4. The UWC Biotechnology 213 class undertook a study to determine the microbiological quality of mince-meat samples that were obtained from four local retail outlets. You have performed the following serial dilution of the mince samples. Firstly, 25 g of the minced samples was transferred to 225 ml 4 strength Ringers'-solution, followed by two (2) 10-fold dilutions and finally three (3) 100-fold dilutions. These dilutions were then pour plated out (1000 μl of each) onto the required medium. The colony forming units (cfu) for the Enterobacteriaceae count is listed in the table below: Total viable count Mold & yeast count Staphylococcal count Enterobacteriaceae count 1 > 300 >300 > 300 >300 > 300 >300 > 300 >300 2 >300 >300 >300 >300 168 156 > 300 >300 3 >300 >300 129 127 18 16 264 248 Determine the log colony forming units per gram of product. 4 274 286 14 13 3 2 27 25 5 28 29 2 1 10 0 3 2 6 3 3 0 0 1 0 0 0

4. The UWC Biotechnology 213 class undertook a study to determine the microbiological quality of mince-meat samples that were obtained from four local retail outlets. You have performed the following serial dilution of the mince samples. Firstly, 25 g of the minced samples was transferred to 225 ml 4 strength Ringers'-solution, followed by two (2) 10-fold dilutions and finally three (3) 100-fold dilutions. These dilutions were then pour plated out (1000 μl of each) onto the required medium. The colony forming units (cfu) for the Enterobacteriaceae count is listed in the table below: Total viable count Mold & yeast count Staphylococcal count Enterobacteriaceae count 1 > 300 >300 > 300 >300 > 300 >300 > 300 >300 2 >300 >300 >300 >300 168 156 > 300 >300 3 >300 >300 129 127 18 16 264 248 Determine the log colony forming units per gram of product. 4 274 286 14 13 3 2 27 25 5 28 29 2 1 10 0 3 2 6 3 3 0 0 1 0 0 0

Biology: The Dynamic Science (MindTap Course List)

4th Edition

ISBN:9781305389892

Author:Peter J. Russell, Paul E. Hertz, Beverly McMillan

Publisher:Peter J. Russell, Paul E. Hertz, Beverly McMillan

Chapter17: Bacterial And Viral Genetics

Section: Chapter Questions

Problem 4TYK

See similar textbooks

Similar questions

1) would you describe the contents of the soil-inoculated broth as being a “pure culture”? Why or why not? 2) How did the uninoculated broth differ in appearance from the broths inoculated with E. Coli and M. Luteus? And then how could you tell if a supposedly sterile, uninoculated broth was contaminated? Please explain in detail and highlight the important parts cuz I am confused and need help! Thanks
1. How is UV radiation a good type of control mechanism against microbial growth? Please explain what happens to the microbe and effects this control causes. 2. Suppose you do the Kirby-Bauer test on a hypothetical Staphylococcus species with penicillin and tetracycline. You record diameters of 20mm for tetracycline and 24mm for penicillin. Which antibiotic is most effective against this bacterium and why? Please explain and interpret these results.
1. List the purpose(s) of the following: • use of Dey-Engley medium in environmental swabs• addition of K2SO3 to the pre-enrichment medium for garlic flakes• addition of Triton X to lactose broth for ground meat
1. How is UV radiation a good type of control mechanism against microbial growth? Please explain what happens to the microbe and effects this control causes. 2. Suppose you do the Kirby-Bauer test on a hypothetical Staphylococcus species with penicillin and tetracycline. You record diameters of 20mm for tetracycline and 24mm for penicillin. Which antibiotic is most effective against this bacterium and why? Please explain and interpret these results. 3. Please provide the scientific name of your microbe that was used in the UV experiment (i.e. S. aureus). Compare your plates and interpret/analyze your results. Please discuss your findings and any patterns you were able to gather. 4. After performing the “Effects of Antiseptics & Disinfectants” lab which agent(s) showed potential to control S. marcescens growth? P. aeruginosa? Please explain why you believe these agent(s) work. 5. What purpose does water serve in the “Effects of Antiseptics & Disinfectants” lab? What did you…
1. What is the importance of using freshly prepared KOH in testing the bacteria? Explain this comprehensively and please, do not just copy from somewhere.
6a. A sample is given to you that contains 6 million cells per ml. You must make a series of serial dilutions in order to get a countable number on a plate to prove that there are indeed 6 million cells per ml. The plate that you eventually put a sample of bacteria on must have between 10 and 100 colonies for ease of counting. What dilutions do you make to get this many colonies on a plate? How many colonies do you have on that plate? Show what dilutions you make (Write exactly how much liquid you move into each test tube and how much liquid was in the test tube, ex. Move 1 ml of culture into 9 ml of water – 10x dilution). Don’t forget to tell me how much liquid you eventually put on your plate. (If you want to draw something out, you could draw then take a picture of it with your phone and submit the image along with the worksheet). 6b. Do the same problem as in 6a, but now you have to do it in 3 test tubes or less. What dilutions do you do now? please use drawings to help…
1. What are the characterisitics of a good diluent in a quantitative bacteriology? List these characteristics and discuss. Please, do not just copy from somewhere.
1) based on the difference in appearance between mixed culture streak plates and broth culture plates, what would lead you to believe that you have created a pure culture when you inoculated the broths? 2) when using the loop dilution technique to produce pour plates, did all the plates produce isolated colonies? If your goal was to ultimately create pure cultures of E. coli, M. luteus, and S. morcescens, which plate or which dilution would you use, and why would you use this plate? 3) What are the advantages and disadvantages of streak plating compared with pour plating?
22) Which of the techniques/characteristics below may be used to identify a target bacterium in a pool of microorganism? a) its morphology b) its growth requirement c) antibody-antigen interaction ) d) all of the above. ) e) a and c 23) What is the process that produces alcohol in S. cerevisiae (yeast)? () a) Respiration ( b) Sedimentation c) Photosynthesis )d) Fermentation 24) Identify the most mistaken (wrong) choice: a) Halophiles are those organisms that like high salt concentrations. ) b) Some bacteria reproduce by binary fission. ( c) A fungus cell contains a true nucleus. d) During the lag phase of growth, the metabolic activity is very low
2. Suppose you do the Kirby-Bauer test on a hypothetical Staphylococcus species with penicillin and tetracycline. You record diameters of 20mm for tetracycline and 24mm for penicillin. Which antibiotic is most effective against this bacterium and why? Please explain and interpret these results.
8. What are the factors that you will consider to ensure that the “oil-eating” bacteria multiply, grow, and thrive efficiently in the Kalba sea area?
1.What advantage(s) does the pour plate method have over the streak-plate method? 2.Why is the loop flamed before it is placed in a culture tube? Why is it flamed after completing the inoculation? 3.Before inoculating and pouring molten nutrient agar into a plate, why must the agar first be cooled to 50° C? 4.Explain why plates should be inverted during incubation. 5.Explain why plates should be inverted during incubation.