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The use of Cistus ladanifer methanolic extract as a 304L stainless steel (304L SS) corrosion inhibitor in 1 M HCl solution was investigated using weight loss measurements and electrochemical tests. The data showed that C. ladanifer extract inhibited 304L SS corrosion, with an inhibition efficiency of 97.8%. The chemical composition of the extract was determined by Fourier-transform infrared spectroscopy. Results confirmed the presence of several functional groups in this extract. The effect of temperature on extract efficiency and thermodynamic parameters was studied. The adsorption of the extract on 304L SS surface obeyed Langmuir adsorption isotherm. Furthermore, the extract effects on 304L SS physicochemical properties, including hydrophobicity and acid–base properties, were investigated using contact angle measurements. The results showed that the treated coupon surfaces became hydrophilic and predominantly electron-donating. Finally, the surface morphologies of 304L SS coupons, in both the absence and presence of C. ladanifer extract, in HCl solution were observed using scanning electron microscopy.

Nanowires have substantial potential as the sensor component in electronic sensing devices. However, surface functionalization of traditional nanowire and nanotube materials with short peptides that increase sensor selectivity and sensitivity requires complex chemistries with toxic reagents. In contrast, microorganisms can assemble pilin monomers into protein nanowires with intrinsic conductivity from renewable feedstocks, yielding an electronic material that is robust and stable in applications, but also biodegradable. Here we report that the sensitivity and selectivity of protein nanowire-based sensors can be modified with a simple plug and play genetic approach in which a short peptide sequence, designed to bind the analyte of interest, is incorporated into the pilin protein that is microbially assembled into nanowires. We employed a scalableEscherichia colichassis to fabricate protein nanowires that displayed either a peptide previously demonstrated to effectively bind ammonia, or a peptide known to bind acetic acid. Sensors comprised of thin films of the nanowires amended with the ammonia-specific peptide had a ca. 100-fold greater response to ammonia than sensors made with unmodified protein nanowires. Protein nanowires with the peptide that binds acetic acid yielded a 4-fold higher response than nanowires without the peptide. The results demonstrate that protein nanowires with enhanced sensor response for analytes of interest can be fabricated with a flexible genetic strategy that sustainably eliminates the energy, environmental, and health concerns associated with other common nanomaterials.

Algae are reported to be corrosive, while little is known about the role of the algae associated bacteria in the corrosion process. In the present study, Halomonas titanicae was isolated from a culture of an alga strain, Spirulina platensis, and identified through 16S rRNA gene analysis. Corrosion behavior of 304L stainless steel (SS) coupons in the presence and absence of H. titanicae was characterized by using electrochemical measurements and surface analysis. The results showed that H. titanicae significantly accelerated the corrosion rate and decreased the pitting potential of 304L SS in the biotic medium. After removal of the corrosion products and biofilms, severe pitting corrosion caused by H. titanicae was observed. The largest pit depth after 14 d reached 6.6 μm, which was 5.5 times higher than that of the sterile control (1.2 μm). This is the first report revealing that an alga associated bacterium can induce microbiologically influenced corrosion (MIC), and a further concern is raised that whether algae play a role in the MIC process.

In nature, microbiologically influenced corrosion (MIC) is often caused by multi-species biofilms rather than single-species biofilms. In this work, the MIC of 316L stainless steel (SS) was investigated in the presence of individual and mixed consortium biofilms of Shewanella oneidensis and Bacillus licheniformis through electrochemical and surface characterizations. Results revealed that MIC of 316L SS was significantly accelerated by the biofilm consortium of S. oneidensis and B. licheniformis compared to single-species biofilms. It was found that the electron shuttle riboflavin secreted by S. oneidensis was utilized by B. licheniformis to accelerate the MIC of 316L SS, providing a new insight into multi-species microbial collaborations in extracellular electron transfer (EET)-MIC.

The mitigation of microbiologically influenced corrosion (MIC) of 304L stainless steel (SS) against Pseudomonas aeruginosa by a Salvia officinalis extract was investigated using electrochemical and surface analysis techniques. The extract was characterized by HPLC-Q-TOF-MS and its antibiofilm property was evaluated. The data revealed the presence of well-known antimicrobial and anticorrosion compounds in the extract. The S. officinalis extract was found effective in preventing biofilm formation and inhibiting mature biofilm. Electrochemical results indicated that P. aeruginosa accelerated the MIC of 304L SS, while the extract was found to prevent the MIC with an inhibition efficiency of 97.5 ± 1.5%. This was attributed to the formation of a protective film by the adsorption of some compounds from the extract on the 304L SS surface.

