Six plates for each media were prepared and inoculated with five known bacteria and the unknown bacteria using the streaking method. BLUISH / GREEN colony color = RISE in pH of media = NO fermentation of sugars but breakdown of proteins = alkaline products made 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. Blue/Green without black precipitate = increase in pH=Protein breakdown=no sugar fermentation = no black precipitate = no sulfur reduction In the two Tryptic Soy Agar plate, there was growth of colonies of Selective media is utilized to isolate specific bacterial strains (Basu et al., 2015). 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) Transcriptome The metachromatic properties of EMB account for the green colonies produced by E. coli, which also ferments lactose (Antony et al., 2016). changes the red indicator to yellow color. Selective media: A selective medium has agents added which will inhibit the growth of one group of organisms while permitting the growth of another. 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. On the other hand, strains that do not utilize lactose metabolize proteins, producing acids that increase the pH (Antony et al., 2016). 2. Observe isolated colonies on the plates of Trypticase Soy agar, Columbia CNA agar, and MacConkey agar. WebCultivation Media for Bacteria. 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. The spin plate method involves diluting the bacterial sample in tubes of sterile water, saline, or broth. After incubation, discrete bacterial colonies can then be found growing both on the agar and in the agar. 2. In other words, they indicate whether or not a certain organism can carry out a specific biochemical reaction during its normal metabolism. 4 and Fig. For example, organisms that Web. Record your observations and conclusions. StudyCorgi. and for Tryptic Soy Agar pour into two separate mediums. Examples of differential media include: This page titled 6.3C: Selective and Differential Media is shared under a CC BY-SA 4.0 license and was authored, remixed, and/or curated by Boundless. Apply correct terminology regarding microbiological techniques, instruments, microbial Biochemical Tests for Staphylococcus Organisms Bacteria that cannot ferment sucrose or lactose tend to show white colonies, for they do not cause any changes in the media. Purple/Black growth/ Green metallic sheen = drop in pH=Large acidic products=fermentation of lactose and sucrose=probable coliform For the subjects with hypertriglyceridemia, the lncRNAs affecting type 2 diabetes mellitus (T2DM) and the specific mechanisms remain unclear. well as Aureus. LWT, 114 , 108365. 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. EMB media contains eosin and methylene blue that are toxic to Gram-positive bacteria (Basu et al., 2015). One plate of each of the following media: Trypticase Soy agar, Columbia CNA agar, and MacConkey agar. Using any of the three plates on which they are growing: a. Aseptically pick off a single isolated colony of each of the two bacteria from your original mixture that you have just identified and aseptically transfer them to separate plates of Trypticase Soy agar (see Fig. 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. 2021. Streak the same mixture for isolation (see Fig. 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. 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). observation and record the results. Course Hero is not sponsored or endorsed by any college or university. Terrific Broth (TB) is used with glycerol in cultivating recombinant strains of Escherichia coli. In Lab 4 we will use this technique as part of the plate count method of enumerating bacteria. 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. MacConkey (MCK), which is differential for lactose fermentationmannitol salt agar (MSA), which is differential for mannitol fermentation. 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. The neutral red in the agar turns red in color once the pH drops below 6.8. (2017). Since gram-negative bacteria have thin cell walls, PEA easily penetrates into the bacteria via cell membranes and disrupts DNA synthesis. A sterile, bent-glass rod is then used to spread the bacteria evenly over the entire agar surface (see Fig. What type of plate would you use to culture, Both microscopy and motility agar are used to confirm microbial mobility. E. faecalis is usually a nonpathogenic intestinal microorganism. June 26, 2021. https://studycorgi.com/bacteria-lab-enriched-selective-differential-media/. The use of selective and differential agars in the isolation of 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). NOT all Gram negative bacteria can ferment lactose to produce acidic compounds It is an enriched medium with sheep blood, tryptones, and soybeans to allow bacteria to obtain nutrients from proteins. Why is MacConkey agar (MAC) classified as a type of both selective and differential medium? WebThese results indicated that most AvNACs evolved mainly under purifying selection, and the segmental duplications were the main driving force during the evolution process. 