...A. faecalis, P. fragi, and E. coli are all Gram negative bacteria.2 The Gram negative bacteria that was in plate B, had a cell shape of coccobacillus and a single cell arrangement. A. faecalis and P. fragi both are coccobacillus and singled celled while E. coli is bacillus and single celled.2 Because all three species are so close to cell shape and arrangement none of the options were yet eliminated. To narrow down the options with biochemical tests, the MOI test was done first. The results came back as positive, negative, negative. This eliminated E. coli as an option because E. coli’s MOI results are positive, negative/positive, and positive. During the 48 hours of incubation time for the MOI test, an oxidase test was also performed. However, the oxidase test came back as negative. Which, does not match up with the MOI...
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...scientists developed tests to show unique characteristics of microbes. This experiment enlists these tests, such as PCR, Simple and Gram staining, anaerobic growth tests, IMViC, Catalase, Oxidase, selective and differential media to identify an unknown microorganism. The Unknown organism studied was labeled “J” and found to be a gram negative, rod shaped bacteria that does not produce endospores. The selective and differential agars produced no growth on the MSA agar plate showing that the bacteria did not favor a salty environment of the Mannitol salts and showed an acidic by product in the selective and differential media of MacConkey’s Agar. The bacteria showed to metabolize sugars but did not produce any gaseous byproducts. After 16s rRNA was processed and run through a PCR, electricphoresis was used to run the RNA out on a gel in order to sequence the RNA which was then compared in a database. Furthermore, the Unknown J did not produce or metabolize starch. The bacteria did not react with the Citrate, KEY oxidase. When compared to other known bacteria tested, unknown J proved to be Escherichia coli. Introduction: Identifying bacterial causes for certain diseases that have affected the population or identifying growth on old bread is not new to science. Joseph Lister developed one of the first ways to separate the desired unknown bacteria from other bacterial colonies in 1867. Lister’s aseptic technique, used in both science and healthcare, destroys the microbes that are...
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...IgM -gram negative rods,Very small cannot be seen under microscope -Slow grow better isolate with CO2 and increase humidity. -Sampled from blood (5 to 7 days b4 giving a negative report) -cultured on chocolate agar(enrichment media). - Wright test (like widal “ anamnastic reaction” ) Transmitted via contaminated food Milk products not from human to human : can be killed at high temperature: - tantalization : 50º - Pasteurization: 70 º - Sterilization : 100 º Treatment: - Tetracyclin - Doxycyclin - Rifampin - For 6 weeks and more - Vaccine is available for animals. Vibrio V. cholerae, V. parahaemolyticus, V. vulnificus Features: - Gram negative - Fermenter bacilli - Facultative anaerobes - Live in halophilic places Identification: - Enrichment medium - alkaline peptone broth Vibrios survive and replicate at high pH - Other organisms are killed or do not multiply - Selective/differential culture medium - TCBS agar - V. cholerae grow as yellow colonies - Biochemical and serological tests Pathogenesis and treatment: Rehydration & supportive therapy Oral Intravenous (IV): - Doxycycline or tetracycline (Test resistance may be developing) of secondary value - Water purification, sanitation & sewage treatment Vaccines Symptoms: - diarrhea - feces-streaked stool changes: Colorless; Odorless; No protein Speckled with mucus Haemophilus H.influenze (meningitidis); H. ducreyi (chanchroid) Features: - Gram-negative and...
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...distinguishes between gram-positive and gram-negative bacteria. Bacteria that stain purple are considered gram-positive and bacteria that stain pink are considered gram-negative. B. What is the difference between gram-positive and gram-negative cell walls? Gram-positive cell walls are thick and have many interconnecting layers of peptidoglycan. Gram-negative cell walls are thin and have only one layer of peptidoglycans that are two or three layers thick. C. What is the purpose of crystal violet in the Gram’s stain procedure? The crystal violet increases the contrast of both gram-negative and gram-positive bacteria making them look purple. D. What is the purpose of iodine in the Gram’s stain procedure? (What is a mordant?) The purpose of iodine in Gram’s stain procedure is it helps set the stain by forming an insoluble crystal violet-iodine complex. It helps keep the crystal violet to the cell. E. What is the purpose of acetone-alcohol in the Gram’s stain procedure? The purpose of acetone-alcohol is it is a decolorizer that distinguishes between gram-negative and gram-positive. Only the gram-positive bacteria will keep the crystal violet-iodine complex. Gram-negative bacteria will not keep the color and the decolorizer will wash off the stain. F. What is the purpose of safranin in the Gram’s stain procedure? The safranin in the Gram’s stain is a basic dye that directly stains the gram-negative bacteria that have become decolorized. The gram-positive bacteria are already stained...