Catechin hydrate (CH) was evaluated for its antimicrobial, antibiofilm and anticorrosion activities for 304L stainless steel against Pseudomonas aeruginosa by means of surface analysis, electrochemical measurements and quantum chemical calculations. Results showed that CH inhibited the P. aeruginosa biofilm formation and killed mature biofilms. Electrochemical data demonstrated that CH inhibited the corrosion induced by P. aeruginosa with an excellent inhibition efficiency of 99.8%. It was also found that CH significantly downregulated the expressions of critical genes for quorum sensing and biofilm formation as revealed by qPCR data. In vitro cytotoxicity assay showed that CH was non-toxic to MC3T3-E1 cells.

In the present study, a novel bacterium (Marinobacter aquaeolei) was examined for its corrosion inhibiting behaviour against X80 pipeline steel. Electrochemical results showed that X80 steel immersed in the solution inoculated with M. aquaeolei possessed very high corrosion resistance compared to that of abiotic control. Besides, scanning electron microscopy, confocal laser scanning microscopy and energy-dispersive X-ray spectroscopy were employed to analyse the corrosion product and the biofilm formed on the metal surface. Fourier-transform infrared spectroscopy was also applied to determine the composition of extracellular polymeric substances (EPS). Above results indicated that the corrosion inhibition efficiency observed in biotic medium was very high (91%), proving that M. aquaeolei was an effective inhibitive agent for the corrosion of carbon steel. The inhibition was credited to the formation of bacterial biofilm and the compact protective layer of the secreted EPS. Thus, this study will introduce a natural, environmentally friendly and cost-effective system for the corrosion control of the carbon steel.

Microbially catalyzed corrosion of metals is a substantial economic concern. Aerobic microbes primarily enhance Fe

Number: 1 Publisher: Multidisciplinary Digital Publishing Institute; Pectobacterium brasiliense (Pbr) is considered as one of the most virulent species among the Pectobacteriaceae. This species has a broad host range within horticulture crops and is well distributed elsewhere. It has been found to be pathogenic not only in the field causing blackleg and soft rot of potato, but it is also transmitted via storage causing soft rot of other vegetables. Genomic analysis and other cost-effective molecular detection methods such as a quantitative polymerase chain reaction (qPCR) are essential to investigate the ecology and pathogenesis of the Pbr. The lack of fast, field deployable point-of-care testing (POCT) methods, specific control strategies and current limited genomic knowledge make management of this species difficult. Thus far, no comprehensive review exists about Pbr, however there is an intense need to research the biology, detection, pathogenicity and management of Pbr, not only because of its fast distribution across Europe and other countries but also due to its increased survival to various climatic conditions. This review outlines the information available in peer-reviewed literature regarding host range, detection methods, genomics, geographical distribution, nomenclature and taxonomical evolution along with some of the possible management and control strategies. In summary, the conclusions and a further directions highlight the management of this species.

Microbially catalyzed corrosion of metals is a substantial economic concern. Aerobic microbes primarily enhance Fe0 oxidation through indirect mechanisms and their impact appears to be limited compared to anaerobic microbes. Several anaerobic mechanisms are known to accelerate Fe0 oxidation. Microbes can consume H2 abiotically generated from the oxidation of Fe0. Microbial H2 removal makes continued Fe0 oxidation more thermodynamically favorable. Extracellular hydrogenases further accelerate Fe0 oxidation. Organic electron shuttles such as flavins, phenazines, and possibly humic substances may replace H2 as the electron carrier between Fe0 and cells. Direct Fe0-to-microbe electron transfer is also possible. Which of these anaerobic mechanisms predominates in model pure culture isolates is typically poorly documented because of a lack of functional genetic studies. Microbial mechanisms for Fe0 oxidation may also apply to some other metals. An ultimate goal of microbial metal corrosion research is to develop molecular tools to diagnose the occurrence, mechanisms, and rates of metal corrosion to guide the implementation of the most effective mitigation strategies. A systems biology approach that includes innovative isolation and characterization methods, as well as functional genomic investigations, will be required in order to identify the diagnostic features to be gleaned from meta-omic analysis of corroding materials. A better understanding of microbial metal corrosion mechanisms is expected to lead to new corrosion mitigation strategies. The understanding of the corrosion microbiome is clearly in its infancy, but interdisciplinary electrochemical, microbiological, and molecular tools are available to make rapid progress in this field.

