Biofilm formation under high shear stress increases resilience to chemical and mechanical challenges

Abstract

The effect that the hydrodynamic conditions under which biofilms are formed has on their persistence is still unknown. This study assessed the behaviour of Pseudomonas fluorescens biofilms, formed on stainless steel under different shear stress (s w ) conditions (1, 2 and 4 Pa), to chemical (benzalkonium chloride -BAC, glutaraldehyde -GLUT and sodium hypochlorite -SHC) and mechanical (20 Pa) treatments (alone and combined). The biofilms formed under different s w showed different structural characteristics. Those formed under a higher s w were invariably more tolerant to chemical and mechanical stresses. SHC was the biocide which caused the highest biofilm killing and removal, followed by BAC. The sequential exposure to biocides and mechanical stress was found to be insufficient for effective biofilm control. A basal layer containing biofilm cells mostly in a viable state remained on the surface of the cylinders, particularly for the 2 and 4 Pa-generated biofilms.

Effects of early biofilm formation on water quality during commissioning of new polyethylene pipes

“…The hydraulics regime during biofilm development will also influence the formation and detachment of the biofilm. 27,28 The average Reynolds number for the flushing period was calculated to approximately 3750 both up-and downstream, and most importantly in the installed PE pipe itself, resulting in transient flow considering the flow of 5 m 3 h −1 and the water temperature of 5 °C. Therefore, there was limited hydraulic interference with microbial growth and biofilm formation in the newly installed pipe.…”

Microstructural and Rheological Transitions in Bacterial Biofilms

“…[ 25 , 59 ] Furthermore, shear stress‐dependent increases in cell density have previously been documented in biofilms growing on surfaces of annular reactors. [ 60 , 61 ] Therefore, understanding packing fraction‐dependent rheology could assist in predicting the shear stress profiles that induce streamer nucleation, drive biofilm colony morphogenesis, and control bioreactor stability. An emerging application of biofilm viscoelasticity lies in the realm of 3D printing, particularly in developing engineered living materials.…”

Evaluation of Biofilm Cultivation Models for Efficacy Testing of Disinfectants against Salmonella Typhimurium Biofilms

“…In the GBA, turbid flow and therefore high shear forces were applied during biofilm formation, whereas cells on stainless-steel or PVC coupons grew under static conditions. Fluid dynamics and therefore shear forces during the biofilm formation process have stimulating effects on matrix production and were observed to increase cell density, biomass, and general biofilm stability, affecting the disinfectant penetration into the biofilm [ 48 , 49 , 50 , 51 ]. Moreover, decreased biofilm stability may result in the dispersal of loosely attached cell aggregates from the substrate and consequently higher variations of recoverable CFU.…”