5. It explains on the three types of mediums thats the complex, selective and Journal of Pure and Applied Microbiology, 10(4), 1-7. Label a sheep blood agar plate and use a loopful of Enterococcus faecalis to inoculate it. Media formulation may combine ingredients of 9). Put in the stir bar and turn on the stir plate so that the surface is just disturbed. "Bacteria Lab: Enriched, Selective, Differential Media." and E. Coli bacteria, their properties and where they are situated (Talahmeh & Al-Razem, 2020). WebDifferential Media. It further explains on the two types of sample organisms that the Aureus 3. 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. If you use an assignment from StudyCorgi website, it should be referenced accordingly. Disclaimer: Services provided by StudyCorgi are to be used for research purposes only. COLORLESS bacterial colonies = NO change in media pH = NO acidic products present = NO fermentation of lactose OR sucrose Blood agar is another form of media that the experiment used in the identification of the unknown bacterium. Then make Thad WebSelective media = Media providing a means of isolating a particular species or type or microorganisms, while inhibiting the growth of others (e.g., EMB, MAC, T-7, MSA, etc.). 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. Wallace, J. S., & Jones, K. (1996). Antony, A., Paul, M. K., & Silvester, R., & Abdulla, M. H. (2016). 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. Staphylococcus aureus ferments mannitol, an acid byproduct is produced which subsequently Another advantage for differential and selective media is that it can yied results faster, especially in cases of screening for key organisms. In Food Microbiology Laboratory for the Food Science the red medium indicator into yellow color. Growth = Not inhibited by Dyes = Gram Negative Objectives. Differential tests are a lot more precise than selective media. Murray, P., Rosenthal, K., & Pfaller, M. (2015). Problems that might have affected the results and identification of the unknown bacterium are contamination and subjective reading of plates. An example of this selection would be using an increased salt concentration to only allow for the growth of halophilic bacteria. : an American History - Chapters 1-5 summaries, SCS 200 Applied Social Sciences Module 1 Short Answers, BI THO LUN LUT LAO NG LN TH NHT 1, Analytical Reading Activity Jefferson and Locke, QSO 321 1-3: Triple Bottom Line Industry Comparison, Recrystallization of Benzoic Acid Lab Report, Leadership class , week 3 executive summary, I am doing my essay on the Ted Talk titaled How One Photo Captured a Humanitie Crisis https, School-Plan - School Plan of San Juan Integrated School, SEC-502-RS-Dispositions Self-Assessment Survey T3 (1), Techniques DE Separation ET Analyse EN Biochimi 1. regions that a yellow and a pink region separated. 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. Given a mixture of a Gram-positive and a Gram-negative bacterium and plates of Columbia CNA, MacConkey, and Trypticase Soy agar, describe the steps you would take to eventually obtain pure cultures of each organism. the S. aureus to produce lactic acid (Ashraf & Shah, 2011). WebEMB Selective Conclusion: PEA Selective Based on the results, my unknown bacteria #590 is gram positive. However, its difference occurs in the degree of hemolysis as S. aureus exhibited gamma-hemolysis, while the unknown bacterium depicted beta-hemolysis. Cover them well and place them into Such a medium normally consists of a mixture of protein digests (peptone, tryptone, etc.) Many types of culture media possess both characteristics, selective and differential, selecting for one type of bacteria and then differentiating among that type. bulgaricus, Streptococcus thermophilus, Lactobacillus acidophilus, NOT all Gram negative bacteria make the same amount of acidic compounds from sugar fermentation Orange/Yellow Growth = drop on pH = Large acidic = products made = fermentation of sugars = Not Salmonella or Shigella The yellow region is due to the fermentation of 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. Most bacteria the required nutrients to sustain its growth and survival. Salmonella, Serratia, Proteus, and Shigella: colorless colonies; agar relatively transparent (see Fig. Mannitol Salt Agar and its expected there would be a change in the medium color due to the Bacteria that ferment sucrose and lactose vigorously, such as fecal coliforms, produce copious acids and exhibit metallic green sheen. 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. in yoghurtA review. dissolution of the powder. Differential media takes advantage of biochemical properties of target organisms, often leading to a visible change when growth of target organisms are present. 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. Test #1: Lab Experiment. 4. section gives a vivid description and a deeper explanation on these responses and reasons behind Depending on the extent of breakdown, bacteria can give beta, alpha, and gamma outcomes, which show complete, partial, and absent hemolysis. A broth culture containing a mixture of one of the following Gram-positive bacteria and one of the following Gram-negative bacteria: During the next three labs you will attempt to obtain pure cultures of each organism in your mixture and determine which two bacteria you have. 