Effect of Nonphosphorus Corrosion Inhibitors on Biofilm Pore Structure and Mechanical Properties

Abstract

Understanding the effects of biofilm structural and mechanical properties, which can influence biofilm cohesiveness and detachment under physical stress, is critical for biofilm and biofilm-associated pathogen control. In this study, we used optical coherence tomography (OCT) and nanoindentation to determine the role of silicate and tin (two experimental nonphosphate corrosion inhibitors) on the porous structure and stiffness of three types of multispecies biofilms. These biofilms were grown from groundwater (a drinking water source), and this groundwater was amended with either tin or silicate corrosion inhibitor (0.5 mg/L as Sn and 20 mg/L as SiO2). Based on the elastic moduli of these biofilms, tin biofilms and groundwater biofilms were the stiffest, followed by silicate biofilms. The thickness normalized by the growth time for silicate biofilms was highest at 38 ± 7.1 μm/month, compared to 21 ± 3.2 and 11 ± 2.4 μm/month for tin biofilms and groundwater biofilms, respectively. The silicate biofilms had the greatest overall porosities and were thickest among the three biofilms. Based on the pore network modeling (PNM) of OCT images, larger pores and connections were found in the silicate biofilms compared to those in tin and groundwater biofilms. Our analysis showed that the thicker and more porous biofilms (silicate biofilms) were potentially less resistant to deformation than the thinner and denser biofilms (tin and groundwater biofilms).

Microbiologically influenced corrosion—more than just microorganisms

“…In some cases, they may even become ineffective (Dariva and Galio 2014 , Mand and Enning 2021 ) or act as a source of nutrients for bacterial growth (Edwards and McNeill 2002 , Fang et al 2009 ) Therefore, it is crucial to fill the knowledge gap regarding the mechanisms of action of corrosion inhibitors and bioactive agents, as well as their effects on the development and resistance of biofilms (Bridier et al 2011 , Bas et al 2017 , Kimbell et al 2020 , Tuck et al 2022 ). Despite progress over recent years, knowledge is still scarce and fragmented (Araújo et al 2014 , Huang et al 2020 , Silva et al 2021 , Lima et al 2022 ).…”

Texture-based speciation of otitis media-related bacterial biofilms from optical coherence tomography images using supervised classification.

“…Optical coherence tomography (OCT) is one such technique that provides label-free 2D cross-sectional images of samples and tissue. OCT has been widely used in the eye (retina) 11 and heart 12 for diagnostics and visualization, and for imaging biofilms to characterize biofilm growth, porosity, and mechanical properties 13 , 14 on both the bench 15 and in vivo 16 .…”