Biodamage of steel by Desulfovibrio oryzae under the influence of supernatant from cultures of Streptomyces gardneri and Bacillus velezensis (original) (raw)
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Influence of Desulfovibrio sp. biofilm on SAE 1018 carbon steel corrosion in synthetic marine medium
Corrosion Science, 2007
This work assessed the effect of an enriched culture medium and synthetic seawater on the growth and production of exopolymeric substances (EPS) of a Desulfovibrio sp. strain, isolated from a Mexican oil well. The EPS (mainly consisting of proteins) growth was only achieved after exposing sulfate-reducing bacteria to culture media under dissimilative conditions that predominantly promoted the growth of the biofilm and a small concentration of microorganisms. Once this EPS film was obtained, the evolution of SAE 1018 carbon steel/biofilm/synthetic seawater (VNNS medium) interface was further studied using electrochemical impedance spectroscopy technique (EIS). This study revealed strong adhesion of the biofilm during the formation of iron sulfide (pirrotite) on carbon steel surface. The biofilm inhibits the accelerated damage of the steel for some time exhibiting impedance values of 30 000 X. However, at longer times the chemical environment around the biofilm, as a result of microbial metabolism, may become quite corrosive to steel.
Desulfovibrio Vulgaris, a species of Sulphate Reducing Bacteria (SRB) that are mostly found living in the absence of oxygen or namely anaerobic condition is an imminent threat to pipeline long-term integrity. Pipeline infrastructure may experience severe metal loss due to corrosion induced by the species and can potentially lead to catastrophic failure. Desulfovibrio Vulgaris (ATCC7757) was cultured in broth number 1249 (Modified Barr's Medium) to study the effect of bacteria growth upon metal loss. The medium was modified to pH 7.0 at 37°C. Carbon steel coupons grade X70 were cut to approximately 10mmx20mmx5mm and kept in anaerobic vials. After 28 days of incubation, samples were retrieved to determine the weight loss of the carbon steel. Based on the weight loss graph pattern, the amount of weight loss significantly depends on the exposure time to the bacteria. The weight lost dramatically increases from day-1 to day-28 to signify the common pattern of corrosion induced by SRB.
Biocorrosion of Low Alloy Steel by Desulfotomaculum sp. and Effect of Biocides on Corrosion Control
ISIJ International, 2007
In this study corrosion behavior of low alloy steel was investigated in the presence of anaerobic sulfatereducing Desulfotomaculum sp. which was isolated from an oil production well. In order to determine corrosion rates, mass loss measurements were performed with and without bacteria in the culture medium. Scanning electron microscopic observations and energy dispersive X-ray spectra analysis were made on steel coupons. The influences of different concentrations of two biocides (formaldehyde and glutaraldehyde) on corrosion behavior and growth of Desulfotomaculum sp. were determined. Formaldehyde was found to be more potent under experimental conditions.
Microbiologically Influenced Corrosion of X-70 Carbon Steel by Desulfovibrio Vulgaris
Advanced Science Letters
Sulphate-reducing bacteria (SRB) as the main source of Microbiologically Influenced Corrosion (MIC) mechanism has a dominant influence upon localized corrosion problems especially for internal piping. In this paper, corrosion behavior of high-strength carbon steel (API 5L X-70) under anaerobic conditions in the presence of SRB's bacteria was studied in batch reactor. The coupons were exposed to the SRB culture for 1, 3, 6, 10, 20 and 30 days at 22 0 C and 37 0 C along with a control set. Corrosion rate in SRB medium at 37 0 C showed a higher dynamic value compared to medium inoculated at 22 o C. The corrosion rate of the carbon steel also showed no correlation with the planktonic or sessile SRB cell numbers.
Corrosion behavior of low-alloy steel in the presence of Desulfotomaculum sp.
Corrosion Science, 2009
The objective of this study was to determine the effect of sulfate-reducing Desulfotomaculum sp. bacteria isolated from a crude oil field on the corrosion of low-alloy steel. The corrosion rate and mechanism were determined with the use of Tafel slopes, mass loss method and electrochemical impedance spectroscopy (EIS). The formation of the biofilm and the corrosion products on the steel surface was determined with scanning electron microscopy (SEM) micrographs and energy dispersive X-ray spectra (EDS) analysis. It was observed from the Tafel plots that the corrosion potential exhibited a cathodic shift that verifies an increase in the corrosion rates. The semicircles tended to open at lower frequencies in the Nyquist plots which indicates the rupture of the protective film. The corrosion current density reached its maximum value at the 14th hour after the inoculation and decreased afterwards. This was attributed to the accumulation of corrosion products on the surface.
Effect of biofilm in the corrosion of austenitic stainless steels in wastewater treatment plants
The hydrogenotrophic sulfate-reducing bacterium (SRB) Desulfovibrio capillatus (DSM14982 T ) was isolated from an oil field separator with serious corrosion problems; this is the study of its role in the corrosion of carbon steels under anaerobic conditions. Immersion tests with two steel alloys, St-35.8 (typical carbon steel employed in European naval industry), and API-5XL52 (weathering alloy steel employed in Mexican oil industries) were performed. Total exposure was 45 days and different concentrations of thiosulfate as electron acceptor for bacterial growth were employed. The samples immersed in media with SRB undergo fast activation and numerous active sites form on the surface. Microscopic observations were made by environmental scanning electron microscopy (ESEM). Weight loss and electrochemical testing included open circuit potential (E corr ), polarization resistance (R p ), electrochemical impedance spectroscopy (EIS) and electrochemical noise (EN) were measured with and without bacteria in the culture medium in order to determine corrosion rates and 0010-938X/$ -see front matter Ó mechanisms. All electrochemical techniques have shown that after the end of the exponential phase the corrosion activity notably increased due to the high concentration of bacterial metabolites. Finally, the corrosion behavior of API-5XL52 was worse than St-35.8.
Journal of Applied Microbiology, 2006
Aims: To study the influence of some metallic elements of stainless steel 304 (SS 304) on the development and activity of a sulfate-reducing bacterial biofilm, using as comparison a reference nonmetallic material polymethylmethacrylate (PMMA). Methods and Results: Desulfovibrio desulfuricans biofilms were developed on SS 304 and on a reference nonmetallic material, PMMA, in a flow cell system. Steady-state biofilms were metabolically more active on SS 304 than on PMMA. Activity tests with bacteria from both biofilms at steady state also showed that the doubling time was lower for bacteria from SS 304 biofilms. The influence of chromium and nickel, elements of SS 304 composition, was also tested on a cellular suspension of Des. desulfuricans. Nickel decreased the bacterial doubling time, while chromium had no significant effect. Conclusions: The following mechanism is hypothesized: a Des. desulfuricans biofilm grown on a SS 304 surface in anaerobic conditions leads to the weakening of the metal passive layer and to the dissolution in the bulk phase of nickel ions that have a positive influence on the sulfate-reducing bacteria metabolism. This phenomenon may enhance the biocorrosion process. Significance and Impact of the Study: A better understanding of the interactions between metallic surfaces such as stainless steel and bacteria commonly implied in the corrosion phenomena which is primordial to fight biocorrosion.
Adhesion of Desulfovibrio desulfuricans and Pseudomonas fluorescens to mild steel surfaces
Journal of Applied Bacteriology, 1989
The adhesion of microorganisms to metal surfaces has been shown to be important in the corrosion process, but the cell surface structures participating in this adhesion have not previously been identified. Evidence is presented that a bacterial substance taking part in the initial adhesion of Pseudomonas fluorescens and Desuljovibrio desuljuricans (New Jersey) to mild steel is polysaccharide in nature. It is likely that this is present in the outer membrane of the bacterial cells as lipopolysaccharide.
International Biodeterioration & Biodegradation
The microbiologically influenced corrosion (MIC) of zinc and galvanized steel caused by a sulfate reducing bacterium (SRB) was investigated. After 7 days of incubation of Desulfovibrio vulgaris in 125 mL anaerobic vials (100 mL culture medium) at 37 • C, the sessile cell coverage on the galvanized steel was slightly higher than that on pure zinc: (1.9 ± 0.2) × 10 9 cells/cm 2 vs. (9.0 ± 1.8) × 10 8 cells/cm 2. The weight losses for galvanized steel and pure zinc were 31.5 ± 2.5 mg/cm 2 and 35.4 ± 4.5 mg/cm 2 , respectively, which were 10 1 higher than that for carbon steel. The corrosion current densities of galvanized and pure zinc were 25.5 μA/cm 2 and 100 μA/cm 2 , respectively after the 7-day incubation, confirming that galvanized steel was less prone to SRB MIC despite having a slightly higher sessile cell count. In both cases, the corrosion product was mainly ZnS. Three MIC mechanisms were possible for the severe corrosion against the two metals. Extracellular electron transfer MIC (EET-MIC) was thermodynamically favorable for zinc. Furthermore, in the presence of Zn coupons, H 2 evolution in the headspace was 5.5 times higher than without Zn coupons, which suggested that proton attack and/or H 2 S attack also occurred in the corrosion process.
Biofilm formation on mild steel coupons byPseudomonasandDesulfovibrio
Biofouling, 1993
Mild steel strip coupons were buried in waterlogged clay soil sitesin the Niger Delta for 190 days, with one site untreated and the other site treated with a tetrakis (hydroxymethyl) phosphoniumsulphate (THPS)-based biocide. Post-exposure analysis of the coupons showed that there was an increasing trend in metal loss in the coupons as the exposure days increased, for both the untreated and treated soil sites. The trend of metal loss showed an average cumulative increase of 46.7% in the untreated soil site and 34.3% in the treated soil site. Average percentage weight loss (APWL) after the 40, 100 and 190-day observational periods, were 2.3%, 5.5% and 8.5% respectively, in the untreated soil; and 1.2%, 2.0% and 2.8% respectively, in the treated soil. Over the period, there was a cumulative 5.4% metal loss in the coupons from the untreated soil and 2.0% in the treated soil. With biocide treatment of the soil, there was a 59.5% decrease in cumulative APWL, comparing the untreated soil and the treated soil sites during each of the observational periods. Total bacterial counts determined by quantitative polymerase chain reaction (qPCR) showed a 5-log, 2-log and 1-log reduction in total bacterial counts after 40, 100 and 190 days, respectively, representing between 94-100% reduction in the bacterial numbersin the soil treated with 250 ppm of the biocide.