Sulfate-reducing Bacteria Biofilm Research Articles

Synthesis and synergistic effects of antibacterial and corrosion inhibition based on concentrated hydrosols of silver nanoparticles

A highly water-soluble and uniformly dispersed concentrate of silver nanoparticles (Ag NPs) hydrosols were synthesized using a chemical reduction method. The Ag NPs hydrosols exhibited remarkable antibacterial activity against sulfate-reducing bacteria (SRB) and can serve as a biocide for anti-corrosion purposes. The addition of 50 ppm Ag NPs hydrosols reduced the corrosion rate by over 91 % in the presence of SRB biofilm compared to untreated conditions. Numerous Ag NPs adsorbed onto the cell wall, with some internalizing and entering the cell, resulting in cytoplasmic efflux and DNA damage, ultimately leading to cell death.

Synergistic addition of Cu and Ce enhanced sulfate reducing bacteria-assisted corrosion cracking resistance of 2205 duplex stainless steel

The corrosion behaviors of 2205, 2205-Cu, and 2205-Cu-Ce duplex stainless steels (DSSs) were studied under static load in the presence of sulfate-reducing bacteria (SRB). The results demonstrated that the addition of Cu and Ce effectively enhanced the resistance of 2205 DSS to SRB-assisted cracking, and 2205-Cu-Ce DSS exhibited the best corrosion resistance and mechanical properties. The Synergistic addition of Cu and Ce not only inhibited the formation of SRB biofilm but also enhanced the hydrogen-induced cracking resistance of DSSs due to the hydrogen trapping by Cu-rich precipitates.

Gas liquid-carried flow accelerates MIC by sulfate reducing bacteria biofilm

The corrosion and perforation leakage of shale gas pipelines can lead to serious environmental damage. By tracking the water and gas components throughout the shale gas production cycle, the main factors that affect corrosion in shale gas pipelines have been identified: carbon dioxide, dissolved oxygen, sulfate-reducing bacteria, and chloride ions. The study focused on understanding the development mechanism of localized corrosion of L360N steel within the upward shale gas gathering pipeline, particularly under the combined influence of sulfate-reducing bacteria and flowing conditions. SRB could form a biofilm on the surface of the steel. Through the Dissimilatory Sulfate Reduction (DSR) process, the metabolites reacted with Fe2+ to produce FeS. The corrosion rate of L360N steel was observed to be higher when exposed to gas-liquid flow compared to static conditions. In the flowing state, the boundary layer within the upward pipeline exhibited backflow tendencies, causing a portion of the corrosion products and biofilm to peel off. This exposure revealed a local surface, acting as an anode. As a result, corrosion pits were further deepened due to microscopic eddy currents, indicating that zero net liquid flow accelerated the corrosion process.

Study on the evolution process of corrosion behavior under the sulfate reducing bacteria biofilm in shale gas gathering pipelines

Pipeline corrosion induced by sulfate-reducing bacteria (SRB) is particularly severe during the hydraulic fracturing technology in shale gas exploitation. To investigate the evolution of corrosion beneath the SRB biofilms, 49-day corrosion experiments were performed with and without SRB. The weight loss experiment demonstrated that the corrosion in the Blank group was mitigated by the corrosion product film. In contrast, the SRB group exhibited an initial inhibitory phase followed by an exacerbation. Scanning electron microscopy (SEM) revealed stratification in the Blank group, whereas SRB initially formed colonies and extracellular polymeric substances (EPS), eventually the biofilm evolved into a mixed layer with the corrosion product. 3D microscopy showed a relatively flat surface in the Blank group. Conversely, corrosion pits beneath SRB biofilm were circular and could reach a depth of 29.77 μm, significantly greater than in the Blank group. Over time, SRB-induced pits deepened from the edges to the center and widened to approximately 740 μm, accompanied by an increase in quantity. Energy Dispersive Spectrometer (EDS) and X-ray photoelectron spectroscopy (XPS) analyses detected the presence of elements P, S, and FeS in the SRB group, serving as important indicators of SRB corrosion. Electrochemical experiments revealed significantly higher corrosion currents in the SRB group. The evolution of SRB corrosion consisted of three phases: initial, intermediate, and starvation phases. During the starvation phase, localized corrosion proved to be the most severe, with a corrosion rate of 1.28 mm/a. Therefore, the study of SRB-induced corrosion should be prioritized to study the localization phenomena.

