(Solved): Laboratory Exercise 25: Bacterial Examination of Water Your task: 1.) Watch the "Laboratory Exerci ...

Laboratory Exercise 25: Bacterial Examination of Water Your task: 1.) Watch the "Laboratory Exercise 25 - Introduction" video. 2.) Please use the results and instructions in the "Results - Laboratory Exercise 25 " file to answer the provided questions. Presumptive Test 1. Identify, count and report the number of water samples containing Coliform bacteria. Note: Coliforms produce acid and gas. 2. Please use the provided MPN table to identify the MPN number for the water sample. Record the MPN number in the table. 3. Define and describe the MPN method? What does the MPN number indicate? 4. What is a positive result from the lactose broth? 5. Define Coliform: he Confirmed Test 6. Describe the result of the EMB agar plate. 7. Is the bacterium growing of the EMB agar plate a Coliform? Justify your answer using the information provided in the "Laboratory Exercise 25-Information" file. 8. Does the confirmed Test indeed confirm the results of the Presumptive Test. 9. Is EMB a differential and/or selective medium? Justify your answer. 10. Based on the obtained result, determine if it is safe to swim in water with the determined MPN. For this question, perform an intemet search to find information that allows you to answer this question (e.g. Test: water sample; Encinitas CA Test: water sample; Encinitas CA Results-1 Task: Identify water samples containing Coliform Coliform Gram-negative rod Lactose fermenter (with gas) Non-endospore Coliform Fermentation: acid production changes color of $\mathrm{pH}$ indicator form red to yellow. Gas production: gas bubbles trapped in Durham tube. Therefore, Tubes containing coliform are yellow and contain gas in Durham tube. Count positives in the $10\mathrm{ml},1\mathrm{ml}$, and $0.1\mathrm{ml}$ groups. Result: $10\mathrm{ml}$ water sample DS Lactose $+10\mathrm{ml}$ water Result: $1\mathrm{ml}$ water sample Result: $0.1\mathrm{ml}$ water sample Result: EMB Plate Growth of different bacteria on EMB agar plate. S. typhimurium: lactose non-fermenter P. acruginosa: lactose non-fermenter P. acruginosa: lactose non-fermenter Unknown: Bacterium in no growth Unknown: Bacterium in a coliform-positive water sample ( $10\mathrm{ml}$ water sample). Based on the information provided in the "Laboratoy file, identify the unknow bacterium.