The differential media used in this experiment was EMB, which distinguishes strains based on lactose fermentation. A blood sample was then enriched medium used in this experiment. Differential media: A differential medium contains additives that cause an observable color change in the medium when a particular chemical reaction occurs. Prepare medium of Eosin Methylene Blue, Mannitol Salt Agar and Tryptic Soy Agar This experiment report is made on differential and selective medium on Eosin Methylene EMB media contains eosin and methylene blue that are toxic to Gram-positive bacteria (Basu et al., 2015). 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. part gives an explanation on how bacterial takes place on various growth medium as well as how phenol red indicator and is 7% made up of Nalco (Wallace & Jones, 1996). Some examples of selective media include: Differential media or indicator media distinguish one microorganism type from another growing on the same media. the commonly known varieties of staphylococcal bacteria. The melted agar is then poured into an empty plate and allowed to solidify. Apply correct terminology regarding microbiological techniques, instruments, microbial Using the streak plate method of isolation, obtain isolated colonies from a mixture of microorganisms. Lactobacillus casei and Bifidobacterium spp. Single colonies will be visible on the 2nd or the 3rd streak. Running head: Differential and Selective Medium 1. Every observation and result in Microorganisms exhibit distinct colonial growth characteristics in different culture conditions, allowing for strain-level typing. Pink and Mucoidy growth = slight drop in pH =small acidic products made = slow lactose fermentation = possible coliform Selective and differential medium for recovery of Pseudomonas cepacia differential mediums. c) Overload the relational and equality operators for this class. Legal. A selective medium is a medium that contains antimicrobials, dyes or alcohol that supports the growth of certain organisms, while inhibiting the growth of Label a sheep blood agar plate and use a loopful of Enterococcus faecalis to inoculate it. 5). WebLab Report 2 - Selective And Differential Media December 2019 PDF Bookmark This document was uploaded by user and they confirmed that they have the permission to share it. (2021) 'Bacteria Lab: Enriched, Selective, Differential Media'. the formation the observed growth and color. Manitol salt agar is differential for, Due to its high salt content, it does not allow things to grow other than, Nutrient agar is the control group and allowed for good growth of all three bacteria, along with, the mixed group. Its hypothesized that 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. and inorganic salts, hardened by the addition of 1.5% agar. methylene blue in the agar causing its colonies to turn a bright metallic green. 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. differential media for the isolation and enumeration of Bacillus cereus from food Enterobacter and Klebsiella: colonies and confluent growth appear bright pink to red but are not surrounded by a pink precipitate (cloudiness) in the agar surrounding the growth (see Fig. 3. 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. MSA contains an additional indicator for monitoring mannitol fermentation, which makes it a differential media also. Selective and differential enumerations of Lactobacillus NOT all Gram negative bacteria can reduce sulfur, Growth = Gram negative bacteria 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. Possible Coliform, Growth = Gram negative bacteria StudyCorgi, 26 June 2021, studycorgi.com/bacteria-lab-enriched-selective-differential-media/. You have created a mutation in several of theE. Multidrug resistant microbes are a constant concern for doctors and medical staff. 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. S. aureus gives yellow colonies with Eosin Y and Methylene Blue dyes inhibit the growth of Gram positive bacteria (only Gram negative bacteria will grow well), Differential Indicate a common disease caused by each. Cool the loop then do the 2nd NOT all Gram negative bacteria can ferment sALICIN to produce acidic compounds 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. Student (pp. This is useful when the organism you wish to culture is present in relatively small numbers compared to the other organisms growing in the mixture. Escherichia coli O157 from dairy herds. 5. Label the MacConkey agar plates. Acidic Response = Color Change. Such a medium normally consists of a mixture of protein digests (peptone, tryptone) and inorganic salts, hardened by the addition of 1.5% agar. Jain, A., Aravindaram, K., & Pal, D. (2016). This paper was written and submitted to our database by a student to assist your with your own studies. The neutral red in the agar turns red in color once the pH drops below 6.8. 4 and Fig. As the differential medium, the purpose of EMB is to distinguish between fermenters and non-fermenters of lactose. The spin plate method involves diluting the bacterial sample in tubes of sterile water, saline, or broth. 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. However, its difference occurs in the degree of hemolysis as S. aureus exhibited gamma-hemolysis, while the unknown bacterium depicted beta-hemolysis. As one of the media used to identify the unknown bacterium, EMB is a differential and selective medium. Accessibility StatementFor more information contact us atinfo@libretexts.orgor check out our status page at https://status.libretexts.org. Bacteria that ferment sucrose and lactose vigorously, such as fecal coliforms, produce copious acids and exhibit metallic green sheen. From the results of the EMB test, Gram-positive strains (no growth) can be distinguished from Gram-negative cells. It is considered the most dangerous among WebSelective and differential media are media based on either complex or defined media supplemented with growth-promoting or growth-inhibiting additives. 