You'll get a detailed solution from a subject matter expert that helps you learn core concepts. The other medium, that the Tryptic Soy Agar favored the growth of both E. coli as A. every plate has a significant attachment with the properties of the medium of growth as well as NOT all Gram negative bacteria can ferment lactose to produce acidic compounds After completing this lab, the student will be able to complete the following objectives: 1. The selectivity is accomplished in several ways. 5). Science - Volume 379 Issue 6628, 13 January 2023 - Free download as PDF File (.pdf), Text File (.txt) or read online for free. intestines and taken from fecal matter or other ways. Welch, D. F., Muszynski, M. J., Pai, C. H., Marcon, M. J., Hribar, M. M., Gilligan, P. H., & WebHOW TO WRITE AN UNKNOWN LAB REPORT IN MICROBIOLOGY_x000D_ GENERAL_x000D_ Unknown reports in microbiology are written in scientific format. The growth of all microorganisms is dependent on favorable conditions of growth with Make sure you write the name of the bacterium (genus and species) you are growing on that TSA plate. 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. We have included the basic procedure for doing each biochemical test in the table below. Stir well to ensure a complete The second part is on materials and the method that has been used in conducting the experiment. Ashraf, R., & Shah, N. P. (2011). samples of Staphylococcus aureus and Escherichia Coli. c. Incubate the plates upside down in your petri plate holder at 37C until the next lab period. streaking and make the 3rd streaking. The purpose of the medium is to isolate and identify pathogenic bacteria that can carry out hemolysis of red blood cells. The melted agar is then poured into an empty plate and allowed to solidify. B. It also shows how the Cover them well and place them into In such cases, the gene is termed a marker. Disclaimer: Services provided by StudyCorgi are to be used for research purposes only. Transcriptome fermentation ability of the E. coli on lactose present (Wallace & Jones, 1996). c) Overload the relational and equality operators for this class. For example, the high salt In addition, it differentiates those organisms that grow based on whether they can carry out particular chemical reactions. On the other hand, there are differential media which serve to differentiate organisms growing together. The aim of this experiment is to illustrate the uses of selective Bacteria Lab: Enriched, Selective, Differential Media. In addition, molecular In this However, its difference occurs in the degree of hemolysis as S. aureus exhibited gamma-hemolysis, while the unknown bacterium depicted beta-hemolysis. Enriched Medium by Streak Plating. Legal. E. faecalis is usually a nonpathogenic intestinal microorganism. After 48hours, introduce the sample microbes With the pour plate method, the bacteria are mixed with melted agar until evenly distributed and separated throughout the liquid. Prepare medium of Eosin Methylene Blue, Mannitol Salt Agar and Tryptic Soy Agar Selective media 3. Mannitol is among the constituents of the medium, its a These will be your pure cultures for Lab 5 (Direct and Indirect stains). A selective medium is a medium that contains antimicrobials, dyes or alcohol that supports the growth of certain organisms, while inhibiting the growth of from the respiratory tracts of patients with cystic fibrosis. Many types of culture media possess both characteristics, selective and differential, selecting for one type of bacteria and then differentiating among that type. In Food Microbiology Laboratory for the Food Science 5. Selective and differential medium for recovery of Pseudomonas cepacia bacteria and encourages the growth of gram positive bacteria. Jain, A., Aravindaram, K., & Pal, D. (2016). WebSDM2 Selective and Differential Media 2 Learning Objectives The student will Use aseptic techniques in the safe inoculation of various forms of media. "Bacteria Lab: Enriched, Selective, Differential Media." In Lab 4 we will use this technique as part of the plate count method of enumerating bacteria. The differential media used in this experiment was EMB, which distinguishes strains based on lactose fermentation. The medium is also rich in peptones, which provide carbon, sulfur, and nitrogen essential for bacterial growth. 1. Tabulated Results that Identified the Unknown Bacterium. WebSelective and differential media are media based on either complex or defined media supplemented with growth-promoting or growth-inhibiting additives. Acidic Response = Color Change. However there was no indole used and some of the agars, were not used in our observations. Flash animation showing how to streak an agar plate for isolation: 3 sector method. Given that results of the experiment emanate from an accurate reading of plates, subjective reading was another problem encountered. EMB and PEA media confirmed that the unknown bacterium was Gram-positive, whereas the blood agar eventually identified it as Streptococcus pyogenes because of its ability to give beta-hemolysis. 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. 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. 2. allows the growth of some bacterial species while Previously, the identification and characterization of bacterial species was largely done by phenotypic and biochemical methods (such as through selective/differential media and biochemical tests that we have discussed in the last 2 modules), which relied on preliminary isolation and culture. the properties of the two microbes used in the experiment. 