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...Introduction Bacteria are microscopic unicellular prokaryotic organisms characterized by the lack of a membrane-bound nucleus and membrane-bound organelles. They are remarkably adaptable to diverse environmental conditions and are found in bodies of all living organisms and on all parts of the earth. The purpose of microbial biochemical tests is to identify the unique traits it yields and with that knowledge we can then categorize them in groups and specify them by scientific name. These experiments included the Triple-sugar iron agar (TSIA), Sulfur Indole Motility (SIM), Methyl Red (MR), Voges-Proskauer (VP), Citrate, Urease, Gelatin, and Oxidase Test. In order for these tests to produce reliable and credible results, the bacterium organism must be grown using strict and meticulous procedure to produce viable colonies of pure culture. Having pure culture is significant to ensure that a single type of bacteria is used for identification without contamination so tests can be run without complications or confusion. Once all these tests are performed, the unknown bacteria in this lab will be one of the following: Escherichia coli, Enterobacter aerogenes, Proteus mirabilis, Klebsiella pneumoniae, or Salmonella typhimurium. This report included the results and details to these experiments which are discussed further on. Abstract Gram negative bacteria Unknown #12 was run through an array of tests which produced positive and negative results. The results obtained from the various...
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...reference 1. Gram Stain * Verify if bacteria are present or not. * Controls – positive (purple) – S.aureus * negative ( red/pink) – E.coli 2. Endospore Staine Positive controller – B. magneterium Green spore- Positive Pink (vegetative ) – Negative 3. Acid fast Positive control – M. smeagmatis Blue – negative Pink /red- positive 4. Motility Positive control - P.vulgaris A. non motile is negative test B. motile is a positive test 5. Carbohydrates fermentation (test for gram -) ( glucose , manitol, lactose) Positive control – ecoli (yellow) Red- no color change – negative test Yellow – color change – positive test 6. Mae Conkey’s Agar Ecoli – positive control Selective for negative gram stain Differential for organism that could ferment lactase Growth pink – positive No growth – negative 7. Gelatin Hydrolysis ( Gelatinase) Positive control – P.aeruginosa Liquid –positive test Solid - Negative test 8. Blood agar Positive control – S. aureus A. Betahemolysis B. alphahemolysis C. gammahemolysis 9. FTM *broth – O2 relationship with 10. MRVP (mix acid fermentation) MR- methyl red (PH lower than 4.4) Positive control – e.coli red color- positive test no red – negative test 11. Voges Proskauer ( acetone) –precursor for those who fermented butane Positive control- E. aerogenosa Red color – positive test No color change – negative test 12. Nitrate...
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...expected to work as a team to figure out the unknown that was chosen. Using steps and experiments from the Bergey’s Manual, we were suppose to figure out the unknown and how the bacteria we had chosen was classified and characterized. My hypothesis when first starting the test was that this unknown was going to be something we had already dealt with in class. I thought our unknown would be Escherichia coli. Materials and Methods When we chose our unknown bacterial microorganism, it had the number one on the side. The broth had a one in turbidity on a scale from one (being the lowest) to four (being the highest). To see more clearly in the tube, swirling was used for sediment to be seen. The first experiment we did was testing the unknown to see if it was a gram-negative bacterium or whether it was a gram-positive bacterium. Majority of the bacteria that had been handled with in class fell under gram negative. How to tell whether the bacteria is gram negative or gram positive is by staining the bacteria and watching it change it’s color. If the bacteria turn purple, that would show that the bacteria are gram-positive. If the bacteria turn red, then that would...
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...of bacterial species based on the differences in the biochemical activities of different bacteria. Beta glucouronidase test is used for the identification of Escherichia coli. An enzyme is produced by E.coli which is beta D glucouronidase. Beta d glucouronidase in turn hydrolyzes beta d glucopyranosid uronic derivatives to aglycons and D glucuronic acid. Bile solubility test is used in laboratory for differentiation of alpha hemolytic Streptococci from Streptococcus pneumoniae. In catalase test it acts as a catalyst for the breakdown of hydrogen peroxide to oxygen and water. Catalase production test is done for an organism by bringing it into association with hydrogen peroxide. If an organism is...