Corrosion inhibition study of marine Streptomyces against sulfate-reducing bacteria in oilfield produced water

A marine Streptomyces sp., which has an inhibitory effect on sulfate-reducing bacteria (SRB), was selected to study inhibitory effect and mechanism of X65 steel on SRB corrosion in oilfield produced water. Streptomyces and SRB had a competitive growth relationship. The Streptomyces metabolites affected the number and activity of SRB and had good corrosion inhibiting properties. The formation and development of SRB biofilm was inhibited. Mixed bacteria inhibited anodic dissolution of X65 steel and slowed down the electrochemical reaction rate. The film layer on the sample was denser, and the average and localized corrosion rates caused by SRB were significantly suppressed.

Nondestructive, reagent-free, low-volume fluidic set-up to study biofilms by using a transparent electrode, allowing simultaneous electrochemical and optical measurements.

The aim was to develop an electrochemical/optical set-up and correlate it (as validation) with other chemical and physical methods to obtain a simple and cost-effective system to study biofilm formation. A simple microfluidic cell and methods allowed continuous monitoring of the first, critical steps of microbial attachment. We monitored sulfate-reducing bacteria (SRB) at the early stages of biofilm formation. Herein, we studied the formation and adherence of SRB consortium biofilms over an indium tin oxide (ITO) conducting surface using microbiological and chemical methods, microscopic observations [scanning electron microscopy (SEM) and optical], and electrochemical impedance spectroscopy (EIS) measurements. The SRB biofilm formation was evaluated for 30 d by SEM and EIS. Charge transfer resistance decreased when the microbial population colonized the electrode. The monitoring of early-stage biofilm formation was performed using EIS at a single frequency of 1Hz during the first 36 h. The simultaneous use of optical, analytical, and microbiological methods allowed us to connect the kinetics of the growth of the microbial consortium to the values obtained via the electrochemical technique. The simple setup we present here can help laboratories with limited resources to study biofilm attachment and facilitates the development of various strategies to control biofilm development in order to avoid damage to metallic structures (microbiologically influenced corrosion, MIC) or the colonization of other industrial structures and medical devices.

“Electrons-siphoning” of sulfate reducing bacteria biofilm induced sharp depletion of Al­-Zn-­In­-Mg-­Si sacrificial anode in the galvanic corrosion coupled with carbon steel

The microbiologically influenced corrosion (MIC) of Al­-Zn-­In­-Mg­-Si sacrificial anode coupled with X80 carbon steel induced by sulfate reducing bacteria (SRB) was investigated. Results revealed that SRB strongly promoted the galvanic current density between the aluminum anode and carbon steel by facilitating the cathodic process of the galvanic corrosion on carbon steel. In the medium with SRB, 73.7% of the corrosion loss of aluminum anode coupled to carbon steel was caused by the enhanced galvanic corrosion. SRB biofilm on the carbon steel continuously obtained electrons from the aluminum anode, which was like an “electrons-siphoning” process in the galvanic corrosion.

Biofilm formation by sulphate-reducing bacteria on different metals and their prospective role in titanium corrosion

ABSTRACT This study describes the biofilm formation by sulphate-reducing bacteria (SRB) on different materials, which has implications for the biomedical, pharmaceutical, food and chemical process industries. SRB was chosen as a model organism being an anaerobic bacterium. Biofilm formation on different materials and corrosion of titanium by SRB were monitored with time using confocal laser scanning microscopy and fluorescent FISH probes were used to authenticate the SRB strain. The thickness of the mono-culture SRB biofilm has ranged from 4 to 24 µm during thed 12–84 hr; however, the maximum biofilm thickness (24 µm) was recorded after 60 hr of growth. Planktonic growth of the SRB strain showed a log phase up to 48 hr and the sulphide production ranged from 2 to 14 mg l−1. For a comparative account, the SRB biofilm formation on copper was chosen as a positive control. Finally, the putative role of extracellular electron transfer by SRB in the biocorrosion process and the plausible mechanism of pitting corrosion of titanium is described in detail.