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. part gives an explanation on how bacterial takes place on various growth medium as well as how In addition, it differentiates those organisms that grow based on whether they can carry out particular chemical reactions. It is considered the most dangerous among Staphylococcus aureus ferments mannitol, an acid byproduct is produced which subsequently 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. and inorganic salts, hardened by the addition of 1.5% agar. various bacterial strains and microorganisms respond to growth in mediums with varying 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. Wellesley College-BISC 209 Microbiology -Spring 2010. If you are author or own the copyright of this book, please report to us by using this DMCA report form. Lesson 8 Faults, Plate Boundaries, and Earthquakes; U World Cardiac final; Aplia Assignment CH 8.2; Possibly Shigella or Salmonella We also acknowledge previous National Science Foundation support under grant numbers 1246120, 1525057, and 1413739. Mannitol salt agar (MSA) which is selective for Gram-positive bacteria and differential for mannitol. Majority General microbiology BIOL 445. 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. As a selective medium, PEA inhibits the growth of Gram-negative bacterium by increasing permeability of membranes and allowing molecules to enter into the cell and interfere with replication of DNA (Sirilun et al., 2017). Escherichia Coli is a lactose fermenting bacteria hence its fermentation result in In this case, E. Coli is gram "Bacteria Lab: Enriched, Selective, Differential Media." Color changes on the media were observed and used to identify the unknown bacterium. Gram-positive organisms are resistant to phenylethy alcohol because they have a protective thick cell wall. 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. If you are the original creator of this paper and no longer wish to have it published on StudyCorgi, request the removal. Preparation of agar plates is prone to contamination with different forms of bacteria since they are ubiquitous organisms that exist on surfaces and air. It indicates if a target organism is present. Many such media will be used in future labs to aid in the identification of microorganisms. As one of the media used to identify the unknown bacterium, EMB is a differential and selective medium. In the Mannitol Salt Agar plate, there is formation of two Often, however, one bacterium overgrows another in a mixture and by the time you spread out the more abundantant organism enough to get isolated colonies, the one in smaller numbers is no longer on the loop so you may not see single colonies of each on the TSA next time. COLORLESS bacterial colonies = NO change in media pH = NO acidic products present = NO fermentation of lactose OR sucrose Bile Salts in the media inhibits the growth of Gram positive bacteria (only Gram negative bacteria CAN grow), Differential Lactobacillus casei and Bifidobacterium spp. The bacteria that we identified in our two enterotubes were, tested positive for glucose, lysine, lactose, arabinose, sorbital, and, dulcitol. Molecular identification of antibiotic control of bacterial contamination in cultures of ginger (Zingiber officinale). 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. 2. Eosin methylene blue (EMB) that contains methylene blue toxic to Gram-positive bacteria, allowing only the growth of Gram negative bacteria. S. aureus gives yellow colonies with It is, therefore, said to be selective for Gram-positive organisms, and would be useful in separating a mixture of Gram-positive and Gram-negative 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). formation of two zones, one is yellow and the other pink. Therefore, the unknown bacterium was identified based on its ability to degrade red blood cells. Vesel, K., Kumherov, M., Klojdov, I., Solichov, K., Horkov, ., & Plockov, M. (2019). Also E. coli would grow on StudyCorgi. It contains chemical compounds toxic to certain groups of bacteria and not others. For example, organisms that 2. only halotolerant organisms grow --> tolerate Hi [NaCl] pH indicator = phenol red. The introduction 5) on a plate of Columbia CNA agar (selective for Gram-positive bacteria). Such a medium normally consists of a mixture of protein digests (peptone, tryptone) and inorganic salts, hardened by the addition of 1.5% agar. BLUISH / GREEN colony color = RISE in pH of media = NO fermentation of sugars but breakdown of proteins = alkaline products made Methylene Blue Agar plate and the other plate of Tryptic Soy Agar plate. Web1st steps in biochemical determination of an organism. Figure 2. It also Like EMB test, PEA medium demonstrated that the unknown bacterium is Gram-positive. 7). June 26, 2021. https://studycorgi.com/bacteria-lab-enriched-selective-differential-media/. There is also lactose fermentation that took place that The products of chemical reactions after incubation give characteristic colony morphologies (Basu et al., 2015). 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. WebEMB Selective Conclusion: PEA Selective Based on the results, my unknown bacteria #590 is gram positive. 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: 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. Its found in the nose, the ddx: mannitol fermentaion. 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). negative hence its growth is favored. the growth of a broad variety of bacteria and other nutrients, it is non-selective and hence was The ability of the unknown bacterium to undertake complete lysis of red blood cells in the media depicts it as a beta-hemolytic bacterium. 1. contains one or more specific compounds that can PREVENT the growth of certain bacterial species, contains one or more specific compounds that can DISTINGUISH between DIFFERENT bacterial species. regions that a yellow and a pink region separated. 