Pseudomonas aeruginosa biofilm sensitivity to biocides: use of hydrogen peroxide as model antimicrobial agent for examining resistance mechanisms.

The biofilm mode of bacterial growth may be the preferred form of existence in nature. Because of the global impact of problematic biofilms, study of the mechanisms affording resistance to various biocides is of dire importance. Furthermore, understanding the physiological differences between biofilm and planktonic organisms ranks particularly high on the list of important and necessary research. Such contributions will only serve to broaden our knowledge base, especially regarding the development of better antimicrobials while also fine-tuning the use of current highly effective antimicrobials. Using H2O2 as a model oxidizing biocide, we demonstrate the marked resistance of biofilm bacteria relative to planktonic cells. Because many biocides are good oxidizing agents (e.g., H2O2, HOCl), understanding the mechanisms by which genes involved in combating oxidative stress are activated is important in determining the overall efficacy of such biocides. Future studies will focus on determining mechanisms of oxidative stress gene regulation in bacterial biofilms.