(65i) Aggregation of Biofilm Forming Bacteria Induced by Insulator Based Dielectrophoresis

Insulator based dielectrophoresis (iDEP) is an attractive technique to concentrate, separate, and characterize bacteria. We've recently found that several species of bacteria known to form biofilms including Pseudomonas aeruginosa, Escherichia coli, and Streptococcus mitis form aggregates during iDEP trapping. In each case, strains known to form biofilms assembled into tightly bound aggregates while strains with compromised ability to form biofilms did not (or did so inconsistently). Biofilm formation is associated with increased virulence and antibiotic resistance in bacterial pathogens. Therefore, the identification of biofilm forming phenotypes bears significant clinical relevance. In this presentation we will discuss experimental results on aggregation of isogenic mutants of P. aeruginosa PA14. We find that iDEP can be utilized to classify cells based on both polarizability and their propensity to aggregate. Aggregation, coupled with cell polarizability, can be used to discriminate bacteria with subtle differences in cell envelope characteristics. We believe that iDEP induced aggregation represents a promising technique to rapidly obtain valuable phenotypic information on pathogenic bacteria.