Growth Of Sulfate-reducing Bacteria Research Articles

Effect of phosphate on ferrihydrite transformation and the associated arsenic behavior mediated by sulfate-reducing bacterium

Although PO43- is commonly found in association with iron (oxyhydr)oxide, the effect of PO43- on ferrihydrite reduction, mineralogical transformation, and associated As behavior in sulfate-reducing bacteria (SRB)-rich environments remains unclear. In this study, batch experiments, together with geochemical, mineralogical, and biological analyses, were conducted to elucidate these processes. The results showed that SRB can reduce ferrihydrite via direct and indirect processes, and PO43- promoted ferrihydrite reduction by supporting SRB growth at low and medium PO43- loadings. However, at high loadings, PO43- stabilized the ferrihydrite. PO43- shifted the transformation of ferrihydrite from magnetite and mackinawite to vivianite, which scavenges As effectively by incorporating As into its particle. In systems with 0.5 mM SO42-, PO43- exerted a weak effect on As mobilization. However, in systems with 10 mM SO42-, substantial amounts of As were released into the solution, and PO43- impacted As behavior strongly. Low PO43- loadings increased the mobilization of As because of the competitive adsorption of PO43- on mackinawite. Medium and high PO43- loadings were beneficial for As immobilization because of the substitution of mackinawite by vivianite. These findings have important implications for understanding the biogeochemistry of iron (oxyhydr)oxide and As behavior in SRB-containing sediments.

Study on Growth Influencing Factors and Desulfurization Performance of Sulfate Reducing Bacteria Based on the Response Surface Methodology.

Sulfate reducing bacteria (SRB) can simultaneously and efficiently remove SO4 2- and heavy metal ions from acid mine drainage (AMD). Environmental factors have a great influence on AMD treated by SRB metabolic reducing sulfate. Providing a suitable growth environment can improve the effect of SRB on AMD. In this paper, the wet soil around the tailings reservoir was used as seed mud to enrich SRB. Based on the single factor experiment method and the response surface methodology (RSM), the effects of temperature, environmental pH value, S2- concentration, and COD/SO4 2- on the growth of SRB were analyzed. The effects of environmental factors such as temperature and pH on the desulfurization performance of SRB were investigated. The results showed that the growth curve of SRB was "S" type. SRB was in the logarithmic phase when cultured for 14-86 h, with high activity and vigorous growth metabolism. When the temperature is 32∼35 °C, the activity of SRB is the highest. With the gradual increase of the S2- concentration in the culture system, SRB activity will be inhibited and even lead to SRB cell death. The environmental pH value that SRB can tolerate is 5∼8, and when the environmental pH value is 7∼8, the SRB activity is the strongest. The chemical oxygen demand (COD)/SO4 2- that is most suitable for SRB growth is 2. The optimal growth conditions of SRB obtained from RSM were as follows: culture temperature at 34.74 °C, initial pH being 8.00, and initial COD/SO4 2- being 1.98. Under these conditions, the OD600 value was 1.45, the pH value was 9.37, the oxidation reduction potential (ORP) value was -399 mV, and the removal percentage of SO4 2- was 88.74%. The results of RSM showed that the effects of culture temperature, environmental pH, and COD/SO4 2- on the desulfurization performance of SRB were extremely significant. The order of affecting the removal of SO4 2- by SRB was environmental pH > temperature > COD/SO4 2-.

A diazotrophy-ammoniotrophy dual growth model for the sulfate reducing bacterium Desulfovibrio vulgaris var. Hildenborough

Sulfate reducing bacteria (SRB) comprise one of the few prokaryotic groups in which biological nitrogen fixation (BNF) is common. Recent studies have highlighted SRB roles in N cycling, particularly in oligotrophic coastal and benthic environments where they could contribute significantly to N input. Most studies of SRB have focused on sulfur cycling and SRB growth models have primarily aimed at understanding the effects of electron sources, with N usually provided as fixed-N (nitrate, ammonium). Mechanistic links between SRB nitrogen-fixing metabolism and growth are not well understood, particularly in environments where fixed-N fluctuates. Here, we investigate diazotrophic growth of the model sulfate reducer Desulfovibrio vulgaris var. Hildenborough under anaerobic heterotrophic conditions and contrasting N availabilities using a simple cellular model with dual ammoniotrophic and diazotrophic modes. The model was calibrated using batch culture experiments with varying initial ammonium concentrations (0–3000 µM) and acetylene reduction assays of BNF activity. The model confirmed the preferential usage of ammonium over BNF for growth and successfully reproduces experimental data, with notably clear bi-phasic growth curves showing an initial ammoniotrophic phase followed by onset of BNF. Our model enables quantification of the energetic cost of each N acquisition strategy and indicates the existence of a BNF-specific limiting phenomenon, not directly linked to micronutrient (Mo, Fe, Ni) concentrations, by-products (hydrogen, hydrogen sulfide), or fundamental model metabolic parameters (death rate, electron acceptor stoichiometry). By providing quantitative predictions of environment and metabolism, this study contributes to a better understanding of anaerobic heterotrophic diazotrophs in environments with fluctuating N conditions.

Versatile Medium for the Isolation of Sulfur-Reducing Bacteria from Natural Ecotypes

Sulfate-reducing bacteria (SRB) are a diverse group of microorganisms that are commonly isolated from anoxygenic environments (lake depths, soil, or swamps) and are also found in the intestines of humans and animals. They are well known for outcompeting methanogens for common substrates thereby helping in the decrease of methane emissions and also playing a major role in sulfur cycling. Therefore, determining the cultivable methods for their isolation is important. Various media has been used for the cultivation and purification of SRB from natural wetlands. The luxuriant growth of SRB was observed in all the media tested, out of which the best suitable media to recover a maximum of colonies from the natural soil/sediment samples was discovered as a modified postage medium. The enumeration of the isolated SRB was done by the most probable number (MPN) technique. A total of twenty pure isolates of SRB were isolated from different ecotypes.