In nature, microbes tend to form synergistic biofilms on a wide range of materials using extracellular polymeric substances to embed sessile cells. Problematic biofilms provide environments conducive to the occurrence of microbiologically influenced corrosion (MIC) in many industries. MIC includes corrosion caused by microbes as well as corrosion by another pre-existing corrosion agent that is accelerated by microbes. There are several distinct types of MIC mechanisms associated with different microbial species and metabolism types. Biofilms employ different defense mechanisms to protect themselves from environmental hazards. This makes sessile cells in biofilms much more resistant to treatment than planktonic cells. Biofilms are often treated with biocides together with physical scrubbing. Various approaches have been developed to boost biocide efficacy. New emerging technologies such as bacterial phages, quorum sensing inhibitors, and special chemicals to enhance biocides have been proposed in recent years. This review evaluates these different treatment methods and various techniques used to assess biocide treatment outcome including microbiology, molecular biology, corrosion testing and electrochemical methods.

Microbiologically influenced corrosion (MIC) is a big threat to the strength and safety of many metallic materials used in different environments throughout the world. The metabolites and bioactivity of the microorganisms cause severe deterioration on the metals. In this study, MIC of pure titanium (Ti) was studied in the presence of a highly corrosive aerobic marine bacterium Pseudomonas aeruginosa. The results obtained from electrochemical test showed that Ti was corrosion resistant in the abiotic culture medium after 14 d, while the increased corrosion current density (icorr) obtained from polarization curves and the decreased charge transfer resistance (Rct) from electrochemical impedance spectroscopy (EIS) indicated the accelerated corrosion of Ti caused by P. aeruginosa biofilm. For further confirmation of the above results, the surface of Ti was investigated using scanning electron microscopy (SEM), confocal laser scanning microscopy (CLSM) and X-ray photoelectron spectroscopy (XPS). According to the XPS results, TiO2 was formed in both abiotic and biotic conditions, while unstable oxide Ti2O3 was detected in the presence of P. aeruginosa, leading to the defects in the passive film and localized corrosion. Pitting corrosion was investigated with the help of CLSM, and the largest pit depth found on Ti surface immersed in P. aeruginosa was 1.2 μm. Ti was not immune to MIC caused by P. aeruginosa.

In this study, the efficiency of Cistus ladanifer ethanolic extract to inhibit the corrosion of 304L stainless steel (SS) in the presence of Pseudomonas aeruginosa was evaluated using electrochemical measurements and surface analysis techniques. The plant extract was characterized by HPLC-Q-TOF-MS. Furthermore, the effect of this extract on the physicochemical properties of 304L SS coupon surfaces was determined by contact angle measurements. The obtained results indicated that P. aeruginosa formed biofilms on the 304L SS coupon surfaces which led to the acceleration of corrosion rate and damage of the surface in form of pitting corrosion with a maximum pit depth of 19.4 μm. Moreover, C. ladanifer extract inhibited the growth of P. aeruginosa planktonic cells and the biofilm formation on the 304L SS coupon surfaces. Also, the extract reduced the biocorrosion rate by approximately 99.36%. Many well-known antimicrobial and anti-corrosion compounds present in the extract were characterized, such as flavonoids, tannins, and phenolic acids, supporting the excellent anti-biofilm and anti-corrosion performances of C. ladanifer extract.

Bioenergetics can be used to analyze the theoretical voltage output of a microbial fuel cell (MFC) and the thermodynamic driving force in microbiologically influenced corrosion (MIC). MFCs involve both inward and outward extracellular electron transfer (EET), whereas only inward EET is behind EET–MIC caused by an electroactive biofilm's harvest of energy from a metal. EET is often rate-limiting, and it is an important process in microbial energy metabolism. EET is critical to the understanding of MFCs and EET–MIC bioelectrochemical processes. Many advances have been made in the past decade on EET by MFC and MIC researchers. Gene manipulations have been used to improve EET in MFCs, leading to enhanced energy output. They have also been used to elucidate the EET processes for better understanding of EET–MIC, which aids in MIC analysis and decision-making of biocide treatment and its efficacy assessment. Researchers are starting to integrate EET knowledge from both fields.

