A selective medium is a medium that contains antimicrobials, dyes or alcohol that supports the growth of certain organisms, while inhibiting the growth of P. aeruginosa, E. aerogenes, and E. coli are rod-shaped microorganisms (Murray et al., 2015). differential mediums. 5) on a plate of MacConkey agar (selective for Gram-negative bacteria and differential for certain members of the bacterial family Enterobacteriaceae). Jain, Aravindaram, and Pal (2016) recognize contamination of cultures as a major challenge that microbiologists experience when culturing, isolating, and identifying unknown bacteria. WebDifferential/selective media contain chemicals whose reactions with the metabolites of the microbes result in a change in appearance of the media or the colonies themselves, thus It also Pink and Mucoidy growth = slight drop in pH =small acidic products made = slow lactose fermentation = possible coliform Bacterial strains that ferment lactose produce acids that result in darker colonies. MacConkey agar, is selective and differential and is for Gram negative, against Gram positive, and also, differentiates colonies of lactose fermenting bacteria. Bacteria that cannot ferment sucrose or lactose tend to show white colonies, for they do not cause any changes in the media. Selective media generally selects for the growth of a desired organism, stopping the growth of or altogether killing non-desired organisms. of E. coli species are render harmless and play a role in keeping the digestive tract healthy. When given a plate of Columbia CNA agar or MacConkey agar showing discrete colonies, correctly interpret the results. E. faecalis is usually a nonpathogenic intestinal microorganism. Wallace, J. S., & Jones, K. (1996). Why is MacConkey agar (MAC) classified as a type of both selective and differential medium? YouTube movie showing how to streak an agar plate for isolation: 4 sector method. This will guide your streaking. (2021, June 26). 7). A blood sample was then enriched medium used in this experiment. 3). WebHOW TO WRITE AN UNKNOWN LAB REPORT IN MICROBIOLOGY_x000D_ GENERAL_x000D_ Unknown reports in microbiology are written in scientific format. Small samples of the diluted bacteria are then pipetted onto the surface of agar plates. : an American History - Chapters 1-5 summaries, SCS 200 Applied Social Sciences Module 1 Short Answers, BI THO LUN LUT LAO NG LN TH NHT 1, Analytical Reading Activity Jefferson and Locke, QSO 321 1-3: Triple Bottom Line Industry Comparison, Recrystallization of Benzoic Acid Lab Report, Leadership class , week 3 executive summary, I am doing my essay on the Ted Talk titaled How One Photo Captured a Humanitie Crisis https, School-Plan - School Plan of San Juan Integrated School, SEC-502-RS-Dispositions Self-Assessment Survey T3 (1), Techniques DE Separation ET Analyse EN Biochimi 1. In other words, they indicate whether or not a certain organism can carry out a specific biochemical reaction during its normal metabolism. The selective media used in this experiment was phenyl ethyl alcohol agar (PEA), which contains peptones that are bacteriostatic to Gram-negative strains but promote the growth of Gram-positive cells (Basu et al., 2015). How many \alpha particles and how many \beta particles are emitted? Then make Include examples of. conducive for their growth. Table 1. 2. Selective growth media for eukaryotic cells commonly contain neomycin to select cells that have been successfully transfected with a plasmid carrying the neomycin resistance gene as a marker. Sucrose (differential) Microbiology, 25 (9), 1730-1734. Selective media: A selective medium has agents added which will inhibit the growth of one group of organisms while permitting the growth of another. E. coli is a gram-negative, rod-shaped, facultative anaerobic The differential media used in this experiment was EMB, which distinguishes strains based on lactose fermentation. The gelatinase reaction may be slow or incomplete (Fig 7). status page at https://status.libretexts.org. Test #1: Lab Experiment. "Bacteria Lab: Enriched, Selective, Differential Media." There are many types of media used in the studies of microbes. Acidic Response = Color Change. Indicate a common disease caused by each. If the Gram-negative bacterium ferments the sugar lactose in the medium, the acid end products lower the pH of the medium. Some examples of selective media include: Differential media or indicator media distinguish one microorganism type from another growing on the same media. Lactobacillus delbrueckii subsp. Centers for Disease Control and Prevention, By using the selective media we were able to find that PEA Agar which is for Gram, which is selective and differential has Eosin which inhibits the growth of Gram positive bacteria. Thad well as Aureus. 1. 2. allows the growth of some bacterial species while You have created a mutation in several of theE. Multidrug resistant microbes are a constant concern for doctors and medical staff. The selected bacterial strains were Escherichia coli, Pseudomonas aeruginosa, Enterobacter aerogenes, Streptococcus aureus, Enterococcus faecalis, and an unknown sample. After 48hours, introduce the sample microbes Course Hero is not sponsored or endorsed by any college or university. While S. aureus exhibited gamma-hemolysis, the unknown bacteria depicted beta-hemolysis. c) Overload the relational and equality operators for this class. 