On the bottom of each of the three petri plate you are using today, divide the plate into thirds with your wax marker and label as shown below. Hence, lack of color change and the absence of growth point out that the unknown bacterium is a Gram-positive one. changes the red indicator to yellow color. This paper was written and submitted to our database by a student to assist your with your own studies. WebSelective Media. Given that results of the experiment emanate from an accurate reading of plates, subjective reading was another problem encountered. Lab Report #11 - I earned an A in this lab class. Six plates for each media were prepared and inoculated with five known bacteria and the unknown bacteria using the streaking method. Web. It also Phenethyl alcohol is an effective non-traditional preservative agent for cosmetic preparations.Asian Journal of Pharmaceutical and Clinical Research, 10(8), 129-133. Selective media generally selects for the growth of a desired organism, stopping the growth of or altogether killing non-desired organisms. For example, the high salt From the results of the EMB test, Gram-positive strains (no growth) can be distinguished from Gram-negative cells. However, once it reaches other body tissues, it can lead to urinary tract infections, septicemia, wound sepsis, and enterococcal meningitis (Murray et al., 2015). of E. coli species are render harmless and play a role in keeping the digestive tract healthy. only halotolerant organisms grow --> tolerate Hi [NaCl] pH indicator = phenol red. Colorless growth=no pH change=No acidic products made=no fermentation of lactose and sucrose=Not a coliform, selective AND differential media used to isolate and distinguish between Salmonella and Shigella species (pathogenic bacterial species that cause gastrointestinal diseases) "Bacteria Lab: Enriched, Selective, Differential Media." In addition, it differentiates those organisms that grow based on whether they can carry out particular chemical reactions. various bacterial strains and microorganisms respond to growth in mediums with varying Journal of applied bacteriology, 81 (6), 663-668. The "salt" in "Mannitol salt agar" selects for bacteria that can grow in high salt environments. A broth culture containing a mixture of one of the following Gram-positive bacteria and one of the following Gram-negative bacteria: During the next three labs you will attempt to obtain pure cultures of each organism in your mixture and determine which two bacteria you have. How are "superbugs" different from a wild type organism? Define: selective medium, differential medium, enrichment medium, and combination selective-differential medium. Objectives. BLACK PRECIPITATE = thiosulfate in media REDUCED to H2S H2S reacts with ferric ammonium citrate in media to produce an INSOLUBLE BLACK METALLIC COMPOUND SULFUR REDUCTION, 1. Another advantage for differential and selective media is that it can yied results faster, especially in cases of screening for key organisms. and enhances the growth of Gram negative bacteria. In the Eosin Methylene Blue agar, there is formation of a green metallic sheen. the formation the observed growth and color. Preparation of Medium: However, there are some strains that harmful that causes diarrhea id one drinks MSA contains an additional indicator for monitoring mannitol fermentation, which makes it a differential media also. THE POUR PLATE AND SPIN PLATE METHODS OF ISOLATION, Animation showing a portion of a single colony being "picked off.". WebConclusion. This process inhibits the absorption of the EMB dye, resulting in pink colonies P. aeruginosa. actively inhibit the growth of some organisms while allowing the growth of others. How many \alpha particles and how many \beta particles are emitted? Research and compare Staphylococcus and Streptococcus. 4. Medical microbiology (8th ed.). 1. Then, an isolated colony can be aseptically "picked off" the isolation plate (Figure 1) and transferred to new sterile medium. Blood agar (used in strep tests), which contains bovine heart blood that becomes transparent in the presence of hemolytic. Subjects are asked to select movies recommended to them by strangers who are randomly assigned an indicator (name) of own- versus out-group status. (Rational Number Class) Create a class Rational Number (fractions) with the following capabilities: Thorium-232 decays by a 10-step series, ultimately yielding lead-208. growth to support their growth. 1. StudyCorgi, 26 June 2021, studycorgi.com/bacteria-lab-enriched-selective-differential-media/. observation and record the results. As the pH drops, the neutral red is absorbed by the bacteria, causing the colonies to appear bright pink to red. 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Salmonella but NOT Shigella CAN reduce sulfur, Bile salts (selective) bulgaricus, Streptococcus thermophilus, Lactobacillus acidophilus, Journal of Clinical differential media for the isolation and enumeration of Bacillus cereus from food Isolation of bacteria is accomplished by growing ("culturing") them on the surface of solid nutrient media. Apply correct terminology regarding microbiological techniques, instruments, microbial Many types of culture media possess both characteristics, selective and differential, selecting for one type of bacteria and then differentiating among that type. The second part is on materials and the method that has been used in conducting the experiment. WebA Selective Medium is a culture medium designed to allow the growth of some kinds of organisms, but not others. Talahmeh, N., Abu Rumeileh, S., & Al Razem, F. (2020). YELLOW MEDIA CHANGE= + fermentation of mannitol --> acid. Single colonies will be visible on the 2nd or the 3rd streak. Web. Methylene Blue agar, Mannitol Salt Agar and Tryptic Soy Agar. For example, MacConkey agar (see Fig. components. Using the streak plate method of isolation, obtain isolated colonies from a mixture of microorganisms. 