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mFC agar is a type of media containing lactose sugar that selectively allows for the growth of coliforms while inhibiting other bacteria, including Gram positives. mFC agar is also differential because it can distinguish fecal coliforms from non-fecal coliforms. The fecal coliforms can ferment lactose present in mFC agar at a higher temperature of 44.5°C. These will form blue colonies. On the other hand, non-fecal coliforms will grow on mFC agar at 44.5°C, but they will not ferment lactose at this temperature. As a result, these will form white/grey colonies. A group of students (group-1) perform an experiment to determine the concentration of coliforms in potable water. In this experiment, 5 mL of water was filtered and the membrane was incubated on mFC agar plates at 44.5°C. After 24 hours, the plate was observed for colonies. Non-fecal coliform A. (1 pt) From the picture above, count the number of total coliforms (fecal and non-fecal) and fecal coliforms in the 5 mL sample of water. Report your answer in CFU units. B. (1 pt) Now, calculate the concentration CFU/100 mL of total coliforms in the water sample. Our standard for reporting is CFU/100mL. Keep in mind that although you have only filtered 5 mL of water, you have to calculate the number of organisms in 100 mL. There are two ways to do this: 1) use the formula in the protocol, or 2) consider that 100 mL is 20-times greater than 5 mL. Be sure to report your answer in (CFU/100 mL) units. C. (0.5 pt) Would you drink this water? Why or Why not? D. (0.5 pt) If you were to gram stain one of the blue colonies on the plate, what would you predict for the results of that gram stain (shape and color)? Student group-2 performed the experiment using the same sample of water as group-1 did. However, they incubated the filtered membrane on a nutrient agar plate (a general-purpose growth medium) instead of mFC Agar. Predict what results they will see on the plate after incubation (for example, will numbers of bacteria increase/decrease/remain the same compared with mFC.? What bacteria will grow on these plates? Student group-3 sampled water from a different source. They diluted 10 mL of water sample with 990 mL of sterile water. Then they filtered 100 mL of the diluted sample through a membrane filter. Upon incubation on mFC plate they saw 55 blue colonies. Calculate the CFU/100 mL of the original water sample used by group-3. SHOW YOUR WORK. (There's more info about these type of calculations in the next) 

          mFC agar is a type of media containing lactose sugar that selectively allows for the growth of coliforms while inhibiting other bacteria, including Gram positives. mFC agar is also differential because it can distinguish fecal coliforms from non-fecal coliforms. The fecal coliforms can ferment lactose present in mFC agar at a higher temperature of 44.5°C. These will form blue colonies. On the other hand, non-fecal coliforms will grow on mFC agar at 44.5°C, but they will not ferment lactose at this temperature. As a result, these will form white/grey colonies.

A group of students (group-1) perform an experiment to determine the concentration of coliforms in potable water. In this experiment, 5 mL of water was filtered and the membrane was incubated on mFC agar plates at 44.5°C. After 24 hours, the plate was observed for colonies.

Non-fecal coliform

A. (1 pt) From the picture above, count the number of total coliforms (fecal and non-fecal) and fecal coliforms in the 5 mL sample of water. Report your answer in CFU units. 

B. (1 pt) Now, calculate the concentration CFU/100 mL of total coliforms in the water sample. Our standard for reporting is CFU/100mL. Keep in mind that although you have only filtered 5 mL of water, you have to calculate the number of organisms in 100 mL. There are two ways to do this: 1) use the formula in the protocol, or 2) consider that 100 mL is 20-times greater than 5 mL. Be sure to report your answer in (CFU/100 mL) units. 

C. (0.5 pt) Would you drink this water? Why or Why not?

D. (0.5 pt) If you were to gram stain one of the blue colonies on the plate, what would you predict for the results of that gram stain (shape and color)? 

Student group-2 performed the experiment using the same sample of water as group-1 did. However, they incubated the filtered membrane on a nutrient agar plate (a general-purpose growth medium) instead of mFC Agar. Predict what results they will see on the plate after incubation (for example, will numbers of bacteria increase/decrease/remain the same compared with mFC.? What bacteria will grow on these plates?

Student group-3 sampled water from a different source. They diluted 10 mL of water sample with 990 mL of sterile water. Then they filtered 100 mL of the diluted sample through a membrane filter. Upon incubation on mFC plate they saw 55 blue colonies. Calculate the CFU/100 mL of the original water sample used by group-3. SHOW YOUR WORK. (There's more info about these type of calculations in the next)
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mfc agar is a type of media containing lactose sugar that selectively allows for the growth of coliforms while inhibiting other bacteria including gram positives mfc agar is also differentia 37191

