Escherichia coliretention on solid surfaces as functions of substratum surface energy and cell growth phase

Abstract

In a flow cell model, substrata of low‐and medium‐surface energies with known multiple attenuated internal reflectance infrared (MAIR‐IR) spectra and contact angles were monitored for stationary‐phase Escherchia coli retention. Exponential‐phase cell retention was also explored. Quantitative numerical counts of retained cells supported qualitative observations with phase contrast microscopy. Medium‐surface‐energy glass plates (critical surface tension, γ_c, 30–35 dynes^.cm⁻¹) were slower to acquire maximum retained E. coli cell populations than lower‐energy (dimethylsilane‐coated) glass plates (critical surface tension, γ_c , 20–25 dynes·cm⁻¹) but retained more cells overall. Stationary‐phase cells resisted detachment from both types of substrata more than exponential‐phase cells. The attachment patterns on the two surfaces were considerably different. E. coli generally were clumped and/or raised above “conditioning”; films on low‐surface‐energy substrata, in contrast to their single, well‐distributed and “buried”; appearance within similar macromolecular films on the medium‐surface‐energy plates.