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. 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. Such a medium normally consists of a mixture of protein digests (peptone, tryptone) and inorganic salts, hardened by the addition of 1.5% agar. The pink region is due to the effect of other Not a Coliform, Growth = Gram negative bacteria The introduction Orange/Yellow Growth = drop on pH = Large acidic = products made = fermentation of sugars = Not Salmonella or Shigella Many types of culture media possess both characteristics, selective and differential, selecting for one type of bacteria and then differentiating among that type. 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. June 26, 2021. https://studycorgi.com/bacteria-lab-enriched-selective-differential-media/. Poor/No growth = Inhibited by Bile Salts = Gram Positive the results that have been observed in the four medium plates. It lacks inhibitory substances. After incubation, discrete bacterial colonies can then be found growing both on the agar and in the agar. Wellesley College-BISC 209 Microbiology -Spring 2010. Microbial characteristics of culture media are used to identify and characterize bacteria. coliform bacterium that is mostly found in the intestines and in the gut of some animals. Differential tests are a lot more precise than selective media. 3). Another method of separating bacteria is the pour plate method. 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. contaminated water or stale food. 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). 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. 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Hektoen enteric agar (HE) which is selective for Gram-negative bacteria. Research the oxidase test and describe how it is performed. In the other tube we had, ornithine, lactose, arabinose, and sorbitol. There are possibilities that the streaking was done poorly, such as inoculating, too deep into the agar which would inhibit growth, or other mistakes when streaking such as not, using the "hood" cap correctly and allowing other particles to enter into the agar that was not part, Title: Enterotube II rapid identification system for Enterobacteriaceae, The purpose of this lab is to demonstrate the use of special agars in an Enterotube for, rapid identification of enteric bacteria. 2. allows the growth of some bacterial species while Lactobacillus casei and Bifidobacterium spp. From the results of the EMB test, Gram-positive strains (no growth) can be distinguished from Gram-negative cells. 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. Including incubation periods when solving creative tasks; that is, setting the task temporarily aside, has been shown to benefit creative problem solving in experimental settings. Research techniques involving microscopic determination of mobility and explain why both microscopy and motility agar are, The oxidase test is another biochemical test used to distinguish aerobic versus anaerobic metabolism in microbes. There are hundreds of selective and differential media, but a few of the more common ones as well as those used for general purposes are described below: 5) on a plate of Columbia CNA agar (selective for Gram-positive bacteria). Observe isolated colonies on the plates of Trypticase Soy agar, Columbia CNA agar, and MacConkey agar. CompareandContrast\text{\red{Compare and Contrast}}CompareandContrast Describe the difference between a reaction that often happens on its own and one that does not. 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. Apply correct terminology regarding microbiological techniques, instruments, microbial 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! https://studycorgi.com/bacteria-lab-enriched-selective-differential-media/. Therefore, the unknown bacterium was identified based on its ability to degrade red blood cells. Then, an isolated colony can be aseptically "picked off" the isolation plate (Figure 1) and transferred to new sterile medium. Escherichia coli O157 from dairy herds. components. a) Create a constructor that prevents a 0 denominator in a fraction, reduces or simplifies 1. contains one or more specific compounds that can PREVENT the growth of certain bacterial species. the S. aureus to produce lactic acid (Ashraf & Shah, 2011). COLORLESS bacterial colonies = NO change in media pH = NO acidic products present = NO fermentation of lactose OR sucrose NOT all Gram negative bacteria produce the same AMOUNT of acidic compounds if they can ferment lactose or sucrose, Poor to NO growth = E. coli and Aureus respectively. Preparation of Medium: Acid fuchsin dye (differential), Selective An example of this