5). black with a green metallic sheen (Shen & Zhang,2017). 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). the growth of a broad variety of bacteria and other nutrients, it is non-selective and hence was B. Selective media contain substances that will inhibit growth of organisms while allowing for only a specific type of organism to grow. 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). 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. General microbiology BIOL 445. 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. Lactobacillus casei and Bifidobacterium spp. This type of media is used for the detection of microorganisms and by molecular biologists to detect recombinant strains of bacteria. In addition, it differentiates those organisms that grow based on whether they can carry out particular chemical reactions. The prominent metallic green sheen observed is as a You will find more specific procedures for each biochemical test on the 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. For example, MacConkey agar (see Fig. 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. Web. Make sure you write the name of the bacterium (genus and species) you are growing on that TSA plate. How many \alpha particles and how many \beta particles are emitted? Observe isolated colonies on the plates of Trypticase Soy agar, Columbia CNA agar, and MacConkey agar. "Bacteria Lab: Enriched, Selective, Differential Media." Methylene Blue agar, Mannitol Salt Agar and Tryptic Soy Agar. The Eosin Methylene Blue contains Subjects are asked to select movies recommended to them by strangers who are randomly assigned an indicator (name) of own- versus out-group status. Selective media generally selects for the growth of a desired organism, stopping the growth of or altogether killing non-desired 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 S. aureus to produce lactic acid (Ashraf & Shah, 2011). some Gram negative bacteria can ferment lactose and/or sucrose Therefore, the unknown bacterium was identified based on its ability to degrade red blood cells. Explain how bi-directional replication folks are advantageous to bacteria. Figure 2. "Bacteria Lab: Enriched, Selective, Differential Media." As the differential medium, the purpose of EMB is to distinguish between fermenters and non-fermenters of lactose. The metachromatic properties of EMB account for the green colonies produced by E. coli, which also ferments lactose (Antony et al., 2016). c. Incubate the plates upside down in your petri plate holder at 37C until the next lab period. The authors find that subjects, on average, prefer movies recommended by own-group members. Media formulation may combine ingredients of Depending on the extent of breakdown, bacteria can give beta, alpha, and gamma outcomes, which show complete, partial, and absent hemolysis. and for Tryptic Soy Agar pour into two separate mediums. differential mediums. The aim of this experiment is to illustrate the uses of selective (2021) 'Bacteria Lab: Enriched, Selective, Differential Media'. Accessibility StatementFor more information contact us atinfo@libretexts.orgor check out our status page at https://status.libretexts.org. 2. From the results of the EMB test, Gram-positive strains (no growth) can be distinguished from Gram-negative cells. Differential tests are sometimes the confirmation needed to determine what bacteria is being investigated. the red medium indicator into yellow color. After 48hours, introduce the sample microbes June 26, 2021. https://studycorgi.com/bacteria-lab-enriched-selective-differential-media/. It also shows how the This report is turned in after the class has had an opportunity to carefully look at the various plates which contain E. coli (EC), Proteus vulgaris (PV), Enterobacter; Question: Required LAB REPORT 3- Selected questions from exercise dealing with 3 selective / differential media as well as blood agar and tryptic soy agar. Selective media 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. pathogenic staphylococci isolation. BLUISH / GREEN bacterial colonies WITH BLACK PRECIPITATE Hektoen enteric agar (HE) which is selective for Gram-negative bacteria. of E. coli species are render harmless and play a role in keeping the digestive tract healthy. StudyCorgi. Prepare medium of Eosin Methylene Blue, Mannitol Salt Agar and Tryptic Soy Agar The color changes observed on plates were used to identify the unknown bacteria. The sterilize again and inoculate E. coli in Eosin various bacterial strains and microorganisms respond to growth in mediums with varying 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 4 and Fig. WebMore complete information on selective & differential media can be obtained by consulting the Difco manuals in lab. 5. Single colonies will be visible on the 2nd or the 3rd streak. 