Question

may you help me figure out how to solve 7-9

Standard plate count. Include formulas and calculations. Scientific notation. Show your work. UNITSI 7. Suppose you have 2.0 ml of an undiluted E.coli broth and need to begin your serial dilution by making a 10. solution. How much diluent would you need if you wanted to use the entire 2 ml of E. coli broth? 110-ml 102 = 2mL ol os dition 10 8. If you transfer 0.1 ml of a stock solution into a 9.9 ml sterile water tube, what is the dilution factor? What would it be after 2 more transfers of the same volume in serial dilution? O dilution Tector vidi= V202 (99/10.) = V (10-3) =9,9x104 1.99 = 107 Mid Yy unclear.. 9. After plating 0.1ml of a 10 dilution, 158 colonies grow. What is the OCD? (CFU/ml) 158 3,514 (105) = 1.58×10 CFU/mL. A account for sci note dec. il culo m uld you renart this info?

Answer 1

1) given that

the volume of undiluted solution is 2ml (V1)

final concentration after dilution = 1/10 of the concentration of undiluted solution( C2 =C1/10)

we know that C1 V1 = C2 V2 FROM THIS

V2 = (C1 *V1)/C2

= (C1 *V1)/C1/10

= 10* V1 =10* 2 =20ML

SO THE EXTRA AMOUNT DILUENT NEED TO ADD TO THE UNDILUTED SOLUTION IS V2- V1=20- 2=18ML

2)given that 0.1 ml of stock solution is added to the 9.0 ml of sterile water

so here

v1= 0.1ml

V2 = 0.1+ 9.9 + 10ML

WE KNOW THAT

C1V1 = C2V2

C1 * 0.1= C2 * 10

C2 = 1/100 C1

SO the dilution factor will be 1/100

from this solution 0.1ml (V2) of solution is further added to 9.9ml of sterile water so that V3= 10ml

C3 = C2V2/ V3

= (C1/100 * 0.1)/ 10

= C1/10000

10^-4 DILUTION

FROM THIS SOLUTION 0.1 ML(v3) is further taken and diluted by adding 9.9 ml ( final volume = 10ml (v4))

result in c4 = c3v3/ v4

= 10^-6 c1

10^-6 dilution

3) OCD = CFU/(DILUTION * VOLUME PLATED)

= 158/ (10^-5 * 0.1) = 1.58 * 10^-4