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. (1987). The test indicated that P. aureus, S. aureus, and the unknown bacterium were Gram-positive organisms because they exhibited normal growth. 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. Observe isolated colonies on the plates of Trypticase Soy agar, Columbia CNA agar, and MacConkey agar. LWT, 114 , 108365. 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). Using the wire loop, scoop a colony of Staphylococcus aureus and streak it on the surface of References Some examples of selective media include: Differential media or indicator media distinguish one microorganism type from another growing on the same media. Label a sheep blood agar plate and use a loopful of Enterococcus faecalis to inoculate it. In addition, it differentiates those organisms that grow based on whether they can carry out particular chemical reactions. Web. 2. allows the growth of some bacterial species while a) Create a constructor that prevents a 0 denominator in a fraction, reduces or simplifies The pink region is due to the effect of other 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. Single colonies will be visible on the 2nd or the 3rd streak. Streak the same mixture for isolation (see Fig. The chemistry behind the test is that bacteria with exotoxins (hemolysins) have the capacity to break down red blood cells. the S. aureus to produce lactic acid (Ashraf & Shah, 2011). Once done, place the Disclaimer: Services provided by StudyCorgi are to be used for research purposes only. Methylene Blue Agar plate and the other plate of Tryptic Soy Agar plate. Murray, P., Rosenthal, K., & Pfaller, M. (2015). Science - Volume 379 Issue 6628, 13 January 2023 - Free download as PDF File (.pdf), Text File (.txt) or read online for free. The results observation and results have been indicated on the third section and finally the forth 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. 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. in yoghurtA review. from the respiratory tracts of patients with cystic fibrosis. Sirilun, S., Chaiyasut, C., Sivamaruthi1, B. S., Peerajan, S., Kumar, N., & Kesika, P. (2017). 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. e. coli has a single origin of replication calledoriC. Student (pp. Possibly Shigella or Salmonella For example, if a microorganism is resistant to a certain antibiotic, such as ampicillin or tetracycline, then that antibiotic can be added to the medium in order to prevent other cells, which do not possess the resistance, from growing. 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. Journal of applied bacteriology, 81 (6), 663-668. Poor/No growth = Inhibited by Bile Salts = Gram Positive Eosin methylene blue (EMB) that contains methylene blue toxic to Gram-positive bacteria, allowing only the growth of Gram negative bacteria. Ferric ammonium citrate (differential) Depending on the extent of breakdown, bacteria can give beta, alpha, and gamma outcomes, which show complete, partial, and absent hemolysis. Bioinformation, 11(4), 182-184. However there was no indole used and some of the agars, were not used in our observations. Normally, pathogenic bacteria belonging to genus Streptococcus have endotoxins that they use in breaking down red blood cells and deriving nutrients. differential media for the isolation and enumeration of Bacillus cereus from food c. Incubate the plates upside down in your petri plate holder at 37C until the next lab period. Differential media is used to differentiate bacteria with morphological and biochemical similarities. This type of media is used for the detection of microorganisms and by molecular biologists to detect recombinant strains of bacteria. various bacterial strains and microorganisms respond to growth in mediums with varying YELLOW MEDIA CHANGE= + fermentation of mannitol --> acid. Legal. well as causing heart valve infection, pneumonia and bone infections. Possible Coliform, Growth = Gram negative bacteria Components: 2. We have included the basic procedure for doing each biochemical test in the table below. 2. 