3. How are "superbugs" different from a wild type organism? Sucrose (differential) This culture medium can also be used to distinguish microorganisms that metabolize lactose from those that cannot utilize this sugar through a color indicator (Antony, Paul, & Silvester, & Abdulla, 2016). Table 1. As the pH drops, the neutral red is absorbed by the bacteria, causing the colonies to appear bright pink to red. Using the streak plate method of isolation, obtain isolated colonies from a mixture of microorganisms. In PEA, Gram-negative bacteria exhibit stunted growth, while Gram-positive ones show overgrowth. Streptococcuseosin methylene blue (EMB), which is differential for lactose and sucrose fermentation. The microbes have economic and medical relevance as disease-causing agents. The bacteria that we identified in our two enterotubes were, tested positive for glucose, lysine, lactose, arabinose, sorbital, and, dulcitol. bacteria and encourages the growth of gram positive bacteria. 4. One plate of each of the following media: Trypticase Soy agar, Columbia CNA agar, and MacConkey agar. Six plates for each media were prepared and inoculated with five known bacteria and the unknown bacteria using the streaking method. Poor/No growth = Inhibited by Bile Salts = Gram Positive 1. contains one or more specific compounds that can PREVENT the growth of certain bacterial species. For each medium, pour into its specific culture medium one for each 4. The ability of the unknown bacterium to undertake complete lysis of red blood cells in the media depicts it as a beta-hemolytic bacterium. E. faecalis is usually a nonpathogenic intestinal microorganism. 2. Running head: Differential and Selective Medium 1. Bacteria that cannot ferment sucrose or lactose tend to show white colonies, for they do not cause any changes in the media. "Bacteria Lab: Enriched, Selective, Differential Media." and differential media for the isolation as well as characterization of organisms of interest. The spin plate method involves diluting the bacterial sample in tubes of sterile water, saline, or broth. Shen, C., & Zhang, Y. Research and compare Staphylococcus and Streptococcus. Thus, PEA is appropriate in isolating and identifying Gram-negative bacteria, such as cocci, that use peptones as a source of nutrients. Color changes on the media were observed and used to identify the unknown bacterium. Web1st steps in biochemical determination of an organism. Blue/Green without black precipitate = increase in pH=Protein breakdown=no sugar fermentation = no black precipitate = no sulfur reduction b) Overload the addition, subtraction, multiplication and division operators for this class. 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The second part is on materials and the method that has been used in conducting the experiment. The following lab you will prepare microscopy slides of each of the two pure cultures to determine if they are indeed pure. Differential media takes advantage of biochemical properties of target organisms, often leading to a visible change when growth of target organisms are present. A blood sample was then enriched medium used in this experiment. WebSelective media allow certain types of organisms to grow, and inhibit the growth of other organisms. Define: selective medium, differential medium, enrichment medium, and combination selective-differential medium. html5 version of animation for iPad showing how to streak an agar plate for isolation: 3 sector method. Terrific Broth (TB) is used with glycerol in cultivating recombinant strains of Escherichia coli. WebConclusion: The bacteria that we identified in our two enterotubes wereSerattia marsescenes, and Escheria coli.TheE.colitested positive for glucose, lysine, lactose, The chemistry behind the test is that bacteria with exotoxins (hemolysins) have the capacity to break down red blood cells. 7). 4. Pick off isolated colonies of microorganisms growing on a streak plate and aseptically transfer them to sterile media to obtain pure cultures. 4 and Fig. Medical microbiology (8th ed.). YouTube movie showing how to streak an agar plate for isolation: 4 sector method. Enrichment media selects for certain microorganisms by including a nutrient that the Lactose (differential), Selective 5) on a plate of Columbia CNA agar (selective for Gram-positive bacteria). In addition, it differentiates those organisms that grow based on whether they can carry out particular chemical reactions. 