Marine Biofilms with Significant Corrosion Inhibition Performance by Secreting Extracellular Polymeric Substances

Abstract

The development of environmentally friendly and sustainable corrosion protection technologies is a longstanding yet difficult problem, especially for the marine environment. The utilization of living biofilms isolated from local environments is an effective strategy for infrastructure protection. In this study, three aerobic marine bacteria, Tenacibaculum mesophilum D-6, Tenacibaculum litoreum W-4, and Bacillus sp. Y-6, with strong biofilm-forming abilities were isolated and evaluated for the corrosion protection of X80 carbon steel. The corrosion inhibitory effect of the bacteria was found to be closely related to their biofilm-forming abilities. This conclusion was corroborated by biofilm characterization, electrochemical tests, weight loss analysis, and corrosion product analysis. Moreover, secreted extracellular polymeric substances were identified to play significant roles in corrosion inhibition. Herein, we proposed a novel, eco-friendly, and cost-effective method for corrosion protection of carbon steels in the marine environment, providing guiding principles for identifying corrosion inhibitory bacteria from the local marine environment.

Extracellular Polymeric Substances and Biocorrosion/Biofouling: Recent Advances and Future Perspectives

“…EPS can adsorb on the metal surface and form a biofilm, which acts as a protective layer, hinders the transmission of oxygen, and separates a metal surface from a corrosive environment, thus, metal corrosion is inhibited [ 53 , 54 , 124 , 125 , 126 , 127 ]. The negatively charged functional groups in EPS, such as -NH 2 , -COOH, -C-O-C, and -OH, first adsorb positively charged metal ions to form complexes.…”

Roles of Microbial Extracellular Polymeric Substances in Corrosion and Scale Inhibition of Circulating Cooling Water

“…megaterium biofilm was found to inhibit stainless steel corrosion . It is well known that EPS accounts for ∼90% of the biofilm; therefore, it is necessary to explore the effect of EPS on the corrosion and scale inhibition process . It has been reported that some Gram-positive bacteria with EPS had significant potential for corrosion and scale inhibition .…”

“…15 Several researchers have reported that some Gram-negative bacteria such as Tenacibaculum spp. 18 and Pseudomonas spp., 11 and Gram-positive bacteria such as Bacillus spp., 19 could secrete EPS with the ability of corrosion and scale inhibition. Among these, the Gram-negative bacteria Pseudomonas spp.…”

Ion Depletion in the Interfacial Microenvironment from Cell–Surface Interactions

“…50,51 Various mechanisms have been proposed to account for this effect, such as the depletion of oxygen through microbial metabolism and the production of metabolites that are themselves corrosion inhibitors. 52 As chloride ions are the primary agents responsible for pitting, 51 a reduction in the interfacial ionic strength provides an additional mechanism by which EPS can contribute to corrosion inhibition. Enhanced understanding of the aqueous surface microenvironment is therefore important for the development of targeted corrosion inhibition strategies involving EPS and synthetic polyelectrolytes.…”

“…Such findings are of direct interest to the study of microbial-induced corrosion inhibition that has been attributed to EPS accumulation. , Various mechanisms have been proposed to account for this effect, such as the depletion of oxygen through microbial metabolism and the production of metabolites that are themselves corrosion inhibitors . As chloride ions are the primary agents responsible for pitting, a reduction in the interfacial ionic strength provides an additional mechanism by which EPS can contribute to corrosion inhibition.…”