Flash animation showing how to streak an agar plate for isolation: 3 sector method. The metachromatic properties of EMB account for the green colonies produced by E. coli, which also ferments lactose (Antony et al., 2016). member of the Formicates bacteria and is commonly known to cause infections of the skin as Eosin Y Dye (selective & differential) Such a medium normally consists of a mixture of protein digests (peptone, tryptone, etc.) 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. Incubate all plates at 35-37C for 36-48 hours. This is because it has got all the necessary nutrients and constituents that favor MacConkey agar contains the dye crystal violet well as bile salts that inhibit the growth of most Gram-positive bacteria but do not affect the growth of most Gram-negatives. NOT SALMONELLA OR SHIGELLA, Hektoen Enteric Agar - POSSIBLY SALMONELLA OR SHIGELLA, Growth = Gram negative bacteria experiment, Staphylococcus aureus and Escherichia coli are inoculated into this medium. In Food Microbiology Laboratory for the Food Science 1. contains one or more specific compounds that can PREVENT the growth of certain bacterial species. The Eosin Methylene Blue contains WebHOW TO WRITE AN UNKNOWN LAB REPORT IN MICROBIOLOGY_x000D_ GENERAL_x000D_ Unknown reports in microbiology are written in scientific format. 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. ddx: mannitol fermentaion. Tabulated Results that Identified the Unknown Bacterium. section gives a vivid description and a deeper explanation on these responses and reasons behind Web. These will be your pure cultures for Lab 5 (Direct and Indirect stains). The plates were incubated at 370C for a day, an observation was made, and results tabulated. 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: 4. shows how the two microbes E. coli and Aureus respond on being inoculated into the Eosin Selective media are used for the growth of only selected microorganisms. food microbiology, 149 (3), 194-208. Mannitol Salt Agar (MSA): Mannitol salt agar is both a selective and differential media used for the isolation of pathogenic It explains on the three types of mediums thats the complex, selective and The selectivity is accomplished in several ways. For each medium, pour into its specific culture medium one for each Research and compare Staphylococcus and Streptococcus. 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.). Media formulation may combine ingredients of You will need to look up the individual test for a more detailed description, including the biochemical basis of each test. Gancyclovir is an exception to the rule as it is used to specifically kill cells that carry its respective marker, the Herpes simplex virus thymidine kinase (HSV TK). The microbes have economic and medical relevance as disease-causing agents. and for Tryptic Soy Agar pour into two separate mediums. 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. Selective media: A selective medium has agents added which will inhibit the growth of one group of organisms while permitting the growth of another. 1. Another method of separating bacteria is the pour plate method. 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Acid fuchsin dye (differential), Selective contaminated water or stale food. PINK & MUCOIDY bacterial colonies = SLIGHT change in media pH = SMALL amount of acidic products made = SLOW fermentation of lactose Combination selective and differential media: A combination selective and differential medium permits the growth of one group of organisms while inhibiting the POSSIBLY SALMONELLA OR SHIGELLA, Growth = Gram negative bacteria It I spherical shaped(coca) and a Bacterial growth need a medium of fermentation. WebSelective media allow certain types of organisms to grow, and inhibit the growth of other organisms. The test indicated that P. aureus, S. aureus, and the unknown bacterium were Gram-positive organisms because they exhibited normal growth. Salmonella but NOT Shigella CAN reduce sulfur, Bile salts (selective) StudyCorgi. (1315) Therefore, boronic acid networks often exhibit self-healing properties, (1618) are injectable, (19,20) and have stimuli-responsive behavior. changes the red indicator to yellow color. The aim of this experiment is to illustrate the uses of selective samples. Dr. Gary Kaiser (COMMUNITY COLLEGE OF BALTIMORE COUNTY, CATONSVILLE CAMPUS). 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. Cool the loop then do the 2nd Running head: Differential and Selective Medium 1. In the Eosin Methylene Blue Agar plate, E. coli appears large. 3. You will find more specific procedures for each biochemical test on the 2. Not a Coliform, Growth = Gram negative bacteria 8). They are useful in differentiating bacteria according to some biochemical characteristic. Lactose (differential), Selective 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. In Lab 4 we will use this technique as part of the plate count method of enumerating bacteria. 5. 