Question

A polluted water sample has 2,400,000 bacteria per ml. You transfer 1.0 ml of sample to a bottle containing 99ml of sterile water. You then take 0.1 ml from this dilution bottle and transfer to a second bottle with 0.9 ml of sterile water. Finally, you transfer 1 ml to a Petri dish with nutrient agar. How many colonies would you expect to find on this plate? Would it be countable?

Answer 1

Simce sample contain 2400000 bacteria permi & 1.00 sample is mixed alith age of sterile water of 99 m. diluted here So, in this (99+) = 100er mixare contain: 2400000 bacteria Now, 100 m diluted mixare contain 24000 oobact. 24ooooo 700 .: OVU 2400048xor 17 = 2400 bact. Now again the first diluted sample o in mixed alita 0.9 of sterile arater. so, volume of second diluted sample & soyt og har = 100 which contain: 2400 bacteria [since of of ent diluted sample contain 2400 bacterial So, then finally set of finally diluted sample is transer then colonies of bacteria is expected 2400 in petri dish auth nutrient ag as. The selfоce of pe the plate a small So, 2400 bacterial colonias à not countable.