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Julianne Zedalis, John Eggebrecht
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mFC agar is a type of media containing lactose sugar that selectively allows for the growth of coliforms while inhibiting other bacteria, including Gram positives. mFC agar is also differential because it can distinguish fecal coliforms from non-fecal coliforms. The fecal coliforms can ferment lactose present in mFC agar at a higher temperature of 44.5°C. These will form blue colonies. On the other hand, non-fecal coliforms will grow on mFC agar at 44.5°C, but they will not ferment lactose at this temperature. As a result, these will form white/grey colonies. A group of students (group-1) perform an experiment to determine the concentration of coliforms in potable water. In this experiment, 5 mL of water was filtered and the membrane was incubated on mFC agar plates at 44.5°C. After 24 hours, the plate was observed for colonies. Non-fecal coliform A. (1 pt) From the picture above, count the number of total coliforms (fecal and non-fecal) and fecal coliforms in the 5 mL sample of water. Report your answer in CFU units. B. (1 pt) Now, calculate the concentration CFU/100 mL of total coliforms in the water sample. Our standard for reporting is CFU/100mL. Keep in mind that although you have only filtered 5 mL of water, you have to calculate the number of organisms in 100 mL. There are two ways to do this: 1) use the formula in the protocol, or 2) consider that 100 mL is 20-times greater than 5 mL. Be sure to report your answer in (CFU/100 mL) units. C. (0.5 pt) Would you drink this water? Why or Why not? D. (0.5 pt) If you were to gram stain one of the blue colonies on the plate, what would you predict for the results of that gram stain (shape and color)? Student group-2 performed the experiment using the same sample of water as group-1 did. However, they incubated the filtered membrane on a nutrient agar plate (a general-purpose growth medium) instead of mFC Agar. Predict what results they will see on the plate after incubation (for example, will numbers of bacteria increase/decrease/remain the same compared with mFC.? What bacteria will grow on these plates? Student group-3 sampled water from a different source. They diluted 10 mL of water sample with 990 mL of sterile water. Then they filtered 100 mL of the diluted sample through a membrane filter. Upon incubation on mFC plate they saw 55 blue colonies. Calculate the CFU/100 mL of the original water sample used by group-3. SHOW YOUR WORK. (There's more info about these type of calculations in the next)
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A group of students (group 1) performed an experiment to determine the concentration of coliforms in potable water. In this experiment, 5 mL of water was filtered and the membrane was incubated on mFC agar plates at 37°C. After 24 hours, the plate was observed for colonies. mFC agar is a selective media that allows for the growth of coliforms. On mFC agar, fecal coliforms form blue colonies and non-fecal coliforms form white colonies. The mFC agar contains selective and differential agents that allow for growth and identification of coliforms. Rosolic acid inhibits bacterial growth in general, except for the growth of coliforms. Bile salts inhibit contaminating gram-positive bacteria. Aniline blue indicates the ability of fecal coliforms to ferment lactose to acid, which causes a pH change in the medium. Lactose utilization (blue color) is the basis for the identification of fecal coliforms. Non-fecal coliform Fecal coliform 2. (0.5 pt) Another group of students (group 2) performed the same experiment as the group in question 1, using the same sample. However, they incubated the filtered membrane on a nutrient agar plate (a general-purpose growth medium instead of mFC agar). Predict what results they will see on the plate after incubation (for example, will the numbers of bacteria increase or decrease compared with mFC? What bacteria will grow on these plates?) What conclusions can they draw from this experiment?

Madhur L.
1-agar-media-can-be-enriched-with-blood-for-the-identification-of-viruses-from-other-microorganisms-bacteria-which-can-grow-in-anaerobic-conditions-bacteria-which-can-grown-in-higher-hydrost-15262

1. Agar media can be enriched with blood for the identification of: - Viruses from other microorganisms - Bacteria which can grow in anaerobic conditions - Bacteria which can grow in higher hydrostatic pressure - Bacteria which can cause hemolysis 2. Isolation of pure culture refers to: - Growing microorganisms on a surface - Separation of a single colony - Introduction of inoculum - Purification of culture 3. A rapid qualitative isolation method involving spreading a loopful of inoculum over the surface of an agar plate is known as: - Stabbing - Identification - Streaking - Isolation 4. A subculture is a: - Culture made from a contaminant - Culture made in an embryo - Culture made from an isolated colony - Colony growing beneath the media surface 5. Which of the following methods can be used to determine the number of bacteria quantitatively? - Streak-plate - Pour plate - Pour-plate and spread plate - Spread-plate 6. Addition of blood to culture medium only allows the hemolytic bacteria that grow on a plate to be picked out. This is an example of: - Selective media - Differential media - Chemically defined media - Complex media 7. Elective media facilitate the growth of only one kind of organism. Sabouraud medium is used to selectively isolate: - Acid-fast organisms - Gram-positive bacteria - Coliform bacteria - Yeasts 8. In the pour-plate method, the medium should be maintained at what temperature? - 45 degrees C - 0 degrees C - 37 degrees C - 67 degrees C 9. The term that refers to the purposeful addition of microorganisms into a laboratory nutrient medium known as: - Contamination - Disinfection - Inoculation - Isolation 10. Which of the following refers to specific procedures used to prevent unwanted microorganisms from contaminating the clinical specimen? - Inoculation - Disinfection technique - Aseptic technique - Needle technique 11. Bacteria that require special growth factors and complex organic substances are called: - Pathogenic - Aerobic - Chemoheterotroph - Anaerobic - Fastidious 12. A microbiology student notices that a culture broth tube was very turbid at the bottom of the tube but clear at the top of the tube. It can be concluded that the: - Organism should be grown in an anaerobic chamber - Organisms are aerobes - Organism can tolerate oxygen - Broth is sterile - Organism cannot produce superoxide dismutase and/or catalase 13. A characteristic of agar is: - It solidifies at 42 degrees C - A common source of nitrogen in liquid media - A polymer extracted from algae that has no nutritional value - It is solid at room temperature 14. Advantage of an agar slant preparation is: - Microbes can slide on agar easily - Less agar powder is needed - More surface area for growth of microbes 15. Which of the following instruments or equipment is used for sterilizing the media after it has been prepared? - Laminar air flow chamber - Inoculating needle - Incubator - Autoclave 16. A culture medium consisting of agar, human/sheep blood, and beef heart is a: - Complex media - Selective media - Reducing media - Chemically defined media - Differential media 17. What is the application of selective medium? - It allows growth of all the microbes inoculated to it - It allows the growth of one species of microorganisms while suppressing the growth of others - It does not allow the growth of any kind of microbes