Polyhexamethylene guanidine molybdate as an efficient antibacterial filler in epoxy coating for inhibiting sulfate reducing bacteria biofilm

Readily synthesized and highly antibacterial polyhexamethylene guanidine molybdate (PHMG-MoO4) can be used as a filler to greatly improve the resistance of epoxy coating to sulfate reducing bacteria (SRB) biofilm. In SRB inoculated medium, no SRB biofilm formed on PHMG-MoO4/epoxy coating after 120 days, and the corrosion current density of the epoxy coating painted carbon steel decreased by 99.0 % after addition of PHMG-MoO4 in the coating. There were also fewer fouling organisms on PHMG-MoO4/epoxy coating after 4 months of immersion in the actual seawater. The PHMG-MoO4 with low water solubility can remain in epoxy coating for a long time and therefore effectively and continuously inhibited the bacteria on the coating.

Quaternary ammonium salt-based cross-linked micelle with copper nanoparticles for treatment of sulfate reducing bacteria biofilm

Sulfate reducing bacteria (SRB) biofilm was the main cause of metal corrosion. However, at present, most antibacterial agents could only effectively kill SRB bacteria, but had nothing to do with its biofilm, as they could hardly penetrate extracellular polymeric substance on the surface of biofilm. Herein, we reported a novel quaternary ammonium salt-based cross-linked micelle with copper nanoparticles (Cu@QAS@CM nanoparticle) for removing SRB biofilm to resist metal corrosion. The Cu@QAS@CM nanoparticle could effectively adsorb on the surface of SRB biofilm because of its positive electricity, then penetrate and diffuse into whole biofilm in the form of nanoparticles. After entering the biofilm, the Cu@QAS@CM nanoparticle was dissociated into Cu and QAS fragments in the acidic environment inside the SRB biofilm due to its pH responsiveness. The QAS fragments could efficiently kill the living bacteria in the SRB biofilm, while copper can affect the mass transfer process of the biofilm, which can synergistically and efficiently remove the SRB biofilm. Hence, the Cu@QAS@CM nanoparticle holds great potential in replacement of traditional antibiotics to treat treating corrosion persistent infection cause by biofilms.

The inhibition of sulfate reducing bacteria adhesion and corrosion on the carbon steel surface using ZnO particles

Sulfate reducing bacteria (SRB) can adhere to the internal surface of the pipelines to form a biofilm under which a serious localized corrosion could easily occur. Therefore, the reduction of the adhesion of SRB biofilm and the inhibition of SRB corrosion are highly significant for the safety of oil and gas production. In this work, two types of zinc oxide (ZnO) particles, the unmodified ZnO particles with smaller specific surface area and the modified one with a larger specific surface area, were employed to inactivate SRB in the test solution. The results show that the sterilization rates of modified ZnO particles are much higher than the unmodified ZnO particles. This can be attributed to the fact that the modified ZnO particles with larger specific surface areas result in the generation of more Zn2+ which limits the growth of SRB. As a result, the adhesion of biofilm on the specimen surface and the corrosion under the biofilm are effectively inhibited.

Gene Sets and Mechanisms of Sulfate-Reducing Bacteria Biofilm Formation and Quorum Sensing With Impact on Corrosion.

Sulfate-reducing bacteria (SRB) have a unique ability to respire under anaerobic conditions using sulfate as a terminal electron acceptor, reducing it to hydrogen sulfide. SRB thrives in many natural environments (freshwater sediments and salty marshes), deep subsurface environments (oil wells and hydrothermal vents), and processing facilities in an industrial setting. Owing to their ability to alter the physicochemical properties of underlying metals, SRB can induce fouling, corrosion, and pipeline clogging challenges. Indigenous SRB causes oil souring and associated product loss and, subsequently, the abandonment of impacted oil wells. The sessile cells in biofilms are 1,000 times more resistant to biocides and induce 100-fold greater corrosion than their planktonic counterparts. To effectively combat the challenges posed by SRB, it is essential to understand their molecular mechanisms of biofilm formation and corrosion. Here, we examine the critical genes involved in biofilm formation and microbiologically influenced corrosion and categorize them into various functional categories. The current effort also discusses chemical and biological methods for controlling the SRB biofilms. Finally, we highlight the importance of surface engineering approaches for controlling biofilm formation on underlying metal surfaces.

