staphylococcus aureus

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

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

After several biochemical tests, Unknown Bacteria #30 was identified as Staphylococcus aureus. After growing the bacteria on Nutrient Agar to ensure a pure sample, it was Gram stained to determine morphology and arrangement. It was observed to be a Gram positive staphylococci. Then, the bacteria was inoculated onto a Mannitol Salt Agar plate. After incubation, it was observed to have bacterial growth and the agar was yellow in color. According to the lab manual (2), MSA contains 7.5% NaCl and phenol red, a pH indicator. Due to the salt content, MSA is selective for salt-tolerant bacteria and the phenol red allows MSA to differentiate for mannitol fermentation. Mannitol fermentation is indicated by a yellow color change, which is the result of acidic byproducts changing the pH of the agar. The results showed that the bacteria was both salt-tolerant and able to ferment mannitol.

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.

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 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

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.

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 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

This laboratory experiment’s objective was to take a pure culture and isolate it from a mixed culture. The other part of the objective was to ascertain what species of bacteria that the pure culture was. The hypothesis made stated that so long as lab protocol was followed, the unidentified culture would be positively recognized/identified. An isolated pure colony of the unknown culture was obtained using the quadrant streak plate method. Afterward, the culture was Gram stained, and the results showed that it was Gram positive. Motility tests were done on the unknown using a filter paper bridge on a petri dish that contained TTC with agar. The unknown was revealed to not be motile, which meant that it did not possess flagella. The last test done was to learn the metabolic capabilities of the unknown bacteria. There were tests done for citrate utilization, the mixed fermentation pathway, catalase presence, carbohydrate fermentation in mannitol, lactose and glucose, urease production and the butanediol fermentation pathway in order to better identify the unknown bacteria. The results from each of the metabolic tests in conjunction with the motility and Gram staining tests were ultimately compared to results from database containing many different kinds of results from various bacteria. The unknown from the mixed culture was identified as Staphylococcus

Depending on what a bacteria can and cannot do, will help to correctly identify it. It is always important to start out with a purity check. To achieve that, you can inoculate an agar plate and incubate for 48 hours. Make sure you only see one type of colonies on the plate. Knowing the optimal temperature for the bacteria will also let a scientist know where to place the different types of medias he/she inoculates with the unknown bacteria. Knowing if you are working with a gram positive or gram negative bacterium, a scientist will need to perform a gram stain. This will also help to see the shape and arrangement of the bacteria. The size can be determined by doing a simple stain. The size of most bacteria ranges from .5- 10um. This specific bacteria that I was working with, was smaller than 2um. Most bacteria can grow with the presence of oxygen. A simple test like the gas pack can be performed to figure out if growth is possible without oxygen is doable. My unknown bacteria needs oxygen to grow. Throughout my study, the unknown bacteria was tested to see if it can grow in acidic conditions, however no growth occurred. Before inoculation, the substrate was a clear yellow color and in liquid state. After receiving the negative result, I kept the broth in the 37C incubator for 7 more days to confirm the negative result. Using premade slants with different types of sugars such as Mannitol, Sorbitol, Lactose, Trehalose, Maltose and Sucrose, to determine if the bacteria can metabolize glucose and if the bacteria is oxidative or fermentative. It was determined that my bacteria is strictly oxidative (needs oxygen to grow) and cannot metabolize glucose. Another test was done to confirm if the bacteria was able to utilize different carbohydrates in the presence of oxygen. I used Cellobiose, Arabinose, Adonitol, Fructose and Malonate wee tabs. Out of the 5 different types of carbohydrates, only 3 different

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.

These isolated bacteria were identified using both morphological culture characteristics (i.e. the color, shape, elevation, capacity, consistency, edge) and biochemical test (i.e. citrate, oxidase, indole, sugar fermentation, test etc.)and the bacteria were identified based on the results obtained from the above mentioned biochemical characterization results and the procedures include.

Three agar plates were examined to see what type of microorganism was growing on each one. The agar plates were MAC (MacConkey), MSA and CLED. MAC plates are designed to selectively grow gram negative bacteria and prevent gram positive bacteria from growing. They are also used to differentiate between lactose and non-lactose gram negative rods.[4[ In the laboratory there were signs of red colonies/growth which indicates a gram negative microorganism present within the agar plate

Another purpose of this experiment is to stress the importance of knowing the identity of a microorganism. Knowing the species of microorganism present in a sample provides a