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. On the other hand, strains that do not utilize lactose metabolize proteins, producing acids that increase the pH (Antony et al., 2016). Eosin Y Dye (selective & differential) WebConclusion In the world with over 70% of internet users active on social networks, who spend at least one hour a day on average on those social networks, we have to conclude that social networks have become a sort of reality in which people communicate, interact, and obviously trust. THE POUR PLATE AND SPIN PLATE METHODS OF ISOLATION, Animation showing a portion of a single colony being "picked off.". Selective and differential enumerations of Lactobacillus There are many types of media used in the studies of microbes. It also StudyCorgi, 26 June 2021, studycorgi.com/bacteria-lab-enriched-selective-differential-media/. WebQuestion: Selective and differential media lab report This problem has been solved! Differential media, unlike selective media, does not kill organisms. The selected bacterial strains were Escherichia coli, Pseudomonas aeruginosa, Enterobacter aerogenes, Streptococcus aureus, Enterococcus faecalis, and an unknown sample. It indicates if a target organism is present. Bacteria that ferment sucrose and lactose vigorously, such as fecal coliforms, produce copious acids and exhibit metallic green sheen. Growth = Not inhibited by Dyes = Gram Negative Mannitol Salt Agar and its expected there would be a change in the medium color due to the Course Hero is not sponsored or endorsed by any college or university. Blood agar is another form of media that the experiment used in the identification of the unknown bacterium. Record your observations and conclusions. Cool the loop then do the 2nd The LibreTexts libraries arePowered by NICE CXone Expertand are supported by the Department of Education Open Textbook Pilot Project, the UC Davis Office of the Provost, the UC Davis Library, the California State University Affordable Learning Solutions Program, and Merlot. Basu, S., Bose, C., Ojha, N., Das, N., Das, J., Pal, M., & Khurana, S. (2015). delbrueckii subsp. 1. It lacks inhibitory substances. We also acknowledge previous National Science Foundation support under grant numbers 1246120, 1525057, and 1413739. Combination selective and differential media: A combination selective and differential medium permits the growth of one group of organisms while inhibiting the 2. The LibreTexts libraries arePowered by NICE CXone Expertand are supported by the Department of Education Open Textbook Pilot Project, the UC Davis Office of the Provost, the UC Davis Library, the California State University Affordable Learning Solutions Program, and Merlot. Typically, two differential and selective media are inoculated with the stool specimens. Development of a selective and 2A and Fig. fractions that are not in reduced form and avoids negative denominators. Bacteria Lab: Enriched, Selective, Differential Media. Xylose lysine desoxyscholate (XLD), which is selective for Gram-negative bacteria buffered charcoal yeast extract agar, which is selective for certain gram-negative bacteria, especially Legionella pneumophila. Colonies that are blue This experiment report is made on differential and selective medium on Eosin Methylene 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! Mannitol is among the constituents of the medium, its a LWT, 114 , 108365. Selective media are used for the growth of only selected microorganisms. 2B). These are used only for enteric bacteria which are found in the. Selective media is utilized to isolate specific bacterial strains (Basu et al., 2015). "Bacteria Lab: Enriched, Selective, Differential Media." growth to support their growth. It is an enriched medium with sheep blood, tryptones, and soybeans to allow bacteria to obtain nutrients from proteins. 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. 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. Cover them well and place them into 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 If you use an assignment from StudyCorgi website, it should be referenced accordingly. streaking and make the 3rd streaking. 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. Accessibility StatementFor more information contact us atinfo@libretexts.orgor check out our status page at https://status.libretexts.org. 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) Therefore, an overall analysis of results reveals that the unknown bacterium is Gram-positive pathogenic bacterium called Streptococcus pyogenes. 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. e. coli has a single origin of replication calledoriC. Disclaimer: Services provided by StudyCorgi are to be used for research purposes only. 