A sample of well water is tested for its bacterial content in a plate count assay. A one-milliliter sample of the water is diluted in a 1:10 dilution series. One milliliter of the fourth dilution tube is plated in a pour plate. After incubation, the plate has 83 colonies. How many bacteria did the original sample contain?

A 0.00001 dilution is performed on a culture of bacteria in order to perform viable plate counts. From the dilution, *0.1 mL* of solution is plated on solid media, and 223 colonies of bacteria grow on the petri dish.  Assuming each colony came from a single bacterium, how many bacteria are in a single mL of the original culture? Express your answer to two decimal places using exponential notation. Since only 0.1 mL is put on the plate, this counts as an extra dilution!!! Any time less than 1 mL is transfered, a dilution is being performed. Any time more than 1 mL is transfered, a concentration is being performed.

A sample is diluted by a factor of 10 five times. The 10^-3 dilution has 272 colonies on it. Assuming you plated the same volume on each plate, how many colonies would you expect to find on the 10^-4 plate? Include units and use OCD formula.

bacterial suspension with a population of 6.3 x 107cells/mL was diluted as follows: 4 mL was removed and added to 16 mL of diluent. This was again diluted 1 in 300.                                                                                                                                                                      Determine the concentration of cells after EACH dilution.   Concentration after the 1st dilution      Concentration after the 2nd dilution

A culture of E. coli is diluted as follows:(1) 65mL are added to 435mL of water.(2) 10uL from (1) are then added to 9.99mL of water.(3) A 10-3 dilution is made from tube # (2).(4) 100uL from (3) are plated for a pour plate and incubated. There were 34 colonies counted on one quarter of the plate following incubation. a) What was the overall dilution?b) How many cfu/mL were present in the original culture?c) How many milliliters of water is needed to make a 10-3 dilution using 1000 uL from the original culture?

In this experiment, different concentrations of sucrose are first prepared. Then, cylinders of potato (Solanum tuberosum) tuber are made using a cork borer, which are then trimmed to remove the skin and be of the same length. The cylinders are blot dried and weighed prior to being placed in each of the test tubes containing the sucrose solution. After 20 minutes, the cylinders were removed from the solution, blot dried, then weighed again. Study the results of the experiment shown in Table 1. Table 1. Changes in the weights of potato tuber tissue immersed in various concentrations of sucrose for 20 minutes Concentration (M) 0.0 0.2 0.4 0.6 0.8 1.0 Initial weight 3.76 3.15 3.29 3.82 3.40 3.52 Final weight 4.44 3.40 3.09 3.32 2.71 2.57 Change in weight (g) 0.68 0.25 -0.20 -0.50 -0.69 -0.95 % Change in weight 18.09 7.94 -6.08 -13.09 -20.29 -26.99 Calculate the water potential of the potato tuber cells. Express the answer in both bars and megapascal

You have retrieved your MHA (Mueller-Hinton agar) plate, your materials, and your E. coli culture.  What is the first step to prepare your Kirby-Bauer test?

If you plated 0.1mL of a 103 dilution and you obtained 235 colonies on your agar plate, how many CFUs per mL were in your original sample? If a bacterium can divide once an hour, then after 5 hours, 1 bacterium will have yielded ______ bacteria