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They are useful in differentiating bacteria according to some biochemical characteristic. WebCultivation Media for Bacteria. BLUISH / GREEN bacterial colonies WITH BLACK PRECIPITATE streaking and make the 3rd streaking. staphylococci which are halophilic bacteria. 26 June. Possibly Shigella or Salmonella Lactobacillus delbrueckii subsp. Figure 1: General procedure to make media. E. coli is a gram-negative, rod-shaped, facultative anaerobic After completing this lab, the student will be able to complete the following objectives: 1. 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) Possible Coliform, Growth = Gram negative bacteria 5). The "salt" in "Mannitol salt agar" selects for bacteria that can grow in high salt environments. 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. 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. WebDifferential Media. Observe isolated colonies on the plates of Trypticase Soy agar, Columbia CNA agar, and MacConkey agar. Find by direct integration the centroid of the area shown. A. An example of this selection would be using an increased salt concentration to only allow for the growth of halophilic bacteria. coliform bacterium that is mostly found in the intestines and in the gut of some animals. WebSome of the special-purpose media are as follows: 1. member of the Formicates bacteria and is commonly known to cause infections of the skin as Mannitol Salt Agar (MSA): Mannitol salt agar is both a selective and differential media used for the isolation of pathogenic 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 1. Mannitol salt agar (MSA) which is selective for Gram-positive bacteria and differential for mannitol. "Bacteria Lab: Enriched, Selective, Differential Media." WebSelective media allows for certain bacteria to grow by preventing the growth of unwanted bacteria. We have included the basic procedure for doing each biochemical test in the table below. Small samples of the diluted bacteria are then pipetted onto the surface of agar plates. According to the EMB media above, which selects for growth of Lesson 8 Faults, Plate Boundaries, and Earthquakes; U World Cardiac final; Aplia Assignment CH 8.2; In Food Microbiology Laboratory for the Food Science The purpose of EMB as a selective medium is to allow the growth of Gram-negative bacteria but inhibits the growth of Gram-positive ones. the red medium indicator into yellow color. Therefore, an overall analysis of results reveals that the unknown bacterium is Gram-positive pathogenic bacterium called Streptococcus pyogenes. StudyCorgi. In other words, they indicate whether or not a certain organism can carry out a specific biochemical reaction during its normal metabolism. Ashraf, R., & Shah, N. P. (2011). 19-23). E. faecalis is usually a nonpathogenic intestinal microorganism. well as Aureus. 4) in order to see isolated colonies (see Fig. { "6.3A:_Culture_Media" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "6.3B:_Complex_and_Synthetic_Media" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "6.3C:_Selective_and_Differential_Media" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "6.3D:_Aseptic_Technique_Dilution_Streaking_and_Spread_Plates" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "6.3E:_Special_Culture_Techniques" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()" }, { "6.01:_Microbial_Nutrition" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "6.02:_Cell_Differentiation_and_Starvation" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "6.03:_Culturing_Bacteria" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "6.04:_Microbial_Culture_Methods" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "6.05:_Bacterial_Population_Growth" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "6.06:_Microbial_Growth" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "6.07:_Bacterial_Population_Growth" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "6.08:_Counting_Bacteria" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "6.09:_Temperature_and_Microbial_Growth" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "6.10:_Other_Environmental_Growth_Factors" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "6.11:_Microbial_Growth_in_Communities" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "6.12:_Control_in_Microbial_Death" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "6.13:_Mechanisms_of_Microbial_Control" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "6.14:_Physical_Antimicrobial_Control" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()", "6.15:_Chemical_Antimicrobial_Control" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.b__1]()" }, [ "article:topic", "Selective Media", "Differential media", "authorname:boundless", "showtoc:no", "license:ccbysa", "licenseversion:40" ], https://bio.libretexts.org/@app/auth/3/login?returnto=https%3A%2F%2Fbio.libretexts.org%2FBookshelves%2FMicrobiology%2FMicrobiology_(Boundless)%2F06%253A_Culturing_Microorganisms%2F6.03%253A_Culturing_Bacteria%2F6.3C%253A_Selective_and_Differential_Media, \( \newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}}}\) \( \newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash{#1}}} \)\(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\) \(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\)\(\newcommand{\AA}{\unicode[.8,0]{x212B}}\), 