title: Studying bacterial hydrophobicity and biofilm formation at liquid-liquid interfaces through interfacial rheology and pendant drop tensiometry.
abstract: Bacterial adsorption to interfaces is a key factor in biofilm formation. One major limitation to understanding biofilm formation and development is the accurate measurement of bacterial cell adhesion to hydrophobic interfaces. With this study, bacterial attachment and biofilm growth over time at water-oil interface was monitored through interfacial rheology and tensiometry. Five model bacteria (Pseudomonas putida KT2442, Pseudomonas putida W2, Salmonella typhimurium, Escherichia coli, and Bacillus subtilis) were allowed to adsorb at the water-oil interface either in their non-growing or growing state. We found that we were able to observe the initial kinetics of bacterial attachment and the transient biofilm formation at the water-oil interface through interfacial rheology and tensiometry. Electrophoretic mobility measurements and bacterial adhesion to hydrocarbons (BATH) tests were performed to characterize the selected bacteria. To validate interfacial rheology and tensiometry measurements, we monitored biofilm formation utilizing both confocal laser scanning microscopy and light microscopy. Using this combination of techniques, we were able to observe the elasticity and tension development over time, from the first bacterial attachment up to biofilm formation.
authors.affiliation: Department of Health, Science and Technology, ETH Zürich, 8092 Zürich, Switzerland. Electronic address: patrick.ruehs@hest.ethz.ch.
authors.forename: P A
authors.initials: PA
authors.lastname: Rühs
authors.affiliation: Department of Health, Science and Technology, ETH Zürich, 8092 Zürich, Switzerland.
authors.forename: L
authors.initials: L
authors.lastname: Böcker
authors.affiliation: Department of Environmental Sciences, ETH Zürich, 8092 Zürich, Switzerland; Department of Environmental Microbiology, EAWAG, 8600 Dübendorf, Switzerland.
authors.forename: R F
authors.initials: RF
authors.lastname: Inglis
authors.affiliation: Department of Health, Science and Technology, ETH Zürich, 8092 Zürich, Switzerland.
authors.forename: P
authors.initials: P
authors.lastname: Fischer
mesh_terms: D001419:Bacteria / Q000378:metabolism*; D018441:Biofilms / Q000254:growth & development*; D004548:Elasticity; D004586:Electrophoresis; D057927:Hydrophobic and Hydrophilic Interactions; D018613:Microscopy, Confocal; D008903:Minerals / Q000737:chemistry; D009821:Oils / Q000737:chemistry; D012212:Rheology / Q000379:methods*; D013500:Surface Tension; D014867:Water / Q000737:chemistry
chemical_list: D008903:Minerals; D009821:Oils; D014867:Water
keywords: BATH test; Bacteria adsorption; Biofilms at liquid–liquid interfaces; Hydrophobicity of bacteria; Interfacial rheology; Pendant drop tensiometry; Pseudomonas putida KT2442