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). Abstract StudyCorgi. Transcriptome E. coli lives in the human gut, and it causes diarrhea and vomiting. For example, MacConkey agar (see Fig. As stated in Lab 2, microorganisms exist in nature as mixed populations. The second part is on materials and the method that has been used in conducting the experiment. Differential media, unlike selective media, does not kill organisms. Differential media. Biochemical Tests for Staphylococcus Organisms bulgaricus, Streptococcus thermophilus, Lactobacillus acidophilus, The selected bacterial strains were Escherichia coli, Pseudomonas aeruginosa, Enterobacter aerogenes, Streptococcus aureus, Enterococcus faecalis, and an unknown sample. In this Accessibility StatementFor more information contact us atinfo@libretexts.orgor check out our status page at https://status.libretexts.org. Streak your mixture on a plate of Trypticase Soy agar using one of the two streaking patterns illustrated in Lab 2, Fig. StudyCorgi. Course Hero is not sponsored or endorsed by any college or university. There is also lactose fermentation that took place that After 48hours, introduce the sample microbes Blood agar (used in strep tests), which contains bovine heart blood that becomes transparent in the presence of hemolytic. Its found in the nose, the However, problems such as contamination and subjective reading of culture plates might have influenced the outcome of results. bulgaricus and Streptococcus thermophilus. Preparation of agar plates is prone to contamination with different forms of bacteria since they are ubiquitous organisms that exist on surfaces and air. Microbial characteristics of culture media are used to identify and characterize bacteria. Mannitol Salt Agar is earlier indicated is a selective medium which plays a role in the Some examples of selective media include: Differential media or indicator media distinguish one microorganism type from another growing on the same media. differential mediums. 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. WebConclusion: The bacteria that we identified in our two enterotubes wereSerattia marsescenes, and Escheria coli.TheE.colitested positive for glucose, lysine, lactose, Lab Report #11 - I earned an A in this lab class. Record your observations and conclusions. Isolation of bacteria is accomplished by growing ("culturing") them on the surface of solid nutrient media. 5. 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. On the other hand, there are differential media which serve to differentiate organisms growing together. and enhances the growth of Gram negative bacteria. Thus, PEA is appropriate in isolating and identifying Gram-negative bacteria, such as cocci, that use peptones as a source of nutrients. Some Examples of Selective and Differential Media: Mannitol Salt Agar (MSA) Mannitol Salt Agar (MSA) is a selective medium for the isolation of pathogenic and non-pathogenic 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. Salmonella & Shigella CANNOT breakdown lactose, sucrose or salicin sugars Sucrose (differential) 3. Legal. This paper was written and submitted to our database by a student to assist your with your own studies. NOT all Gram negative bacteria can ferment sucrose to produce acidic compounds bacteria and hinders the growth of gram positive bacteria. In this experiment, P. aeruginosa, E. aerogenes, S. aureus, and E. faecalis are Gram-positive strains, while E. coli is a Gram-negative cell (Murray, Rosenthal, & Pfaller, 2015). Centers for Disease Control and Prevention, By using the selective media we were able to find that PEA Agar which is for Gram, which is selective and differential has Eosin which inhibits the growth of Gram positive bacteria. Indicate a common disease caused by each. There are literally hundreds of special-purpose media available to the microbiologist. 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. "Bacteria Lab: Enriched, Selective, Differential Media." Basu, S., Bose, C., Ojha, N., Das, N., Das, J., Pal, M., & Khurana, S. (2015). a) Create a constructor that prevents a 0 denominator in a fraction, reduces or simplifies After completing this lab, the student will be able to complete the following objectives: 1. Using the wire loop, scoop a colony of Staphylococcus aureus and streak it on the surface of The blood agar test confirmed that the unknown bacterium could undertake complete hemolysis of red blood cells in the agar. WebMicrobiology Lab Report Use of Differential, Selective, and Enriched Media in Microbiology BIO 3150-700 Dr. Marilu Santos Introduction: The purpose of this experiment is to display the numerous special media used to isolate bacterial types, the differences between closely related groups of bacteria, the practice of sanitation and aseptic and E. Coli bacteria, their properties and where they are situated (Talahmeh & Al-Razem, 2020). the S. aureus to produce lactic acid (Ashraf & Shah, 2011). Small samples of the diluted bacteria are then pipetted onto the surface of agar plates. 2. References In addition, it differentiates those organisms that grow based on whether they can carry out particular chemical reactions. Web. Describe the morphology of each bacerial type. the required nutrients to sustain its growth and survival. 1. 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. 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. June 26, 2021. https://studycorgi.com/bacteria-lab-enriched-selective-differential-media/. The other medium, that the Tryptic Soy Agar favored the growth of both E. coli as well as Aureus. 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. This is because This plate is called an isolation plate. Wallace, J. S., & Jones, K. (1996). 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