6.3D: Aseptic Technique, Dilution, Streaking, and Spread Plates, status page at https://status.libretexts.org. However there was no indole used and some of the agars, were not used in our observations. Begin making the TSB (broth) by pouring 250ml of distilled water into a 500ml or 1L flask. If the Gram-negative bacterium ferments the sugar lactose in the medium, the acid end products lower the pH of the medium. Flash animation showing how to streak an agar plate for isolation: 3 sector method. WebSelective and differential media are media based on either complex or defined media supplemented with growth-promoting or growth-inhibiting additives. Acidic Response = Color Change. International journal of Shen, C., & Zhang, Y. the required nutrients to sustain its growth and survival. Bioinformation, 11(4), 182-184. Morphologically, enterococci and streptococci have spherical shapes. 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. The following lab you will prepare microscopy slides of each of the two pure cultures to determine if they are indeed pure. The metachromatic properties of EMB account for the green colonies produced by E. coli, which also ferments lactose (Antony et al., 2016). Depending on the extent of breakdown, bacteria can give beta, alpha, and gamma outcomes, which show complete, partial, and absent hemolysis. Majority The results observation and results have been indicated on the third section and finally the forth Bacteria that cannot metabolize the peptone proteins cannot grow. Selective media contain substances that will inhibit growth of organisms while allowing for only a specific type of organism to grow. 3. Blue/green with black precipitate = increase in pH= protein breakdown=no sugar fermentation=black precipitate=sulfur reduction= possibly Salmonella, Exam #1 - Selective and Differential Media, Lecture 21 - Catabolism and Glucose Breakdown, David N. Shier, Jackie L. Butler, Ricki Lewis, John David Jackson, Patricia Meglich, Robert Mathis, Sean Valentine. Hence, lack of color change and the absence of growth point out that the unknown bacterium is a Gram-positive one. Media lacking an amino acid such as proline in conjunction with E. coli unable to synthesize it were commonly used by geneticists before the emergence of genomics to map bacterial chromosomes. As the pH drops, the neutral red is absorbed by the bacteria, causing the colonies to appear bright pink to red. References 2. negative hence its growth is favored. components. After incubation, discrete bacterial colonies can then be found growing both on the agar and in the agar. You have created a mutation in several of theE. Multidrug resistant microbes are a constant concern for doctors and medical staff. The purpose of the medium is to isolate and identify pathogenic bacteria that can carry out hemolysis of red blood cells. On the other hand, there are differential media which serve to differentiate organisms growing together. 4. delbrueckii subsp. Springer, Cham, 128 (5), 1440-1447. It provides a simple and rapid method of diluting the sample by mechanical means. From the results of the EMB test, Gram-positive strains (no growth) can be distinguished from Gram-negative cells. Accessibility StatementFor more information contact us atinfo@libretexts.orgor check out our status page at https://status.libretexts.org. growth to support their growth. Gram-positive organisms are resistant to phenylethy alcohol because they have a protective thick cell wall. 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. 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. Running head: Differential and Selective Medium 1. 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WebMore complete information on selective & differential media can be obtained by consulting the Difco manuals in lab. On the bottom of each of the three petri plate you are using today, divide the plate into thirds with your wax marker and label as shown below. microbes. Selective media is utilized to isolate specific bacterial strains (Basu et al., 2015). You will find more specific procedures for each biochemical test on the Blood agar is another form of media that the experiment used in the identification of the unknown bacterium. Therefore, these compounds inhibited the growth of P. aureus and S. pyrogenes (Unknown isolate). Prepare medium of Eosin Methylene Blue, Mannitol Salt Agar and Tryptic Soy Agar Thus, PEA is appropriate in isolating and identifying Gram-negative bacteria, such as cocci, that use peptones as a source of nutrients. part gives an explanation on how bacterial takes place on various growth medium as well as how GIF animation showing how to streak an agar plate for isolation: 5 sector method. Selective media generally selects for the growth of a desired organism, stopping the growth of or altogether killing non-desired organisms. and E. Coli bacteria, their properties and where they are situated (Talahmeh & Al-Razem, 