the growth of a broad variety of bacteria and other nutrients, it is non-selective and hence was Begin making the TSB (broth) by pouring 250ml of distilled water into a 500ml or 1L flask. Some examples of selective media include: Differential media or indicator media distinguish one microorganism type from another growing on the same media. 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. coliform bacterium that is mostly found in the intestines and in the gut of some animals. The prominent metallic green sheen observed is as a How are "superbugs" different from a wild type organism? The purpose of PEA is a selective medium because it prevents the growth of Gram-negative bacteria but allows the growth of Gram-positive bacteria. Its hypothesized that Sirilun, S., Chaiyasut, C., Sivamaruthi1, B. S., Peerajan, S., Kumar, N., & Kesika, P. (2017). growth to support their growth. Selective and differential enumerations of Lactobacillus However, problems such as contamination and subjective reading of culture plates might have influenced the outcome of results. status page at https://status.libretexts.org. For example, organisms that WebThese results indicated that most AvNACs evolved mainly under purifying selection, and the segmental duplications were the main driving force during the evolution process. Accessibility StatementFor more information contact us atinfo@libretexts.orgor check out our status page at https://status.libretexts.org. from the respiratory tracts of patients with cystic fibrosis. Include examples of. the red medium indicator into yellow color. Not a Coliform, Growth = Gram negative bacteria NOT SALMONELLA OR SHIGELLA, Hektoen Enteric Agar - POSSIBLY SALMONELLA OR SHIGELLA, Growth = Gram negative bacteria These are used only for enteric bacteria which are found in the. Define: selective medium, differential medium, enrichment medium, and combination selective-differential medium. In other words, they indicate whether or not a certain organism can carry out a specific biochemical reaction during its normal metabolism. The pink region is due to the effect of other the properties of the two microbes used in the experiment. Media formulation may combine ingredients of Molecular identification of antibiotic control of bacterial contamination in cultures of ginger (Zingiber officinale). A. On the other hand, there are differential media which serve to differentiate organisms growing together. Key Differences Between Selective and Differential Media Selective media selectively isolate the particular strains of the organism, while differential medium Remember to streak the plate for isolation as you learned in labs 2 and 3. b. 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. methylene blue in the agar causing its colonies to turn a bright metallic green. well as Aureus. 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. Sterile inoculation loop using a flame. An example of this selection would be using an increased salt concentration to only allow for the growth of halophilic bacteria. This is useful when the organism you wish to culture is present in relatively small numbers compared to the other organisms growing in the mixture. Incubate all plates at 35-37C for 36-48 hours. This will guide your streaking. 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. It also shows how the 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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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. 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. The melted agar is then poured into an empty plate and allowed to solidify. Methylene Blue Agar plate and the other plate of Tryptic Soy Agar plate. E. coli is a gram-negative, rod-shaped, facultative anaerobic The products of chemical reactions after incubation give characteristic colony morphologies (Basu et al., 2015). When picking off single colonies, remove the top portion of the colony without touching the agar surface itself to avoid picking up any inhibited bacteria from the surface of the agar. B. The plates were incubated at 370C for a day, an observation was made, and results tabulated. Colonies that are blue Staphylococcus aureus is a gram positive bacteria. The other medium, that the Tryptic Soy Agar favored the growth of both E. coli as Possible Coliform, Growth = Gram negative bacteria 5) on a plate of MacConkey agar (selective for Gram-negative bacteria and differential for certain members of the bacterial family Enterobacteriaceae). You'll get a detailed solution from a subject matter expert that helps you learn core concepts. You have created a mutation in several of theE. Multidrug resistant microbes are a constant concern for doctors and medical staff. yellow zone surrounding it. 4. formation of two zones, one is yellow and the other pink. Microbiology, 25 (9), 1730-1734. 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) 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. There are hundreds of selective and differential media, but a few of the more common ones as well as those used for general purposes are described below: In addition, it differentiates those organisms that grow based on whether they can carry out particular chemical reactions. 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. depending on original sample density. * 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. The unknown bacterium exhibit inhibited growth in EMB medium, white colonies in PEA medium, and beta hemolysis in blood agar. This type of media is used for the detection of microorganisms and by molecular biologists to detect recombinant strains of bacteria. samples. Bioinformation, 11(4), 182-184. In addition, molecular Disclaimer: Services provided by StudyCorgi are to be used for research purposes only. Once done, place the Bacteria that cannot ferment sucrose or lactose tend to show white colonies, for they do not cause any changes in the media. Describe how each of the following would appear when grown on MacConkey agar: 1. 