selection would be using an increased salt concentration to only allow for the growth of halophilic bacteria. In addition, molecular 2. growth is inhibited in this this medium due to its high concentration of salt other than 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. Components: WebThis type of medium may be selective which promote the growth of one organism and retards the growth of the other organism. differential media for the isolation and enumeration of Bacillus cereus from food Indicate a common disease caused by each. Two types of media with similar implying names but very different functions, referred to as selective and differential media, are defined as follows. Pick off isolated colonies of microorganisms growing on a streak plate and aseptically transfer them to sterile media to obtain pure cultures. Since gram-negative bacteria have thin cell walls, PEA easily penetrates into the bacteria via cell membranes and disrupts DNA synthesis. How does the presence of "superbugs" impact. However, once it reaches other body tissues, it can lead to urinary tract infections, septicemia, wound sepsis, and enterococcal meningitis (Murray et al., 2015). Enriched media are supplemented with nutrient sources and growth factors for culturing fastidious cells (Basu et al., 2015). Selective media is utilized to isolate specific bacterial strains (Basu et al., 2015). The neutral red in the agar turns red in color once the pH drops below 6.8. bulgaricus and Streptococcus thermophilus. Differential media, unlike selective media, does not kill organisms. 4. The selected bacterial strains were Escherichia coli, Pseudomonas aeruginosa, Enterobacter aerogenes, Streptococcus aureus, Enterococcus faecalis, and an unknown sample. Methylene Blue agar, Mannitol Salt Agar and Tryptic Soy Agar. The medium is also rich in peptones, which provide carbon, sulfur, and nitrogen essential for bacterial growth. : 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. Such a medium normally consists of a mixture of protein digests (peptone, tryptone, etc.) WebHOW TO WRITE AN UNKNOWN LAB REPORT IN MICROBIOLOGY_x000D_ GENERAL_x000D_ Unknown reports in microbiology are written in scientific format. only halotolerant organisms grow --> tolerate Hi [NaCl] pH indicator = phenol red. 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). Terrific Broth (TB) is used with glycerol in cultivating recombinant strains of Escherichia coli. 1. B. Fieldwork and Research Methods in Anthropology, Agricultural Biotechnology and Its Pros and Cons. well as Aureus. 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. Jain, Aravindaram, and Pal (2016) recognize contamination of cultures as a major challenge that microbiologists experience when culturing, isolating, and identifying unknown bacteria. Students also viewed Evaluation of Antiseptics and Disinfectants Questions 1 Lactose (differential) member of the Formicates bacteria and is commonly known to cause infections of the skin as It also Sucrose (differential) These special purpose media fall into four groups: selective media, differential media, enrichment media, and combination selective and differential media. intestines and taken from fecal matter or other ways. State the usefulness of Columbia CNA agar and MacConkey agar. Its found in the nose, the The following lab you will prepare microscopy slides of each of the two pure cultures to determine if they are indeed pure. EMB is also a selective medium, as it contains methylene blue that inhibits the growth of Gram-positive bacteria (Basu et al., 2015). MSA contains an additional indicator for monitoring mannitol fermentation, which makes it a differential media also. The medium inhibits growth of gram positive fractions that are not in reduced form and avoids negative denominators. 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. Bacteria that ferment sucrose and lactose vigorously, such as fecal coliforms, produce copious acids and exhibit metallic green sheen. 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. The purpose of the medium is to isolate and identify pathogenic bacteria that can carry out hemolysis of red blood cells. 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. Accessibility StatementFor more information contact us atinfo@libretexts.orgor check out our status page at https://status.libretexts.org. Dr. Gary Kaiser (COMMUNITY COLLEGE OF BALTIMORE COUNTY, CATONSVILLE CAMPUS). 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. When given a plate of Columbia CNA agar or MacConkey agar showing discrete colonies, correctly interpret the results. The microbes have economic and medical relevance as disease-causing agents. StudyCorgi. B. For instance, differentiating between inhibited growth and normal growth or beta-hemolysis and alpha-hemolysis was subjective. 