Simulation of catalase-dependent tolerance of microbial biofilm to hydrogen peroxide with a biofilm computer model

Hydrogen peroxide (HP) is a common disinfectant and antiseptic. When applied to a biofilm, it may be expected that the top layer of the biofilm would be killed by HP, the HP would penetrate further, and eventually eradicate the entire biofilm. However, using the Biofilm.jl computer model, we demonstrate a mechanism by which the biofilm can persist, and even become thicker, in the indefinite treatment with an HP solution at concentrations that are lethal to planktonic microorganisms. This surprising result is found to be dependent on the neutralization of HP by dead biomass, which provides protection for living biomass deeper within the biofilm. Practically, to control a biofilm, this result leads to the concept of treating with an HP dose exceeding a critical threshold concentration rather than a sustained, lower-concentration treatment.