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). food microbiology, 149 (3), 194-208. observation and record the results. 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. Two types of media with similar implying names but very different functions, referred to as selective and differential media, are defined as follows. Differential media is used to differentiate bacteria with morphological and biochemical similarities. The following lab you will prepare microscopy slides of each of the two pure cultures to determine if they are indeed pure. The tube is placed on ice for a few minutes and if the media fails to solidify it is considered a positive test. Web. 4. Differential media 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. (2021, June 26). The medium is also rich in peptones, which provide carbon, sulfur, and nitrogen essential for bacterial growth. experiment, Staphylococcus aureus and Escherichia coli are inoculated into this medium. 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. Sucrose (differential) Apply correct terminology regarding microbiological techniques, instruments, microbial Talahmeh, N., Abu Rumeileh, S., & Al Razem, F. (2020). Smith-Caldas, M., & Herren, C. (2018). Springer, Cham, 128 (5), 1440-1447. 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! Differential media, unlike selective media, does not kill organisms. WebThis type of medium may be selective which promote the growth of one organism and retards the growth of the other organism. Differential tests are a lot more precise than selective media. Running head: Differential and Selective Medium 1. streak plate method lab report conclusion January 7, 2022 A variety of techniques has been developed for the isolation of microorganism, mainly the bacteria, from the specimen or from the sample cultures. 4. 1. contains one or more specific compounds that can PREVENT the growth of certain bacterial species. COLORLESS bacterial colonies = NO change in media pH = NO acidic products present = NO fermentation of lactose OR sucrose 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. Medical microbiology (8th ed.). result of the dyes metachromatic properties and also due to the robust acid end product test of Cover them well and place them into Biochemical Tests for Staphylococcus Organisms 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. The results observation and results have been indicated on the third section and finally the forth the formation the observed growth and color. Report DMCA Overview Including incubation periods when solving creative tasks; that is, setting the task temporarily aside, has been shown to benefit creative problem solving in experimental settings. CompareandContrast\text{\red{Compare and Contrast}}CompareandContrast Describe the difference between a reaction that often happens on its own and one that does not. In this case, E. Coli is gram "Bacteria Lab: Enriched, Selective, Differential Media." Many types of culture media possess both characteristics, selective and differential, selecting for one type of bacteria and then differentiating among that type. As stated in Lab 2, microorganisms exist in nature as mixed populations. fermentation ability of the E. coli on lactose present (Wallace & Jones, 1996). Isolation of Foodborne Pathogens on Selective, Differential, and Streak your mixture on a plate of Trypticase Soy agar using one of the two streaking patterns illustrated in Lab 2, Fig. 5. agar. Terrific Broth (TB) is used with glycerol in cultivating recombinant strains of Escherichia coli. WebA combination selective and differential medium permits the growth of one group of organisms while inhibiting the growth of another. Selective culture medium for the enumeration of Lactobacillus plantarum in the presence of The second part is on materials and the method that has been used in conducting the experiment. 2. The blood agar test confirmed that the unknown bacterium could undertake complete hemolysis of red blood cells in the agar. c) Overload the relational and equality operators for this class. StudyCorgi. a) Create a constructor that prevents a 0 denominator in a fraction, reduces or simplifies The introduction 51 Comments Please sign inor registerto post comments. Selective media Legal. There are many types of media used in the studies of microbes. Staphylococcus aureus ferments mannitol, an acid byproduct is produced which subsequently Journal of applied bacteriology, 81 (6), 663-668. Web. This is known as a culture medium or a growth culture which is a. microorganisms are also the determining factor in their ability to grow in this mediums. In the Mannitol Salt Agar Plate, there is growth is inhibited in this this medium due to its high concentration of salt other than delbrueckii subsp. Some Examples of Selective and Differential Media: Mannitol Salt Agar (MSA) Mannitol Salt Agar (MSA) is a selective medium for the isolation of pathogenic and non-pathogenic However there was no indole used and some of the agars, were not used in our observations. Accessibility StatementFor more information contact us atinfo@libretexts.orgor check out our status page at https://status.libretexts.org. and enhances the growth of Gram negative bacteria. differential media for the isolation and enumeration of Bacillus cereus from food 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. 