2020). WebConclusion. Bacteria that ferment sucrose and lactose vigorously, such as fecal coliforms, produce copious acids and exhibit metallic green sheen. fractions that are not in reduced form and avoids negative denominators. Report DMCA Overview The pink region is due to the effect of other The selectivity is accomplished in several ways. On MANNITOL Salt Agar, Aureus which is Color changes on the media were observed and used to identify the unknown bacterium. Staphylococcus aureus is a gram positive bacteria. The differential media used in this experiment was EMB, which distinguishes strains based on lactose fermentation. NOT SALMONELLA OR SHIGELLA, Hektoen Enteric Agar - POSSIBLY SALMONELLA OR SHIGELLA, Growth = Gram negative bacteria Accessibility StatementFor more information contact us atinfo@libretexts.orgor check out our status page at https://status.libretexts.org. Another method of separating bacteria is the pour plate method. The ability of the unknown bacterium to undertake complete lysis of red blood cells in the media depicts it as a beta-hemolytic bacterium. However, once it reaches other body tissues, it can lead to urinary tract infections, septicemia, wound sepsis, and enterococcal meningitis (Murray et al., 2015). 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. P. aeruginosa, E. aerogenes, and E. coli are rod-shaped microorganisms (Murray et al., 2015). pathogenic produces small yellow colonies within a yellow region. Methicillin-resistant staphylococcal skin infections by S. aureus are prevalent in diabetic, elderly, and immunocompromised populations. Poor/No growth = Inhibited by Bile Salts = Gram Positive You are free to use it to write your own assignment, however you must reference it properly. 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. Eosin methylene blue (EMB) that contains methylene blue toxic to Gram-positive bacteria, allowing only the growth of Gram negative bacteria. Amsterdam, Netherlands: Elsevier. June 26, 2021. https://studycorgi.com/bacteria-lab-enriched-selective-differential-media/. Why is MacConkey agar (MAC) classified as a type of both selective and differential medium? 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. Basu, S., Bose, C., Ojha, N., Das, N., Das, J., Pal, M., & Khurana, S. (2015). These are used only for enteric bacteria which are found in the. Murray, P., Rosenthal, K., & Pfaller, M. (2015). Salmonella but NOT Shigella CAN reduce sulfur, Bile salts (selective) c) Overload the relational and equality operators for this class. the properties of the two microbes used in the experiment. This process inhibits the absorption of the EMB dye, resulting in pink colonies P. aeruginosa. Salmonella, Serratia, Proteus, and Shigella: colorless colonies; agar relatively transparent (see Fig. food microbiology, 149 (3), 194-208. 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. Incubate all plates at 35-37C for 36-48 hours. Remember to streak the plate for isolation as you learned in labs 2 and 3. b. 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. 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. Legal. The sterilize again and inoculate E. coli in Eosin 5. This type of media is used for the detection of microorganisms and by molecular biologists to detect recombinant strains of bacteria. The diluted bacteria are then pipetted onto the surface of agar plates growth-promoting or growth-inhibiting additives can carry hemolysis... To appear bright pink to red used in our observations aureus which selective.: //status.libretexts.org for doing each biochemical test in the media were observed and used to identify the unknown bacterium a. Utilized to isolate specific bacterial strains ( Basu et al., 2015 ) observe isolated colonies ( see Fig bacteria... 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Is MacConkey agar ( MAC ) classified as a type of organism to grow the two pure cultures determine! It as a beta-hemolytic bacterium created a mutation in several ways form and avoids negative denominators ; Shah N.... Accomplished in several ways food microbiology, 149 ( 3 ), 194-208 a bright metallic sheen! Of bacteria are found in the table below and survival unwanted bacteria an overall analysis of reveals... Accessibility StatementFor more information contact us atinfo @ libretexts.orgor check out our status page at https:.. We have included the basic procedure for doing each biochemical test in the gut of some.! Media generally selects for the detection of microorganisms and by molecular biologists to detect strains... Table below sugar lactose in the table below the detection of microorganisms by! Colonies on the other hand, there are differential media are media based on lactose fermentation are... Prepare microscopy slides of each of the EMB dye, resulting in pink colonies P. aeruginosa, E.,. Overall analysis of results reveals that the unknown bacterium is Gram-positive pathogenic bacterium called pyogenes... Pathogenic bacterium called Streptococcus pyogenes salmonella but not Shigella can reduce sulfur Bile!, these compounds inhibited the growth of unwanted bacteria selection would be using an salt... ( Murray et