title: Analysis of the contribution of sedimentation to bacterial mass transport in a parallel plate flow chamber.
abstract: In order to investigate bacterium-substratum interactions, understanding of bacterial mass transport is necessary. Comparisons of experimentally observed initial deposition rates with mass transport rates in parallel-plate-flow-chambers (PPFC) predicted by convective-diffusion yielded deposition efficiencies above unity, despite electrostatic repulsion. It is hypothesized that sedimentation is the major mass transport mechanism in a PPFC. The contribution of sedimentation to the mass transport in a PPFC was experimentally investigated by introducing a novel microscopy-based method. First, height-dependent bacterial concentrations were measured at different times and flow rates and used to calculate bacterial sedimentation velocities. For Staphylococcus aureus ATCC 12600, a sedimentation velocity of 240 μm h(-1) was obtained. Therewith, sedimentation appeared as the predominant contribution to mass transport in a PPFC. Also in the current study, deposition efficiencies of S. aureus ATCC 12600 with respect to the Smoluchowski-Levich solution of the convective-diffusion equation were four-to-five fold higher than unity. However, calculation of deposition efficiencies with respect to sedimentation were below unity and decreased from 0.78 to 0.36 when flow rates increased from 0.017 to 0.33 cm(3) s(-1). The proposed analysis of bacterial mass transport processes is simple, does not require additional equipment and yields a more reasonable interpretation of bacterial deposition in a PPFC.
authors.affiliation: Department of Biomedical Engineering, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.
authors.forename: Jiuyi
authors.initials: J
authors.lastname: Li
authors.forename: Henk J
authors.initials: HJ
authors.lastname: Busscher
authors.forename: Willem
authors.initials: W
authors.lastname: Norde
authors.forename: Jelmer
authors.initials: J
authors.lastname: Sjollema
mesh_terms: D001422:Bacterial Adhesion; D001692:Biological Transport; D003102:Colloids / Q000737:chemistry; D031521:Fractionation, Field Flow / Q000295:instrumentation / Q000379:methods; D013499:Surface Properties
chemical_list: D003102:Colloids