An investigation of antimicrobial detergents. (Senior Division).
This experiment investigated how well antimicrobial dishwashing
detergents perform. A nonpathogenic strain of Escherichia coli was grown
on nutrient agar plates to serve as a stock population. This stock
population of E. coli was then transferred to nutrient broth and
incubated at 24 degrees Celsius for 24 hours. The E. coli broth was then
diluted and mixed with varying solutions of antimicrobial detergents and
water. Three different antimicrobial detergents were tested: Dawn, Sun,
and Palmolive. Each of these detergents contained the antimicrobial
agent triclosan. These detergent, water and E. coli solutions were then
plated out on nutrient agar and incubated for 48 hours at 24 degrees
Celsius. Though the results were somewhat erratic, it was obvious that
all three brands of antimicrobial detergent were effective at killing
the E. coli except in the very dilute trials. Other trials were
performed using paper disks saturated with the detergents to identify
zones of inhibition on the nutrient, agar plates with a lawn of E. coli.
Sam Huang and Andy Lin, Cherry Creek High School.