title: Role of biofilm roughness and hydrodynamic conditions in Legionella pneumophila adhesion to and detachment from simulated drinking water biofilms.
abstract: Biofilms in drinking water distribution systems (DWDS) could exacerbate the persistence and associated risks of pathogenic Legionella pneumophila (L. pneumophila), thus raising human health concerns. However, mechanisms controlling adhesion and subsequent detachment of L. pneumophila associated with biofilms remain unclear. We determined the connection between L. pneumophila adhesion and subsequent detachment with biofilm physical structure characterization using optical coherence tomography (OCT) imaging technique. Analysis of the OCT images of multispecies biofilms grown under low nutrient condition up to 34 weeks revealed the lack of biofilm deformation even when these biofilms were exposed to flow velocity of 0.7 m/s, typical flow for DWDS. L. pneumophila adhesion on these biofilm under low flow velocity (0.007 m/s) positively correlated with biofilm roughness due to enlarged biofilm surface area and local flow conditions created by roughness asperities. The preadhered L. pneumophila on selected rough and smooth biofilms were found to detach when these biofilms were subjected to higher flow velocity. At the flow velocity of 0.1 and 0.3 m/s, the ratio of detached cell from the smooth biofilm surface was from 1.3 to 1.4 times higher than that from the rough biofilm surface, presumably because of the low shear stress zones near roughness asperities. This study determined that physical structure and local hydrodynamics control L. pneumophila adhesion to and detachment from simulated drinking water biofilm, thus it is the first step toward reducing the risk of L. pneumophila exposure and subsequent infections.
authors.affiliation: †Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States.
authors.forename: Yun
authors.initials: Y
authors.lastname: Shen
authors.affiliation: ‡Department of Bioengineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States.
authors.forename: Guillermo L
authors.initials: GL
authors.lastname: Monroy
authors.affiliation: ∥Eawag: Swiss Federal Institute of Aquatic Science and Technology, 8600 Dübendorf, Switzerland.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Derlon
authors.affiliation: †Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States.
authors.forename: Dao
authors.initials: D
authors.lastname: Janjaroen
authors.affiliation: †Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States.
authors.forename: Conghui
authors.initials: C
authors.lastname: Huang
authors.affiliation: ∥Eawag: Swiss Federal Institute of Aquatic Science and Technology, 8600 Dübendorf, Switzerland.|⊥ETH Zürich, Institute of Environmental Engineering, 8093 Zürich, Switzerland.
authors.forename: Eberhard
authors.initials: E
authors.lastname: Morgenroth
authors.affiliation: ‡Department of Bioengineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States.|§Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States.
authors.forename: Stephen A
authors.initials: SA
authors.lastname: Boppart
authors.affiliation: #School of Public Health, University of Alberta, Edmonton, Alberta T6G 2G7, Canada.
authors.forename: Nicholas J
authors.initials: NJ
authors.lastname: Ashbolt
authors.affiliation: †Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States.
authors.forename: Wen-Tso
authors.initials: WT
authors.lastname: Liu
authors.affiliation: †Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States.
authors.forename: Thanh H
authors.initials: TH
authors.lastname: Nguyen
mesh_terms: D001422:Bacterial Adhesion; D018441:Biofilms; D060766:Drinking Water / Q000382:microbiology*; D057446:Hydrodynamics; D016952:Legionella pneumophila / Q000472:pathogenicity / Q000502:physiology*; D014054:Tomography
chemical_list: D060766:Drinking Water