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...What is the mechanism that Bordetella pertussis uses to invade epithelial cells in the lungs? The bacteria, Bordetella pertussis causes cough which becomes serious cough as the bacteria stays in the upper respiratory track and releases toxins which lead to the inflammation. The lungs consist of the Epithelial cell lining which is invaded by this bacteria. There are two stages for this disease the first stage is the colonization of the bacteria in the upper respiratory track. And the second stage is known as toxemic stage. During the first stage fever, cough is observed and during the toxemic stage there will be prolonged cough. We need to identify in the first stage itself as the medication will be working but the medication will not be working in the second stage. Why does this Gram-negative bacteria cause the characteristic cough that it does? Dry cough and sore throat are the common symptoms which are seen with Gram- negative bacteria. Cough lasts for almost 7-10 days. The Gram negative bacteria enters in to the respiratory track and involves in production of mucous and this results in the excess mucous production due to which cough effects the patient. Respiratory track is blocked by this mucous which leads to the breathing hard and whopping sound is also observed while coughing. Why is infant mortality high? All age groups might be affected with the disease; infants are at the high risk. As vaccination is not done infant mortality rate is high. Booster vaccines...
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...such as creating nitrogen fertilizer at the root zones of certain crops. Other several pathogens that can cause serious harm, even immediate death due to the diseases or disease causing products they produce. Overall, microorganisms play an important role in life. 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 bacteria based on specific biochemical characteristics. The differential tests used to identify the unknown cultures were Gram staining, oxidase, indole test, urea test, and casein test. MATERIALS AND METHODS: The unknown bacteria were given out by the lab instructor. Each student chose their own unknown bacteria according to the number. All methods have been practiced to ensure proper procedure identifying bacteria have been applied to this unknown. Procedures were followed as stated in the course laboratory manual provided by the instructor, unless otherwise noted. Each test performed identified was used to determine the specifics and identify the unknown bacterium. All of the following tests were performed on this unknown on February 09, 2008. Some of the tests required a follow-up right after the next lab. The first procedure that needed to be accomplished was to streak the unknown out on a Trypticase Soy Agar plate, using the T streak method...
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...during this process. Using this provided guidance as well as organization as to what the result may be. Upon obtaining the unknown organism, it was important to make a streak plate of the bacteria on TSA. The purpose of doing so ensures that we have pure cultures of the unknown to be used in further testing and not a mixed culture. The first test used was a gram stain. It is a differential stain that helps distinguish between gram-positive and gram-negative bacteria. After performing the gram stain, it was clear that the unknown was a gram negative due to its pink color. Gram staining involves doing a simple smear, drying, and then heat fixing. Then using the staining technique with crystal violet, gram’s iodine, ethanol, and safranin, a pink or purple color should result when looking at the slide under a microscope. A gram-positive, or purple stained bacteria, means that there are multiple layers of peptidoglycan in the cell wall. A gram-negative means that there in a thin layer of peptidoglycan that is removed by the ethanol and stained pink by the counterstain. All gram-positive bacteria could now be ruled out. The gram-positive bacteria included: Enterococcus faecalis, Bacillus subtilis, Staphylococcus aureus, and Staphylococcus epidermidis. Confirming that the unknown was a gram-negative bacterium, the next step on the flow chart was a glucose test. In order to do so, fermentation tubes were used. Fermentation tubes include peptone, an acid-base indicator (or phenol red)...
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...HOW TO WRITE AN UNKNOWN LAB REPORT IN MICROBIOLOGY GENERAL Unknown reports in microbiology are written in scientific format. Scientific writing is written differently from other types of writing. The results of the exercise or experiment are what are being showcased, not the writing. The purpose of scientific writing is not to entertain, but to inform. The writing should be simple and easy to understand. There is a specific style that must be followed when writing scientific reports. Scientific writing is typically written in the passive voice. The pronouns "I", "We" and "They" are not typically used.. For example, instead of writing "I used a TSA agar plate to isolate my unknown," it is customary to write, "A trypticase soy agar (TSA) plate was used to isolate the unknown." It is also customary to write in the past tense for most of the report. This includes the introduction, the summary, the description of the materials and methods and the results. The present tense is reserved for the conclusions about the results. See the examples given below. Some other general rules that should be followed are: Microbial nomenclature: The name of the bacterium should written and spelled correctly. The name should be italicized or underlined. Italicized is preferred. For example, Staphylococcus aureus. The genus is capitalized but the species is not. After the full genus name is given in the paper, it can be written as S. aureus, but still italicized. This is as long as there in no other...