Screening the growth inhibition mechanism of sulfate reducing bacteria by chitosan/lignosulfonate nanocomposite (CS@LS) in seawater media

Sulfate-reducing bacteria (SRBs) induced biofilm formation is a global industrial concern due to its role in the development of microbial-induced corrosion (MIC). Herein, we have developed a biodegradable chitosan/lignosulfonate nanocomposite (CS@LS) as an efficient green biocide for the inhibition of SRBs biofilms. We investigated in detail the inhibition mechanism of SRBs by CS@LS in seawater media. Stable CS@LS-1:1 with 150–200 nm average size, and zeta potential of + 34.25 mV was synthesized. The biocidal performance of CS@LS was evaluated by sulfate reduction profiles coupled with analysis of extracted extracellular polymeric substances (EPS) and lactate dehydrogenase (LDH) release assays. As the nanocomposite concentration was increased from 50 to 500 µg/mL, the specific sulfate reduction rate (SSRR) decreased from 0.278 to 0.036 g-sulfate/g-VSS*day showing a relative sulfate reduction inhibition of 86.64% as compared to that of control. Similarly, the specific organic uptake rate (SOUR) decreased from 0.082 to 0.039 0.036 g-TOC/g-VSS*day giving a relative co-substrate oxidation inhibition of 52.19% as compared to that of control. The SRBs spiked with 500 µg/mL CS@LS showed a reduction in cell viability to 1.5 × 106 MPN/mL. To assess the biosafety of the nanocomposite on the marine biota, the 72-hours acute toxicity assays using zebrafish embryo model revealed that the LC50 for the CS@LS was 103.3 µg/mL. Thus, CS@LS can be classified as environment friendly. The nanocomposite showed long-term stability and excellent antibacterial properties against SRBs growth and is thus potentially useful for combating the problems of biofilm growth in harsh marine and aquatic environments.

Exogenous autoinducer-2 inhibits biofilm development of Desulfovibrio sp. Huiquan2017.

Sulfate-reducing bacteria (SRB) are culprits for microbiologically influenced corrosion, and biofilms are believed to play essential roles in the corrosion induced by SRB. However, little is known about the regulation of SRB biofilms. Quorum sensing signal molecules acyl-homoserine lactones (AHLs) and autoinducer-2 (AI-2) regulate biofilm formation of many bacteria. In this study, the production of AHLs and AI-2 by one SRB strain, Desulfovibrio sp. Huiquan2017, was detected, and the effect of exogenous AI-2 on bacterial biofilm formation was discussed. It was found that the cell-free supernatants of Desulfovibrio sp. Huiquan2017 induced luminescence in a ∆luxS mutant strain Vibrio harveyi BB170, indicating the production of functional AI-2 by the bacterium. In the presence of exogenous AI-2, the growth of Desulfovibrio sp. Huiquan2017 and early biofilm formation were not affected, but the later stage of biofilm development was inhibited significantly. The biofilms became looser, smaller, and thinner, and contained less bacteria and extracellular polymeric substances (EPS). The inhibition effect of AI-2 on the biofilm development of Desulfovibrio sp. Huiquan2017 was mainly achieved through reducing the amount of EPS in biofilms. These findings shed light on the biofilm regulation of SRB.

Effect of Sulfate-Reducing Bacteria (SRB) on the Corrosion of Buried Pipe Steel in Acidic Soil Solution

The influence of sulfate-reducing bacteria (SRB) on the corrosion behaviors of X80 pipeline steel was investigated in a soil environment by electrochemical techniques and surface analysis. It was found that SRB grew well in the acidic soil environment and further attached to the coupon surface, resulting in microbiologically influenced corrosion (MIC) of the steel. The corrosion process of X80 steel was significantly affected by the SRB biofilm on the steel surface. Steel corrosion was inhibited by the highly bioactive SRB biofilm at the early stage of the experiment, while SRB can accelerate the corrosion of steel at the later stage of the experiment. The steel surface suffered severe pitting corrosion in the SRB-containing soil solution.