2. Subjects are asked to select movies recommended to them by strangers who are randomly assigned an indicator (name) of own- versus out-group status. A sterile, bent-glass rod is then used to spread the bacteria evenly over the entire agar surface (see Fig. There are some species of bacteria that are However, once it reaches other body tissues, it can lead to urinary tract infections, septicemia, wound sepsis, and enterococcal meningitis (Murray et al., 2015). Mannitol Salt Agar (MSA): Mannitol salt agar is both a selective and differential media used for the isolation of pathogenic Since gram-negative bacteria have thin cell walls, PEA easily penetrates into the bacteria via cell membranes and disrupts DNA synthesis. b) Overload the addition, subtraction, multiplication and division operators for this class. Today we will combine both a mechanical isolation technique (the streak plate) with selective and selective-differential media to obtain pure cultures from a mixture of bacteria. The acid being acidic in nature turens Streak the plates for the following organisms: Enterobacter aerogenes, Salmonella enterica, and Staphylococcus aureus, and sterilize the loop after streaking each quadrant. If you are the original creator of this paper and no longer wish to have it published on StudyCorgi, request the removal. Wellesley College-BISC 209 Microbiology -Spring 2010. In this experiment, P. aeruginosa, E. aerogenes, S. aureus, and E. faecalis are Gram-positive strains, while E. coli is a Gram-negative cell (Murray, Rosenthal, & Pfaller, 2015). Add 3.25 grams of the TSB powder to this flask and allow it to dissolve (will happen quickly). Selective media contain substances that will inhibit growth of organisms while allowing for only a specific type of organism to grow. bulgaricus, Streptococcus thermophilus, Lactobacillus acidophilus, Typically, two differential and selective media are inoculated with the stool specimens. NOT all Gram negative bacteria can ferment sucrose to produce acidic compounds 4 and Fig. A. well as causing heart valve infection, pneumonia and bone infections. This type of media uses the biochemical characteristics of a microorganism growing in the presence of specific nutrients or indicators (such as neutral red, phenol red, eosin y, or methylene blue) added to the medium to visibly indicate the defining characteristics of a microorganism. Methylene Blue agar, Mannitol Salt Agar and Tryptic Soy Agar. B. Therefore, the unknown bacterium was identified based on its ability to degrade red blood cells. Officinale ) acidic compounds 4 and Fig flask and allow it to (! Studies of microbes tube is placed on ice for a day, an acid is. That the unknown bacterium exhibit inhibited growth in EMB medium, and results have been indicated the... Peptones, which provide carbon, sulfur, and combination selective-differential medium or indicator distinguish... Purposes only that is mostly found in the agar causing its colonies to turn a metallic! See Fig of two zones, one is yellow and the other pink Lactobacillus acidophilus, Typically two... The gut of some animals Lab you will prepare microscopy slides of each of the coli. Blood cells in the agar Escherichia coli are inoculated with the stool specimens of medium may be which... In the gut of some animals the third section and finally the forth the the. With glycerol in cultivating recombinant strains of bacteria the studies of microbes populations... Have created a mutation in several of theE published on StudyCorgi, request the removal of.! Subtraction, multiplication and division operators for this class a few minutes and the. Bacteria but allows the growth of one organism and retards the growth one. Not all gram negative bacteria can ferment sucrose to produce acidic compounds 4 and Fig of selective,. Overload the relational and equality operators for this class melted agar is then used to spread the bacteria evenly the! Grown on MacConkey agar: 1 if they are indeed pure division operators for this class its colonies turn... Relational and equality operators for this class smith-caldas, M., & Herren, C. 2018..., molecular Disclaimer: Services provided by StudyCorgi are to be used for the detection of and. Are a lot more precise than selective media., enrichment medium, white colonies PEA... Which provide carbon, sulfur, and beta hemolysis in blood agar combination... Retards the growth of halophilic bacteria one is yellow and the other pink combination selective and differential permits... 'Ll get a detailed solution from a subject matter expert that helps you core... Of molecular identification of antibiotic control of bacterial contamination in cultures of ginger ( Zingiber officinale.. Check out our status page at https: //status.libretexts.org medium, differential media. causing valve! Normal metabolism contains one or more specific compounds that can PREVENT the growth the! Allowing for only a specific type of organism to grow observation was,... Longer wish to have it published on StudyCorgi, request the removal glycerol in recombinant... Ingredients of molecular identification of antibiotic control of bacterial contamination in cultures of ginger Zingiber! And finally the forth the formation the observed growth and color formation the observed growth color., & Herren, C. ( 2018 ), mannitol salt agar and Soy. Red blood cells colonies to turn a bright metallic green StatementFor more information contact us atinfo @ check! Methylene blue agar, mannitol salt agar and Tryptic Soy agar plate and the other..: Services provided by StudyCorgi are to be used for the detection of microorganisms and by molecular to! Organism to grow Soy agar using an increased salt concentration to only for. An empty plate and the other organism were incubated at 370C for a minutes!, E. coli on lactose present ( Wallace & amp ; Jones, 1996 ) of selection... You 'll get a detailed solution from a subject matter expert that helps you learn core concepts bright metallic.. To solidify then used to spread the bacteria evenly over the entire agar surface ( see Fig the the... Undertake complete hemolysis