The Effect Of Tests On M.

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

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 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.

PH can affect the way fermentation occurs due to the irregularity of the acidity or alkalinity within the glucose solution. This is an enzyme-based reaction that is susceptible to pH. The aim of this experiment was to determine how pH affects the yeast fermentation rate by performing the experiment numerous times with a different pH of glucose solution which included pH 3, 5, 7, 9, 11. The hypothesis was ‘If the pH is lower than the neutral point then the fermentation reaction will occur faster?’ The experiment conducted was to measure the amount of C02 produced by the yeast going into fermentation, however varying the pH of glucose solution by using different pHs . To test this every 5 minutes the volume of gas in the test tube was observed and recorded until a period of 30 minutes had been. The end results

The unknown bacteria plate chosen was plate #2. It was identified to be Micrococcus luteus. It is a gram positive, Coccus bacteria that is commonly found in dust, water, soil, and the air. M. luteus also thrives in the human mouth and upper respiratory tract. Sir Alexander Fleming discovered it in 1928 before he identified penicillin. It is part of the normal flora on human skin as well as other mammals. Since it is part of normal flora it is normally not pathogenic, but can become opportunistic in an immune-deficient person. It has been known to cause septic shock, UTI’s, and even pneumonia. Micrococcus luteus is both urease and catalase positive. It does not utilize tryptophan for indole production. It is a facultative anaerobe. Mobility is not present for this bacterium. Starch is also not hydrolyzed and oxidase is not present.

I identified Citrobacter freundii, the gram negative rod, by running a series of tests. I began with the Phenol Red Lactose tests, which tests if the organism contains various enzymes that determine if it can ferment lactose. The broth turned yellow after it was incubated, indicating that the lactose was fermented to acid, and there was also gas present in the Durham tube. Since the Phenol Red Lactose Test was positive, I then ran the Phenol Red Sucrose test, which tests if the bacteria contain different enzymes that determine if sucrose can be fermented. After incubation, the broth was yellow, indicating that sugar was fermented to acid, and there was also gas present in the Durham tube. Next, I ran the Sulfide Production, Indole Formation, Motility test, but I was only testing for Hydrogen Sulfide Production to differentiate between the organisms Citrobacter freundii and Enterobacter aerogenes. This test detects if the organisms can metabolize sulfur into hydrogen sulfide, which is revealed by the formation of ferrous sulfide that causes blackening around the growth. The test also reveals if the organism can break tryptophan into indole or migrate away from initial stab area. After incubation, the agar slant was completely black, indicating that the organism produces hydrogen sulfide and is motile proving that it was Citrobacter

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

Often scientists work with bacteria that do not come in a labeled test tube— for example, bacterial samples taken from infected human tissue or from the soil—and the scientist must then identify the unknown microorganism in order to understand what behavior to expect from the organism, for example, a certain type of infection or antibiotic resistance. However, because of the relatively few forms of bacteria compared to animals and because of the lack of bacterial fossil records due to their asexually reproductive nature, the taxonomy used to classify animals cannot be applied to bacteria (Brown 275). In order to classify unknown bacteria, a variety of physiological and metabolic tests are available to narrow a sample down from the fathomless number of possibilities into a more manageable range. Once these tests have been performed, the researcher can consult Bergey’s Manual of Determinative Bacteriology, a systematically arranged and continually updated collection of all known bacteria based on their structure, metabolism, and other attributes.

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

Micrococcus luteus was first isolated and discovered in 1929 by Alexander Fleming. Is a gram positive bacteria that is commonly found on human skin, water, soil and dust. Since it is an obligate aerobe and thrives in the presence of oxygen, it is also found in the human respiratory tract. It takes the shape of cocci and is often clumped irregularly, in tetrads, or groups of four. It is also non-motile and does not form endospores. Although it has a specific optimal temperature range of about 37 to 45 degrees Celsius, it is halophilic. Micrococcus luteus is also catalase positive, meaning that it produces an enzyme that protects it from any harmful oxygen metabolism by-products (Bergey, 1923).

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

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

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.

These positive test results helped to form a identification code (50743) for the unknown microflora. The microflora that was identified was Klebsiella pneumoniae. Klebsiella pneumoniae is a gram-negative mucoid lactose fermenting bacterium. Klebsiella pneumoniae is commonly found on the skin, mouth, and intestines. Also, another test that was performed was the Oxidase test.