TY - CONF A1 - Wen, Keqing T1 - In situ analysis of biofilm formation under different flow regimes with the help of a microfluidic platform N2 - Bacteria often live in habitats characterized by fluid flow, which is ubiquitous in a diverse range of environments such as surface waters, wastewater treatment facilities, pipelines, and medical implants. Bacterial adhesion on surfaces may lead to biocorrosion and biodegradation. In comparison to traditional static and macro flow chamber assays for biofilm formation studies, microfluidic chips allow in situ monitoring of biofilm formation and biofilm related gene expression under various flow regimes. We developed a complete microfluidic platform to investigate biofilms under precisely controlled flow conditions. This platform central unit is a single-inlet microfluidic flow cell with a 5 mm wide chamber tested and analyzed by imaging tracking velocimetry (PIV) to achieve ultra-homogenous flow in the central area of the chamber. Additionally, dedicated microstructures were introduced to the chamber’s center to favor and localize bacterial adhesion and biofilm formation pattern. The flows and vortices induced by the structure were analyzed by computational fluid dynamics (CFD) and related to shape and dimension of the biofilm formed by Escherichia coli TG1. The major proteinaceous component of E. coli biofilms are extracellular amyloid fibers (curli) consisting of major (CsgA) and minor (CsgB) subunits. We used the promotor probe plasmid pRU1701 to monitor csgB-promotor activity under different flow regimes in complex and minimal medium. For comparison, csgB promotor activity in a batch liquid culture and curli production on LB and M9 agar plates were assessed. The microfluidic platform represents a powerful and versatile tool for studying biofilm in flow. The setup shows great potential for the yet not too much explored in flow monitoring of biofilm formation and related gene expression under hydrodynamic stresses. T2 - International Biodeterioration and Biodegradation Symposium (IBBS) 19 CY - Berlin, Germany DA - 09.09.2024 KW - Microfluidics KW - Biofilm KW - Escherichia coli KW - Curli PY - 2024 AN - OPUS4-61911 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Wen, Keqing A1 - Gorbushina, Anna A1 - Schwibbert, Karin A1 - Bell, Jérémy T1 - A microfluidic platform for monitoring biofilm formation in flow under defined hydrodynamic conditions N2 - Bacterial adhesion on surfaces of medical, water and food applications may lead to infections, water or food spoilage and human illness. In comparison to traditional static and macro flow chamber assays for biofilm formation studies, microfluidic chips allow in situ monitoring of biofilm formation under various flow regimes, have better environment control and smaller sample requirements. In this work, a novel microfluidic platform is developed to investigate biofilm adhesion under precisely controlled bacteria concentration, temperature, and flow conditions. This platform central unit is a single-inlet microfluidic flow cell with a 5 mm wide chamber designed and tested to achieve ultra-homogenous flow in the central area of chamber. Within this area, defined microstructures are integrated that will disturb the homogeneity of the flow, thus changing bacterial adhesion pattern. Here we present the monitoring of bacterial biofilm formation in a microfluidic chip equipped with a microstructure known as micro-trap. This feature is based on a 3D bacteria trap designed by Di Giacomo et al. and successfully used to sequester motile bacteria. At first, fluorescent particles similar in size to Escherichia coli (E. coli) are used to simulate bacteria flow inside the flow cell and at the micro-trap. The turbulences induced by the trap are analyzed by imaging and particle tracking velocimetry (PTV). Secondly, the model strain E. coli TG1, ideal and well described for biofilm studies, is used to analyze biofilm formation in the micro-trap. Therefore, a stable fluorescent strain E. coli TG1-MRE-Tn7-141 is constructed by using Tn7 transposon mutagenesis according to the method described by Schlechter et al. Sequestering of E. coli cells within the micro-trap was followed using epifluorescence microscopy. The novel microfluidic platform shows great potential for assessment of bacterial adhesion under various flow regimes. The performance of structural feature with respect to the generation of turbulences that promote or reduce bacterial adhesion can be systematically examined. The combination of flow analysis and fluorescent strain injection into the microfluidic chip shows that the micro-trap is useful for capturing bacteria at defined positions and to study how flow conditions, especially micro-turbulences, can affect biofilm formation. It represents a powerful and versatile tool for studying the relation between topography and bacteria adhesion. T2 - International Conference on Miniaturized Systems for Chemistry and Life Sciences CY - Katowice, Poland DA - 15.10.2023 KW - Biofilm KW - E. coli KW - Microfluidics KW - Velocimetry KW - Fluorescence PY - 2023 AN - OPUS4-59593 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -