D-064. The Effect of Polysorbate 80 on Pseudomonas aeruginosa and its Ability to Form Biofilms
The gram-negative bacterium Pseudomonas aeruginosa is responsible for many hospital and community-acquired infections. Biofilm formation has been shown to be a key element in many of these infections rendering them difficult to eradicate using traditional regimens of antibiotics. Polysorbate 80 (PS80) is a nonionic surfactant commonly used by the food, cosmetic and pharmaceutical industries as an emulsifier and dispersing agent. Because it is widely used in various medications, we studied the effects of PS80 on P. aeruginosa in the context of biofilm formation. We previously showed that PS80 inhibits biofilm formation of P. aeruginosa PA14 on various medically relevant surfaces, without affecting the growth. In this work, we tried to understand the mechanisms by which PS80 inhibits bacterial attachment using a genetic approach. All assays were done following previously published protocols. We screened a library of 6000 transposon mutants in P. aeruginosa PA14 to look for strains able to form biofilms in presence of 0.01% PS80. We identified 20 mutants meeting these criteria and they were classified into four categories according to their predicted function: transmembrane proteins, secretion and transport, metabolism and enzymatic activity, hypothetical and unknown proteins. Genetic and phenotypic analysis of these mutants will be presented. Surfactants are known to reduce bacterial attachment under some circumstances, but the exact mechanisms are not fully understood. Some believe that surfactants modify the chemistry of the surface rendering it inhospitable for bacteria, others propose that surfactants modify the bacterial physiology or surface properties. The results of our screen suggest that the presence of PS80 in the environment leads to an active response from the bacteria. This work could eventually give a better understanding on how PS80 could be used in medicine to help prevent infections.