Question

"After washing your hands for twenty seconds, you leave 8 bacterial cells using a new bar of soap. After 24 hours of the soap sitting in a soap dish, you dilute 1g of of the soap 1:1,000,000 and plate it on heterotrophic plate count agar. After 24 hours, there are 150 colonies. How many bacteria are on the soap piece before the dilution

Answer 1

Answer: 150,000,000 bacteria are on the soap piece before dilution.

Explanation:

The dilution factor is 1:1,000,000 or (1/1,000,000) This means that the 1g of soap was diluted 1,000,000 times.

After 24 hours, there are 150 colonies.

To get the number of bacteria before dilution, we simply multiply the number of colonies by the denominator of the dilution factor which is 1,000,000. We have:

150 x 1,000,000

= 150,000,000

Therefore, there were 150,000,000 bacteria before dilution.