. It can also be found in the environment for instance, air conditioning units, liquid soap dispensers and tap
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.
This experiment was centered on metabolic and biochemical testing procedures. The rationale of performing these tests was to distinguish six different microbes from one another and to compare how their metabolic and biochemical processes differ from species to species to determine the unknown sample.
The Gram stain was used to determine if the bacteria was gram positive or negative. A negative test shows a pink color and a positive test is a purple color. When a bacterium is negative it is because it has an outer membrane and a thin layer of peptidoglycan that is much harder to stain. A positive bacterium has a thick layer of peptidoglycan and no outer membrane that can be penetrated by crystal violet.
My unknown organism #6 is Morganella morganii, which is a gram-negative bacillus rods commonly found in the environment and also in the intestinal tracts of humans, mammals, and reptiles as a normal flora. (3, 5) This bacterium Morganella morganii, was first discovered in the 1906 by a British bacteriologist named H. de R. Morgan. (2) Despite its wide distribution, it is an uncommon cause of community-acquired infection and is most often encountered inpostoperative and other nosocomial settings. (2, 3) Morganella morganii infections respond well to appropriate antibiotic therapy; however, its
There are many reasons for knowing the identity of microorganisms. The reasons range from knowing the causative agent of a disease in a patient, so as to know how it can be treated, to knowing the correct microorganism to be used for making certain foods or antibiotics. This study was done by applying all of the methods that I have been learned so far in the microbiology laboratory class for the identification of an unknown bacterium.
Table 3 shows Gram stain results that indicated C. Freundii as a gram negative bacterium in rod shapes scattered in singles and some in pairs. Each gram stain produced the same results. The Bartholomew and Mittwer method of endospore staining indicated that C. Freundii tested negative for endospore formation. Table 4 shows the biochemical test results of the unknown and the official test results for comparison.
There are many reasons for knowing the identity of microorganisms. The reasons range from knowing the causative agent of a disease in a patient, so as to know how it can be treated, to knowing the correct microorganism to be used for making certain foods or antibiotics. This study was done by applying all of the methods that have been learned so far in the microbiology laboratory class for the identification of unknown bacteria. The identification process can be completed with a series of deferential stains and biochemical tests. Creating a dichotomous key helps to limit the amount of biochemical tests done on an unknown organism and by observation
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
This experiment was given to us to utilized previous knowledge learned throughout the semester to identify a gram negative unknown bacterium. We had to first learn the difference between a gram negative and a gram positive organism. We started off with doing gram stains to determine whether it was positive or negative. Based on the gram stains, a gram positive stains purple and a gram negative stains pink. A gram positive stains purple because the cell walls is made of a thick peptidoglycan layer and doesn’t
Microorganisms are both beneficial and harmful. These microorganisms are important to humans because they play a role in the ecology of life, by decomposing wastes, both natural and man-made, such as creating nitrogen fertilizer at the root zones of certain crops. Other several pathogens that can cause serious harm, even immediate death due to the diseases or disease causing products they produce. Overall, microorganisms play an important role in life.
The purpose of this lab was to identify an unknown microorganism using lab techniques. The importance of identifying microorganisms is essential to the survival of humans, expansion of modern day medicine and improvement of quality of life. In 1884, Hans Christian Gram designed a differential staining technique to identify bacteria that would change the future of microbiology. He give rise to a staining process, known as the Gram stain to differentiate microorganisms into two groups between positive and negative gram staining microorganisms. The Gram stain is essential in a lab technique as it distinguishes the cells based on the physical properties of the individual cell walls, and is almost always the first test preformed to differentiate a microorganism. The identification of weather a microorganism is gram positive or negative can revel the bacteria’s virulence, cell wall structure, resistance to antibiotics, resistance to physical disruptions and so much more. In order to identify the unknown provided, unknown #27, the Gram stain was the first test preformed. After discovering that the unknown bacterium was indefinitely a gram positive microorganism, the vast possibilities were narrowed down. However, In order to more definitively identify the unknown, the next step was to preform biochemical tests. A biochemical test identifies metabolic
Oxidase Test: Using a sterilized loop inoculate a loopful of bacteria into the test square and
An unknown microorganism from three potential microbes—Bacillus megaterium, Escherichia coli, and Enterococcus faecalis—was determined by performing eight biochemical tests. Biochemical tests that were used to differentiate these possible microorganisms from each other were gram staining, motility with a semi-solid agar tube, oxygen requirements, catalase test, phenylalanine deaminase test, eosin methylene blue agar (EMB) and mannitol salt agar (MSA). The unknown microorganism was further clarified through a polymerase chain reaction (PCR) test and basic local alignment search tool (BLAST) database. Based on all the observations of the tests, the unknown bacterium was identified as B. megaterium.
The results my microbe produced were negative. The test is used to identify organisms that produce the enzyme crytochrome oxidase. A color change indicates cytochrome is present. There was no color change in my test. If my test had been positive the color would have changed to blue or purple.
Hypothesis: If the bacteria turns out pink/red then the gram test is negative. Null Hypothesis: If the bacteria turns out pink/red then the gram test is not negative. Purpose: Identify the three morphological types of bacteria and use the Gram’s test to examine the bacteria infection by the stain technique. Differ between plant and animal cells and the different cellular components of eukaryotic cell.