Surface plasmon resonance shows that type IV pili are important in surface attachment by Pseudomonas aeruginosa

Abstract

Type IV pili have been shown to play a role in the early stages of bacterial biofilm formation, but not in initial bacterial attachment. Here, using the surface analytical technique, surface plasmon resonance (SPR), we follow the attachment of the bacterium Pseudomonas aeruginosa in real time. In contrast to previous studies, we show that type IV pili mutants are defective in attachment. Both mutants lacking pili (pilA), and those possessing an overabundance of pili (pilT), showed reduced SPR measured attachment compared with the wild-type PAO1 strain. Both pil mutants also showed reduced pathogenicity in a model insect host, as measured by percentage mortality after 24 h. SPR revealed differences in the kinetics of attachment between pilA and pilT, differences obscured by endpoint assays using crystal violet stain. These results highlight the power of SPR in monitoring bacterial attachment in real time and also demonstrate an additional role for type IV pili beyond bacterial aggregation and micro-colony formation.

Iron-depletion prevents biofilm formation in Pseudomonas aeruginosa through twitching motility and quorum sensing

“…Twitching motility, mediated by pilus extension and contraction, is required for the formation of biofilms in P. aeruginosa (10, 21). Quorum-sensing (QS) system in bacteria detects cell density and regulates the expression of many genes at high cell densities.…”

“…Previous studies suggested that twitching motility is necessary for microcolony formation and thus essential for normal biofilm development (10, 15, 21). However, our study showed that IV pili mutant strain PAO-ΔpilHIJK formed almost the same amount of biofilm compared to the wild-type strain, PAO1.…”

Eradication of Bacteria in Suspension and Biofilms Using Methylene Blue-Loaded Dynamic Nanoplatforms

“…Different from the killing efficacy of the MB-PAA-DNP, the dispersal efficacy seemed to be about the same for both gram-positive and gram-negative bacteria, although the biofilm dispersing mechanism by MB-PAA-DNP is not yet known. One possibility might be that the singlet oxygen produced by MB-PAA-DNP would cause damage to cell membranes (lipid), pili (proteins), extracellular DNA, and other biological molecules, all of which play important roles in biofilm formation (1,5,7,12,19). These hypothetical targets warrant further studies to elucidate the dispersion mechanisms.…”

Surface Plasmon Resonance Assay for Real-Time Monitoring of Somatic Coliphages in Wastewaters

“…Recent work by Jenkins has shown that SPR is sensitive to bacterial attachment, despite the fact that bacteria are larger than the evanescent-decay length of the resonant surface plasmons. Moreover, SPR could accurately discriminate between pil mutants of Pseudomonas aeruginosa and the wild type during ear-stage attachment (16).…”

“…Schematic representation of the SPR setup used in this study (adapted from the work of Jenkins et al[16]). P-polarized light is reflected, forming an energy wave at the gold surface.…”