Biocorrosion by microbial biofilms is also termed microbiologically influenced corrosion (MIC). For many decades in MIC research, people focused on corrosive metabolites. In the past decade, researchers started to apply bioenergetics to MIC science research. They realized that extracellular oxidation of a metal can supply electrons for microbial respiration, which causes MIC. Because these electrons must be transported to the cytoplasm via extracellular electron transfer (EET), this kind of MIC is called EET-MIC, which is different from metabolite-MIC (M-MIC). Advances have been made to decipher inward EET involved in MIC. Carbon source starvation and electron mediator acceleration have been used to study impact of EET on MIC. More recently, manipulations of electron mediator-related genes have been used to elucidate EET in MIC. EET in energy metabolism in microbiology and EET for MIC are intertwined. Well-established corrosion research tools, especially electrochemical methods that are highly sensitive, are useful for microbiologists to study EET.

In this study, three samples of olive oil wastes: Olive Rinse Water (OR), Olive Mill Wastewater (OM) and Olive Pomace (OP), which were collected from an olive oil mill located at Fez-Morocco, were analyzed for their microbiota. A total of 81 isolates were obtained and constituted a microbial bank formed of 35 bacteria, 41 yeasts and 5 fungi. The microbial communities have been compared in term of metabolic potential by testing hydrolytic enzymes activities of lipase, protease, amylase, cellulase, pectinase and tannase on agar plate media. The results reveal that among the examined microorganisms, 68 isolates were able to produce at least one of the screened enzymes. The pectinase activity was the predominant one (39.51%), followed by cellulase activity (34.57%) and by lipase activity (27.16%). However, the amylase activity was observed only for 11.11% of the studied isolates, followed by protease activity (9.88%) and by tannase activity 6.17%. Thereby, considering the isolates ability to produce enzymes, they can be considered as potential candidates for industrial and biotechnological applications. Lipases are versatile enzymes that are used widely, it’s why the mostly aim of this work was to isolate new bacterial strains producing high level of lipases with interesting biochemical criteria. Thus, two isolates OR34 and OM2 showed the maximum lipase production under the standard conditions, about 9 U/ml and 11 U/ml, respectively, using pH-stat technique. They were identified as Proteus vulgaris and Serratia marcescens, respectively, via partial 16S rDNA gene sequence analysis.

Chlorhexidine (CHX) mouthwash is widely used clinically to remove the established Streptococcus mutans biofilm and prevent caries. However, the long-term use with high concentration of CHX leads to the staining of tooth and mucous membrane. In this study, d -leucine ( d -leu) was used as an antimicrobial enhancer for CHX against mature S. mutans biofilm. The biocidal efficacy was evaluated by means of quantitative antibacterial test and biofilm observation. The results indicated that 100 ppm d -leu alone was ineffective to remove the S. mutans biofilm. Moreover, the biocidal effect of 1 ppm CHX was also inadequate to eradicate the biofilm. When 100 ppm d -leu was mixed with 1 ppm CHX, most of the mature S. mutans biofilm on 316L stainless steel coupon surfaces were successfully removed, and the removal efficacy was equivalent to that of 10 ppm CHX alone. The results confirmed that d -leu significantly enhanced the antibiofilm effect of CHX, dissembling the tenacious biofilm into easily killed planktonic counterparts. d -leu represents a novel strategy to reduce the dosage of CHX with a guaranteed effect for caries prevention.

The microbiologically influenced corrosion (MIC) susceptibility of friction stir welded (FSW) S32654 super austenitic stainless steel (SASS) in the presence of acid producing bacterium Acidithiobacillus caldus SM-1 was investigated by surface analysis techniques and electrochemical measurements. The average depth of pits shown on the FSW coupon surface was 2.8 ± 0.5 μm after 14 days of immersion in A. caldus SM-1 broth, which was similar to that of the control base metal (BM) coupon (2.7 ± 0.6 μm). The results of electrochemical measurements showed that control BM and FSW coupons had very close corrosion rates in both abiotic and biotic media. The results indicated that the FSW process did not decrease the corrosion resistance of S32654 SASS. In addition, A. caldus SM-l significantly accelerated the general corrosion and pitting corrosion of control BM and FSW coupons. The lowest pH value of A. caldus SM-1 inoculated medium arrived at 1.81 ± 0.09 after 14 days of incubation. The acceleration of corrosion rate may be attributed to the generation and enrichment of aggressive acidic metabolites of A. caldus SM-l underneath the biofilm.