A simple alginate bead biofilm model for undergraduate teaching of antimicrobial tolerance

Biofilms play a crucial role in medical, industrial, and environmental microbiology, yet their structural complexity often makes them challenging to study in undergraduate teaching laboratories. We present a simple, fast, and effective method for exploring bacterial behavior within an artificial biofilm model. Through a hands-on activity, bacteria are entrapped in calcium alginate beads to simulate biofilm conditions and then exposed to an antimicrobial. Their viability is compared to that of the same bacteria in the planktonic state. This classroom approach introduces students to the impact of living in a sessile state on bacterial tolerance to antimicrobials, offering valuable insights into how the biofilm structure contributes to antimicrobial tolerance.