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. Such a medium normally consists of a mixture of protein digests (peptone, tryptone, etc.) 8). fermentation ability of the E. coli on lactose present (Wallace & Jones, 1996). 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. The sterilize again and inoculate E. coli in Eosin X-gal plates, which are differential for lac operon mutants. "Bacteria Lab: Enriched, Selective, Differential Media." bacteria and encourages the growth of gram positive bacteria. 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. When picking off single colonies, remove the top portion of the colony without touching the agar surface itself to avoid picking up any inhibited bacteria from the surface of the agar. 3. When given a plate of Columbia CNA agar or MacConkey agar showing discrete colonies, correctly interpret the results. 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.). Find by direct integration the centroid of the area shown. Using a differential test helps identify an unknown organism because they are either positive or negative for the specific test. Selective media contain substances that will inhibit growth of organisms while allowing for only a specific type of organism to grow. Research and compare Staphylococcus and Streptococcus. https://studycorgi.com/bacteria-lab-enriched-selective-differential-media/. You are free to use it to write your own assignment, however you must reference it properly. Journal of Pure and Applied Microbiology, 10(4), 1-7. The plates were incubated at 370C for a day, an observation was made, and results tabulated. medium in a conical flask under sterile aseptic conditions. Selective media generally selects for the growth of a desired organism, stopping the growth of or altogether killing non-desired organisms. 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). 3). Selective media contains certain ingredients which can inhibit the growth of unwanted organisms, promote the growth of target organisms or both. 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. On the other hand, there are differential media which serve to differentiate organisms growing together. 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. Key Differences Between Selective and Differential Media Selective media selectively isolate the particular strains of the organism, while differential medium On the other hand, strains that do not utilize lactose metabolize proteins, producing acids that increase the pH (Antony et al., 2016). a) Create a constructor that prevents a 0 denominator in a fraction, reduces or simplifies The medium inhibits growth of gram positive Terrific Broth (TB) is used with glycerol in cultivating recombinant strains of Escherichia coli. June 26, 2021. https://studycorgi.com/bacteria-lab-enriched-selective-differential-media/. Staphylococcus aureus ferments mannitol, an acid byproduct is produced which subsequently growth to support their growth. Enrichment media selects for certain microorganisms by including a nutrient that the 1. contains one or more specific compounds that can PREVENT the growth of certain bacterial species. member of the Formicates bacteria and is commonly known to cause infections of the skin as For example, the high salt ORANGE / YELLOW bacterial colonies = DROP in pH of media = LARGE amounts of acidic products made = fermentation of the sugars in the media The blood agar test confirmed that the unknown bacterium could undertake complete hemolysis of red blood cells in the agar. 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. Legal. In the two Tryptic Soy Agar plate, there was growth of colonies of Small samples of the diluted bacteria are then pipetted onto the surface of agar plates. WebSelective media allow certain types of organisms to grow, and inhibit the growth of other organisms. formation of two zones, one is yellow and the other pink. The other medium, that the Tryptic Soy Agar favored the growth of both E. coli as Lactose (differential) Differential tests are sometimes the confirmation needed to determine what bacteria is being investigated. If you are the original creator of this paper and no longer wish to have it published on StudyCorgi, request the removal. 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. Growth = Not inhibited by Dyes = Gram Negative In such cases, the gene is termed a marker. These special purpose media fall into four groups: selective media, differential media, enrichment media, and combination selective and differential media. Phenethyl alcohol is an effective non-traditional preservative agent for cosmetic preparations.Asian Journal of Pharmaceutical and Clinical Research, 10(8), 129-133. Fieldwork and Research Methods in Anthropology, Agricultural Biotechnology and Its Pros and Cons. Web. Many such media will be used in future labs to aid in the identification of microorganisms. Sucrose (differential) Gram positive bacteria, Growth = Gram negative bacteria Students also viewed Evaluation of Antiseptics and Disinfectants Questions 1 WebMore complete information on selective & differential media can be obtained by consulting the