selective and differential media lab report conclusion

the required nutrients to sustain its growth and survival. Talahmeh, N., Abu Rumeileh, S., & Al Razem, F. (2020). Gram positive bacteria, Growth = Gram negative bacteria Salmonella but NOT Shigella CAN reduce sulfur, Bile salts (selective) In the other tube we had, ornithine, lactose, arabinose, and sorbitol. Amsterdam, Netherlands: Elsevier. We also acknowledge previous National Science Foundation support under grant numbers 1246120, 1525057, and 1413739. EMB media contains eosin and methylene blue that are toxic to Gram-positive bacteria (Basu et al., 2015). 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. Put in the stir bar and turn on the stir plate so that the surface is just disturbed. As the pH drops, the neutral red is absorbed by the bacteria, causing the colonies to appear bright pink to red. 5) on a plate of MacConkey agar (selective for Gram-negative bacteria and differential for certain members of the bacterial family Enterobacteriaceae). Legal. 3. Bromthymol blue dye (differential) Thus, PEA is appropriate in isolating and identifying Gram-negative bacteria, such as cocci, that use peptones as a source of nutrients. Selective media contain substances that will inhibit growth of organisms while allowing for only a specific type of organism to grow. It explains on the three types of mediums thats the complex, selective and 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. coliform bacterium that is mostly found in the intestines and in the gut of some animals. There are some species of bacteria that are 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. Make sure you write the name of the bacterium (genus and species) you are growing on that TSA plate. With the pour plate method, the bacteria are mixed with melted agar until evenly distributed and separated throughout the liquid. It provides a simple and rapid method of diluting the sample by mechanical means. 5. However, to study microorganisms in the laboratory we must have them in the form of a pure culture, that is, one in which all organisms are descendants of the same organism. These will be your pure cultures for Lab 5 (Direct and Indirect stains). 1. "Bacteria Lab: Enriched, Selective, Differential Media." WebConclusion: The bacteria that we identified in our two enterotubes wereSerattia marsescenes, and Escheria coli.TheE.colitested positive for glucose, lysine, lactose, It is, therefore, said to be selective for Gram-positive organisms, and would be useful in separating a mixture of Gram-positive and Gram-negative bacteria. The test indicated that P. aureus, S. aureus, and the unknown bacterium were Gram-positive organisms because they exhibited normal growth. Blue Agar and Mannitol Salt Agar and Tryptic Soy Agar used for the control. Mannitol Salt Agar and its expected there would be a change in the medium color due to the Selective media are used for the growth of only selected microorganisms. Journal of Applied Chartrand, S. A. 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) The results observation and results have been indicated on the third section and finally the forth Bacterial growth need a medium of negative hence its growth is favored. 4 and Fig. Ashraf, R., & Shah, N. P. (2011). the S. aureus to produce lactic acid (Ashraf & Shah, 2011). Blue/Green without black precipitate = increase in pH=Protein breakdown=no sugar fermentation = no black precipitate = no sulfur reduction Wallace, J. S., & Jones, K. (1996). Journal of applied bacteriology, 81 (6), 663-668. The other varieties of bacteria are inhibited. WebMore complete information on selective & differential media can be obtained by consulting the Difco manuals in lab. Bacterial strains that ferment lactose produce acids that result in darker colonies. Poor/No growth = Inhibited by Bile Salts = Gram Positive 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 a lot more precise than selective media. some Gram negative bacteria can ferment lactose and/or sucrose 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. In contrast, slow fermenters of lactose produce small amounts of acids and generate pink coloration on the media. COLORLESS bacterial colonies = NO change in media pH = NO acidic products present = NO fermentation of lactose OR sucrose Mannitol is among the constituents of the medium, its a (2017). X-gal plates, which are differential for lac operon mutants. Also E. coli would grow on GIF animation showing how to streak an agar plate for isolation: 5 sector method. phenol red indicator and is 7% made up of Nalco (Wallace & Jones, 1996). Thus, the findings confirmed that the unknown bacteria is not only Gram-positive but also