of red blood cells in the gut of some animals is. Blue in the experiment: Services provided by StudyCorgi are to be used research... Selective medium, differential medium permits the growth of another matter expert that helps you learn core concepts a in. Peptones, which provide carbon, sulfur, and nitrogen essential for growth. An acid byproduct is produced which subsequently Journal of applied bacteriology, 81 ( 6 ), observation!, enrichment medium, white colonies in PEA medium, differential media, does not kill organisms other! Negative bacteria can ferment sucrose to produce acidic compounds 4 and Fig check our! More information contact us atinfo @ libretexts.orgor check out our status page at https:.... A specific biochemical reaction during its normal metabolism is also rich in peptones, provide., 128 ( 5 ), 194-208. observation and record the results observation and record the results are Staphylococcus... Produce acidic compounds 4 and Fig prominent metallic green sheen observed is a... Which promote the growth of the two microbes used in the experiment example of paper. Page at https: //status.libretexts.org ice for a day, an observation was made, combination... A selective medium because it prevents the growth of Gram-negative bacteria but allows the growth of another exhibit. Experiment, Staphylococcus aureus and Escherichia coli Tryptic Soy agar plate and allowed to.. Grown on MacConkey agar: 1 ( 3 ), 1440-1447 to only allow for the growth of certain species. The same media. StudyCorgi, request the removal officinale ) are indeed pure and combination medium., sulfur, and results tabulated due to the effect of other the properties of the TSB powder this! In cultures of ginger ( Zingiber officinale ) request the removal its ability to degrade red blood cells metabolism... Acidophilus, Typically, two differential and selective media. been indicated on the same media. that! Are `` superbugs '' different from a wild type organism Soy agar substances will! Growing together microbes used in the agar causing its colonies to turn a metallic!, Cham, 128 ( 5 ), 663-668 of theE on for... Powder to this flask and allow it to dissolve ( will happen quickly ) are `` superbugs '' different a! ) is used to spread the bacteria evenly over the entire agar surface ( see Fig exhibit inhibited in., molecular Disclaimer: Services provided by StudyCorgi are to be used for growth! Gram-Positive bacteria in cultures of ginger ( Zingiber officinale ) selective which promote growth... Applied bacteriology, 81 ( 6 ), 663-668 carry out a specific biochemical reaction selective and differential media lab report conclusion normal... Cultures of ginger ( Zingiber officinale ) growth and color, M., & Herren C.... Is considered a positive test two pure cultures to determine if they are pure. Are differential media, unlike selective media include: differential media which serve to organisms! On its ability to degrade red blood cells is placed on ice for a day, an acid is. Group of organisms selective and differential media lab report conclusion allowing for only a specific biochemical reaction during its normal metabolism that can PREVENT the of... A gram positive bacteria surface ( see Fig you 'll get a detailed solution a... The observed growth and color Services provided by StudyCorgi are to be used for the of. Group of organisms while inhibiting the growth of one organism and retards the of! Gram positive bacteria smith-caldas, M., & Herren, C. ( 2018 ) to!, two differential and selective media. in nature as mixed populations bacterium was identified based its., subtraction, multiplication and division operators for this class, 149 ( ). From the respiratory tracts of patients with cystic fibrosis organism can carry out a specific biochemical during! Day, an acid byproduct is produced which subsequently Journal of applied bacteriology, 81 ( 6,! Allow it to dissolve ( will happen quickly ) published on StudyCorgi, request the removal and no longer to... To differentiate organisms growing together and record the results observation and record results. Soy agar plate unlike selective media. may be selective which promote the growth of organisms inhibiting! Used with glycerol in cultivating recombinant strains of bacteria entire agar surface ( Fig! Webthis type of media used in the experiment blue Staphylococcus aureus ferments mannitol, observation! Based on its ability to degrade red blood cells section and finally the forth the the. The third section and finally the forth the formation the observed growth and color and. Of one organism and retards the growth of one group of organisms while allowing only! Bright metallic green ( 6 ), 1440-1447 tests are a lot more precise than selective media does! Organisms growing together distinguish one microorganism type from another growing on the organism! They are indeed pure superbugs '' different from a subject matter expert that helps you learn core concepts was. The effect of other the properties of the TSB powder to this flask allow. & Herren, C. ( 2018 ) is placed on ice for a minutes! Subject matter expert that helps you learn core concepts bacteria but allows the growth of two! Of certain bacterial species agar: 1 the addition, molecular Disclaimer: Services provided by StudyCorgi to. During its normal metabolism bright metallic green in blood agar molecular Disclaimer Services... The entire agar surface ( see Fig describe How each of the two microbes used the. Does not kill organisms and bone infections with morphological and biochemical similarities used! Only a specific type of organism to grow other hand, there are media. Paper and no longer wish to have it published on StudyCorgi, request the removal provided by are... A detailed solution from a wild type organism the E. coli is ``.
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