Level of Fimbriation Alters the Adhesion of Escherichia coli Bacteria to Interfaces

Abstract

Adhesion of bacteria to interfaces is the first step in pathogenic infection, in biofilm formation, and in bioremediation of oil spills and other pollutants. Bacteria use a variety of surface structures to promote interfacial adhesion, with the level of expression of these structures varying in response to local conditions and environmental signals. Here, we investigated how overexpression of type 1 fimbriae, one such appendage, modifies the ability of Escherichia coli to adhere to solid substrates, via biofilm formation and yeast agglomeration, and to oil/water interfaces, via a microbial adhesion to hydrocarbon assay. A plasmid that enables inducible expression of E. coli MG1655 type 1 fimbriae was transformed into fimbriae-deficient mutant strain MG1655ΔfimA. The level of fimH gene expression in the engineered strain, measured using quantitative real-time PCR, could be tuned by changing the concentration of inducer isopropyl β-d-1-thiogalactopyranoside (IPTG), and was higher than that in strain MG1655. Increasing the degree of fimbriation only slightly modified the surface energy and zeta potential of the bacteria, but enhanced their ability to agglomerate yeast cells and to adhere to solid substrates (as measured by biofilm formation) and to oil/water interfaces. We anticipate that the tunable extent of fimbriation accessible with this engineered strain can be used to investigate how adhesin expression modifies the ability of bacteria to adhere to interfaces and to actively self-assemble there.

Mechanics of biofilms formed of bacteria with fimbriae appendages

“…Cohen et al [26] showed that presence of fimbriae enhances aggregation of E. coli with small clay particles. McLay et al [27] gradually varied the degree of fimbriation (by varying the number of fimbriae attached to the cells), and showed that the ability of cells to adhere gradually decreases as the degree of fimbriation is decreased.…”

Hydrodynamic Interaction Enhances Colonization of Sinking Nutrient Sources by Motile Microorganisms

“…We performed simulations like those discussed before, for rising oil drops and found that the amplification is practically non-existent, irrespective of bacteria being chemotactic or non-chemotactic. Therefore, bacteria must attach onto the rising oil drops via interfacial phenomena other than near-surface hydrodynamics, possibly via adsorption after a random encounter (Vaccari et al, 2017; Dewangan and Conrad, 2018; McLay et al, 2018). However, surfactant addition breaks down larger oil drops into droplets ranging from 20-60 μm in diameter (Atlas and Hazen, 2011), which are almost neutrally buoyant and get trapped in sub-surface hydrocarbon plumes (Camilli et al, 2010; Ryerson et al, 2012) or pycnoclines (Paris et al, 2012).…”

Thermodynamic Surface Analyses to Inform Biofilm Resistance

“…For example, the surface protein SdrC of S. aureus has been shown to use Ca 2+ -mediated chelation of the N2 domains as a primary contributor to biofilm formation; the use of a metal salt associated with the substrate may disrupt the aforementioned chelation illustrating how metal salts effectively inhibit biofilm formation (Pi et al, 2020). To further illustrate the diversity in the adhesion process, McLay et al were able to genetically alter Escherichia coli to demonstrate that the amount of fimbriation contributes to adhesion of the bacterium (McLay et al, 2018). The concentration dependence of adhesion is probably a kinetic effect unique to each bacterium.…”

“…The parallel alignment is likely thermodynamically driven, whereas non-parallel alignment is kinetically controlled. The kinetic (i.e., dynamic) component has been modeled using complex algorithms and applied theories to describe bacterial attachment (Conrad and Poling-Skutvik, 2018;McLay et al, 2018;Vissers et al, 2019).…”