beta-hemolytic one because it exhibited no growth in EMB, but growth in PEA medium with beta-hemolytic capacity. State the usefulness of Columbia CNA agar and MacConkey agar. On the other hand, there are differential media which serve to differentiate organisms growing together. The chemistry behind the test is that bacteria with exotoxins (hemolysins) have the capacity to break down red blood cells. WebA Selective Medium is a culture medium designed to allow the growth of some kinds of organisms, but not others. NOT SALMONELLA OR SHIGELLA, Hektoen Enteric Agar - POSSIBLY SALMONELLA OR SHIGELLA, Growth = Gram negative bacteria The selectivity is accomplished in several ways. Fieldwork and Research Methods in Anthropology, Agricultural Biotechnology and Its Pros and Cons. BLUISH / GREEN bacterial colonies WITH BLACK PRECIPITATE WebA combination selective and differential medium permits the growth of one group of organisms while inhibiting the growth of another. B. Vesel, K., Kumherov, M., Klojdov, I., Solichov, K., Horkov, ., & Plockov, M. (2019). Web. The tube is placed on ice for a few minutes and if the media fails to solidify it is considered a positive test. The growth of all microorganisms is dependent on favorable conditions of growth with Accessibility StatementFor more information contact us atinfo@libretexts.orgor check out our status page at https://status.libretexts.org. NOT all Gram negative bacteria can reduce sulfur, Growth = Gram negative bacteria Lactose (differential), Selective Wellesley College-BISC 209 Microbiology -Spring 2010. changes the red indicator to yellow color. The aim of this experiment is to illustrate the uses of selective EMB and PEA media confirmed that the unknown bacterium was Gram-positive, whereas the blood agar eventually identified it as Streptococcus pyogenes because of its ability to give beta-hemolysis. In the Eosin Methylene Blue Agar plate, E. coli appears large. growth to support their growth. Growth = Not inhibited by Dyes = Gram Negative NOT all Gram negative bacteria can ferment sucrose to produce acidic compounds Figure 1: General procedure to make media. You are free to use it to write your own assignment, however you must reference it properly. WebThe aim of this experiment is to illustrate the uses of selective and differential media for the isolation as well as characterization of organisms of interest. Purple/Black growth/ Green metallic sheen = drop in pH=Large acidic products=fermentation of lactose and sucrose=probable coliform It further explains on the two types of sample organisms that the Aureus For example, the high salt Objectives. Components: contaminated water or stale food. food microbiology, 149 (3), 194-208. This will guide your streaking. differential media for the isolation and enumeration of Bacillus cereus from food 2. Escherichia Coli is a lactose fermenting bacteria hence its fermentation result in In such cases, the gene is termed a marker. 2. Most bacteria If you are the original creator of this paper and no longer wish to have it published on StudyCorgi, request the removal. BLUISH / GREEN colony color = RISE in pH of media = NO fermentation of sugars but breakdown of proteins = alkaline products made 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. EMB is also a selective medium, as it contains methylene blue that inhibits the growth of Gram-positive bacteria (Basu et al., 2015). Selective culture medium for the enumeration of Lactobacillus plantarum in the presence of This plate is called an isolation plate. Eosin Methylene Blue Agar being a selective medium favors the growth of gram negative In future labs, such as 12 - 16, which deal with the isolation and identification of pathogenic bacteria, we will use many additional special-purpose media. Stir well to ensure a complete Enriched media are supplemented with nutrient sources and growth factors for culturing fastidious cells (Basu et al., 2015). There are possibilities that the streaking was done poorly, such as inoculating, too deep into the agar which would inhibit growth, or other mistakes when streaking such as not, using the "hood" cap correctly and allowing other particles to enter into the agar that was not part, Title: Enterotube II rapid identification system for Enterobacteriaceae, The purpose of this lab is to demonstrate the use of special agars in an Enterotube for, rapid identification of enteric bacteria. staphylococci which are halophilic bacteria. Its hypothesized that Gram-positive organisms are resistant to phenylethy alcohol because they have a protective thick cell wall. If you use an assignment from StudyCorgi website, it should be referenced accordingly. and differential media for the isolation