50 g of food is homogenized in 450 mL of water. From this, 1 mL is added to 29 mL of water, and then a 1:90 dilution is made from this, and then 1 mL from this is added to 99 mL of water, and then 100 uL of this last dilution is plated and after incubation 164 colonies are counted.a) What was the overall dilution factor?b) What was the total CFU/g of the original sample?

A milk sample was tested for the presence of typhimurium. Using a 10 microliter calibrated loop, a sample was taken directly from the milk and plated onto nutrient agar and the following day after incubation 98 colonies were counted.  What is the CFU/ml of the S. typhimurium in this sample?

On the basis of the appearance of this place, what are you testing for? When you added a reagent to this plate, these bubbles appeared. What is the name of this reagent and what are those bubbles?

Using saline tubes containing 9 ml of saline (for dilutions), draw a diagram that would yield between 30 and 300 colonies from an original broth culture that contains 5 * 10^8 cells/ml. Indicate volumes used and dilutions made for each tube and plate.

Jordan is working with an 60% stock concentration of Windex. She decides to add 100 μL of bacteria to atube containing 3 mL of nutrient broth and then adds 1000μL of the Windex stock to the tube as well.What is the unknown concentration of the tube?

At the station there is a 2 mL microcentrifuge tube containing sheep blood and 3 tubes containing the following solutions: 0 mM, 300 mM, 600 mM of sucrose. The tubes are randomly labelled A, B, C.  2 mL of each solution were transferred to a different microcentrifuge tube, 20 ul of blood were then added to each tube, and they were mixed well by inverting the tube for multiple times.  They were observed and it was determined whether the solution in each tube was hypotonic (Yes or No) relative to the blood cells. In addition, the solutions were diluted with water to help you determine which solution is which sucrose concentration. What sucrose concentration corresponds with each tube?   Tube Hypotonic (Yes/No) Hypotonic after 1:1 dilution with water (Yes/No) Most likely Sucrose concentration (mM) A No Yes   B Yes Yes   C No No

Tube A is a 1/5 dilution and then,  using Tube A,  is diluted to make a 1/10 labeled Tube B.  What is the dilution to be made for each tube, is using serum and saline? What is the dilution of the solution in tube 1 and 2 .

How much serum is needed to create 2μL of a 1:20 dilution?

why is the recommended incubation procedure for the API 20e system 18 to 24 hours ?

How do you know if you have a ‘countable’ plate when doing a dilution series?   Two plates received 0.1 mL of the same dilution tube. The first has 293 colonies and the second has 158 colonies. Suggest a reasonable reason why this happened.