The Role of Growth Temperature in the Adhesion and Mechanics of Pathogenic L. monocytogenes: An AFM Study

Abstract

The adhesion strengths of pathogenic L. monocytogenes EGDe to a model surface of silicon nitride were quantified using atomic force microscopy (AFM) in water for cells grown under five different temperatures (10, 20, 30, 37, and 40 °C). The temperature range investigated was chosen to bracket the thermal conditions in which L. monocytogenes survive in the environment. Our results indicated that adhesion force and energy quantified were at their maximum when the bacteria were grown at 30 °C. The higher adhesion observed at 30 °C compared to the adhesion quantified for bacterial cells grown at 37, 40, 20, and 10 °C was associated with longer and denser bacterial surface biopolymer brushes as predicted from fitting a model of steric repulsion to the approach distance-force data as well from the results of protein colorimetric assays. Theoretically predicted adhesion energies based on soft-particle DLVO theory agreed well with the adhesion energies computed from AFM force-distance retraction data (r(2) = 0.94); showing a minimum energy barrier to adhesion at 30 °C.

Natural organic matter interactions with polyamide and polysulfone membranes: Formation of conditioning film

“…The adhesion forces were normalized to the radius of the colloidal probe [14]. Adhesion energies were calculated by integrating the adhesion forces with the separation distances using the trapezoidal rule as described elsewhere [22]. Nevertheless, a statistical approach was necessary to draw a A c c e p t e d M a n u s c r i p t 10 comprehensive picture on NOM/membrane interactions due to the physical/chemical heterogeneity of membrane surface and NOM isolates [23,24].…”

Impact of ionic strength of growth on the physiochemical properties, structure, and adhesion of Listeria monocytogenes polyelectrolyte brushes to a silicon nitride surface in water

“…The strain was activated by growing for 12 h at 30°C in a temperature controlled shaker rotating at a 150 rpm in Difco™ brain heart infusion broth (BHIB without dextrose). Following activation, cells were cultured in BHIB (dissolved in water with IS of 0.003 M [31,33]) and in BHIB with added NaCl (IS of 0.05 M, 0.1 M, 0.3 M, and 0.5 M added NaCl) at 30°C fixed temperature.…”

“…Retraction curves were considered individually because of the complex and heterogeneous nature of the interactions observed between the bacterial surface biopolymers and the AFM silicon nitride cantilever [33][34][35][36][39][40][41]. Bacterial adhesion was quantified from the retraction curves in terms of adhesion energy in atto-Joule (AJ) by converting the mechanical energy needed to pull the AFM tip from the bacterial surface into the bacterial adhesion energies.…”

“…where A 132 is the ''effective'' Hamaker constant of the interacting system (J), and k c is the ''characteristic wavelength'' of the interaction, often assumed to be 100 nm [31,33].…”

Characterization of Skeletonema costatum intracellular organic matter and study of nanomechanical properties under different solution conditions

“….e., F: interacting force, kb: Boltzmann's constant, T: temperature, R: AFM probe radius, d: separation distance)[31]. Polymer length (L0) and polymer grafting density (were determined as the fitting parameters.…”