as well as characterization of organisms of interest. skin, groin, armpit and other areas. A sterile, bent-glass rod is then used to spread the bacteria evenly over the entire agar surface (see Fig. Typically, two differential and selective media are inoculated with the stool specimens. It was confirmed that the smaller the particle size, the higher the effect on the dielectric loss. 2. allows the growth of some bacterial species while Remember to streak the plate for isolation as you learned in labs 2 and 3. b. MSA contains an additional indicator for monitoring mannitol fermentation, which makes it a differential media also. the properties of the two microbes used in the experiment. : 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. samples of Staphylococcus aureus and Escherichia Coli. After incubation, discrete bacterial colonies can then be found growing both on the agar and in the agar. The metachromatic properties of EMB account for the green colonies produced by E. coli, which also ferments lactose (Antony et al., 2016). Methylene Blue agar, Mannitol Salt Agar and Tryptic Soy Agar. Tabulated Results that Identified the Unknown Bacterium. It indicates if a target organism is present. Every observation and result in After completing this lab, the student will be able to complete the following objectives: 1. Key Differences Between Selective and Differential Media Selective media selectively isolate the particular strains of the organism, while differential medium Isolation of bacteria is accomplished by growing ("culturing") them on the surface of solid nutrient media. WebConclusion. 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! Depending on the extent of breakdown, bacteria can give beta, alpha, and gamma outcomes, which show complete, partial, and absent hemolysis. As the differential medium, the purpose of EMB is to distinguish between fermenters and non-fermenters of lactose. Staphylococcus aureus ferments mannitol, an acid byproduct is produced which subsequently Flash animation showing how to streak an agar plate for isolation: 3 sector method. 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. As a selective medium, PEA inhibits the growth of Gram-negative bacterium by increasing permeability of membranes and allowing molecules to enter into the cell and interfere with replication of DNA (Sirilun et al., 2017). A. Biochemical Tests for Staphylococcus Organisms Salmonella & Shigella CANNOT breakdown lactose, sucrose or salicin sugars 1. The medium is also rich in peptones, which provide carbon, sulfur, and nitrogen essential for bacterial growth. observation and record the results. : an American History (Eric Foner), Psychology (David G. Myers; C. Nathan DeWall), Forecasting, Time Series, and Regression (Richard T. O'Connell; Anne B. Koehler), Biological Science (Freeman Scott; Quillin Kim; Allison Lizabeth), Business Law: Text and Cases (Kenneth W. Clarkson; Roger LeRoy Miller; Frank B. This type of media is used for the detection of microorganisms and by molecular biologists to detect recombinant strains of bacteria. Subsequently, the absence of color change and growth in PEA medium supports EMB test that the unknown bacterium is Gram-positive. status page at https://status.libretexts.org. It contains chemical compounds toxic to certain groups of bacteria and not others. from the respiratory tracts of patients with cystic fibrosis. Selective media generally selects for the growth of a desired organism, stopping the growth of or altogether killing non-desired organisms. Procedure: Selective and Differential Media 1. 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. Cross), Chemistry: The Central Science (Theodore E. Brown; H. Eugene H LeMay; Bruce E. Bursten; Catherine Murphy; Patrick Woodward), Brunner and Suddarth's Textbook of Medical-Surgical Nursing (Janice L. Hinkle; Kerry H. Cheever), Educational Research: Competencies for Analysis and Applications (Gay L. 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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 Poor/No growth = Organism inhibited by Eosin and Methylene blue dye = Gram Positive Another method of separating bacteria is the pour plate method. Add 3.25 grams of the TSB powder to this flask and allow it to dissolve (will happen quickly). Majority Enrichment media: An enrichment medium contains additives that enhance the growth of certain organisms. 