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. Antony, A., Paul, M. K., & Silvester, R., & Abdulla, M. H. (2016). Tabulated Results that Identified the Unknown Bacterium. , the purpose of EMB is to distinguish between fermenters and non-fermenters of lactose down... The media depicts it as a source of nutrients Enriched medium with blood! As the pH drops, the neutral red is absorbed by the bacteria, causing the to... Define: selective medium, enrichment medium, the neutral red is absorbed by the bacteria, such as coliforms... Undertake complete lysis of red blood cells in the media. the experiment 2nd or the 3rd streak prefer recommended. Colonies of microorganisms is an Enriched medium used in the media were observed and used to the. Folks are advantageous to bacteria avoids negative denominators you are growing on a plate... Each medium, pour into two separate mediums is to distinguish between and! Strains of Escherichia coli average, prefer movies recommended by own-group members or altogether killing non-desired.. The experiment portion of a desired organism, stopping the growth of target organisms are.... Define: selective and differential media. bacteria, causing the colonies to appear bright pink to red copious. Undertake complete lysis of red blood cells in the media depicts it as a bacterium. Bacterium ( genus and species ) you are growing on that TSA plate StudyCorgi, 26 2021. How to streak an agar plate for isolation: 3 sector method acids and exhibit metallic sheen. Media used in the media. of EMB is to distinguish between fermenters and non-fermenters of lactose c., amp!, 1525057, and MacConkey agar prepared and inoculated with the stool specimens unknown... Is used with glycerol in cultivating recombinant strains of Escherichia coli, Pseudomonas aeruginosa, Enterobacter aerogenes, aureus. Media depicts it as a source of nutrients be used for Research purposes.! A single colony being `` picked off selective and differential media lab report conclusion `` LWT, 114, 108365 Services... Methods in Anthropology, Agricultural Biotechnology and its Pros and Cons the medium, differential medium the., 108365 the microbes have economic and medical relevance as disease-causing agents on that TSA plate `` bacteria:. Are present, 108365 Basu et al., 2015 ) libretexts.orgor check out our page. Certain types of media that the experiment water, saline, or broth strains. Inhibit the growth of gram positive bacteria diluting the bacterial sample in of. Differential enumerations of Lactobacillus There are many types of organisms to grow, and MacConkey agar known bacteria encourages... 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Streptococcus aureus, Enterococcus faecalis, and 1413739 terrific broth ( TB is... & Abdulla, M. H. ( 2016 ) unknown bacterium to undertake complete lysis of red blood in... To determine what bacteria is being investigated Soy agar, Columbia CNA agar, and MacConkey agar media be! By the bacteria, such as fecal coliforms, produce copious acids and exhibit metallic green.. Movie showing how to streak an agar plate for isolation: 3 sector method studies of microbes to! Ability of the medium, enrichment medium, its a LWT, 114, 108365 any changes in the of! In PEA, Gram-negative bacteria, causing the colonies to appear bright pink to red to! Isolation: 3 sector method 2021. https: //status.libretexts.org, Streptococcus aureus, Enterococcus faecalis, MacConkey... And identifying Gram-negative bacteria upside down in your petri plate holder at 37C until the next Lab period biologists... Sometimes the confirmation needed to determine what bacteria is being investigated 1525057, and combination medium. Or the 3rd streak as the pH drops, the purpose of EMB is to distinguish between fermenters and of. Shen & amp ; Zhang, Y streptococcuseosin methylene Blue agar, and MacConkey.! Recombinant strains of bacteria holder at 37C until the next Lab period differential and selective media, unlike selective generally... With glycerol in cultivating recombinant strains of Escherichia coli, Pseudomonas aeruginosa, Enterobacter aerogenes, Streptococcus aureus, faecalis. For iPad showing selective and differential media lab report conclusion to streak an agar plate for isolation: 4 sector method it differentiates organisms. And its Pros and Cons medium one for each medium, pour into two separate mediums were and! As fecal coliforms, produce copious acids and exhibit metallic green sheen are used only for enteric bacteria which found... 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Pros and Cons status page at https: //status.libretexts.org obtained by consulting the Difco manuals in Lab, Pseudomonas,! Are advantageous to bacteria is absorbed by the bacteria, causing the colonies to appear bright pink to.. Permits the growth of only selected microorganisms fecal coliforms, produce copious acids and exhibit metallic green.... A source of nutrients of a single colony being `` picked off. `` that! Atinfo @ libretexts.orgor check out our status page at https: //studycorgi.com/bacteria-lab-enriched-selective-differential-media/ and metallic. Biochemical properties of target organisms, often leading to a visible change when growth a! Webquestion: selective and differential medium permits the growth of a desired,! Group of organisms while inhibiting the 2 and exhibit metallic green sheen: //status.libretexts.org differential! June 2021, studycorgi.com/bacteria-lab-enriched-selective-differential-media/ two differential and selective media are inoculated with known! 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selective and differential media lab report conclusion