Question

bio 152 Serial Dilutions: if the fourth plate has 32 colonies, what is the O.C.D. of the original inoculum? (proper units required)

Serial dilutions Original Indau broth in each tube 1TOLDO 1:100.000 111000 1:100,000 If the fourth plate has 32 colonies, what is the O.C.D. of the original inoculum? (proper units required)

Answer 1

dilution in each tube is given

dilution in tube 4=1/10000

volume plated= 1 mL

number of colonies formed= 32

CFU/mL= number of colonies/( volume plated in mL $\times$ dilution)

CFU/mL=32/(1$\times$1/10000)

= 320000

= 3.2$\times$10^5 /mL

original cell density is the CFU/mL of the original bacterial solution so the OCD= 3.2$\times$10^5 /mL