How many colony-forming units were present per ml of the original culture?

Five ml (not one!) of an undiluted spring water sample were added to a petri dish to which 15 ml of Show more Five ml (not one!) of an undiluted spring water sample were added to a petri dish to which 15 ml of melted Plate Count Agar were then added. After mixing the plate was allowed to solidify and then was incubated appropriately. After incubation 50 colonies were counted. How many CFUs were present per one ml of the original undiluted spring water sample? 4- One ml of a bacterial culture was pipetted into a 9 ml dilution blank. One-tenth ml (0.1 ml) of this dilution was pipetted into a 9.9 ml dilution blank. From this dilution one-tenth ml was plated with 25 ml of culture medium. 220 colonies arose after incubation. How many colony-forming units were present per ml of the original culture? 5-Thirty-six colonies grew in nutrient agar from 1.0 ml of sample withdrawn from a solution diluted to 10-5 in a standard plate count procedure. How many cells were in the original sample? 6- One ml of a water sample is added to 9 ml of sterile water. This is mixed well and further diluted by 4 successive 1/10 dilutions. One-tenth of a ml of each dilution is spread on a plate of nutrient agar. After incubation the following data were obtained: Show less

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