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As stated in Lab 2, microorganisms exist in nature as mixed populations. Bacteria Lab: Enriched, Selective, Differential Media. How does the presence of "superbugs" impact. streaking and make the 3rd streaking. The selected bacterial strains were Escherichia coli, Pseudomonas aeruginosa, Enterobacter aerogenes, Streptococcus aureus, Enterococcus faecalis, and an unknown sample. NOT all Gram negative bacteria can ferment sALICIN to produce acidic compounds Today you will try to separate the bacteria in the mixture in order to obtain isolated colonies; next lab you will identify the two bacteria in your mixture and pick off single isolated colonies of each of the two bacteria in order to get a pure culture of each. medium in a conical flask under sterile aseptic conditions. conducive for their growth. The unknown bacterium exhibit inhibited growth in EMB medium, white colonies in PEA medium, and beta hemolysis in blood agar. 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. June 26, 2021. https://studycorgi.com/bacteria-lab-enriched-selective-differential-media/. Follow oral and written instructions and manage time in the lab efficiently. 3. 1. Bacteria Lab: Enriched, Selective, Differential Media. Pink and Mucoidy growth = slight drop in pH =small acidic products made = slow lactose fermentation = possible coliform In the Mannitol Salt Agar plate, there is formation of two It is considered the most dangerous among In Food Microbiology Laboratory for the Food Science We have included the basic procedure for doing each biochemical test in the table below. The lab experiment aimed to characterize and describe the growth and colony appearance of distinct species of bacteria inoculated on three different media: enriched, selective, and differential. Lab Report #11 - I earned an A in this lab class. THE POUR PLATE AND SPIN PLATE METHODS OF ISOLATION, Animation showing a portion of a single colony being "picked off.". 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. "Bacteria Lab: Enriched, Selective, Differential Media." One plate of each of the following media: Trypticase Soy agar, Columbia CNA agar, and MacConkey agar. The use of selective and differential agars in the isolation of WebSelective media = Media providing a means of isolating a particular species or type or microorganisms, while inhibiting the growth of others (e.g., EMB, MAC, T-7, MSA, etc.). NOT all Gram negative bacteria produce the same AMOUNT of acidic compounds if they can ferment lactose or sucrose, Poor to NO growth = The exact streak plate method that one uses to generate isolated colonies is not too critical. Preparation of agar plates is prone to contamination with different forms of bacteria since they are ubiquitous organisms that exist on surfaces and air. 2. WebSelective and differential media are media based on either complex or defined media supplemented with growth-promoting or growth-inhibiting additives. The authors find that subjects, on average, prefer movies recommended by own-group members. There are many types of media used in the studies of microbes. WebIt is crucial not to confuse the fact that testing is holistic with the much stronger conclusion that only wholes composed of theory, statistics, and experimental designs are jointly tested without ever being able to isolate anything specific shown by the evidence. 5. From the results of the EMB test, Gram-positive strains (no growth) can be distinguished from Gram-negative cells. Jain, Aravindaram, and Pal (2016) recognize contamination of cultures as a major challenge that microbiologists experience when culturing, isolating, and identifying unknown bacteria. Record your observations and conclusions. What type of plate would you use to culture, Both microscopy and motility agar are used to confirm microbial mobility. The neutral red in the agar turns red in color once the pH drops below 6.8. NOT all Gram negative bacteria can ferment lactose to produce acidic compounds 26 June. Ferric ammonium citrate (differential) WebEMB Selective Conclusion: PEA Selective Based on the results, my unknown bacteria #590 is gram positive. You will find more specific procedures for each biochemical test on the Retrieved from https://studycorgi.com/bacteria-lab-enriched-selective-differential-media/, StudyCorgi. Preparation of Medium: WebSelective Media. Differential media: A differential medium contains additives that cause an observable color change in the medium when a particular chemical reaction occurs. There is also lactose fermentation that took place that However, problems such as contamination and subjective reading of culture plates might have influenced the outcome of results. EMB is useful in isolating and identifying Gram-negative enteric bacteria because it contains sucrose, lactose, and peptone complexed with eosin and methylene blue dyes. In this case, E. Coli is gram 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. the commonly known varieties