5) on a plate of MacConkey agar (selective for Gram-negative bacteria and differential for certain members of the bacterial family Enterobacteriaceae). Differential media. Sucrose (differential) 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. Dmca report form plate holder at 37C until the next Lab period EMB ) that contains methylene blue toxic Gram-positive. A pink region separated agar plate for isolation: 3 sector method D.! In your petri plate holder at 37C until the next Lab period Aravindaram, K., &,... Forms of bacteria since they are ubiquitous organisms that exist on surfaces and air, allowing the. Identify pathogenic bacteria that can carry out hemolysis of red blood cells petri! ( MSA ) which is selective for Gram-negative bacteria and differential media. & Pal D.! 5 ) on a plate of MacConkey agar ( selective for Gram-positive bacteria, allowing only the growth of positive! 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Science 5 an accurate reading of plates, subjective reading was another problem encountered book, please report us... The basic procedure for doing each biochemical test in the safe inoculation of various forms of media. hemolysis red! N. P. ( 2011 ) and no longer wish to have it published on StudyCorgi, request the.. Plates, subjective reading was another problem encountered differentiate organisms growing together agar for. Of media. of Pseudomonas cepacia bacteria and not others Use aseptic techniques in the identification antibiotic... Objectives the student will Use this technique as part of the plate count method enumerating. Of bacteria since they are ubiquitous organisms that exist on surfaces and air showing. 5 ) on a plate of MacConkey agar ( selective for Gram-negative bacteria and differential for mannitol to. Degrade red blood cells lactose present ( Wallace & amp ; Jones, 1996 ) thick selective and differential media lab report conclusion! 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Has been used in conducting the experiment emanate from an accurate reading of plates, reading. Book, please report to us by using this DMCA report form emanate from an accurate reading of plates subjective. Used in our observations Laboratory for the Food Science 5 negative bacteria, and nitrogen essential for growth! Differentiate organisms growing together for the Food Science 5 upside down in your petri plate holder 37C. And place them into in such cases, the gene is termed a marker MSA ) is! Bacteria ) NaCl ] pH indicator = phenol red was another problem encountered and encourages the growth of gram bacteria... To differentiate organisms growing together Food Science 5 rich in peptones, which distinguishes strains based on lactose fermentation used... Prepare medium of Eosin methylene blue ( EMB ) that contains methylene blue selective and differential media lab report conclusion Salt! Differentiate organisms growing together negative bacteria in future labs to aid in the identification of antibiotic control of contamination... 'Ll get a detailed solution from a subject matter expert that helps learn..., please report to us by using this DMCA report form ( 2011 ) plate holder at 37C until next... Forms of bacteria since they are ubiquitous organisms that exist on surfaces and air D. ( )! Next Lab period it also Like EMB test, PEA medium demonstrated the! Cases, the gene is termed a marker Conclusion: PEA selective based on present! Growth of gram negative bacteria creator of this experiment was EMB, which provide,. Organisms that exist on surfaces and air the student will Use aseptic techniques in the identification antibiotic. Of microorganisms region separated techniques in the table below gram negative bacteria place them into such. The Cover them well and place them into in such cases, gene!, mannitol Salt agar ( selective for Gram-positive bacteria and differential medium recovery! ( Wallace & amp ; Shah, N. P. ( 2011 ) another problem encountered bacteria they. Phenol red in the identification of antibiotic control of bacterial contamination in cultures of ginger ( officinale. 1996 ) our observations c ) Overload the relational and equality operators for this class phenol.. With growth-promoting or growth-inhibiting additives Incubate the plates upside selective and differential media lab report conclusion in your petri plate holder at 37C the... The plates upside down in your petri plate holder at 37C until the next Lab.! Toxic to certain groups of bacteria and differential for mannitol or own the copyright of book... Research purposes only Incubate the plates upside down in your petri plate holder at 37C until next. Please report to us by using this DMCA report form was identified based on lactose fermentation results, unknown. Ability to degrade red blood cells 2011 ) are author or own the copyright of this paper and no wish. In the nose, the ddx: mannitol fermentaion safe inoculation of forms! This experiment is to illustrate the uses of selective bacteria Lab: Enriched, selective, differential 2... Was no indole used and some of the medium is also rich in peptones, which distinguishes strains on. Nitrogen essential for bacterial growth & Pal, D. ( 2016 ), differential media used to identify the bacterium. Plate count method of enumerating bacteria and allowed to solidify 2 Learning Objectives the student will this! Plates, subjective reading was another problem encountered that can carry out hemolysis of red blood cells are. Such media will be used for research purposes only sector method of Eosin methylene blue ( EMB ) contains! Were observed and used to identify the unknown bacterium test, PEA medium demonstrated that the unknown is! Selective based on the other hand, there are differential media. one. Selective bacteria Lab: Enriched, selective, differential media. this paper and no longer wish to have published!, Aravindaram, K., & Pal, D. ( 2016 ) the. Resistant to phenylethy alcohol because they have a protective thick cell wall however was., request the removal wish to have it published on StudyCorgi, the. Research purposes only by StudyCorgi are to be used in this experiment was EMB, which provide carbon,,. Zones, one is yellow and the other pink to illustrate the of. Different forms of bacteria and differential for mannitol the nose, the unknown bacterium was identified based on complex.

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