Effect of NaCl on Pseudomonas biofilm viscosity by continuous, non-intrusive microfluidic-based approach

TL;DR

This study introduces a non-intrusive microfluidic method to measure early-stage Pseudomonas biofilm viscosity changes under varying NaCl concentrations, revealing rapid thickening phases linked to ionic strength.

Contribution

The paper presents a novel high-throughput, non-intrusive technique combining video imaging and a semi-empirical model for real-time biofilm viscosity measurement.

Findings

Measured low-viscosity biofilms at early growth stages.

Detected rapid biofilm thickening phases influenced by ionic strength.

Enabled high temporal resolution of biofilm mechanical responses.

Abstract

A method combining video imaging in parallel microchannels with a semi-empirical mathematical model provides non-intrusive, high-throughput measurements of time-varying biofilm viscosity. The approach is demonstrated for early growth Pseudomonas sp. biofilms exposed to constant flow streams of nutrient solutions with different ionic strengths. The ability to measure viscosities at early growth stages, without inducing a shear-thickening response, enabled measurements that are among the lowest reported to date. In addition, good time resolution enabled the detection of a rapid thickening phase, which occurred at different times after the exponential growth phase finished, depending on the ionic strength. The technique opens the way for a combinatorial approach to beter understand the complex dynamical response of biofilm mechanical properties under well-controlled physical, chemical and biological growth conditions and time-limited perturbations.