Dwr-SECM Testing of Pseudomonas Aeruginosa Biofilms

Pseudomonas aeruginosa biofilms are multicellular assemblies held together by an extracellular polymeric substance (EPS). P. aeruginosa begins to form biofilms once pyocyanin – a small toxic molecule excreted by P. aeruginosa – concentrations overcomes a certain threshold. Through quorum sensing, the bacteria will detect this chemical composition and subsequently change its defense mechanism by changing its phenotype. In a healthy human, P. aeruginosa lives within the mucus of the lungs without detriment to the human. In humans with cystic fibrosis (CF), these biofilms can make the person’s mucus even more viscous, leading to serious health complications. We designed and tested a novel apparatus that combined double wall ring (DRW) interfacial rheology with scanning electrochemical microscopy (SECM) probe. By doing DWR-SECM rheology on the biofilm, we are able to directly correlate the presence of high concentrations of pyocyanin to the rheological increase in modulus resulting from the release of pyocyanin quorum sensing.