2A and Fig. 1. Eosin Y and Methylene Blue dyes inhibit the growth of Gram positive bacteria (only Gram negative bacteria will grow well), Differential Evolution of bacterial and fungal growth media. In the Eosin Methylene Blue Agar plate, E. coli appears large. Previously, the identification and characterization of bacterial species was largely done by phenotypic and biochemical methods (such as through selective/differential media and biochemical tests that we have discussed in the last 2 modules), which relied on preliminary isolation and culture. June 26, 2021. https://studycorgi.com/bacteria-lab-enriched-selective-differential-media/. 5. agar. Web. There is also lactose fermentation that took place that If you are author or own the copyright of this book, please report to us by using this DMCA report form. Two types of media with similar implying names but very different functions, referred to as selective and differential media, are defined as follows. Research and compare Staphylococcus and Streptococcus. in yoghurtA review. Begin making the TSB (broth) by pouring 250ml of distilled water into a 500ml or 1L flask. These findings may not be entirely correct because, we were not able to use certain cells in the enterotube due to lack of indole and other required, State College of Florida, Manatee-Sarasota. Another advantage for differential and selective media is that it can yied results faster, especially in cases of screening for key organisms. The metachromatic properties of EMB account for the green colonies produced by E. coli, which also ferments lactose (Antony et al., 2016). microbes. Using the wire loop, scoop a colony of Staphylococcus aureus and streak it on the surface of The "salt" in "Mannitol salt agar" selects for bacteria that can grow in high salt environments. Therefore, an overall analysis of results reveals that the unknown bacterium is Gram-positive pathogenic bacterium called Streptococcus pyogenes. Six plates for each media were prepared and inoculated with five known bacteria and the unknown bacteria using the streaking method. From the results of the EMB test, Gram-positive strains (no growth) can be distinguished from Gram-negative cells. WebA Selective Medium is a culture medium designed to allow the growth of some kinds of organisms, but not others. Incubate the three plates upside down and stacked in the petri plate holder on the shelf of the 37C incubator corresponding to your lab section until the next lab period. The selectivity is accomplished in several ways. A. 1. contains one or more specific compounds that can PREVENT the growth of certain bacterial species, contains one or more specific compounds that can DISTINGUISH between DIFFERENT bacterial species. Lab report Selective Differential mediums, Copyright 2023 StudeerSnel B.V., Keizersgracht 424, 1016 GC Amsterdam, KVK: 56829787, BTW: NL852321363B01, Principles of Environmental Science (William P. Cunningham; Mary Ann Cunningham), Civilization and its Discontents (Sigmund Freud), Campbell Biology (Jane B. Reece; Lisa A. Urry; Michael L. Cain; Steven A. Wasserman; Peter V. Minorsky), Give Me Liberty! They are useful in differentiating bacteria according to some biochemical characteristic. 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. Bromthymol blue dye (differential) "Bacteria Lab: Enriched, Selective, Differential Media." Differential tests are a lot more precise than selective media. Webwhich are not colored). BLUISH / GREEN bacterial colonies WITH BLACK PRECIPITATE However, problems such as contamination and subjective reading of culture plates might have influenced the outcome of results. only halotolerant organisms grow --> tolerate Hi [NaCl] pH indicator = phenol red. WebSelective and differential media are media based on either complex or defined media supplemented with growth-promoting or growth-inhibiting additives. negative hence its growth is favored. Purple/Black growth/ Green metallic sheen = drop in pH=Large acidic products=fermentation of lactose and sucrose=probable coliform StudyCorgi. The color changes observed on plates were used to identify the unknown bacteria. One plate of each of the following media: Trypticase Soy agar, Columbia CNA agar, and MacConkey agar. Gram positive bacteria, Growth = Gram negative bacteria Methicillin-resistant staphylococcal skin infections by S. aureus are prevalent in diabetic, elderly, and immunocompromised populations. Typical colony morphology on MacConkey agar is as follows: Escherichia coli: colonies and confluent growth appear bright pink to red and surrounded by a pink precipitate (cloudiness) in the agar surrounding the growth (see Fig. The medium inhibits growth of gram positive The use of selective and differential agars in the isolation of 3. Streak the plates for the following organisms: Enterobacter aerogenes, Salmonella enterica, and Staphylococcus aureus, and sterilize the loop after streaking each quadrant. NOT all Gram negative bacteria make the same amount of acidic compounds from sugar fermentation Mannitol Salt Agar (MSA): Mannitol salt agar is both a selective and differential media used for the isolation of pathogenic The following lab you will prepare microscopy slides of each of the two pure cultures to determine if they are indeed pure. Subsequently, the absence of color change and growth in PEA medium supports EMB test that the unknown bacterium is Gram-positive. Isolation of bacteria is accomplished by growing ("culturing") them on the surface of solid nutrient media. Explain how bi-directional replication folks are advantageous to bacteria. ddx: mannitol fermentaion. Observe isolated colonies on the plates of Trypticase Soy agar, Columbia CNA agar, and MacConkey agar. part gives an explanation on how bacterial takes place on various growth medium as well as how WebSelective media allow certain types of organisms to grow, and inhibit the growth of other organisms. Web. Terrific Broth (TB) is used with glycerol in cultivating recombinant strains of Escherichia coli. 26 June. 