Bacteri Escherichia Coli, Enterobacter Aerogenes Essay

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

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.

This experiment was conducted to find the genus and species of an unknown bacteria prescribed by the lab teacher, which was unknown bacteria GA3 in my case. Identification of unknown bacteria techniques are used on an every day basis to figure out what type of bacteria it is and to find the best method of how to treat a patient with this bacteria (1). All five “I’s” of Microbiology were used in the testing for the unknown culture. Inoculation was used several times to put the unknown culture into agar plates or into biochemical test tubes. After Inoculation of these tubes or plates, they always were placed into the incubator for further growth and development. Isolation was used to make sure we got the correct bacteria we were testing for. After each further isolation, we gram stained the culture and inspected the culture under a microscope to further help in the identification process of the unknown bacteria. Multiple tests were done on the unknown culture to make sure we were confident in what kind of bacteria the unknown was.

Escherichia coli cells would be pink following a gram stain. E. coli is a gram negative cell due to its thin peptidoglycan layer and its outer membrane structure. In the gram staining process, the outer membrane does not play a role in staining but the peptidoglycan

The objective of the investigation was to perform multiple experiments that would lead to the identification of an unknown bacteria. This bacteria was causing a urinary tract infection on a patient. A sample of the bacteria causing the infection was received and analyzed. The first step was to isolate the bacteria to insure that sample was free of contamination. A MAC plate, a PEA plate, along with a Nutrient agar plate where used to produce pure colonies by using the quadrant streak method on each plate. After a 24 hour incubation period the colonies where isolated. The bacteria collected was inoculated into slants, nutrient broth for cultivation. A sample from the MAC plate and the PEA plate were collected and gram

I inoculated a T-Soy agar with bacteria number 118, for this I used a streak isolation method. Next, in order to distinguish between Gram positive and Gram negative I used a streak isolation technique on a CNA plate, then performed the same exact procedure on a MacConkey plate. The results from the CNA plate showed the Gram Positive bacteria was an Alpha hemolyzer. Next, I used a P Disc on a T-Soy agar inoculated with bacteria 118 and determined the Gram Positive bacteria was not sensitive to P Disc antibiotics. This revealed the Gram Positive bacteria to be Streptococcus Mitis. The results from the MacConkey plate proved the Gram Negative bacteria to be a lactose fermenter. With the Gram Negative bacteria I performed a lysine test with positive results. Next, I performed an ornithine test on the Gram Negative bacteria, with negative results, therefore I concluded the Gram Negative bacteria was Klebsiella pneumoniae.

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.

As the flowchart shows, a series of tests were conducted to identify the unknown bacterium #65. Microscopic observation of the gram stain indicated a gram-positive coccus bacterium. S. epidermidis was used as the gram-positive control while E. coli was used as the gram-negative control. This observation led to the elimination of all gram negative and rod-shaped genera: Enterobacter, Citrobacter, Klebsiella, Escherichia, Pseudomonas, Serratia, Alcaligenes, Neisseria, Proteus, Salmonella, Shigella, Erwinia, Veillonella, Flavobacterium, Bacillus, Arthrobacter, Lactobacillus, Listeria and Kurthia (2). By performing the catalase test, it was determined that the bacterium was catalase negative and it did not produce bubbles. M. luteus and E. faecalis were used as positive and negative controls, respectively.

The importance of identification of a certain microorganisms can range between a life threatening diseases to a creation of certain antibiotic. Understanding the principals of living microbes and identifying my unknown bacteria through numerous biochemical and metabolism tests, with the outmost confidence, Proteus vulgaris had the precise qualifications. The point of this report is to further explore the identification of my unknown bacteria by revealing the results of the experiments and comparing them to the other six known bacteria: Micrococcus luteus, Staphylococcus aureus, Staphylococcus epidermidis, Alcaligenes faecalis, Escherichia coli, and Proteus vulgaris that were used in the lab, as well as comparing and

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

In the world of microbiology it is vitally important to be able to discern the identities of microorganisms. Not only is it important in a lab setting but as well as in healthcare in general. Properly identify what strain of bacteria a person has will aid in the proper medicine and dose given. Throughout the semester we have learned about different types of bacteria and certain test that can clearly identify them. The purpose of this lab report is to identify a Gram-positive or Gram-negative bacterium. Using all the knowledge of procedures and lab techniques identify the unknown and discuss all the tests you performed.

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.

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.

Enterobacter aerogenes is a species of rod shaped gram negative bacterium in the family of enterobacteriaceae. It is a facultative anaerobe, meaning that it can grow in either the presence of oxygen or in the absence of oxygen. It also uses fermentation as the means of gathering energy that protect it from reative oxygen species, and allowing it to live in oxygenated environments. Enterobacter aerogenes is a nosocomial and pathogenic bacterium that cause opportunistic infections. The majority are sensitive to most antibiotics designed for this bacteria class, but it can be complicated due to their resistance mechanism such as lactamas, which quickly become resistant to standard antibiotics during the treatment. Enterobacter aerogenes is found in human gastrointestinal tract, and it does not generally cause disease in healthy individuals. It has been found to live in

In all areas of biology, it is easy to see that structure is related to function. This statement holds true in microbiology as well, the study of microorganisms, including bacteria. One characterizing feature of bacteria is the cell wall, which can generally (although not in all situations) be categorized into one of two categories: either Gram positive or Gram negative. Gram positive bacteria’s cell walls are composed of a large peptidoglycan layer (up to 90% of their cell wall). Within this large peptidoglycan layer, one can find techoic acids, which contribute to the maintenance of cell wall structure, and lipotechoic acids, which attach to membrane lipids. Gram positive bacteria that act as pathogens can also potentially release exotoxins, which can have very dangerous effects on humans. Gram negative bacteria, on the other hand, have a very small layer of peptidoglycan in their cell wall, which is surrounded by an outer membrane. Within the outer membrane, one can find the lipopolysaccharide layer, which is one of the most distinguishing factors of Gram-negative bacteria. It is important to note that Gram negative bacteria fail to possess techoic