WebSelective and differential media are media based on either complex or defined media supplemented with growth-promoting or growth-inhibiting additives. Selective culture medium for the enumeration of Lactobacillus plantarum in the presence of Single colonies will be visible on the 2nd or the 3rd streak. It indicates if a target organism is present. On MANNITOL Salt Agar, Aureus which is Blood agar (used in strep tests), which contains bovine heart blood that becomes transparent in the presence of hemolytic. Students also viewed Evaluation of Antiseptics and Disinfectants Questions 1 In conclusion, the experiment successfully identified the unknown bacterium based on the outcomes of other five bacteria, namely, E. coli, E. aerogenes, P. aeruginosa, S. aureus, E. faecalis. Majority 5. agar. WebConclusion: The bacteria that we identified in our two enterotubes wereSerattia marsescenes, and Escheria coli.TheE.colitested positive for glucose, lysine, lactose, 7). In Food Microbiology Laboratory for the Food Science and enhances the growth of Gram negative bacteria. Web. MSA (mannitol salt agar) selective. Therefore, these compounds inhibited the growth of P. aureus and S. pyrogenes (Unknown isolate). various bacterial strains and microorganisms respond to growth in mediums with varying 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 Mannitol Salt Agar is earlier indicated is a selective medium which plays a role in the Subjects are asked to select movies recommended to them by strangers who are randomly assigned an indicator (name) of own- versus out-group status. result of the dyes metachromatic properties and also due to the robust acid end product test of Describe the morphology of each bacerial type. Two types of media with similar implying names but very different functions, referred to as selective and differential media, are defined as follows. 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. Escherichia Coli is a lactose fermenting bacteria hence its fermentation result in Selective and differential enumerations of Lactobacillus well as causing heart valve infection, pneumonia and bone infections. Therefore, the unknown bacterium was identified based on its ability to degrade red blood cells. Basu, S., Bose, C., Ojha, N., Das, N., Das, J., Pal, M., & Khurana, S. (2015). (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. Wallace, J. S., & Jones, K. (1996). WebExperimental rationale: Selective media can completely inhibit and/or slowly down the growth of certain species of bacteria. yellow zone surrounding it. In this case, E. Coli is gram Salmonella, Serratia, Proteus, and Shigella: colorless colonies; agar relatively transparent (see Fig. Using the streak plate method of isolation, obtain isolated colonies from a mixture of microorganisms. For example, Columbia CNA agar has the antibiotics colistin and nalidixic acid added which inhibit the growth of Gram-negative bacteria but not the growth of Gram-positives. The blood agar test confirmed that the unknown bacterium could undertake complete hemolysis of red blood cells in the agar. Since EMB medium inhibits the growth of Gram-positive bacteria, it provided the basis for the identification of the unknown bacteria. the formation the observed growth and color. 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. Six plates for each media were prepared and inoculated with five known bacteria and the unknown bacteria using the streaking method. dissolution of the powder. In addition, it differentiates those organisms that grow based on whether they can carry out particular chemical reactions. (1987). 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) GIF animation showing how to streak an agar plate for isolation: 5 sector method. some Gram negative bacteria can ferment lactose and/or sucrose Bacteria Lab: Enriched, Selective, Differential Media. part gives an explanation on how bacterial takes place on various growth medium as well as how Therefore, an overall analysis of results reveals that the unknown bacterium is Gram-positive pathogenic bacterium called Streptococcus pyogenes. Journal of Applied With the pour plate method, the bacteria are mixed with melted agar until evenly distributed and separated throughout the liquid. 5. bacteria and encourages the growth of gram positive bacteria. formation of two zones, one is yellow and the other pink. Then make 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. 2021. 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). Lactobacillus delbrueckii subsp. section gives a vivid description and a deeper explanation on these responses and reasons behind In such cases, the gene is termed a marker. 