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 Salicin (differential) 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. stain that renders gram positive bacteria. Some of these strains P. aeruginosa and E. aerogenes are opportunistic pathogens that cause pulmonary, gastrointestinal, and urinary tract infections as well as sepsis, particularly in hospitalized patients (Murray et al., 2015). Combination selective and differential media: A combination selective and differential medium permits the growth of one group of organisms while inhibiting the The following lab you will prepare microscopy slides of each of the two pure cultures to determine if they are indeed pure. Possible Coliform, Growth = Gram negative bacteria B. YouTube movie showing how to streak an agar plate for isolation: 4 sector method. differential media for the isolation and enumeration of Bacillus cereus from food various bacterial strains and microorganisms respond to growth in mediums with varying A selective medium has an inhibitory agent which favors the growth of certain bacteria by inhibiting others. Single colonies will be visible on the 2nd or the 3rd streak. Pick off isolated colonies of microorganisms growing on a streak plate and aseptically transfer them to sterile media to obtain pure cultures. The color changes observed on plates were used to identify the unknown bacteria. Color changes on the media were observed and used to identify the unknown bacterium. Student (pp. NOT all Gram negative bacteria can ferment sucrose to produce acidic compounds E. coli lives in the human gut, and it causes diarrhea and vomiting. fractions that are not in reduced form and avoids negative denominators. Poor/No growth = Organism inhibited by Eosin and Methylene blue dye = Gram Positive member of the Formicates bacteria and is commonly known to cause infections of the skin as 1. THE POUR PLATE AND SPIN PLATE METHODS OF ISOLATION, Animation showing a portion of a single colony being "picked off.". Key Differences Between Selective and Differential Media Selective media selectively isolate the particular strains of the organism, while differential medium Using the wire loop, scoop a colony of Staphylococcus aureus and streak it on the surface of Enriched media are supplemented with nutrient sources and growth factors for culturing fastidious cells (Basu et al., 2015). Methylene Blue Agar plate and the other plate of Tryptic Soy Agar plate. E. coli is a gram-negative, rod-shaped, facultative anaerobic formation of two zones, one is yellow and the other pink. contaminated water or stale food. Springer, Cham, 128 (5), 1440-1447. Selective growth media are also used in cell culture to ensure the survival or proliferation of cells with certain properties, such as antibiotic resistance or the ability to synthesize a certain metabolite. 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. 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 This is because it has got all the necessary nutrients and constituents that favor Selective and differential medium for recovery of Pseudomonas cepacia 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. 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. part gives an explanation on how bacterial takes place on various growth medium as well as how Bile Salts in the media inhibits the growth of Gram positive bacteria (only Gram negative bacteria CAN grow), Differential The other varieties of bacteria are inhibited. The ability of the unknown bacterium to undertake complete lysis of red blood cells in the media depicts it as a beta-hemolytic bacterium. In the Mannitol Salt Agar Plate, there is NOT all Gram negative bacteria can ferment lactose to produce acidic compounds MacConkey agar for Gram-negative bacteria. Accessibility StatementFor more information contact us atinfo@libretexts.orgor check out our status page at https://status.libretexts.org. Evolution of bacterial and fungal growth media. Differential media, unlike selective media, does not kill organisms. methylene blue in the agar causing its colonies to turn a bright metallic green. bacteria and encourages the growth of gram positive bacteria. Vesel, K., Kumherov, M., Klojdov, I., Solichov, K., Horkov, ., & Plockov, M. (2019). As one of the media used to identify the unknown bacterium, EMB is a differential and selective medium. The aim of this experiment is to illustrate the uses of selective 1. 5) on a plate of Columbia CNA agar (selective for Gram-positive bacteria). This process inhibits the absorption of the EMB dye, resulting in pink colonies P. aeruginosa. WebLab Procedure. Describe the morphology of each bacerial type. If the Gram-negative bacterium ferments the sugar lactose in the medium, the acid end products lower the pH of the medium. The authors find that subjects, on average, prefer movies recommended by own-group members. The tube is placed on ice for a few minutes and if the media fails to solidify it is considered a positive test. There are some species of bacteria that are Label the MacConkey agar plates. MSA contains an additional indicator for monitoring mannitol fermentation, which makes it a differential media also. However there was no indole used and some of the agars, were not used in our observations. It lacks inhibitory substances. Bacteria that cannot metabolize the peptone proteins cannot grow. medium in a conical flask under sterile aseptic conditions. References Stir well to ensure a complete These findings may not be entirely correct because, we were not able to use certain cells in the enterotube due to lack of indole and other required, State College of Florida, Manatee-Sarasota. In this YM (yeast and mold) which has a low pH, deterring bacterial growth. This experiment report is made on differential and selective medium on Eosin Methylene In the Eosin Methylene Blue Agar plate, E. coli appears large. In addition, it differentiates those organisms that grow based on whether they can carry out particular chemical reactions. The differential media used in this experiment was EMB, which distinguishes strains based on lactose fermentation. Lactobacillus delbrueckii subsp. (2021) 'Bacteria Lab: Enriched, Selective, Differential Media'. 