Synergistic effect of carbon starvation and exogenous redox mediators on corrosion of X70 pipeline steel induced by Desulfovibrio singaporenus

In microbiologically influenced corrosion (MIC) induced by sulfate-reducing bacteria (SRB), the electrons released from iron were transferred via extracellular electron transfer (EET) to the inner cells. Electron mediators and carbon starvation have also been found to promote steel corrosion. This study aimed to investigate the synergistic effects of electron mediators and carbon starvation on MIC and their effect on biofilm catalytic activity. The results demonstrated that the weight losses of X70 steel were 0.68 and 1.03 mg/cm2 in 100% and 10% carbon source (CS) SRB solution, respectively. The addition of riboflavin and cytochrome c increased the corrosion rate by 1.76 and 1.87 times, respectively, in the 100% CS SRB medium compared to the medium without exogenous redox mediators. For the 10% CS SRB medium, the corrosion rate increased by 1.40 and 1.89 times, respectively, when riboflavin and cytochrome c were added. The addition of riboflavin and cytochrome c also enhanced the biocatalytic activity of the SRB biofilm in both the 100% and 10% CS SRB media.

Effects of silver nanoparticles added into polyurea coating on sulfate-reducing bacteria activity and electrochemical properties; an environmental nano-biotechnology investigation

In the present work, Ag nanoparticles were added to polyurea coating in order to improve its antibacterial and electrochemical properties in sulfide-reducing bacteria-containing media. To this end, Ag nano-powder was mixed with two component polyuria, and then the antibacterial behavior of the nanocomposite coating was studied in sulfate-reducing bacteria (SRB)-containing medium. The results revealed the inhibitory effects of nanocomposite coating on the formation of SRB biofilms on the samples. Moreover, the SRB population decreased in contact with the Ag nanoparticles-mixed coating over 7 days. Investigation of the growth and activity of the bacteria represented the effective antibacterial properties of Ag nanoparticles in the polyurea matrix. Furthermore, EIS (electrochemical impedance spectroscopy) measurements indicated that the corrosion properties of the nanocomposite coating improved considerably over 7 days. The coating resistance increased 2 times by adding Ag nanoparticles after 1 day and 3.3 times after 7 days. In accordance with the same results, the charge transfer resistance increased 1.5 times and 1.1 times by adding Ag nanoparticles after 1 day and 7 days, respectively. The improvement in the protective properties of the nanocomposite coating are reflected in the increase in both film and charge transfer resistance.

Specificity of Lectins Labeled with Colloidal Gold to the Exopolymeric Matrix Carbohydrates of the Sulfate-Reducing Bacteria Biofilm Formed on Steel