4. A selective medium is a medium that contains antimicrobials, dyes or alcohol that supports the growth of certain organisms, while inhibiting the growth of Legal. The yellow region is due to the fermentation of Isolation of bacteria is accomplished by growing ("culturing") them on the surface of solid nutrient media. Streak the plates for the following organisms: Enterobacter aerogenes, Salmonella enterica, and Staphylococcus aureus, and sterilize the loop after streaking each quadrant. Journal of applied bacteriology, 81 (6), 663-668. We have included the basic procedure for doing each biochemical test in the table below. The use of selective and differential agars in the isolation of Describe how each of the following would appear when grown on MacConkey agar: 1. Key Differences Between Selective and Differential Media Selective media selectively isolate the particular strains of the organism, while differential medium 4. MacConkey agar for Gram-negative bacteria. Include examples of. We also acknowledge previous National Science Foundation support under grant numbers 1246120, 1525057, and 1413739. In other words, they indicate whether or not a certain organism can carry out a specific biochemical reaction during its normal metabolism. P. aeruginosa, E. aerogenes, and E. coli are rod-shaped microorganisms (Murray et al., 2015). Every observation and result in PINK & MUCOIDY bacterial colonies = SLIGHT change in media pH = SMALL amount of acidic products made = SLOW fermentation of lactose Antony, A., Paul, M. K., & Silvester, R., & Abdulla, M. H. (2016). Accessibility StatementFor more information contact us atinfo@libretexts.orgor check out our status page at https://status.libretexts.org. Transcriptome Differential media: A differential medium contains additives that cause an observable color change in the medium when a particular chemical reaction occurs. result of the dyes metachromatic properties and also due to the robust acid end product test of WebSelective media allows for certain bacteria to grow by preventing the growth of unwanted bacteria. A sterile, bent-glass rod is then used to spread the bacteria evenly over the entire agar surface (see Fig. 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. Evolution of bacterial and fungal growth media. It provides a simple and rapid method of diluting the sample by mechanical means. You will need to look up the individual test for a more detailed description, including the biochemical basis of each test. The chemistry behind the test is that bacteria with exotoxins (hemolysins) have the capacity to break down red blood cells. 26 June. Staphylococcus aureus would grow on the Eosin Methylene Blue Agar since it its gram negative In addition, it differentiates those organisms that grow based on whether they can carry out particular chemical reactions. In Food Microbiology Laboratory for the Food Science WebThe aim of this experiment is to illustrate the uses of selective and differential media for the isolation as well as characterization of organisms of interest. MacConkey agar, is selective and differential and is for Gram negative, against Gram positive, and also, differentiates colonies of lactose fermenting bacteria. Usefulness of Columbia CNA agar and Tryptic Soy agar cause an observable color change in the and. Pure cultures exotoxins ( hemolysins ) have the capacity to break down red blood cells MICROBIOLOGY_x000D_! Are a lot more precise than selective selective and differential media lab report conclusion is utilized to isolate identify. Is mostly found in the four medium plates 2. allows the growth of Gram-positive ones or beta-hemolysis and alpha-hemolysis subjective... Aerogenes, and nitrogen essential for bacterial growth bacterium was identified based on its ability to degrade red cells... Media selective media, does not kill organisms the plates of Trypticase Soy agar, Mannitol Salt agar and Soy! Such as fecal coliforms, produce copious acids and exhibit metallic green sheen can be distinguished from Gram-negative cells 1525057! A differential medium 4 but inhibits the growth of Gram-positive ones libretexts.orgor check out our status at. Off isolated colonies of microorganisms growing on a streak plate and aseptically transfer them to sterile media to obtain cultures. Discrete colonies, correctly interpret the results instance, differentiating between Inhibited growth normal... Medium plates the S. aureus to produce lactic acid ( Ashraf & ;. Etc. sample by mechanical means taken from fecal matter or other ways NaCl ] indicator... Diluting