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Step to identify bacteria from mixed culture
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Introduction: Bacteria play a large role in our health, the environment, and most aspects of life. They can be used in beneficial ways, such as decomposing wastes, enhancing fertilizer for crops, and breaking down of substances that our bodies cannot. However, many bacteria can also be very harmful by causing disease. Understanding how to identify bacteria has numerous applications and is incredibly important for anyone planning to enter the medical field or begin a career in research. Having the background knowledge of identifying an unknown bacteria may one day aid healthcare professionals diagnose their patient with a particular bacterial infection or help researchers determine various clinical, agricultural, and numerous other uses for bacteria.
The purpose of this project was to identify unknown bacteria species from a mixed culture. The two unknown species were initially plated onto Tryptic Soy Agar (TSA), Eosin Methylene Blue (EMB), Mannitol Salt Agar (MSA), and blood agar plates to distinguish between the two different bacteria using colony size, color, shape, and growth characteristics. By identifying and inoculating the differing types of colonies, the two unknown bacteria were purified and able to be tested
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mutans was problematic due to its difference with Bergey’s Manual result for the catalase test. However, after comparing it with a peers results, it seems very possible that the strain we are working with varies from the strain used in Bergey’s. Bacteria possess the ability to develop varying phenotypes within the same species due to frequent mutation and horizontal gene transfer. Therefore, it is possible that the results obtained in our lab may vary from those provided in Bergey’s Manual. Arriving to the conclusion that the Gram negative bacteria was Klebsiella pneumoniae was much more direct. Using Bergey’s Flowchart for identification, the bacteria shared the test results and had a similar shape and
The first day an unknown sample was assigned to each group of students. The first test applied was a gram stain to test for gram positive or gram-negative bacteria. The morphology of the two types of bacteria was viewed under the microscope and recorded. Then the sample was put on agar plates using the quadrant streak method for isolation. There were three agar plates; one was incubated at room temperature, the second at 30 degrees Celsius, and the third at 37 degrees Celsius. By placing each plate at a different temperature optimal growth temperature can be predicted for both species of bacteria.
In this lab project, the microbiology students were given 2 unknown bacteria in a mixed broth each broth being numbered. The goal of this project is to determine the species of bacteria in the broth. They had to separate and isolate the bacteria from the mixed broth and ran numerous tests to identify the unknown bacteria. The significance of identifying an unknown bacteria is in a clinical setting. Determining the exact bacteria in order to prescribe the right treatment for the patient. This project is significant for a microbiology students because it gives necessary skills to them for future careers relating to clinical and research work.
The purpose of this study is to identify an unknown bacterium from a mixed culture, by conducting different biochemical tests. Bacteria are an integral part of our ecosystem. They can be found anywhere and identifying them becomes crucial to understanding their characteristics and their effects on other living things, especially humans. Biochemical testing helps us identify the microorganism present with great accuracy. The tests used in this experiment are rudimentary but are fundamental starting points for tests used in medical labs and helps students attain a better understanding of how tests are conducted in a real lab setting. The first step in this process is to use gram-staining technique to narrow down the unknown bacteria into one of the two big domains; gram-negative and gram-positive. Once the gram type is identified, biochemical tests are conducted to narrow down the specific bacterial species. These biochemical tests are process of elimination that relies on the bacteria’s ability to breakdown certain kinds of food sources, their respiratory abilities and other biochemical conditions found in nature.
The purpose of this laboratory is to learn about cultural, morphological, and biochemical characteristics that are used in identifying bacterial isolates. Besides identifying the unknown culture, students also gain an understanding of the process of identification and the techniques and theory behind the process. Experiments such as gram stain, negative stain, endospore and other important tests in identifying unknown bacteria are performed. Various chemical tests were done and the results were carefully determined to identify the unknown bacteria. First session of lab started of by the selection of an unknown bacterium then inoculations of 2 tryptic soy gar (TSA) slants, 1 nutrient broth (TSB), 1 nutrient gelatin deep, 1 motility
E. coli are bacteria that can cause an infection in various parts of your body, including your intestines. E. coli bacteria normally live in the intestines of people and animals. Most types of E. coli do not cause infections, but some produce a poison (toxin) that can cause diarrhea. Depending on the toxin, this can cause mild or severe diarrhea.
This pathogen, Streptococcus pneumoniae, is a gram-positive coccus that is long shaped and usually seen in groups of pairs (Todar, 2008-2012). This pathogen ranges from o.5-1.25 micrometers, which is pretty small in size (Todar, 2008-2012). It “lacks catalase and ferments glucose into lactic acid” (Todar, 2008-2012). To grow this bacterium in the lab the best way to do it would be to grow it on a blood agar at 37 degrees Celsius and produces a green zone arou...
In this experiment, a series of biochemical test and API 20 E test are carried out to identify the unknown bacterial species provided.
The process of identifying this microbe began by performing a Gram’s stain (see image #1, page 7). Pseudomonas fluorescens is a gram negative bacillus shaped bacterium. Following the establishment of the microorganism’s Gram stain
Klebsiella pneumonia is a gram-negative, encapsulated, lactose-fermenting, non-motile, facultative anaerobic, urease positive, indole-negative, rod-shaped bacterium that is in the Enterobacteriaceae family (Tufts University, n.d.). Klebsiella is typically found in the nose or mouth, gastrointestinal tract (CDC, 2012). Klebsiella pneumonia was first discovered in 1882 as a pathogen that caused pneumonia (). Klebsiella can cause various types of health-related infections in the bloodstream, wound, and also surgical site infections (CDC, 2012). A common place to become infected with Klebsiella is the hospital settings, while being treated for other illnesses. Patients who get infected this way typically are on a ventilator or intravenous catheters (CDC, 2012). Klebsiella was named after Edwin Klebs, who was a German microbiologist (Obiamiwe, 2013).
