Gram-Negative Unknown Lab Report

An unknown bacterium was handed out by Dr. Honer. The appropriate tests were prepared and applied. The first procedure that was done was the gram stain. Under a microscope, if the gram stain is purple, the bacterium is gram positive, if the stain is red, it is gram negative. The next test was the fermentation tests for glucose, sucrose and

The purpose of this lab was to identify an unknown bacteria culture using differential tests. The identification of the unknown culture was accomplished by identifying the bacteria based on its specific metabolic characteristics and morphology. It is suggested that culture 11 is a sample of Enterobacter aerogenes.

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 purpose of this lab was to identify two unknown bacteria cultures using various differential tests. The identification of these unknown cultures was accomplished by separating and differentiating possible

For the Urease test, I incoluated my Urea test tube with my unkown bacteria from a TSA plate using and inoculating loop. The Urea tube was then incubated at 37 degrees Celsius for 8 days to observe for a color change. The Urea tests for the ability of a bacteria grown in urea broth produces urease. This medium contains the pH indicator phenol red. If urease is produced the pH of the media will raise thus causing the phenol red to change from yellow to a pink color.

This lab experiment was done for the purpose of learning how to determine a gram negative bacterium based on multiple tests learned throughout the semester. My gram negative unknown bacterium given to me was Salmonella typhimurium based off of the following tests; Triple Sugar Iron Agar (TSIA), Sulfate Indole Motility (SIM), Methyl Red (MR), Voges-Proskaur (VP), Citrate, Urea Hydrolysis, and Gelatin Hydrolysis. Each test performed gives results such as motility, acid production, fermentation, carbon requirements, or detection of certain coenzymes. With a process of elimination, I determined which bacteria it was not and which bacterium I had, S. typhimurium. The expectation was to master the techniques for each test and utilize the results to determine the unknown bacterium I was given within a two-week period.

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

The bases of this experiment was to discover the identify of the unknown from three possible specimens: Klebsiella pneumonia, Escherichia coli, and Enterobacter aerogenes. Utilizaing the T streak technique, the bacteria was isolated into pure colonies for further study. The Gram Stain method was used to identity the morhphology of the bacteria such as the shape and whether the bacteria was Gram positive or Gram negative. Biochemical test were also used to help identify the unknown bacteria. The biochemical test used was the Triple Sugar Iron Agar, Sulfur Indole Motility test, Methyl Red test, Voges-Proskauer test, Citrate test, Urease test, and the Gelatin test. After observing the morphology of the bacteria using the Gram Stain method and utilizing all the possible biochemical test, the bacteria was identified to be Enterobacter aerogenes.

Klebsiella pneumoniae is a gram-negative bacilli bacterium 0.3-1.0um in diameter and 0.6-6.0 um in length. Cells are capsulated and arranged in pairs or in short chains. K. pneumoniae can cause different types of healthcare associated infections that include pneumonia, blood, and wound infections along with meningitis. K. pneumoniae is normally found in the intestines of human stool. Infections are most common with people who require ventilators, intravenous catheters or patients taking long courses of antibiotics. The primary portal of entry is through the respiratory tract to cause pneumonia or through the blood to cause bacteremia. People with healthy immune systems usually do not get k. pneumoniae infections but should

It is important for one to understand how microorganisms function as well as their identity. Identifying unknown microorganisms are beneficial to both scientist and patients. Reason being is due to bacterium capable of becoming resistant to antibiotics over a period of time. In order for doctors to treat patients to the best of their ability it is vital that they are able to identify the bacteria first in order to provide proper treatment. In order to identify the two unknown bacterium proper procedures were done. This study was done by applying all of the necessary methods that have been learned thus far in the microbiology laboratory.

Introduction: Background: This lab report will discuss the identification of an unknown microbial organism by utilizing Bergey’s Manual , the scientific method as well as the necessary laboratory experiments prescribed by the dichotomous key for the specific bacteria type that is determined. Purpose: To utilize Bergey’s Manual along with other prescribed processes in order to satisfactorily grow, collect data on and successfully identify an unknown given culture. Materials and Methods: 1.

After conducting the necessary experiments, it was found that the two bacteria in the mixed culture of TSB test tube labeled 10, were Proteus mirabilis and Staphylococcus saprophyticus. Proteus mirabilis being the rod shaped, gram-negative bacteria that grew were the small, shiny, and round with a convex elevation, and Staphylococcus saprophyticus being the cocci shaped, gram-positive bacteria that grew a creamy, off white color and round. Proteus mirabilis comes from the Enterobacteriaceae family, which consist of gram-negative bacteria some being harmless, while the majority ae considered as pathogens. “Within this family are genera such as, Shigella, Salmonella, Klebsiella, Serratia, and Enterobacter (Guentzel, 1996).” Staphylococcus saprophyticus

According to (Case, 1946) urea is a waste product of protein digestion in vertebrates and is excreted in the urine. The presence of urea liberates ammonia from urea which is helpful in identifying bacteria. The pH of a medium urea is about 6.8 or below, if tested positive, the pH will have an increase to about 8.4 or above causing the solution to go from a yellow color to a hot pink color, this is mainly due to the ammonia produced. This experiment is done by following the lab of “Preparation of Smears.” Unknown 3, showed a change from a yellowish solution to a hot pink color, helping to concluded that it tested positive to having a pH of 8.4 or above and able to liberate

Once the results were obtained by the different biochemical tests, the genus and species of the organism was identified as Salmonella typhimurium. These tests were chosen because these tests are frequently used to determine Gram-negative bacteria. During the Citrate test, S. typhimurium produced a positive result, which indicated sodium carbonate was present (Pearson’s 2011). A positive result was obtained during the Methyl Red test, which indicated that the organism was capable of fermenting glucose and contained a higher hydrogen ion concentration (Pearson’s 2011). S. typhimurium produced negative results during the Indole test, which showed that tryptophan was unable to be hydrolyzed (Pearson’s 2011). The Lactose and Sucrose Ferment tests both produced negative results and no production of gas, indicating that there was no change in the pH and fermentation did not occur (Pearson’s 2011). Positive results and a gas bubble was present in the Glucose Ferment test, which concluded that S. typhimurium caused an acidic change in the pH and fermentation occurred (Pearson’s 2011). S. typhimurium produced positive results for the Nitrate Reduction test, indicating that nitrates were not reduced to nitrates by the bacterium (Pearson’s 2011). Negative results were obtained through the Urea test, which showed that S. typhimurium was unable to produce urease (Pearson’s 2011). The

The Peptidoglycan impacts the cell wall of the bacterium; a Gram-positive bacteria’s cell wall is usually thicker than a Gram-negative bacteria due to the Peptidoglycan concentration, but Gram-stain-negative bacteria tend to have a two-layered cell wall and Gram-positive bacteria only have a single cell wall layer. Unfortunately, Gram stains are not always completely effective; in some bacteria, the Gram-stain is completely ineffective or displays that half the cells are positive and half the cells are negative. In such a case, a Gram-stain is not enough to determine the characteristics of that