Alexander B.
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Illness and food spoilage can result from microbial growth in foods. The sanitary control of food quality is concerned with testing foods for the presence of pathogens. During processing (grinding, washing, and packaging), food may be contaminated with soil microbes and microbiota from animals, food handlers, and machinery. Standard plate counts are routinely performed on food and milk by food-processing companies and public health agencies. The standard plate count is used to determine the total number of viable bacteria in a food sample. The presence of large numbers of bacteria is undesirable in most foods because it increases the likelihood that pathogens will be present, and it increases the potential for food spoilage. In a standard plate count, the number of colony-forming units (CFU) is determined. Foods are the primary vehicle responsible for the transmission of diseases of the digestive system. For this reason, they are examined for the presence of coliforms because the presence of coliforms usually indicates fecal contamination. Eosin Methylene Blue (EMB) agar is used for isolation of coliforms. It contains peptone, lactose, sucrose, and the dyes eosin Y and methylene blue. The sugars provide fermentable substrates to encourage growth of coliforms. The dyes inhibit the growth of Gram-positive organisms and, under acidic conditions, also produce a dark purple complex usually accompanied by a green metallic sheen in fecal coliforms (e.g. E. coli). This sheen serves as an indicator of the vigorous lactose or sucrose fermentation typical of fecal coliforms. Smaller amounts of acid production (typical of Enterobacter aerogenes and slow lactose fermenters) result in a dark pink/purple coloration of the colonies (darker than the medium). Non-fermenters (i.e. non-coliforms) retain their normal color or take on the coloration of the medium. Growth on EMB media Scenario Imagine that you are working as a microbiologist for the FDA. Your job requires you to test raw hamburger meat before it is distributed for public consumption. The FDA standards for hamburger are from 2.5×10^5 to 1×10^7 bacteria per gram (total count). The typical number of coliforms is 2-3 orders of magnitude lower than the total count. Your most recent inspection of a ground hamburger sample from the Happy Cow meat purveyors yielded the following results: Total bacterial count: 8.2×10^6 CFU/g (as determined from plating on TSA medium) Coliform bacterial count: 2.24×10^4 CFU/g (as determined from plating on EMB medium) Objectives: To submit your findings you must present the details of the experiment performed that yielded these results. Specifically, a detailed account of your experimental approach and methods, a diagram of your dilution/plating scheme, a table showing dilutions and volumes used for plating and number of colonies counted for each medium, all pertinent calculations. See details below under Reporting. Materials: Ground meat Sterile empty petri dishes and sterile spatulas or tongue depressors (to be used for weighing ground meat subsample) 50-mL sterile centrifuge tube Sterile saline for dilutions 5 sterile microcentrifuge tubes for dilutions Automatic pipettors and sterile tips L-shaped cell spreaders 3 TSA plates 3 EMB plates Hints: Model your experiment design on the experimental design found in the Soil Microbiology Lab as a guide. The suggested approach is as follows: a subsample of hamburger is weighed aseptically, placed in a known volume of sterile saline, mixed thoroughly, serial dilutions are prepared, known volumes of the dilutions are then plated onto suitable media. Spread plate technique is employed. After incubation, the number of colonies is counted. Plates that have between 30 and 300 colonies are suitable for counting. CFU/g of hamburger are calculated for total bacteria and coliforms. Reporting You should explain in writing how you approached the task and your experimental design (~1 page, typed, 12-pt font size). Be sure to address the following. Why did you use both TSA and EMB? Why did you use a serial dilution approach? Why did you choose your selected incubation time and temperature?

Sri K.
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Transcript

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00:01 Hello students, we want to know how we can determine the presence of coliforms in potable water.
00:13 Now as far as coliforms are concerned, they serve as indicators for the water quality and basically represent various types of pathogenic bacteria.
00:25 More specifically, coliforms are gram negative, non -spore forming bacillus.
00:33 Bacillus obviously means rod -shaped bacteria.
00:37 We have some specific shaped bacteria present in nature.
00:42 We have rod -shaped, we have spherical, then we have comma -shaped and we have spiral -shaped as well.
00:50 Now as far as the determination procedure is concerned, first of all we have to collect water in a sterile container...
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