Question

Explain how to make 5 tubes of a 1/10 serial dilution. Part A. If your starting solution in tube 1 is at 10% concentration. What will the next 5 tubes' concentrations be AND how to make them? Part B. If the amount of bacteria in your initial tube at 10% concentration was estimated to be 20,000,000 microbes, how many microbes would you have in each dilution tube you created in part A?

Answer 1

To make 5 tubes of a 1/10 serial dilution, start with a 10% concentration solution and mix 1 mL with 9 mL of sterile broth for each tube. The concentrations in the dilution tubes will decrease with each step. If the starting solution has 20,000,000 microbes, the concentrations in the dilution tubes will be as follows: Tube 1: 2,000,000 microbes, Tube 2: 200,000 microbes, Tube 3: 20,000 microbes, Tube 4: 2,000 microbes, and Tube 5: 200 microbes.

Step-by-step explanation:

To make 5 tubes of a 1/10 serial dilution, you will need to start with a solution that is 10% concentration. Part A: For each tube, mix 1 mL of the starting solution with 9 mL of sterile broth. This will result in a 1:10 dilution. Repeat this process by taking 1 mL from each of the diluted tubes and adding it to a fresh tube containing 9 mL of sterile broth. This will result in a 1:100 dilution. Repeat this process four more times, resulting in a total of five dilution tubes.

Part B: If the starting solution had an estimated 20,000,000 microbes, each dilution tube would have the following concentrations: Tube 1: 2,000,000 microbes, Tube 2: 200,000 microbes, Tube 3: 20,000 microbes, Tube 4: 2,000 microbes, and Tube 5: 200 microbes.