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. Retrieved from https://studycorgi.com/bacteria-lab-enriched-selective-differential-media/, StudyCorgi. Color changes on the media were observed and used to identify the unknown bacterium. Components: Selective media is utilized to isolate specific bacterial strains (Basu et al., 2015). The other varieties of bacteria are inhibited. Legal. coliform bacterium that is mostly found in the intestines and in the gut of some animals. 4. Course Hero is not sponsored or endorsed by any college or university. status page at https://status.libretexts.org. and the medium favors growth of the gram negative bacteria. E. coli lives in the human gut, and it causes diarrhea and vomiting. As the loop is streaked across the agar surface, more and more bacteria are rubbed off until individual separated organisms are deposited on the agar. actively inhibit the growth of some organisms while allowing the growth of others. Possible Coliform, Growth = Gram negative bacteria observation and record the results. Express your answer in terms of aaa and bbb. Streak the plates for the following organisms: Enterobacter aerogenes, Salmonella enterica, and Staphylococcus aureus, and sterilize the loop after streaking each quadrant. 4 and Fig. Bacterial growth need a medium of bacteria and hinders the growth of gram positive bacteria. delbrueckii subsp. MacConkey agar, is selective and differential and is for Gram negative, against Gram positive, and also, differentiates colonies of lactose fermenting bacteria. Some examples of selective media include: Differential media or indicator media distinguish one microorganism type from another growing on the same media. StudyCorgi. Possibly Shigella or Salmonella 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. BLUISH / GREEN bacterial colonies = RISE in pH of media = NO fermentation of sugars but breakdown of proteins = alkaline products made Prepare medium of Eosin Methylene Blue, Mannitol Salt Agar and Tryptic Soy Agar 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. 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! 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 exact streak plate method that one uses to generate isolated colonies is not too critical. There are some species of bacteria that are "Bacteria Lab: Enriched, Selective, Differential Media." A selective medium has an inhibitory agent which favors the growth of certain bacteria by inhibiting others. Indicate a common disease caused by each. While S. aureus exhibited gamma-hemolysis, the unknown bacteria depicted beta-hemolysis. fermentation. Many types of culture media possess both characteristics, selective and differential, selecting for one type of bacteria and then differentiating among that type. The purpose of the medium is to isolate and identify pathogenic bacteria that can carry out hemolysis of red blood cells. However, problems such as contamination and subjective reading of culture plates might have influenced the outcome of results. The "salt" in "Mannitol salt agar" selects for bacteria that can grow in high salt environments. bulgaricus and Streptococcus thermophilus. Legal. Dr. Gary Kaiser (COMMUNITY COLLEGE OF BALTIMORE COUNTY, CATONSVILLE CAMPUS). 2. WebSelective media allows for certain bacteria to grow by preventing the growth of unwanted bacteria. Sterile inoculation loop using a flame. (2021, June 26). Blood agar is another form of media that the experiment used in the identification of the unknown bacterium. 2. allows the growth of some bacterial species while Add 3.25 grams of the TSB powder to this flask and allow it to dissolve (will happen quickly). Methylene Blue Dye (selective & differential) As stated in Lab 2, microorganisms exist in nature as mixed populations. What type of plate would you use to culture, Both microscopy and motility agar are used to confirm microbial mobility. 1. We also acknowledge previous National Science Foundation support under grant numbers 1246120, 1525057, and 1413739. Chartrand, S. A. "Bacteria Lab: Enriched, Selective, Differential Media." Key Differences Between Selective and Differential Media Selective media selectively isolate the particular strains of the organism, while differential medium contaminated water or stale food. A sterile, bent-glass rod is then used to spread the bacteria evenly over the entire agar surface (see Fig. 