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...In biology, in order to purify biological molecules, a common process called chromatography is often used. This process involves the separation of the large particles in the solution from the smaller particles. This is instrumental in filtering the solution, but without specialty scientific instruments, there is no way to immediately know the concentration of the, now separated, solution. However, there are multiple processes that are utilized to find unknown concentrations of a solution. One of these, known as the Bradford method, allows for an accurate, fairly simple, and timely assessment of these unknown concentrations by using a dye called the Coomassie Brilliant Blue G-250. The samples that contain this dye are run through a spectrophotometer, which reads the absorbance levels of the solution. Generally, the darker the solution is, the higher the concentration will be. This experiment utilizes both chromatography and the Bradford method to determine the concentrations of various protein samples. In this experiment, we worked with proteins over the course of two weeks in order to learn how to purify proteins in a solution by using chromatography and how to calculate the protein concentration in that solution. In the first week, protein samples were collected using chromatography, which is a process that is used to purify biological molecules. Two phases make up the chromatography process: the mobile phase, which consists of the solvent and molecules that are going to be...
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...Report The mixed unknowns were gram stained and looked under the microscope. There were gram-positive cocci and gram-negative bacilli. The unknowns were inoculated in blood agar and Mac-conkey. Three types of colonies were seen in the blood agar. All the three organisms showed different hemolysis, as there were alpha, beta and gamma hemolysis present. In the mac-conkey, there was colorless colony that denotes lactose non-fermenter. Each colonies were then inoculated into different blood agar to do further testing. Organism A I. Microscope- Gram positive cocci II. Blood Agar – Beta hemolysis Complete hemolysis. III. Catalase test– Positive Presence of bubbles when catalase was added to the slide with the organism in it as it can convert hydrogen peroxide into water and oxygen. 2H2O2---- 2H2O + O2 The organism falls in the genus Staphylococcus or Micrococcus. IV. Coagulase test, Staphylococcus Latex test – Positive Clumping of the latex reagent seen within 20 seconds. The organism makes coagulase. These tests suggest that the organism is Staphylococcus aureus. So for confirmatory test, the organism was inoculated in mannitol salt agar and incubated. The result was yellow color colony (mannitol fermenter), which means it is S. aureus. Organism B I. Microscope- Gram negative bacilli II. Blood agar- Gamma hemolysis No hemolysis. III. Mac. Conkey- Colorless colony The organism does not ferment lactose. IV. Oxidase test- Negative The organism falls under enterobacteriacea...
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...Materials and methods Location of the experiments This study was performed at the Plant Pathology Department, Faculty of Agriculture, Cairo University, Giza, Egypt Isolation of the pathogens Lettuce plant (cv. Aviram) showing wilt symptoms were collected from different fields located at Giza, Qalubiya, and Behira governorates. The infected roots were washed several times with tap water, cut tissues with the discolored vascular system or cortex after removing and discarding the epidermis into small pieces (Hubbard & Gerik 1993), surface sterilized by immersing in 2% sodium hypochlorite for 2 min, washed in several changes of sterile water and finally aseptically transferred onto potato dextrose agar medium (PDA) in Petri plates and incubated at 28±1ºC for 7 days. The growing fungi were purified and identified according to their morphological and molecular characteristics. Pathogenicity tests Inoculum preparation F. oxysporum f. sp. lactucae isolates Fo-1, Fo-2, and Fo-3 which yielded from Giza, Qalubiya, and Behera governorates, respectively were separately grown onto 250 ml flasks containing 100 ml autoclaved potato dextrose broth medium. The flasks were inoculated with one disk (4 mm diameter) taken from the margins of fresh cultures grown on PDA medium then incubated at 28±1ºC for 14 days. The suspension was filtered through two layers of cloth sheet. The concentration of the spores was determined by hemocytometer and diluted with sterile distilled water to obtain a final...
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