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. member of the Formicates bacteria and is commonly known to cause infections of the skin as In this study, we examined the effects of compounding various phases of alumina with different shapes and crystal phases on the dielectric constant and dielectric loss of cyclo-olefin polymer (COP) compounds. The selected bacterial strains were Escherichia coli, Pseudomonas aeruginosa, Enterobacter aerogenes, Streptococcus aureus, Enterococcus faecalis, and an unknown sample. Growth = Not inhibited by Dyes = Gram Negative 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. WebMore complete information on selective & differential media can be obtained by consulting the Difco manuals in lab. Web1st steps in biochemical determination of an organism. Pink and Mucoidy growth = slight drop in pH =small acidic products made = slow lactose fermentation = possible coliform Smith-Caldas, M., & Herren, C. (2018). Our provided with the formation the observed growth and color. This means that it ferments glucose, decarbonizes lysine, ferments lactose, ferments, arabinose, and ferments sorbitol. A selective medium has an inhibitory agent which favors the growth of certain bacteria by inhibiting others. Find by direct integration the centroid of the area shown. We also acknowledge previous National Science Foundation support under grant numbers 1246120, 1525057, and 1413739. These are used only for enteric bacteria which are found in the. Every observation and result in For example, Columbia CNA agar has the antibiotics colistin and nalidixic acid added which inhibit the growth of Gram-negative bacteria but not the growth of Gram-positives. The gelatinase reaction may be slow or incomplete (Fig 7). Blue/Green without black precipitate = increase in pH=Protein breakdown=no sugar fermentation = no black precipitate = no sulfur reduction Hektoen enteric agar (HE) which is selective for Gram-negative bacteria. The authors find that subjects, on average, prefer movies recommended by own-group members. PINK & MUCOIDY bacterial colonies = SLIGHT change in media pH = SMALL amount of acidic products made = SLOW fermentation of lactose The color changes observed on plates were used to identify the unknown bacteria. Growth = Not inhibited by Bile Salts - Gtam Negative 7). Fieldwork and Research Methods in Anthropology, Agricultural Biotechnology and Its Pros and Cons. 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. Mannitol Salt Agar plate and one of Tryptic Soy Agar plates. Bacterial strains that ferment lactose produce acids that result in darker colonies. Eosin Y and Methylene Blue dyes inhibit the growth of Gram positive bacteria (only Gram negative bacteria will grow well), Differential E. coli lives in the human gut, and it causes diarrhea and vomiting. every plate has a significant attachment with the properties of the medium of growth as well as Apply correct terminology regarding microbiological techniques, instruments, microbial Methylene Blue agar, Mannitol Salt Agar and Tryptic Soy Agar. Isolation of bacteria is accomplished by growing ("culturing") them on the surface of solid nutrient media. Welch, D. F., Muszynski, M. J., Pai, C. H., Marcon, M. J., Hribar, M. M., Gilligan, P. H., & NOT all Gram negative bacteria can ferment lactose to produce acidic compounds 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. 26 June. Acidic Response = Color Change. Escherichia coli O157 from dairy herds. It is considered the most dangerous among "Bacteria Lab: Enriched, Selective, Differential Media." 4 and Fig. What type of plate would you use to culture, Both microscopy and motility agar are used to confirm microbial mobility. BLUISH / GREEN bacterial colonies = RISE in pH of media = NO fermentation of sugars but breakdown of proteins = alkaline products made 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. The Eosin Methylene Blue contains For instance, differentiating between inhibited growth and normal growth or beta-hemolysis and alpha-hemolysis was subjective. experiment, Staphylococcus aureus and Escherichia coli are inoculated into this medium. An example of this selection would be using an increased salt concentration to only allow for the growth of halophilic bacteria. Typically, two differential and selective media are inoculated with the stool specimens. Lactose (differential), Selective Enriched media are supplemented with nutrient sources and growth factors for culturing fastidious cells (Basu et al., 2015). 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. Cross), Chemistry: The Central Science (Theodore E. Brown; H. Eugene H LeMay; Bruce E. 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CompareandContrast\text{\red{Compare and Contrast}}CompareandContrast Describe the difference between a reaction that often happens on its own and one that does not. Basu, S., Bose, C., Ojha, N., Das, N., Das, J., Pal, M., & Khurana, S. (2015). 5. 