Helical Pseudomonas biofilms in cylindrical flow systems

Beautiful pictures on helicoidal spread of Pseudomonas putida biofilms in the new Scientific Reports paper from the group of Victor de Lorenzo.

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David R. Espeso, Ana Carpio, Esteban Martínez-García & Victor de Lorenzo (2016)
Stenosis triggers spread of helical Pseudomonas biofilms in cylindrical flow systems.
Scientific Reports 6, Article number: 27170 doi:10.1038/srep27170


Biofilms are multicellular bacterial structures that adhere to surfaces and often endow the bacterial population with tolerance to antibiotics and other environmental insults. Biofilms frequently colonize the tubing of medical devices through mechanisms that are poorly understood. Here we studied the helicoidal spread of Pseudomonas putida biofilms through cylindrical conduits of varied diameters in slow laminar flow regimes. Numerical simulations of such flows reveal vortical motion at stenoses and junctions, which enhances bacterial adhesion and fosters formation of filamentous structures. Formation of long, downstream-flowing bacterial threads that stem from narrowings and connections was detected experimentally, as predicted by our model. Accumulation of bacterial biomass makes the resulting filaments undergo a helical instability. These incipient helices then coarsened until constrained by the tubing walls, and spread along the whole tube length without obstructing the flow. A three-dimensional discrete filament model supports this coarsening mechanism and yields simulations of helix dynamics in accordance with our experimental observations. These findings describe an unanticipated mechanism for bacterial spreading in tubing networks which might be involved in some hospital-acquired infections and bacterial contamination of catheters.

Akos T Kovacs

Professor of Bacterial Physiology and Genetics, Technical University of Denmark, DTU Bioengineering

07/2017 - Professor of Bacterial Physiology and Genetics, DTU Denmark 10/2012-07/2017 Group Leader, FSU Jena, Germany 07/2005-07-2012 Post Doc, University Groningen, The Netherlands (w/ Oscar Kuipers) 09/2003-05/2005 Post Doc, Biological Research Centre, Hungarian Academy of Sciences, Szeged, Hungary (w/ Kornel Kovacs) 09/2000-09/2003 PhD fellow, University of Szeged, Hungary (w/ Kornel Kovacs) 09/1995-07/2000 BSc/MSc student, University of Szeged, Hungary