Modelling the combined effect of surface roughness and topography on bacterial attachment

Biofilm Formation and Biofouling Development on Different Ultrafiltration Membranes by Natural Anaerobes from an Anaerobic Membrane Bioreactor

“…This agrees with previous findings that hydrophobic surfaces have a higher biofouling propensity than hydrophilic surfaces because stronger hydrophobic interactions occur between foulants and hydrophobic membranes. ,, In particular, a steep increase in the TMP of the PVDF membrane occurred after 24 h (Figure ), indicating that a biofilm formed and consolidated . Moreover, the positive correlation between the membrane surface roughness and the biofilm characteristics (biovolume, thickness, and substratum coverage of live and dead cells, biofilm stiffness, EPS composition, and hydrophobicity) (Figure S6) was probably due to the small effect of the hydrodynamic shear on the anaerobes attached to a rough surface, which provided more locations for microbes to colonize and promoted the subsequent biofilm growth. ,,, A variance of a few nanometers in surface roughness can make a significant difference in microbial primary docking and anchoring to a surface since it is done with the help of their nanoscale appendages (such as pili, fimbriae, and flagella). , In addition, the lower polysaccharide-to-protein ratio of the PVDF membranes compared with the PAN membranes led to the formation of a stiffer biofilm and more hydrophobic EPS on the PVDF membranes than on the PAN membranes. ,, The stiffer biofilm and more hydrophobic EPS increased the tolerance of the biofilm on the PVDF membranes to hydraulic scouring and physical backwashing and thus led to lower biofouling reversibility. − Moreover, the importance of backwashing was supported by preliminary biofouling experiments conducted under similar conditions but at constant TMP and without backwashing, which demonstrated that the permeate flux of all three membranes decreased steeply within the first 12 h of filtration and continued to decrease throughout the experiment (results not shown).…”

“…43 Moreover, the positive correlation between the membrane surface roughness and the biofilm characteristics (biovolume, thickness, and substratum coverage of live and dead cells, biofilm stiffness, EPS composition, and hydrophobicity) (Figure S6) was probably due to the small effect of the hydrodynamic shear on the anaerobes attached to a rough surface, which provided more locations for microbes to colonize and promoted the subsequent biofilm growth. 19,41,42,44 A variance of a few nanometers in surface roughness can make a significant difference in microbial primary docking and anchoring to a surface since it is done with the help of their nanoscale appendages (such as pili, fimbriae, and flagella). 45,46 In addition, the lower polysaccharide-to-protein ratio of the PVDF membranes compared with the PAN membranes led to the formation of a stiffer biofilm and more hydrophobic EPS on the PVDF membranes than on the PAN membranes.…”

DLVO Interactions between Particles and Rough Surfaces: An Extended Surface Element Integration Method

“…Furthermore, these exact methods calculate only the van der Waals interaction; to characterize colloidal systems, incorporating double-layer interactions is crucial. Instead, studies calculating both van der Waals and double-layer interactions between particles and surfaces with non-uniform morphology have generally used one of two approximate methods: the SEI method (extension A) ,,,− or modified Derjaguin methods. ,,,− …”

“…Many previous studies applied the SEI method to rough surfaces by approximating the interaction between d S and the surface by the interaction between d S and an infinite flat surface separated by the vertical distance between d S and the rough surface. ,,,− This flat surface is oriented perpendicular to unit vector k such that the component of d S parallel to this flat surface is given by n p · k d S , and the total interaction is given by eq , where h z is the vertical (in the z -direction) distance between d S and the rough surface. The approximation used in this approach is depicted in Figure a, and we denote the SEI method using this approximation as “SEI extension A”.…”

Precision Design of Antimicrobial Surfaces

“…In this regard, a dissection of the interactions occurring at the interface of antimicrobial surfaces and the outermost external components of bacterial cells has become crucial in order to explain how surfaces can either kill or repel bacteria (or both) directly upon contact. Such explorations have often been complemented by computational models to predict bacterial attachment ( 33 , 34 ). These surfaces are referred to as contact-active, and typically they are complex, either entailing a pattern at the surface or a random arrangement, yet their mode of action is independent of any leaching substance.…”