We will be making the following salt solution for the growth of sulfur reducing

Question

We will be making the following salt solution for the growth of sulfur reducing bacteria (SRB). Based on the formula weights, calculate the amount of each compound needed to make one liter of the following 10X solution: Dilution: will have a negative exponent (10^-5) Dilution factor: the inverse of the dilution (1/3.5 times 10^-5 or 3.5 times 10^5 bacteria/ml) A serial dilution was prepared by adding 0.1 mL to 9.9 mL, and 0.1 of that to 9.9 mL of fresh diluent. Then, 0.1 mL of the last dilution was spread. Later, 561 colonies were counted. What was the original CFU/mL? A sample was diluted by placing a 0.1 mL aliquot into 0.9 mL of diluent, and 1 mL of this dilution was pour-plated. After incubation, 217 colonies appeared. What is the CFU/mL in the original specimen? How would you prepare 100-fold serial dilution starting with a stock culture thru 10^-10? How much suspension would you add to TSA plate to obtain a 10^-4, 10^-5, 10^-6, 10^-7 and 10^-8 CFU plates? A culture was diluted by adding a 0.1 mL aliquot to 0.9 mL water. Then, 0.1 mL of this dilution was plated out, yielding 73 colonies. Calculate the CFU/100 mL in the original culture. 0.1 mL of urine plated out on nutrient agar. After incubation at 37 degree C, 279 colonies appeared. Give the CFU/mL. How many CFU are there per 100 mL?

Explanation / Answer

(1)

Original CFU/ml = ?

Calculation of total dilution factor:

0.1 mL + 9.9 mL diluent= 10^-2

0.1 mL of above solution +9.9 mL diluent= 10^-2

Total Dilution factor= 10^-4

Number of colonies= 561

Volume of sample = 0.1 mL to the plate

cfu/ml = (no. of colonies)/ (dilution factor x volume of culture plate)

=561/ (10^-4 x 0.1)

= 561x 10^5

=5.6 x 10^7 CFU/mL

(2)

Total Dilution factor= 10

CFU/mL = 2.17 x 10^3

Related Questions

Navigate

• Browse (All)
• Browse W
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.