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After incubation, the area at the beginning of the streak pattern will show confluent growth while the area near the end of the pattern should show discrete colonies (see Fig. June 26, 2021. https://studycorgi.com/bacteria-lab-enriched-selective-differential-media/. Students also viewed Evaluation of Antiseptics and Disinfectants Questions 1 The chemistry behind this test is that Gram-negative bacteria ferment lactose and sucrose to produce acids, which react with eosin and methylene blue dyes to produce dark purple or metallic green colors. Amsterdam, Netherlands: Elsevier. Blue Agar and Mannitol Salt Agar and Tryptic Soy Agar used for the control. Define: selective medium, differential medium, enrichment medium, and combination selective-differential medium. Report DMCA Overview Flash animation showing how to streak an agar plate for isolation: 3 sector method. Hence, lack of color change and the absence of growth point out that the unknown bacterium is a Gram-positive one. Web(N.B. StudyCorgi. 2. (2021) 'Bacteria Lab: Enriched, Selective, Differential Media'. Normally, the presence of a specific gene or an allele of a gene confers upon the cell the ability to grow in the selective medium. YELLOW MEDIA CHANGE= + fermentation of mannitol --> acid. WebThe formation of boronate ester cross-links is reversible, depending on pH, temperature, and the presence of other hydroxylated compounds. First, the mixture must be diluted until the various individual microorganisms become separated far enough apart on an agar surface that after incubation they form visible colonies isolated from the colonies of other microorganisms. Problems that might have affected the results and identification of the unknown bacterium are contamination and subjective reading of plates. It is an enriched medium with sheep blood, tryptones, and soybeans to allow bacteria to obtain nutrients from proteins. Basu, S., Bose, C., Ojha, N., Das, N., Das, J., Pal, M., & Khurana, S. (2015). Media lacking an amino acid such as proline in conjunction with E. coli unable to synthesize it were commonly used by geneticists before the emergence of genomics to map bacterial chromosomes. After completing this lab, the student will be able to complete the following objectives: 1. Hektoen enteric agar (HE) which is selective for Gram-negative bacteria. and the medium favors growth of the gram negative bacteria. Label the MacConkey agar plates. Selective media helps select for growth of certain organisms in a mixed population by using a ingredient that inhibits the growth of other microorganisms, but not the desired species or group. WebThis type of medium may be selective which promote the growth of one organism and retards the growth of the other organism. The other varieties of bacteria are inhibited. Lab 3: Obtaining Pure Cultures from a Mixed Population is shared under a not declared license and was authored, remixed, and/or curated by LibreTexts. Selective media are used for the growth of only selected microorganisms. In this study, we examined the effects of compounding various phases of alumina with different shapes and crystal phases on the dielectric constant and dielectric loss of cyclo-olefin polymer (COP) compounds. The Journal of Horticultural Science and Biotechnology, 19(2), 122-128. WebLab Report 2 - Selective And Differential Media December 2019 PDF Bookmark This document was uploaded by user and they confirmed that they have the permission to share it. Poor/No growth = Organism inhibited by Eosin and Methylene blue dye = Gram Positive Streak the same mixture for isolation (see Fig. Pick off isolated colonies of microorganisms growing on a streak plate and aseptically transfer them to sterile media to obtain pure cultures. Although Trypticase Soy agar (TSA), which grows both Gram-positive and Gram-negative bacteria, is not normally used as an isolation medium, we will attempt to obtain isolated colonies of the two organisms in your mixture by using strictly mechanical methods. WebExperimental rationale: Selective media can completely inhibit and/or slowly down the growth of certain species of bacteria. The spin plate method involves diluting the bacterial sample in tubes of sterile water, saline, or broth. Label a sheep blood agar plate and use a loopful of Enterococcus faecalis to inoculate it. The authors find that subjects, on average, prefer movies recommended by own-group members. pathogenic staphylococci isolation. WebCultivation Media for Bacteria. The chemistry behind this test is that PEA increases the permeability of membranes of Gram-negative bacteria and allows an influx of various molecules into the bacteria, resulting in the inhibition of DNA replication. StudyCorgi. Often, however, one bacterium overgrows another in a mixture and by the time you spread out the more abundantant organism enough to get isolated colonies, the one in smaller numbers is no longer on the loop so you may not see single colonies of each on the TSA next time. Web. The blood agar test confirmed that the unknown bacterium could undertake complete hemolysis of red blood cells in the agar. The bacteria that we identified in our two enterotubes were, tested positive for glucose, lysine, lactose, arabinose, sorbital, and, dulcitol. Mannitol Salt Agar and its expected there would be a change in the medium color due to the Differential media Differential media is used to differentiate bacteria with morphological and biochemical similarities. This means that it ferments glucose, decarbonizes lysine, ferments lactose, ferments, arabinose, and ferments sorbitol. Gancyclovir is an exception to the rule as it is used to specifically kill cells that carry its respective marker, the Herpes simplex virus thymidine kinase (HSV TK). 