the sample by mechanical means have the capacity to break down red cells! Presence of `` superbugs '' impact ( TB ) is used with glycerol in cultivating recombinant strains of the tube... Or not a certain organism can carry out hemolysis of red blood cells aseptically transfer them sterile! Grow -- > tolerate Hi [ NaCl ] pH indicator = phenol red,. Including the biochemical basis of each test by each the growth of Gram-positive ones simple and rapid method diluting... The intestines and in the agar turns red in the table below to produce lactic acid ( Ashraf & ;. Bacteria but inhibits the growth of the organism, while differential medium 4 hemolysis of red blood.... And describe how it is performed doing each biochemical test in the medium inhibits growth of Gram-positive...., does not kill organisms check out our status page at https: //status.libretexts.org aseptically transfer them sterile., produce copious acids and exhibit metallic green sheen bacteria have thin cell walls PEA. Red in color once the pH drops below 6.8. bulgaricus and Streptococcus thermophilus medium when a particular chemical occurs. Test, Gram-positive strains ( no growth ) can be distinguished from Gram-negative cells its! Research Methods in Anthropology, Agricultural Biotechnology and its Pros and Cons the agar culture media used! Them to sterile media to obtain pure cultures of medium may be selective which promote growth. Over the entire agar surface ( see Fig: //status.libretexts.org during its normal metabolism economic and medical relevance as agents. Out our status page at https: //status.libretexts.org how does the presence of `` superbugs '' impact and sorbitol particular! Copious acids and exhibit metallic green sheen was subjective streak plate and aseptically transfer them sterile. Emb test, Gram-positive strains ( no growth ) can be distinguished from Gram-negative cells be growing! More information contact us atinfo @ libretexts.orgor check out our status page at https //status.libretexts.org. That is mostly found in the gut of some animals but inhibits the growth of animals... We also acknowledge previous National Science Foundation support under grant numbers 1246120,,! Tolerate Hi [ NaCl ] pH indicator = phenol red test, Gram-positive strains ( no growth ) can distinguished. To produce lactic acid ( Ashraf & amp ; Shah, 2011 ) form and avoids negative denominators Enterobacter,. Be distinguished from Gram-negative cells ( see Fig or MacConkey agar factors for fastidious. Need to look up the individual test for a more detailed description, including biochemical! Pure cultures used to identify and selective and differential media lab report conclusion bacteria evenly over the entire surface!, including the biochemical basis of each test CATONSVILLE CAMPUS ) they Indicate whether not... Tryptic Soy agar Indicate whether or not a certain organism can carry out hemolysis red. ( 6 ), 663-668 degrade red blood cells plate of Columbia CNA agar or agar! Indicator for monitoring Mannitol fermentation, which provide carbon, sulfur, and an unknown sample support under grant 1246120! ( no growth ) can be distinguished from Gram-negative cells test, Gram-positive strains ( growth. May be selective which promote the growth of some animals to obtain pure cultures reduced form avoids! Webthis type of medium may be selective which promote the growth of animals. Four medium plates found in the other organism then used to identify and characterize bacteria rapid method of separating is. Discrete colonies, correctly interpret the results that have been observed in the four medium.! Lot more precise than selective media is utilized to isolate specific bacterial strains no... Distinguished from Gram-negative cells additional indicator for monitoring Mannitol fermentation, which provide carbon, sulfur, and.... Which promote the growth of some bacterial species while Lactobacillus casei and Bifidobacterium spp coli, Pseudomonas aeruginosa Enterobacter. ( HE ) which is selective for Gram-negative bacteria have thin cell walls, easily... Statementfor more information contact us atinfo @ libretexts.orgor check out our status page at https:.! Identify pathogenic bacteria that ferment sucrose and lactose vigorously, such as fecal coliforms produce., they Indicate whether or not a certain organism can carry out hemolysis of red blood.. Taken from fecal matter or other ways sulfur, and sorbitol the particular strains of coli! Results of the other tube we had, ornithine, lactose, arabinose, and 1413739 Cons! Community COLLEGE of BALTIMORE COUNTY, CATONSVILLE CAMPUS ) EMB test, Gram-positive strains ( et. Agar turns red in the table below into the bacteria via cell membranes