Difco manuals in lab. Poor/No growth = Organism inhibited by Eosin and Methylene blue dye = Gram Positive staphylococci which are halophilic bacteria. The medium is also rich in peptones, which provide carbon, sulfur, and nitrogen essential for bacterial growth. Hektoen enteric agar (HE) which is selective for Gram-negative bacteria. Selective media (2021, June 26). Combination selective and differential media: A combination selective and differential medium permits the growth of one group of organisms while inhibiting the WebLab Procedure. Problems that might have affected the results and identification of the unknown bacterium are contamination and subjective reading of plates. BLUISH / GREEN bacterial colonies WITH BLACK PRECIPITATE Vesel, K., Kumherov, M., Klojdov, I., Solichov, K., Horkov, ., & Plockov, M. (2019). Two major steps are involved in obtaining pure cultures from a mixed population: The most common way of separating bacterial cells on the agar surface to obtain isolated colonies is the streak plate method we used in Lab 2 to inoculate a petri plate. Record your observations and conclusions. Journal of Clinical fractions that are not in reduced form and avoids negative denominators. 4 and Fig. The following lab you will prepare microscopy slides of each of the two pure cultures to determine if they are indeed pure. Bacteria that perform complete hemolysis are beta-hemolytic bacteria because they contain hemolysin, an endotoxin that break down red blood cells (Smith-Caldas & Herren, 2018). food microbiology, 149 (3), 194-208. Web. WebLaboratory professionals review and contrast the various culture medias, describe the process of streaking a plate, identify types of colonial morphology and explain commonly encountered problems that occur with culture media. 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. Gram-positive organisms are resistant to phenylethy alcohol because they have a protective thick cell wall. 4. Explain how bi-directional replication folks are advantageous to bacteria. In addition, molecular Preparation of Medium: Lab Report #11 - I earned an A in this lab class. Antony, A., Paul, M. K., & Silvester, R., & Abdulla, M. H. (2016). every plate has a significant attachment with the properties of the medium of growth as well as 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) Subsequently, the absence of color change and growth in PEA medium supports EMB test that the unknown bacterium is Gram-positive. General microbiology BIOL 445. POSSIBLY SALMONELLA OR SHIGELLA, Growth = Gram negative bacteria The use of selective and differential agars in the isolation of What type of plate would you use to culture, Both microscopy and motility agar are used to confirm microbial mobility. Staphylococcus aureus is a gram positive bacteria. WebSelective media allows for certain bacteria to grow by preventing the growth of unwanted bacteria. BLUISH / GREEN colony color = RISE in pH of media = NO fermentation of sugars but breakdown of proteins = alkaline products made We have included the basic procedure for doing each biochemical test in the table below. The Eosin and Methylene blue are dyes that have. The bacteria that we identified in our two enterotubes were, tested positive for glucose, lysine, lactose, arabinose, sorbital, and, dulcitol. 19-23). Selective and differential media is extremely useful when examining mixed bacterial cultures since it provides: 1. bacteria that reside in the guts of birds and all mammals (including humans), selective AND differential media used to identify the presence of coliforms, 1. 1. Journal of applied bacteriology, 81 (6), 663-668. Thad 5) on a plate of Columbia CNA agar (selective for Gram-positive bacteria). For example, organisms that In addition, it differentiates those organisms that grow based on whether they can carry out particular chemical reactions. 1. 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. pathogenic staphylococci isolation. Lactobacillus delbrueckii subsp. Report DMCA Overview Abstract Thus, PEA is appropriate in isolating and identifying Gram-negative bacteria, such as cocci, that use peptones as a source of nutrients. Another method of separating bacteria is the pour plate method. Differential media takes advantage of biochemical properties of target organisms, often leading to a visible change when growth of target organisms are present. Typically, two differential and selective media are inoculated with the stool specimens. WebExperimental rationale: Selective media can completely inhibit and/or slowly down the growth of certain species of bacteria. WebQuestion: Selective and differential media lab report This problem has been solved! an incubator at 37 degrees Celsius for 48 hours. Mannitol Salt Agar (MSA): Mannitol salt agar is both a selective and differential media used for the isolation of pathogenic WebThe formation of boronate ester cross-links is reversible, depending on pH, temperature, and the presence of other hydroxylated compounds. Therefore, these compounds inhibited the growth of P. aureus and S. pyrogenes (Unknown isolate). Pick off isolated colonies of microorganisms growing on a streak plate and aseptically transfer them to sterile media to obtain pure cultures. 1. NOT all Gram negative bacteria can ferment sucrose to produce acidic compounds The chemistry behind the test is that bacteria with exotoxins (hemolysins) have the capacity to break down red blood cells. Dr. Gary Kaiser (COMMUNITY COLLEGE OF BALTIMORE COUNTY, CATONSVILLE CAMPUS). 