Science Research 7Calculate the colony forming units (cfu) per ml. of starter culture. Choose a plate with between 50 and 150 colonies. Calculate the cfu/mL of culture by using the following proportion. # of colonies x dilution of plate X ------------------------------------------------ = -------------volume of culture on plate 1 ml. For example, if you counted 24 colonies on the 105 dilution plate you would use the following proportion and solve for X using the following steps. 1) set up proportion 24 x 105 ------------0.25 X = ------1 2) cross multiply 0.25 x = 1 (24 x 105 ) 3) divide to get x alone 0.25 x 1 (24 x 105 ) --------- = ----------0.25 0.25 4) use calculator to solve (24 x 105 ) ------------0.25 5) put answer in scientific notation X = 9600000 X = 9.6 x 106 1 ml x 10^5 = 46.7 x 10^6 Note: cfu means colony forming unit which is equivalent to a bacterium as long as the bacteria are single-celled and are not clumps or groups when plated.000 cfu/ml or 14. 10^-6. How do I get the Cfu/ml?? • • 10 months ago Report Abuse by bradlepe Member since: March 25.1 ml x 10 x 10 x 10 = 800.1 ml x 10^4 = 14. So once your incubation is done. For the first tube of bacteria I grew 400 colonies on a plate after pipetting 100 ul onto the plate with a 10^-5 dilution. the .000 cfu/ml or 0.700. • 3 years ago We did an experiment where we did 10^-5 . A CFU is basically just a single.Chosen by Voters CFU = colony forming unit.Science Research 7 Calculate the cfu/mL of culture.115 (Level 5) • • Add Contact Block Best Answer . Show all your work! number of colonies __42__ dilution of plate __106___ number of colonies __57__ dilution of plate __105___ number of colonies __75___ dilution of plate ___104___ number of colonies __62___ dilution of plate ___106___ A: 80 cfu/0.000. 40 for the 10^-6 dilution.000 cfu/ml or 46 x 10^6 C: 147 cfu/0. this is true for many strains of Escherichia coli and other organisms commonly used in the lab. and 8 for the 10^-7.8 x 10^6 B: 46/0. 2008 Total points: 8. 10^-7 dilutions. viable cell that's capable of dividing and form a colony after some incubation period. Chosen by Asker 44 colonies / 0. So at dilutions of 10^-5: CFU/mL = (400 * 10^5)/(0. Hope this helps! • 10 months ago Best Answer .1 mL) = 4*10^8 CFU/mL At 10^-7: CFU/mL = (8 * 10^7)/(0.1 mL) = 8*10^8 CFU/mL. CFU / mL = (# colonies)*(dilution factor)/(volume plated in mL) Dilution factor is the same as the dilution you've written above.1 mL) = 4*10^8 CFU/mL At 10^-6: CFU/mL = (40 * 10^6)/(0.1 mL = 440 cfu/mL But you did a 50 fold dilution so 440 x 50 = 22000 cfu/mL in the original sample • • • 1 year ago Report Abuse 1 person rated this as good Asker's Rating: Asker's Comment: thanks Not the right answer? Try Yahoo! . except the exponent should be positive instead of negative.Science Research 7 number of colonies present should be the same as the number of CFUs that were originally plated. 2.1 C + 0.you know this. 100 mL C x (1.1 mL D 0.1 ml aliquot to 0.127 (Level 7) Badge Image: • • Add Contact Block Best Answer . And 0...0 mL "D" right? (D is 0..3x10^5 CFU / 100 mL ************ couple of quick conversions.1 mL C) x (73 CFU / 0..200 mL . 73 CFU = 0.. 0. yielding 73 colonies... Then.1 mL D) = 7.. 200 microliters x (1 mL / 1000 microliters) = 0. and 50 microliter of the dilution was plated.0 mL ?) next.1 C went into 1.1 C mL = 1. If there were 141 colonies on the plate. 2006 Total points: 132.Science Research 7 Biology CFU calculations A culture was diluted by adding a 0...9 ml of water.3x10^5 CFU. Calculate the CFU/100 ml in the original culture. 200 microliter of milk was mixed with 9..8 ml of water..9 water = 1.0 mL D and you want to know how many CFU's in 100 mL of C. 1.Chosen by Voters let's call the culture "C" and the dilution "D"... what was the original CFU/ml in the milk? please show your work! Thanks! :D • • 2 years ago Report Abuse by m w Member since: May 09.so.1 ml of this dilution was plated out.. so the answer is 7.0 mL D / 0.. 0 mL dilution / 0.Science Research 7 50 microliters x (1 mL / 1000 microliters) = 0.050 mL dilution = 141 CFU and you want to know how many CFU's per 1 mL.0 mL of diluted solution..41x10^5 CFU / mL ******* do you need help with the equations above? • • 2 years ago Report Abuse 100% 2 Votes • 1 person rated this as good Not the right answer? Try Yahoo! Search Search Yahoo! for þÿ Search There are currently no comments for this question.0 mL dilution 0.. you know this. Sign in or Register.41x10^5 CFU so the answer is 1.905 (Level 7) Badge Image: o o Add Contact Block .8 mL = 10..050 mL 0... * You must be logged into Answers to add comments..so. 2006 Total points: 40. .. Member since: June 15..200 mL milk) x (141 CFU / 0. next.050 mL dilution) = 1.200 mL + 9.. 1 mL milk x (10. Other Answers (1) • by hcbioche....200 mL milk = 10. o o 2 years ago Report Abuse .1 mL = 730 CFU/mL by that is a 10-fold dilution. Since you want CFU/100 mL.2 = 50). so 2820 X 50 = 141. so 730 X 10 = 7300 CFU/mL of the original culture.Science Research 7 1. 73 CFU/ 0. 141 CFU/0.05 mL = 2820 CFU/mL of the 50-fold dilution.000 CFU/mL of the original milk. 200 uL to 9.8 mL is a 50-fold dilution (10/.000 CFU/100mL 2. multiply7300 X 100 = 730.