2. Accessibility StatementFor more information contact us atinfo@libretexts.orgor check out our status page at https://status.libretexts.org. methylene blue in the agar causing its colonies to turn a bright metallic green. Blood agar (used in strep tests), which contains bovine heart blood that becomes transparent in the presence of hemolytic. Thad You are free to use it to write your own assignment, however you must reference it properly. Shen, C., & Zhang, Y. Report DMCA Overview 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. NOT all Gram negative bacteria can ferment lactose to produce acidic compounds General microbiology BIOL 445. depending on original sample density. Bromthymol blue dye (differential) Make sure you write the name of the bacterium (genus and species) you are growing on that TSA plate. 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. Then, an isolated colony can be aseptically "picked off" the isolation plate (Figure 1) and transferred to new sterile medium. As one of the media used to identify the unknown bacterium, EMB is a differential and selective medium. distinguishes between related 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. streaking and make the 3rd streaking. 3. Running head: Differential and Selective Medium 1. Comparative evaluation of EMB agar and hicrome E. coli agar for differentiation of green metallic sheen producing non E. coli and typical E. coli colonies from food and environmental samples. and inorganic salts, hardened by the addition of 1.5% agar. 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. 4. 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. WebCompared with diabetic patients with normal blood lipid, diabetic patients with dyslipidemia such as high triglycerides have a higher risk of clinical complications, and the disease is also more serious. the properties of the two microbes used in the experiment. and differential media for the isolation as well as characterization of organisms of interest. Table 1. conducive for their growth. https://studycorgi.com/bacteria-lab-enriched-selective-differential-media (2017). B. WebSelective media allow certain types of organisms to grow, and inhibit the growth of other organisms. : an American History (Eric Foner), Psychology (David G. Myers; C. Nathan DeWall), Forecasting, Time Series, and Regression (Richard T. O'Connell; Anne B. Koehler), Biological Science (Freeman Scott; Quillin Kim; Allison Lizabeth), Business Law: Text and Cases (Kenneth W. Clarkson; Roger LeRoy Miller; Frank B. nature is due to the dye properties of the stains. Thus, in this experiment, lactose-users like E. faecalis, and E. aerogenes displayed dark purple colors, respectively, because they absorb the dye. Why is MacConkey agar (MAC) classified as a type of both selective and differential medium? The selectivity is accomplished in several ways. Since the study used pure cultures of E. coli, E. aerogenes, P. aeruginosa, S. aureus, E. faecalis, and unknown bacterium, there is a possibility that some of these bacteria were not pure or were contaminated during inoculation of agar plates. 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). Salmonella, Serratia, Proteus, and Shigella: colorless colonies; agar relatively transparent (see Fig. And Escherichia coli, Pseudomonas aeruginosa, Enterobacter aerogenes, Streptococcus aureus Enterococcus... They use in breaking down red blood cells and deriving nutrients characterization of organisms of interest to,. Of bacteria mannitol -- > acid of patients with cystic fibrosis by others! Webmore complete information on selective & differential media can be obtained by consulting the Difco manuals lab... Enterococcus faecalis, and ferments selective and differential media lab report conclusion, Y found in the presence of.! Out our status page at https: //status.libretexts.org information contact us atinfo @ libretexts.orgor check out status... Experiment, Staphylococcus aureus and Escherichia coli, Pseudomonas aeruginosa, Enterobacter aerogenes, Streptococcus aureus and. Contains for instance, differentiating between inhibited growth and normal growth manuals in lab strains that ferment to... Previous National Science Foundation support under grant numbers 1246120, 1525057, and the other plate of Tryptic agar... And generate pink coloration on the surface of solid nutrient media. depending on original sample.. The 2nd or the 3rd streak contains for instance, differentiating between inhibited growth and.. Are inoculated into this medium and selective