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. Its found in the nose, the Morphologically, enterococci and streptococci have spherical shapes. Legal. It was confirmed that the smaller the particle size, the higher the effect on the dielectric loss. Ferric ammonium citrate (differential) Scientific writing is written_x000D_ dif In the other tube we had, ornithine, lactose, arabinose, and sorbitol. Explain how bi-directional replication folks are advantageous to bacteria. Define: selective medium, differential medium, enrichment medium, and combination selective-differential medium. Microbial characteristics of culture media are used to identify and characterize bacteria. ORANGE / YELLOW bacterial colonies = DROP in pH of media = LARGE amounts of acidic products made = fermentation of the sugars in the media For example, Hektoen and xylose-lysine-deoxycholate (XLD) agars are highly selective, and both detect H 2 S production, facilitating the identification and detection of Salmonella strains. For each medium, pour into its specific culture medium one for each Microorganisms exhibit distinct colonial growth characteristics in different culture conditions, allowing for strain-level typing. 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. There is also lactose fermentation that took place that Indicate a common disease caused by each. 4 and Fig. distinguishes between related and differential media for the isolation as well as characterization of organisms of interest. Bacteria Lab: Enriched, Selective, Differential Media. resulted in te nature of the medium. black with a green metallic sheen (Shen & Zhang,2017). Combination selective and differential media: A combination selective and differential medium permits the growth of one group of organisms while inhibiting the growth of another. Add 3.25 grams of the TSB powder to this flask and allow it to dissolve (will happen quickly). Eosin methylene blue (EMB) that contains methylene blue toxic to Gram-positive bacteria, allowing only the growth of Gram negative bacteria. In addition, it differentiates those organisms that grow based on whether they can carry out particular chemical reactions. The growth of all microorganisms is dependent on favorable conditions of growth with The selectivity is accomplished in several ways. This type of media is used for the detection of microorganisms and by molecular biologists to detect recombinant strains of bacteria. The prominent metallic green sheen observed is as a actively inhibit the growth of some organisms while allowing the growth of others. Hektoen enteric agar (HE) which is selective for Gram-negative bacteria. Selective media are used for the growth of only selected microorganisms. Enriched Medium by Streak Plating. A Selective Medium is a culture medium designed to ________ (inhibit or allow) the growth of ________ (all or some) kinds of organisms, but not others. e. coli has a single origin of replication calledoriC. WebHOW TO WRITE AN UNKNOWN LAB REPORT IN MICROBIOLOGY_x000D_ GENERAL_x000D_ Unknown reports in microbiology are written in scientific format. Subsequently, the absence of color change and growth in PEA medium supports EMB test that the unknown bacterium is Gram-positive. The chemistry behind the test is that bacteria with exotoxins (hemolysins) have the capacity to break down red blood cells. Staphylococcus aureus would grow on the Eosin Methylene Blue Agar since it its gram negative Molecular identification of antibiotic control of bacterial contamination in cultures of ginger (Zingiber officinale). Mannitol Salt Agar is earlier indicated is a selective medium which plays a role in the 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. the formation the observed growth and color. The Eosin and Methylene blue are dyes that have. 2. 2. Sucrose (differential) 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. Small samples of the diluted bacteria are then pipetted onto the surface of agar plates. WebA combination selective and differential medium permits the growth of one group of organisms while inhibiting the growth of another. Differential tests are sometimes the confirmation needed to determine what bacteria is being investigated. 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. WebA selective media include ingredients that support growth of one type of microorganisms, but suppress growth of another. c) Overload the relational and equality operators for this class. { "6.3A:_Culture_Media" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.
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