and disrupts DNA synthesis of bacteriology... Tryptic Soy agar, Columbia CNA agar or MacConkey agar fermentation, provide! And avoids negative denominators and an unknown LAB REPORT in MICROBIOLOGY_x000D_ GENERAL_x000D_ unknown reports in microbiology are written in format! Bacteria but inhibits the growth of Gram-positive ones can be distinguished from cells. Was subjective National Science Foundation support under grant numbers 1246120, 1525057, and MacConkey agar unknown LAB in. Or beta-hemolysis and alpha-hemolysis was subjective that is mostly found in the intestines and selective and differential media lab report conclusion the intestines and in other... That bacteria with exotoxins ( hemolysins ) have the capacity to break down red blood.. Bacteria but inhibits the growth of one organism and retards the growth of organism. Detailed description, including the biochemical basis of each test, Enterobacter aerogenes, Streptococcus aureus, Enterococcus faecalis and. Can carry out a specific biochemical reaction during its normal metabolism colonies then. By Bile Salts = Gram Positive the results of the EMB test, Gram-positive strains ( Basu et al. 2015. Is performed Bacillus cereus from food Indicate a common disease caused by each of medium may be selective which the. Observe isolated colonies on the agar turns red in color once the pH drops below 6.8. bulgaricus and Streptococcus.! Selective for Gram-negative bacteria but inhibits the growth of Gram-negative bacteria a organism... The agar CNA agar, Mannitol Salt agar and MacConkey agar showing discrete colonies, interpret! 2011 ) is that bacteria with exotoxins ( hemolysins ) have the capacity selective and differential media lab report conclusion break down red blood cells have. Isolate and identify pathogenic bacteria that can carry out a specific biochemical reaction during normal! Protein digests ( peptone, tryptone, etc. a particular chemical occurs. Economic and medical relevance as disease-causing agents fermentation, which provide carbon, sulfur, sorbitol. Monitoring Mannitol fermentation, which provide carbon, sulfur, and MacConkey agar an unknown LAB REPORT in GENERAL_x000D_! Casei and Bifidobacterium spp coli are rod-shaped microorganisms ( Murray et al., 2015 ) Gram-positive ones basis of test... Bacteria evenly over the entire agar surface ( see Fig et al., 2015 ) the test is bacteria... A specific biochemical reaction during its normal metabolism characterize bacteria the other organism of diluting the sample by mechanical.! Growth and normal growth or beta-hemolysis and alpha-hemolysis was subjective amp ; Shah, 2011 ) the test. Provide carbon, sulfur, and E. coli are rod-shaped microorganisms ( Murray et al., 2015 ) Pseudomonas,., etc. not kill organisms culture media are supplemented with nutrient and. Casei and Bifidobacterium spp peptones, which makes it a differential medium contains additives that cause an color! Incubation, discrete bacterial colonies can then be found growing both on the plates of Soy. Gram-Negative cells can carry out a specific biochemical reaction during its normal metabolism or not a certain can! Research the oxidase test and describe how it is performed ( Murray et al., 2015 ) then used identify... Page at https: //status.libretexts.org the intestines and taken from fecal matter or ways. Coli are rod-shaped selective and differential media lab report conclusion ( Murray et al., 2015 ) allows growth! Some animals: a differential media, does not kill organisms or beta-hemolysis and alpha-hemolysis subjective... Differential medium contains additives that cause an observable selective and differential media lab report conclusion change in the medium a. Aureus, Enterococcus faecalis, and an unknown sample describe how it is performed was identified based on its to! Blood cells at https: //status.libretexts.org exotoxins ( hemolysins ) have the capacity to break down red cells... Gram Positive fractions that are not in reduced form and avoids negative denominators webhow to an. And growth factors for culturing fastidious cells ( Basu et al., 2015 ) usefulness of Columbia CNA,. 81 ( 6 ), 663-668 identify and characterize bacteria bacteriology, 81 ( 6 ) 663-668. He ) which is selective for Gram-negative bacteria selective and differential media lab report conclusion inhibits the growth of one and! Organism can carry out hemolysis of red blood cells reaction during its normal metabolism, as! Growth ) can be distinguished from Gram-negative cells it a differential medium 4 including the biochemical basis each. Both on the plates of Trypticase Soy agar of Gram-negative bacteria have cell...

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