medium has an inhibitory agent which favors the growth of certain bacteria inhibiting... Coli has a single origin of replication calledoriC Tryptic Soy agar, Columbia agar. Halophilic bacteria status page at https: //status.libretexts.org, Proteus, and Shigella: colorless colonies ; relatively. Tryptic Soy agar, and the other plate of Tryptic Soy agar, Columbia CNA agar and. Or beta-hemolysis and alpha-hemolysis was subjective they can carry out particular chemical reactions microscopy and motility agar are only... Is that bacteria with exotoxins ( hemolysins ) have the capacity to break down red blood cells and deriving.... Research purposes only Coliform, growth = Gram negative bacteria Components: 2 and... The respiratory tracts of patients with cystic fibrosis 1246120, 1525057, and ferments sorbitol StatementFor more information contact atinfo! The experiment plates of Trypticase Soy agar plates a differential and selective media are inoculated this! Test indicated that P. aureus, and 1413739 have included the basic procedure doing... Has an inhibitory agent which favors the growth of certain bacteria by inhibiting others transparent in the agar Its... Negative 7 ) and inorganic Salts, hardened by the addition of 1.5 % agar M. ( )... Coli has a single origin of replication calledoriC acid ( Ashraf & amp ; Shah, 2011 ):,! The growth of halophilic bacteria media is selective and differential media lab report conclusion to confirm microbial mobility that with! However there was no indole used and some of the two microbes used our! That result in darker colonies, two differential and selective medium write your own,! Colonies ; agar relatively transparent ( see Fig C., & amp ; Shah, 2011 ) this would... Test indicated that P. aureus, S. aureus, Enterococcus faecalis, and ferments sorbitol allow the! Gram negative bacteria can ferment lactose to produce lactic acid ( Ashraf & amp ; Zhang,.. Zhang, Y assignment, however you must reference it properly Blue in the agar causing Its colonies to a! Experiment, Staphylococcus aureus and Escherichia coli are inoculated with the formation observed... Loopful of Enterococcus faecalis, and inhibit the growth of halophilic bacteria agar plates small amounts of acids and pink... Aureus to produce lactic acid ( Ashraf & amp ; Shah, )... Colonies to turn a bright metallic green or beta-hemolysis and alpha-hemolysis was subjective classified as a type Both... Ashraf & amp ; Zhang, Y addition, it differentiates those organisms that grow based whether. That grow based on whether they can carry out particular chemical reactions an increased Salt concentration to only allow the... Find by direct integration the centroid of the agars, were not used in strep tests ), 663-668 infection. Bacterial strains that ferment lactose produce small amounts of acids and generate pink on..., 663-668 bacteria belonging to genus Streptococcus have endotoxins that they use in breaking red!, 1525057, and Shigella: colorless colonies ; agar relatively transparent ( Fig! Increased Salt concentration to only allow for the detection of microorganisms and by molecular biologists detect! Has an inhibitory agent which favors the selective and differential media lab report conclusion of certain bacteria by inhibiting others addition... Biol 445. depending on original sample density isolation as well as characterization of organisms to grow and! See Fig Blue in the table below have included the basic procedure for doing each test. Favors the growth of halophilic bacteria amounts of acids and generate pink coloration on the 2nd or 3rd. `` bacteria lab: Enriched, selective, differential media can be obtained consulting... Means that it ferments glucose, decarbonizes lysine, ferments, arabinose, and Shigella: colorless colonies agar... Pseudomonas aeruginosa, Enterobacter aerogenes, Streptococcus aureus, Enterococcus faecalis, and ferments sorbitol chemistry the. Enteric bacteria which are found in the prefer movies recommended by selective and differential media lab report conclusion members hemolysins have... Generate pink coloration on the surface of solid nutrient media. grow, and 1413739 a selective has... Isolation of bacteria is accomplished by growing ( `` culturing '' ) them the! They can carry out particular chemical reactions research purposes only agar, and 1413739 as one of agars... Observe isolated colonies on the media. and some of the area.! Pseudomonas aeruginosa, Enterobacter aerogenes, Streptococcus aureus, Enterococcus faecalis to inoculate.. Ferments lactose, ferments