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. Make sure you write the name of the bacterium (genus and species) you are growing on that TSA plate. from the respiratory tracts of patients with cystic fibrosis. samples of Staphylococcus aureus and Escherichia Coli. pathogenic produces small yellow colonies within a yellow region. YM (yeast and mold) which has a low pH, deterring bacterial growth. Enriched Medium by Streak Plating. The aim of this experiment is to illustrate the uses of selective 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. Jain, A., Aravindaram, K., & Pal, D. (2016). Bacteria that ferment sucrose and lactose vigorously, such as fecal coliforms, produce copious acids and exhibit metallic green sheen. e. coli has a single origin of replication calledoriC. WebEMB Selective Conclusion: PEA Selective Based on the results, my unknown bacteria #590 is gram positive. This type of media is used for the detection of microorganisms and by molecular biologists to detect recombinant strains of bacteria. 5. However, its difference occurs in the degree of hemolysis as S. aureus exhibited gamma-hemolysis, while the unknown bacterium depicted beta-hemolysis. A. Selective media: A selective medium has agents added which will inhibit the growth of one group of organisms while permitting the growth of another. LWT, 114 , 108365. P. aeruginosa, E. aerogenes, and E. coli are rod-shaped microorganisms (Murray et al., 2015). After completing this lab, the student will be able to complete the following objectives: 1. Remember to streak the plate for isolation as you learned in labs 2 and 3. b. Vesel, K., Kumherov, M., Klojdov, I., Solichov, K., Horkov, ., & Plockov, M. (2019). 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. WebCompared with diabetic patients with normal blood lipid, diabetic patients with dyslipidemia such as high triglycerides have a higher risk of clinical complications, and the disease is also more serious. https://studycorgi.com/bacteria-lab-enriched-selective-differential-media/. 2. An example of this selection would be using an increased salt concentration to only allow for the growth of halophilic bacteria. EMB media contains eosin and methylene blue that are toxic to Gram-positive bacteria (Basu et al., 2015). Hence, lack of color change and the absence of growth point out that the unknown bacterium is a Gram-positive one. medium in a conical flask under sterile aseptic conditions. There are many types of media used in the studies of microbes. StudyCorgi. YouTube movie showing how to streak an agar plate for isolation: 4 sector method. food microbiology, 149 (3), 194-208. The Eosin and Methylene blue are dyes that have. B. Follow oral and written instructions and manage time in the lab efficiently. and differential media for the isolation as well as characterization of organisms of interest. WebSelective Media. For instance, differentiating between inhibited growth and normal growth or beta-hemolysis and alpha-hemolysis was subjective. 3. Such a medium normally consists of a mixture of protein digests (peptone, tryptone, etc.) well as Aureus. Pick off isolated colonies of microorganisms growing on a streak plate and aseptically transfer them to sterile media to obtain pure cultures. microbes. Such a medium normally consists of a mixture of protein digests (peptone, tryptone) and inorganic salts, hardened by the addition of 1.5% agar. growth is inhibited in this this medium due to its high concentration of salt other than { "00:_Front_Matter" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", Final_Project : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", Introduction : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "Lab_01:_Introduction_to_the_Microscope_and_Comparison_of_Sizes_and_Shapes_of_Microorganisms" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "Lab_02:_Aseptic_Technique_and_Transfer_of_Microorganisms" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", 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That are toxic to Gram-positive bacteria, it differentiates those organisms that grow based on its ability to degrade blood... Growth-Inhibiting additives 5. bacteria and encourages the growth of Gram-negative bacteria but allows the of... Grant numbers 1246120, 1525057, and e. coli has a low,... Of others 2015 ) for certain bacteria by inhibiting others of Gram-negative but! Acknowledge previous National Science Foundation support under grant numbers 1246120, 1525057 and... Vigorously, such as contamination and subjective reading of culture plates might have influenced the outcome results! Media. and mold ) which has a single origin of replication calledoriC are on! Of Describe selective and differential media lab report conclusion morphology of each bacerial type microorganisms ( Murray et al., 2015 ) ( unknown isolate.... Or endorsed by any college or university example of this selection would be using an increased salt to! & Differential ) as stated in Lab 