The studies of the carbohydrate composition of the sulfate-reducing bacteria (SRB) biofilms formed on the steel surface, which are a factor of microbial corrosion, are significant. Since exopolymers synthesized by bacteria could activate corrosive processes. The aim of the study was to investigate the specificity of commercial lectins, labeled with colloidal gold to carbohydrates in the biofilm exopolymeric matrix produced by the corrosive-relevant SRB strains from man-caused ecotopes. Methods. Microbiological methods (obtaining of the SRB biofilms during cultivation in liquid Postgate B media under microaerophilic conditions), biochemical methods (lectin-binding analysis of 10 commercial lectins, labeled with colloidal gold), transmission electron microscopy using JEM-1400 JEOL. Results. It was shown using transmission electron microscopy that the binding of lectins with carbohydrates in the biofilm of the studied SRB strains occurred directly in the exopolymerіс matrix, as well as on the surfaces of bacterial cells, as seen by the presence of colloidal gold particles. For detection of the neutral carbohydrates (D-glucose and D-mannose) in the biofilm of almost all studied bacterial strains PSA lectin was the most specific. This lectin binding in biofilms of Desulfotomaculum sp. К1/3 and Desulfovibrio sp. 10 strains was higher in 90.8% and 94.4%, respectively, then for ConA lectin. The presence of fucose in the SRB biofilms was detected using LABA lectin, that showed specificity to the biofilm EPS of all the studied strains. LBA lectin was the most specific to N-аcetyl-D-galactosamine for determination of amino sugars in the biofilm. The amount of this lectin binding in D. vulgaris DSM644 biofilm was 30.3, 10.1 and 9.3 times higher than SBA, SNA and PNA lectins, respectively. STA, LVA and WGA lectins were used to detect the N-acetyl-Dglucosamine and sialic acid in the biofilm. WGA lectin showed specificity to N-acetyl-D-glucosamine in the biofilm of all the studied SRB; maximum number of bounded colloidal gold particles (175 particles/μm2) was found in the Desulfotomaculum sp. TC3 biofilm. STA lectin was interacted most actively with N-acetyl-D-glucosamine in Desulfotomaculum sp. TC3 and Desulfomicrobium sp. TC4 biofilms. The number of bounded colloidal gold particles was in 9.2 and 7.4 times higher, respectively, than using LVA lectin. The lowest binding of colloidal gold particles was observed for LVA lectin. Conclusions. It was identified the individual specificity of the 10 commercial lectins to the carbohydrates of biofilm matrix on the steel surface, produced by SRB. It was estimated that lectins with identical carbohydrates specificity had variation in binding to the biofilm carbohydrates of different SRB strains. Establishing of the lectin range selected for each culture lead to the reduction of the scope of studies and labor time in the researching of the peculiarities of exopolymeric matrix composition of biofilms formed by corrosiverelevant SRB.

Microdefects of Biocorroded Pipe Steel Surfaces and Safety Assessment of Localized Stress Concentrators

The effect of sulfate-reducing bacteria (SRB) on the corrosion of steel 20 was investigated. Results demonstrated that the chemical composition of corrosion products, the corrosion rate, and corrosion type were altered due to the adherence of SRB and the subsequent formation of biofilm on the steel 20 surface. The micromechanisms of biocorrosion damage of specimens from pipe steel 20 were quantified on the basis of the microgeometry of the degraded surface and the localization parameters of corrosive stress microconcentrators. Stress concentrators in the vicinity of the micro-cuts, which are the depths of the profilograms, make it possible to evaluate safe (allowable) microcorrosion damage. The proposed approach complements the well-known methods for monitoring biodeterioration of pipe steels. With its help, it was found that a decrease in the corrosion rate of specimens with the addition of an inhibitor does not always clearly indicate its effectiveness. The case where the introduction of an inhibitor led to the destruction of the SRB biofilm on the surface of specimens from steel 20, but caused the activation of local corrosion processes and the formation of a more developed microrelief, is considered. The hollows of such microrelief are potential places of origin of defects, which require additional control.

Mitigation of sulphate-reducing bacteria attack on the corrosion of 20SiMn steel rebar in sulphoaluminate concrete using organic silicon quaternary ammonium salt

This research was carried out to evaluate the effect of sulphate-reducing bacteria (SRB) on the corrosion of reinforced concrete (RC) using sulphoaluminate cement and also to proffer mitigation measure for reducing the adverse effect of SRB by adopting organic silicon quaternary ammonium salt (OSA) as a bacteriostatic agent. Three different systems were employed for this study: RC with sterilized NaCl (CS), RC with sterilized NaCl and SRB (CS-1), and RC with sterilized NaCl, SRB and OSA (CS-2). The 28 days SRB biofilm growth showed optimized number of sessile cells in the early immersion periods but reduced with extending the time. Consequently, the sessile cells induced the breakdown of the passive film through metabolic reactions of SRB. The corrosion resistance of rebar in different systems reflected by surface morphologies and electrochemical analysis follows the order of CS > CS-2 > CS-1. The proposed mitigation mechanism shows that the silicate component of the OSA adheres on steel surface to prevent the formation of biofilm while the ammonium component adsorbs on SRB cells changing the permeability of bacteria cell wall, reduces the metabolic activities of SRB leading to its death. This implies that OSA played a vital role in reducing the optimized growth of SRB and thus enhances the corrosion resistance of the rebar in concrete.