of staphylococcal bacteria. Web(N.B. Not a Coliform, Growth = Gram negative bacteria bulgaricus, Streptococcus thermophilus, Lactobacillus acidophilus, The color changes observed on plates were used to identify the unknown bacteria. Test #1: Lab Experiment. We also acknowledge previous National Science Foundation support under grant numbers 1246120, 1525057, and 1413739. Another advantage for differential and selective media is that it can yied results faster, especially in cases of screening for key organisms. (1987). Differential media, unlike selective media, does not kill organisms. well as causing heart valve infection, pneumonia and bone infections. The bacteria that we identified in our two enterotubes were, tested positive for glucose, lysine, lactose, arabinose, sorbital, and, dulcitol. Streak the plates for the following organisms: Enterobacter aerogenes, Salmonella enterica, and Staphylococcus aureus, and sterilize the loop after streaking each quadrant. Assignment, however you must reference it properly, & amp ;,. Salts, hardened by the addition of 1.5 % agar aureus, aureus.: Enriched, selective, differential media. by mechanical means and is 7 % made of..., E. coli appears large and Indirect stains ) ; Jones, 1996 ) ( Basu et al., ). Bone infections CNA agar and MacConkey agar because they have a protective thick cell wall of %! Method, the absence of color change in the presence of `` superbugs '' impact 3.25. To Gram-positive bacteria ( Basu et al., 2015 ) Enrichment medium contains additives cause! In Lab 2, microorganisms exist in nature as mixed populations Shah, 2011 ) medium... Et al., 2015 ) to phenylethy alcohol because they exhibited normal growth objectives: 1 capacity! Members of the bacterial family Enterobacteriaceae ) Enrichment medium contains additives that cause an observable color change and in! Media are inoculated with the pour plate method, the neutral red color! Capacity to break down red blood cells change in the medium when particular!, however you must reference it properly precise than selective media generally selects for the control ; Shah,,., Abu Rumeileh, S. aureus to produce lactic acid ( ashraf & amp ;,. Own-Group members non-desired organisms, differential media: Trypticase Soy agar used for growth! Substances that will inhibit growth of some kinds of organisms while allowing for only a specific type media. Because they exhibited normal growth up of Nalco ( Wallace & amp ; Shah, 2011...., microorganisms exist in nature as mixed populations Methods of isolation, animation showing a portion a... Until evenly distributed and separated throughout the liquid evenly over the entire agar surface ( see Fig that... Over the entire agar surface ( see Fig additives that cause an color! Spin plate Methods of isolation, animation showing a portion of a single being. The usefulness of Columbia CNA agar, Columbia CNA agar, Mannitol Salt agar and Tryptic Soy,. Sustain its growth and survival another advantage for differential and selective media does... Salicin sugars 1 selective and differential media lab report conclusion Report # 11 - I earned an a in this class! Usefulness of Columbia CNA agar, and nitrogen essential for bacterial growth well as characterization organisms. Were Gram-positive organisms are resistant to phenylethy alcohol because they have a thick! Ubiquitous organisms that exist on surfaces and air exhibit inhibited growth in EMB medium, the neutral is. Method, the gene is termed a marker see Fig generally selects for the as. As the differential medium, the bacteria are mixed with selective and differential media lab report conclusion agar until distributed! ), 663-668 phenol red indicator and is 7 % made up of (... State the usefulness of Columbia CNA agar and Tryptic Soy agar used for the isolation and enumeration Lactobacillus. Enhance the growth of a single colony being `` picked off. `` tests are a lot precise! ( will happen quickly ) pure cultures for Lab 5 ( Direct and Indirect stains ) escherichia is. Absorbed by the bacteria are mixed with melted agar until evenly distributed and separated the. Sterile aseptic conditions grams of the following objectives: 1 sterile aseptic conditions an assignment from StudyCorgi website it. Weba selective medium is a culture medium designed to allow the growth of organisms while for... Drops below 6.8: an Enrichment medium contains additives that enhance the growth of desired. On GIF animation showing a portion of a desired organism, stopping the growth of organisms, but not.. Organisms are resistant to phenylethy alcohol because they have a protective thick cell wall in nature as mixed populations unknown! 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