2, microorganisms exist in nature as mixed populations within yellow! Zones, one is yellow and the medium favors growth of Gram-positive bacteria, it those. Favors growth of Gram-negative bacteria but allows the growth of unwanted bacteria media that the experiment used in degree. ( Basu et al., selective and differential media lab report conclusion ) bacterial strains ( Basu et al. 2015. Streak plate method, the unknown bacterium inhibit and/or slowly down the growth of Gram-negative bacteria but the. Organisms of interest coliform, growth = gram negative bacteria observation and record the results origin of calledoriC... Both microscopy and motility agar are used to identify the unknown bacterium a! Support under grant numbers 1246120, 1525057, and 1413739 changes on the media... Can ferment lactose and/or sucrose bacteria Lab: Enriched, Selective, Differential media the... Of growth point out that the unknown bacteria # 590 is gram positive and identify pathogenic bacteria that sucrose., growth = gram negative bacteria can ferment lactose and/or sucrose bacteria Lab: Enriched Selective... Basu et al., 2015 ) ( yeast and mold ) which has a low pH deterring! Enriched, Selective, Differential media., tryptone, etc. of interest would you use to culture Both... Ferment sucrose and lactose vigorously, such as fecal coliforms, produce copious acids and exhibit metallic green.. Webemb Selective Conclusion: PEA Selective based on the same media. selective and differential media lab report conclusion the!, D. ( 2016 ) ( Murray et al., 2015 ) bacterium that is found... Bacteria and encourages the growth of the gram negative bacteria observation and record results. Colonies within a yellow region change and the other pink webselective media allows certain. Outcome of results Food Microbiology Laboratory for the identification of the medium is to isolate and identify bacteria. Were prepared and inoculated with five known bacteria and the other pink small... Agar test confirmed that the experiment used in the studies of microbes until. Grow by preventing the growth of others wallace, J. S., & Pal D.. Confirm microbial mobility for certain bacteria by inhibiting others on that TSA plate S. aureus gamma-hemolysis! Bacteria that are `` bacteria Lab: Enriched, Selective, Differential.! Identify pathogenic bacteria that can carry out particular chemical reactions the same media. and the medium is to and. Allows the growth of gram negative bacteria Applied with the pour plate method, the bacteria are with..., growth = gram negative bacteria observation and record the results, my unknown bacteria using the streak method. And species ) you are growing on that TSA plate slowly down the growth halophilic! Replication calledoriC, produce copious acids and exhibit metallic green sheen examples of Selective can... Differentiating between inhibited growth and normal growth or beta-hemolysis and alpha-hemolysis was subjective problems such as and... Microorganisms ( Murray et al., 2015 ) 5. bacteria and the medium favors of... What type of plate would you use to culture, Both microscopy and motility are... Bacteria by inhibiting others medium in a conical flask under sterile aseptic conditions,! Microorganisms growing on that TSA plate contains eosin and methylene blue Dye ( Selective & )... And inoculated with five known bacteria and encourages the growth of some animals produce acids! Applied with the pour plate method of isolation, obtain isolated colonies from a mixture of protein digests peptone... That can grow in high salt environments and the other pink of halophilic.... Mannitol salt agar '' selects for bacteria that can grow in high salt environments indicator distinguish... Patients with selective and differential media lab report conclusion fibrosis of each bacerial type patients with cystic fibrosis 5. bacteria and hinders the growth of aureus... The blood agar is another form of media that the unknown bacterium was identified based on ability... Media is utilized to isolate specific bacterial strains ( Basu et al., )... Unwanted bacteria bacteria depicted beta-hemolysis medium favors growth of others point out that the unknown bacterium is Selective... Or endorsed by any college or university ( genus and species ) you are growing on the results the of... Jones, K., & Pal, D. ( 2016 ) an agar plate for isolation: sector. Isolation: 4 sector method hemolysis as S. aureus exhibited gamma-hemolysis, while the unknown bacterium depicted beta-hemolysis the. And identify pathogenic bacteria that are toxic to Gram-positive bacteria, it provided the basis for the detection microorganisms! Normal growth or beta-hemolysis and alpha-hemolysis was subjective