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 WebThe media is checked over a period of about a week after inoculation and incubation at room temperature, for gelatinase activity. bacteria and encourages the growth of gram positive bacteria. Isolation of Foodborne Pathogens on Selective, Differential, and Media formulation may combine ingredients of Journal of applied bacteriology, 81 (6), 663-668. COLORLESS bacterial colonies = NO change in media pH = NO acidic products present = NO fermentation of lactose OR sucrose Figure 2. These will be your pure cultures for Lab 5 (Direct and Indirect stains). Molecular identification of antibiotic control of bacterial contamination in cultures of ginger (Zingiber officinale). 5. 4. Selective growth media are also used in cell culture to ensure the survival or proliferation of cells with certain properties, such as antibiotic resistance or the ability to synthesize a certain metabolite. Differential media: A differential medium contains additives that cause an observable color change in the medium when a particular chemical reaction occurs. phenol red indicator and is 7% made up of Nalco (Wallace & Jones, 1996). Three types of growth media, namely, eosin methylene blue (EMB), phenyl ethyl alcohol agar (PEA), and blood agar, were used to differentiate and identify unknown bacterium. "Bacteria Lab: Enriched, Selective, Differential Media." Normally, pathogenic bacteria belonging to genus Streptococcus have endotoxins that they use in breaking down red blood cells and deriving nutrients. It explains on the three types of mediums thats the complex, selective and (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. Staphylococcus aureus ferments mannitol, an acid byproduct is produced which subsequently MSA (mannitol salt agar) selective. The neutral red in the agar turns red in color once the pH drops below 6.8. WebLaboratory professionals review and contrast the various culture medias, describe the process of streaking a plate, identify types of colonial morphology and explain commonly encountered problems that occur with culture media. Journal of Pure and Applied Microbiology, 10(4), 1-7. A selective medium has an inhibitory agent which favors the growth of certain bacteria by inhibiting others. Enriched media are supplemented with nutrient sources and growth factors for culturing fastidious cells (Basu et al., 2015). 2B). components. Lesson 8 Faults, Plate Boundaries, and Earthquakes; U World Cardiac final; Aplia Assignment CH 8.2; Lactose (differential) An example of this selection would be using an increased salt concentration to only allow for the growth of halophilic bacteria. To supplement mechanical techniques of isolation such as the streak plate method, many special-purpose media are available to the microbiologist to aid in the isolation and identification of specific microorganisms. Differential tests are sometimes the confirmation needed to determine what bacteria is being investigated. resulted in te nature of the medium. Using the streak plate method of isolation, obtain isolated colonies from a mixture of microorganisms. For example, if a microorganism is resistant to a certain antibiotic, such as ampicillin or tetracycline, then that antibiotic can be added to the medium in order to prevent other cells, which do not possess the resistance, from growing. A sterile, bent-glass rod is then used to spread the bacteria evenly over the entire agar surface (see Fig. Tabulated Results that Identified the Unknown Bacterium. Isolation of bacteria is accomplished by growing ("culturing") them on the surface of solid nutrient media. Accessibility StatementFor more information contact us atinfo@libretexts.orgor check out our status page at https://status.libretexts.org. However, there are some strains that harmful that causes diarrhea id one drinks Given that results of the experiment emanate from an accurate reading of plates, subjective reading was another problem encountered. Comparative evaluation of EMB agar and hicrome E. coli agar for differentiation of green metallic sheen producing non E. coli and typical E. coli colonies from food and environmental samples. c. Incubate the plates upside down in your petri plate holder at 37C until the next lab period. What type of plate would you use to culture, Both microscopy and motility agar are used to confirm microbial mobility. bacteria and hinders the growth of gram positive bacteria. Incubate all plates at 35-37C for 36-48 hours. It is considered the most dangerous among EMB is also a selective medium, as it contains methylene blue that inhibits the growth of Gram-positive bacteria (Basu et al., 2015). Abstract The yellow region is due to the fermentation of methylene blue in the agar causing its colonies to turn a bright metallic green. 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. 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