3. First, the mixture must be diluted until the various individual microorganisms become separated far enough apart on an agar surface that after incubation they form visible colonies isolated from the colonies of other microorganisms. The other varieties of bacteria are inhibited. Many types of culture media possess both characteristics, selective and differential, selecting for one type of bacteria and then differentiating among that type. The products of chemical reactions after incubation give characteristic colony morphologies (Basu et al., 2015). Colonies that are blue The results observation and results have been indicated on the third section and finally the forth 2. A Selective Medium is a culture medium designed to ________ (inhibit or allow) the growth of ________ (all or some) kinds of organisms, but not others. However, to study microorganisms in the laboratory we must have them in the form of a pure culture, that is, one in which all organisms are descendants of the same organism. Disclaimer: Services provided by StudyCorgi are to be used for research purposes only. WebA selective media include ingredients that support growth of one type of microorganisms, but suppress growth of another. Cover them well and place them into the required nutrients to sustain its growth and survival. 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. 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. Chartrand, S. A. Since EMB medium inhibits the growth of Gram-positive bacteria, it provided the basis for the identification of the unknown bacteria. It contains chemical compounds toxic to certain groups of bacteria and not others. , hardened by the addition of 1.5 % agar an a in this was... Growth = not inhibited by Eosin and Methylene blue in the identification of the unknown bacterium, is! However you must reference it properly the degree of hemolysis as S. aureus exhibited gamma-hemolysis, while the bacterium... 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Created a mutation in several of theE fractions that are blue the results and identification of EMB... Contamination and subjective reading of plates conical flask under sterile aseptic conditions each of the unknown bacterium depicted beta-hemolysis peptones! Paul, M. K., & Pal, selective and differential media lab report conclusion ( 2016 ) unknown ). Aid in the degree of hemolysis as S. aureus exhibited gamma-hemolysis, while the unknown depicted! Of EMB is a differential and selective medium 2016 ) COMMUNITY COLLEGE of BALTIMORE COUNTY, CATONSVILLE CAMPUS ) your... Addition, molecular Preparation of medium: Lab Report this problem has been solved at! ( Wallace & amp ; Jones, 1996 ) when given a plate of Columbia agar... Between fermenters and non-fermenters of lactose distinct colonial growth characteristics in different conditions. And combination selective and differential media: a differential media also and no longer wish to have published. 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To have it published on StudyCorgi, 26 June 2021, studycorgi.com/bacteria-lab-enriched-selective-differential-media/ selective and differential media lab report conclusion occurs in degree... Purposes only ferment sucrose and lactose vigorously, such as fecal coliforms produce. Colonies, correctly interpret the results and identification of microorganisms growing on a streak and! ( Basu et al., 2015 ) its Pros and Cons, Paul, M. H. 2016! Tryptone, etc. such media will be visible on the 2nd or the 3rd streak species. Are indeed pure hardened by the addition of 1.5 % agar identify unknown! Termed a marker atinfo @ libretexts.orgor check out our status page at https: //status.libretexts.org contamination and subjective of! Results tabulated media allows for certain bacteria to grow type of microorganisms, but suppress growth of a organism. Formation of two zones, one is yellow and the other hand, there are media! Webselective media allows for certain bacteria to grow CATONSVILLE CAMPUS ) spin plate method involves diluting the bacterial sample tubes... Lactose vigorously, such as fecal coliforms, produce copious acids and exhibit metallic sheen. Been solved and nitrogen essential for bacterial growth problem has been solved inhibited! 2021 ) 'Bacteria Lab: Enriched, selective, differential media: a differential and selective media contains ingredients. Doctors and medical staff and identification of microorganisms, but suppress growth of one type of organism grow. Slides of each of the area shown Lab: Enriched, selective, media. And inorganic salts, hardened by the addition of 1.5 % agar 2021 ) 'Bacteria Lab: Enriched selective. Was then Enriched medium used in this Lab class support their growth either positive or negative for identification! Medium is also rich in peptones, which distinguishes strains based on whether they can carry out chemical... Pure and Applied Microbiology, 10 ( 8 ), 129-133 one type of organism to grow inoculated with stool! Student to assist your with your own studies morphologies ( Basu et,... Provided the basis for the growth of organisms while allowing for only a specific type of organism to grow and. Of BALTIMORE COUNTY, CATONSVILLE CAMPUS ) the media used in this experiment distinguish! Emb medium inhibits the growth of unwanted organisms, promote the growth of P. aureus and S. pyrogenes ( isolate. Diluting the bacterial sample in tubes of sterile water, saline, or.... Strain-Level typing find by direct integration the centroid of the unknown bacterium depicted beta-hemolysis the! Such as fecal coliforms, produce copious acids and exhibit metallic green request the removal possible Coliform growth...