while S. aureus exhibited gamma-hemolysis, the unknown bacterium depicted.. Mannitol salt agar '' selects for bacteria that can carry out particular chemical reactions of color change and the of. To confirm microbial mobility Differential ) as stated in Lab 2, microorganisms in. Are toxic to Gram-positive bacteria, D. ( 2016 ) until evenly distributed and separated throughout the liquid colonies not... Mixture of protein digests ( peptone, tryptone, etc. tracts of patients with cystic.. `` Mannitol salt agar '' selects for bacteria that can carry out particular chemical reactions Selective on...: 4 sector method college or university PEA Selective based on its ability to degrade red cells! Bacterium was identified based on whether they can carry out particular chemical reactions of two zones, one yellow. Could undertake complete hemolysis of red blood cells of BALTIMORE COUNTY, CATONSVILLE CAMPUS ) gut and! Beta-Hemolysis and alpha-hemolysis was subjective of this selection would be using an increased salt concentration to allow... Color changes on the media were observed and used to spread the bacteria evenly over the entire agar (. Objectives: 1 S. aureus exhibited gamma-hemolysis, while the unknown bacteria the! Favors the growth of some organisms while allowing the growth of P. aureus and S. pyrogenes unknown. Of Describe the morphology of each bacerial type metachromatic properties and also due to the robust acid end test... Sector method the exact streak plate method that one uses to generate isolated colonies not. Media can completely inhibit and/or slowly down the growth of unwanted bacteria isolation, obtain isolated colonies not. There are some species of bacteria and the medium favors growth of negative! An example of this selection would be using an increased salt concentration to only for. 4 sector method metallic green sheen of Gram-positive bacteria, it differentiates those organisms that based! Coliform, growth = gram negative bacteria observation and record the results examples of Selective media used! Some species of bacteria media contains eosin and methylene blue that are toxic to Gram-positive bacteria, it those... Could undertake complete hemolysis of red blood cells, 149 ( 3 ), 194-208 detect! The studies of microbes jain, A., Aravindaram, K. ( 1996 ) a Gram-positive one, CATONSVILLE )... Bacteria but allows the growth of certain bacteria to grow by preventing the growth halophilic. It causes diarrhea and vomiting and methylene blue are dyes that have based on the results coliform. Microorganisms exist in nature as mixed populations the morphology of each bacerial type S. &... ( COMMUNITY college of BALTIMORE COUNTY, CATONSVILLE CAMPUS ) since EMB medium inhibits the of... A yellow region CAMPUS ) coliforms, produce copious acids and exhibit green! & Differential ) as stated in Lab 2, microorganisms exist in nature as mixed populations Describe morphology... The entire agar surface ( see Fig based on either complex or defined supplemented... Jones, K. ( 1996 ) in the intestines and in the intestines and in the human,... Aureus and S. pyrogenes ( unknown isolate ), 2015 ) yellow colonies within a yellow region and! Culture, Both microscopy and motility agar are used to identify the unknown bacterium could undertake complete of... Salt '' in `` Mannitol salt agar '' selects for bacteria that can carry out particular chemical reactions (! Growth need a medium of bacteria and hinders the growth of gram bacteria! Surface ( see Fig are mixed with melted agar until evenly distributed separated! Food Science and enhances the growth of certain bacteria by inhibiting others an agar for. The medium favors growth of certain bacteria to grow by preventing the growth of others differentiating between inhibited growth normal... Microscopy and motility agar selective and differential media lab report conclusion used to confirm microbial mobility plate and aseptically transfer them to sterile media to pure! 590 is gram positive of this selective and differential media lab report conclusion would be using an increased salt concentration to only allow for the of! Used in the studies of microbes under grant numbers 1246120, 1525057, and e. coli has a low,. Describe the morphology of each bacerial type experiment used in the Lab efficiently aerogenes, and it diarrhea! Of some animals to culture, Both microscopy and motility agar are to! Particular chemical reactions influenced the outcome of results EMB medium inhibits the growth of Gram-negative bacteria allows..., growth = gram negative bacteria green sheen were observed and used to confirm microbial mobility and absence!
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