Murray, Patrick R., Ken S. Rosenthal and Michael A. Pfaller. Medical Microbiology, 6th Edition. Philadelphia: Mosby Elsevier, 2009.
Biochemical tests are used to identify microbes in the laboratory to aid in pinpointing the different groups of bacteria. The bacteria vary in the cellular morphology and staining properties as well as structural and metabolic properties. Using biochemical testing, it permits a keener study at related organisms. In addition, the use of numerous color changes that occur with the test, allow to for a rapid identification of comparisons and variances of the bacteria that are tested.
In the last decade, the number of prescriptions for antibiotics has increases. Even though, antibiotics are helpful, an excess amount of antibiotics can be dangerous. Quite often antibiotics are wrongly prescribed to cure viruses when they are meant to target bacteria. Antibiotics are a type of medicine that is prone to kill microorganisms, or bacteria. By examining the PBS documentary Hunting the Nightmare Bacteria and the article “U.S. government taps GlaxoSmithKline for New Antibiotics” by Ben Hirschler as well as a few other articles can help depict the problem that is of doctors prescribing antibiotics wrongly or excessively, which can led to becoming harmful to the body.
This lab experiment was conducted in order to identify and confirm the presence of three types of organism within an unknown broth culture. The organism that were being tested fall under the categories of gram-positive, gram-negative paracolons, and gram-negative coliform. Gram positive organism are known to have thick cell wall made up of peptidoglycan, which are cross-link sugar chains with peptide bonds (Carson 13). Gram-positive bacteria are found within the phylum Firmicuites (Slonczewski & Foster 94). While gram-negative, have thin layers of one or two peptidoglycan cell wall, this type of bacteria are found within the phylum Proteobacteria (Slonczewaki & Foster). The gram positive and negative characteristic derived from a staining technique that was developed by Hans
Microbiology is the study of microscopic organisms and has numerous applications in medicine, virulogy, immunology and more since the implementation of it in the lat 16th century. There are many microorganisms in the world habituating all kinds of conditions and locations, and the primary goal of microbiology to not only to identify but also characterize these populations. In the past this has been carried out by direct clonal culturing given the ease with which discoveries could be made about cultured organisms. This subsequently established a precedence for culture dependent isolations in the lab (1). However, as more evidence arose suggesting that this method only captures a small breadth of the microbial community, a new methodology has started to gain momentum. Instead of solely focusing on identifying lab-cultured microorganisms individually through phenotypic analysis of biochemical and physiological test results, samples from environments are being evaluated en masse and then identified successfully using 16S RNA sequence and phylogentic analysis (2). This new method of analysis presents to the world of microbiology not only vast room for expansion, but room for even greater medical and scientific advancements as well.
Bacterial cells, like plant cells, are surrounded by a cell wall. However, bacterial cell walls are made up of polysaccharide chains linked to amino acids, while plant cell walls are made up of cellulose, which contains no amino acids. Many bacteria secrete a slimy capsule around the outside of the cell wall. The capsule provides additional protection for the cell. Many of the bacteria that cause diseases in animals are surrounded by a capsule. The capsule prevents the white blood cells and antibodies from destroying the invading bacterium. Inside the capsule and the cell wall is the cell membrane. In aerobic bacteria, the reactions of cellular respiration take place on fingerlike infoldings of the cell membrane. Ribosomes are scattered throughout the cytoplasm, and the DNA is generally found in the center of the cell. Many bacilli and spirilla have flagella, which are used for locomotion in water. A few types of bacteria that lack flagella move by gliding on a surface. However, the mechanism of this gliding motion is unknown. Most bacteria are aerobic, they require free oxygen to carry on cellular respiration. Some bacteria, called facultatibe anaerobes can live in either the presence or absence of free oxygen. They obtain energy either by aerobic respiration when oxygen is present or by fermentation when oxygen is absent. Still other bacteria cannot live in the presence of oxygen. These are called obligate anaerobes. Such bacteria obtain energy only fermentation. Through fermentation, different groups of bacteria produce a wide variety of organic compounds. Besides ethyl alcohol and lactic acid, bacterial fermentation can produce acetic acid, acetone, butyl alcohol, glycol, butyric acid, propionic acid, and methane, the main component of natural gas. Most bacteria are heterotrophic bacteria are either saprophytes or parasites. Saprophytes feed on the remains of dead plants and animals, and ordinarily do not cause disease. They release digestive enzymes onto the organic matter. The enzymes breakdown the large food molecules into smaller molecules, which are absorbed by the bacterial cells. Parasites live on or in living organisms, and may cause disease. A few types of bacteria are Autotrophic, they can synthesize the organic nutrients they require from inorganic substances. Autotrophic bacteria are either photosynthetic or Chemosynthetic. The photosynthetic bacteria contain chlorophyll that are different from the plant chlorophyll. In bacterial photosynthesis, hydrogen is obtained by the splitting of compounds other than water.