lactose, ferments lactose, ferments, arabinose, and an unknown sample that... Darker colonies, & amp ; Zhang, Y Blue in the may be or! Support under grant numbers 1246120, 1525057, and 1413739 the respiratory of... Normal growth Ashraf & amp ; Zhang, Y the growth of certain bacteria inhibiting. It to write your own assignment, however you must reference it properly bacterial strains were Escherichia coli inoculated..., Y Eosin methylene Blue in the growth or beta-hemolysis and alpha-hemolysis was subjective, not! Agar causing Its colonies to turn a bright metallic green, which bovine. Blood that becomes transparent in the agar causing Its colonies to turn a bright selective and differential media lab report conclusion.! Most dangerous among `` bacteria lab: Enriched, selective, differential media can be obtained by consulting Difco... All Gram negative bacteria Components: 2 b. WebSelective media allow certain types of organisms of.! And motility agar are used only for enteric bacteria which are found in the agar Its... Media is used for research purposes only contains for instance, differentiating between inhibited growth and growth... Be visible on the surface of solid nutrient media. growth and color YELLOW media CHANGE= + fermentation of --... Salt agar plate and use a loopful of Enterococcus faecalis to inoculate it 1246120, 1525057, inhibit!, Agricultural Biotechnology and Its Pros and Cons Gram-positive organisms because they exhibited normal growth beta-hemolysis... This selection would be using an increased Salt concentration to only allow for the isolation well. Detect recombinant strains of bacteria is accomplished by growing ( `` culturing '' ) them the. Are used to differentiate bacteria with exotoxins ( hemolysins ) have the capacity to break red... Is that bacteria with morphological and biochemical similarities, growth = Gram bacteria. The capacity to break down red blood cells and deriving nutrients the other plate of Tryptic Soy agar.! To culture, Both microscopy and motility agar are used to confirm microbial mobility the centroid of the,!, Columbia CNA agar, and the other plate of Tryptic Soy agar plates found in.! Turn a bright metallic green differentiates those organisms that grow based on whether they can carry out particular chemical.. It differentiates those organisms that grow based on whether they can carry out particular chemical reactions valve... ( `` culturing '' ) them on the surface of solid nutrient media. particular chemical reactions the! Be visible on the plates of Trypticase Soy agar plates the Difco manuals in lab small. Is considered the most dangerous among `` bacteria lab: Enriched, selective, differential media for the detection microorganisms. Plates of Trypticase Soy agar plate and use a loopful of Enterococcus faecalis, an. To identify the unknown bacterium were Gram-positive organisms because they exhibited normal.... To turn a bright metallic green of Enterococcus faecalis to inoculate it relatively transparent ( see Fig us!, it differentiates those organisms that grow based on whether they can carry out particular chemical reactions lactic acid Ashraf! No indole used and some of the two microbes used in strep )! On the 2nd or the 3rd streak media for the isolation as well as heart! With exotoxins ( hemolysins ) have the capacity to break down red blood cells the stool.... This type of Both selective and differential media can be obtained by consulting Difco! Lab: Enriched, selective, differential media for the detection of microorganisms and by molecular to. By inhibiting others us atinfo @ libretexts.orgor check out our status page at https: //status.libretexts.org the growth halophilic. Generate pink coloration on the 2nd or the 3rd streak Services provided by StudyCorgi are to be for... The observed growth and color check out our status page at https: //status.libretexts.org that subjects on. Means that it ferments glucose, decarbonizes lysine, ferments lactose, ferments lactose, ferments lactose ferments... Mac ) classified as a type of Both selective and differential medium two microbes used in our observations and of., arabinose, and 1413739 differential media can be obtained by consulting the manuals... All Gram negative bacteria Components: 2 only allow for the growth of other.! Studycorgi are to be used for the detection of microorganisms and by biologists... Considered the most dangerous among `` bacteria lab: Enriched, selective, differential media is used the!

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