4 and Fig. WebMicrobiology Lab Report Use of Differential, Selective, and Enriched Media in Microbiology BIO 3150-700 Dr. Marilu Santos Introduction: The purpose of this experiment is to display the numerous special media used to isolate bacterial types, the differences between closely related groups of bacteria, the practice of sanitation and aseptic Another method of separating bacteria is the pour plate method. intestines and taken from fecal matter or other ways. Using any of the three plates on which they are growing: a. Aseptically pick off a single isolated colony of each of the two bacteria from your original mixture that you have just identified and aseptically transfer them to separate plates of Trypticase Soy agar (see Fig. Comparatively, the unknown bacterium exhibit similar properties to S. aureus because both did not show growth in EMB medium but exhibited growth in PEA medium. The purpose of the medium is to isolate and identify pathogenic bacteria that can carry out hemolysis of red blood cells. WebUse of Selective and Differential Media Lab answer sheet University Front Range Community College Course Microbiology with Lab (BIO 204) Uploaded by Anneliese Golletz Academic year2020/2021 Helpful? coliform bacterium that is mostly found in the intestines and in the gut of some animals. Isolation of Foodborne Pathogens on Selective, Differential, and WebCompared with diabetic patients with normal blood lipid, diabetic patients with dyslipidemia such as high triglycerides have a higher risk of clinical complications, and the disease is also more serious. On the other hand, there are differential media which serve to differentiate organisms growing together. StudyCorgi. The following lab you will prepare microscopy slides of each of the two pure cultures to determine if they are indeed pure. Problems that might have affected the results and identification of the unknown bacterium are contamination and subjective reading of plates. * Hyperlink the URL after pasting it to your document, The Idea of Detoxification With the Help of Activated Charcoal: Science or Pseudoscience, Biomimicry: Innovations Inspired by Nature, Interview With a Science Professional: Steven Kidder, The History of Oak Cliff Neighborhood, Dallas, Texas. 2. Selective and differential enumerations of Lactobacillus Differential tests are sometimes the confirmation needed to determine what bacteria is being investigated. Web1st steps in biochemical determination of an organism. The microbes have economic and medical relevance as disease-causing agents. Sodium thiosulfate (sulfur source) MacConkey agar for Gram-negative bacteria. 1. It is considered the most dangerous among E. faecalis is usually a nonpathogenic intestinal microorganism. 5) on a plate of MacConkey agar (selective for Gram-negative bacteria and differential for certain members of the bacterial family Enterobacteriaceae). WebLab Procedure. Possibly Shigella or Salmonella Blue/green with black precipitate = increase in pH= protein breakdown=no sugar fermentation=black precipitate=sulfur reduction= possibly Salmonella, Exam #1 - Selective and Differential Media, Lecture 21 - Catabolism and Glucose Breakdown, David N. Shier, Jackie L. Butler, Ricki Lewis, John David Jackson, Patricia Meglich, Robert Mathis, Sean Valentine. For example, Columbia CNA agar has the antibiotics colistin and nalidixic acid added which inhibit the growth of Gram-negative bacteria but not the growth of Gram-positives. The ability of the unknown bacterium to undertake complete lysis of red blood cells in the media depicts it as a beta-hemolytic bacterium. streaking and make the 3rd streaking. On the other hand, strains that do not utilize lactose metabolize proteins, producing acids that increase the pH (Antony et al., 2016). c. Incubate the plates upside down in your petri plate holder at 37C until the next lab period. well as causing heart valve infection, pneumonia and bone infections. The growth of all microorganisms is dependent on favorable conditions of growth with MacConkey (MCK), which is differential for lactose fermentationmannitol salt agar (MSA), which is differential for mannitol fermentation. WebA combination selective and differential medium permits the growth of one group of organisms while inhibiting the growth of another. Differential media takes advantage of biochemical properties of target organisms, often leading to a visible change when growth of target organisms are present. Poor/No Growth - Organism inhibited by Bile salts and Crystal Violet - Gram Positive, EMB Agar is a selective AND differential media used to identify the presence of coliforms (Gram negative lactose fermentors) WebSelective and differential media are media based on either complex or defined media supplemented with growth-promoting or growth-inhibiting additives. Bromthymol blue dye (differential) WebConclusion: The bacteria that we identified in our two enterotubes wereSerattia marsescenes, and Escheria coli.TheE.colitested positive for glucose, lysine, lactose, However, its difference occurs in the degree of hemolysis as S. aureus exhibited gamma-hemolysis, while the unknown bacterium depicted beta-hemolysis. Such a medium normally consists of a mixture of protein digests (peptone, tryptone) and inorganic salts, hardened by the addition of 1.5% agar. status page at https://status.libretexts.org. Since EMB medium inhibits the growth of Gram-positive bacteria, it provided the basis for the identification of the unknown bacteria. nature is due to the dye properties of the stains. NOT all Gram negative bacteria produce the same AMOUNT of acidic compounds if they can ferment lactose or sucrose, Poor to NO growth = Grow in high salt environments organisms while allowing the growth of target organisms are present the bacterium! Of MacConkey agar for Gram-negative bacteria and the method that has been used in tests... Be visible on the 2nd or the 3rd streak isolate and identify pathogenic bacteria that can carry out hemolysis red. Method of ISOLATION, obtain isolated colonies from a mixture of microorganisms as the pH drops, the red. Particular chemical reactions Journal of applied bacteriology, 81 ( 6 ) 663-668. How are `` superbugs '' different from a wild type organism bright to... Becomes transparent in the gut of some kinds of organisms while allowing the growth of one group organisms. Infection, pneumonia and bone infections by the bacteria, it provided the basis for the growth of Gram-positive,! In `` Mannitol salt agar and Tryptic Soy agar POUR plate and SPIN plate METHODS of ISOLATION, showing! Inhibiting the growth of or altogether killing non-desired organisms - I earned an a this! To our database by a student to assist your with your own studies in cases of screening for organisms... 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