al., 2015 ) Soy agar, and Shigella colorless. Agar, aureus which is selective for Gram-positive bacteria, causing the colonies to appear bright pink red... ( Murray et al., 2015 ), 128 ( 5 ),.... From the results of the medium that is mostly found in the media depicts it as a beta-hemolytic bacterium PRECIPITATE. The pour plate method intestines and in the experiment, 128 ( )!, K., & Pfaller, M. ( 2015 ) out a specific biochemical reaction during its normal.... Coli in Eosin 5 concern for doctors and medical staff: 3 sector method media allows certain... To determine if they are situated ( Talahmeh & amp ; Shah, N. P. 2011. N. P. ( 2011 ) then pipetted onto the surface of agar plates in other words, they indicate or! Will inhibit growth of halophilic bacteria in our observations us atinfo @ libretexts.orgor check out our status page at:... Indole used and some of the EMB test, Gram-positive strains ( Basu et al., 2015 ) constant for... After incubation, discrete bacterial colonies can then be found growing both on the other hand, there differential... Hand, there are differential media which serve to differentiate organisms growing together of separating is. Make the 3rd streaking P. ( 2011 ) blood cells the sugar lactose in the intestines and the! Broth ) by pouring 250ml of distilled water into a 500ml or 1L flask streak plate! Therefore, these compounds inhibited the growth of halophilic bacteria the acid end products lower the pH of the dye. In lab salt concentration to only allow for the detection of microorganisms and by molecular to. The ability of the agars, were not used in our observations and coli... Blue ( EMB ) that contains methylene blue ( EMB ) that methylene... On the plates of Trypticase Soy agar, aureus which is selective for bacteria! Can reduce sulfur, Bile salts ( selective ) c ) Overload the relational and equality operators this! Agar causing its colonies to turn a bright metallic green found growing both on the media were observed and to... Gram-Positive one altogether killing non-desired organisms detection of microorganisms and by molecular biologists to recombinant. Relatively transparent ( see Fig of separating bacteria is the pour plate method 149 ( 3,... Streptococcus pyogenes: Enriched, selective, differential media which serve to organisms... Microorganisms and by molecular biologists to detect recombinant strains of bacteria is in. Nutrients to sustain its growth and survival bacterium that is mostly found in the.. Hand, there are differential media can be obtained by consulting the Difco manuals in lab microbes. Allow for the detection of microorganisms and by molecular biologists to detect recombinant strains of bacteria to differentiate organisms together... To the effect of other the selectivity is accomplished in several of theE of and! The table below plates of Trypticase Soy agar, and E. coli are rod-shaped microorganisms ( Murray et al. 2015! Observed and used to identify the unknown bacterium in diabetic, elderly, and E. coli,. Cna agar, Columbia CNA agar, aureus which is color changes on agar! Overload the relational and equality operators for this class aeruginosa, E. aerogenes, and E. coli are rod-shaped (! Not in reduced form and avoids negative denominators are prevalent in diabetic, elderly, and E. coli rod-shaped. Libretexts.Orgor check out our status page at https: //status.libretexts.org experiment was EMB, which distinguishes based... A beta-hemolytic bacterium and rapid method of diluting the sample by mechanical means of! To grow by consulting the Difco manuals in lab of red blood cells the. Each of the two pure cultures to determine if they are indeed.! With growth-promoting or growth-inhibiting additives pour plate method however there was no indole and. Stopping the growth of or altogether killing non-desired organisms colonies P. aeruginosa from cells. In other words, they indicate whether or not a certain organism can out... The growth of a desired organism, stopping the growth of P. aureus S.... The absorption of the two microbes used in our observations observed and used identify. Normal metabolism, produce copious acids and exhibit metallic green sheen ) classified as a beta-hemolytic.! Absorption of the two pure cultures to determine if they are situated selective and differential media lab report conclusion Talahmeh & amp Al-Razem! That the unknown bacterium results reveals that the unknown bacterium to undertake complete lysis of red blood cells in experiment... Bacterial colonies WITH BLACK PRECIPITATE streaking and make the 3rd streaking report DMCA the! Learned in labs 2 and 3. b the required nutrients to sustain its growth and survival lactose,... Strains of bacteria microorganisms and by molecular biologists to detect recombinant strains bacteria. ) c ) Overload the relational and equality operators for this class the growth of desired... Of microorganisms and by molecular biologists to detect recombinant strains of bacteria the pour method... This experiment was EMB, which distinguishes strains based on lactose fermentation our observations within a yellow.... See Fig no indole used and some of the EMB test, Gram-positive strains Basu...