Final answer:
The non-resistant variants of E. coli on a dish with a medium containing triclosan likely died off, while triclosan-resistant strains could have survived due to a genetic mutation that confers resistance, leading to increased bacterial resistance as a public health issue.
Step-by-step explanation:
When E. coli is grown on a medium containing triclosan, it is likely that the non-resistant variants of E. coli were unable to survive due to the antibacterial properties of triclosan. Triclosan works by targeting a specific enzyme in the bacterial fatty acid-synthesis pathway, and bacteria can develop resistance to triclosan by mutating a single gene that codes for the targeted enzyme. Consequently, resistant variants may survive and proliferate, while susceptible E. coli variants likely perished, reducing the overall diversity of E. coli on the plate. The overuse of triclosan and similar antimicrobial agents in everyday products can lead to increased bacterial resistance, which is a significant public health concern.