Effect of Sulfate-Reducing Bacteria on the Production of Iron Sulfides

Using Fourier transform infrared spectroscopy (FTIR) to identify the sulfate-reducing bacteria (SRB) in Daqing Oilfield sewage. The growth curve of SRB and the adsorption ability of extracellular polymeric substances (EPS) to the Fe2+ were combined to explore iron sulfide generation. X-ray diffraction (XRD) results showed that different species of SRB produce iron sulfides, mainly composed of mackinawite. The growth characteristics of SRB affected the formation of iron sulfides and had a negative charge. Various SRB growth trends were different. The growth of the bacterium in an exponential phase or log phase can be described by the greater concentration of inoculation. And smooth growth trends were contributed to the formation of FeS. At the same time, sulfur-rich, like FeS2, was easily formed when S2− (or S2 2−) played a major role compared with the protein and polysaccharide functional groups in the negatively charged EPS at the process of Fe2+ adsorption.

Metagenomics diversity analysis of sulfate-reducing bacteria and their impact on biocorrosion and mitigation approach using an organometallic inhibitor

Sulfate-reducing bacteria (SRB) have impacted the biocorrosion process for various industrial sectors, especially in the oil and gas industry. The higher stability over extreme conditions is the key parameter for their survival in such environments. So far, many materials have been tried to minimize or control the growth of SRB. In the present study, an organo-metallic compound of the zinc sorbate (ZS) was successfully synthesized by the simple co-precipitation method and its improved antibacterial activity against SRB. The SRB consortia are enriched from the sub-surface soil sample and identified by 16s rDNA sequencing by targeting the V3-V4 region. The most dominating genera identified with sulfate-reducing capability are Sulfurospirillum (42 %), Shewanella (19 %) Bacteroides (14 %), and Desulfovibrio (8 %). Further biocorrosion experiments are conducted by weight loss methods. Higher corrosion current density (Icorr) and less charge transfer resistance (Rct) are observed for the SRB consortia. Concurrently, higher Rct is kept for the inhibitor-included systems. The slowest release of the sorbate into the medium suppressed the growth of the SRB bacterial cells with 86 ± 3 % corrosion inhibition efficiency and prevented further corrosion reactions by forming a protective layer over the surface of the carbon steel API 5LX. The surface analysis strongly confirmed that SRB caused pitting corrosion, which has been suppressed in the inhibitor-included systems.

Corrosion inhibition of sulphate-reducing bacterial by Ag/Cu bimetallic nanoparticles synthesised from ginger extract

The growth of sulphate-reducing bacteria (SRB) in oilfield produced water and resistance to antibiotics has become an important issue for safe and clean production. Bimetallic nanomaterials with antibacterial effects are a potential candidate to confront microbial resistance. Environmentally friendly methods for the synthesis of bimetallic nanomaterials are an important factor to be considered in production. This study proposed a green method to synthesise Ag/Cu bimetallic nanoparticles (BNPs) as novel corrosion inhibitors and biocides using ginger rhizome extracts.The results showed that 6.25 μg mL−1 BNPs synthesised from ginger extract could disrupt the integrity of SRB cells and reduce adhesion on the surface of carbon steel over 65%. The corrosion rate of BNPs-treated SRB cultures on carbon steel was verified by weight tests, decreasing from 0.453 mm·a−1 to 0.05 mm·a−1. The changes of carbon steel surface morphology and SRB cell structure after BNPs treatment were observed in order to illustrate the inhibition mechanism of BNPs. The corrosive inhibitors prepared by this method have potential in inhibiting the corrosion behaviour of SRBs and are expected for applications in oilfield production for pipeline corrosion protection.

Microbial Corrosion in Orthodontics

Even with the exponential popularity of the contemporary clear aligners, the main stream of orthodontic practice still remains to be metal braces especially in adolescent age-group.1 Along with the advantages of metal braces such as lower cost, reduced friction, etc., there goes the disadvantages such as corrosion possibility, reduced esthetics, etc. Corrosion of orthodontic appliances is a widely researched topic.2-5 It is surprising to learn that microbially induced corrosion (MIC) has not been addressed in orthodontic literature till date. Microbial corrosion is an interesting arena which requires knowledge of both corrosion science and microbiology. The microorganisms capable of corrosion include various bacteria, fungi, and algae. The most common among them which has been widely indicated in MIC are the bacteria belonging to the sulfur cycle especially the sulfate-reducing bacteria (SRB). The connecting knot with orthodontics is the reported prevalence of these SRB in the oral cavity. SRB is prevalent in healthy individuals,6,7 patients associated with periodontitis6-11 and patients with gastrointestinal issues.12-14 The prevalence of SRB in the oral cavity has a greater clinical implication since the SRB have been proven to cause corrosion of stainless steel.15-24 There is literature attributing SRB as a potential cause in periodontal diseases7-11 as well as gastrointestinal diseases such as ulcerative colitis, inflammatory bowel diseases, and Crohn's disease.12 With its presence in the healthy oral environment already reported in the previous studies,6,7,25,26 it further emphasizes the absolute need to be researching on its corrosion possibility in the intra oral environment. The genus generally found intraorally was Desulfovibrio and Desulfobacter10 which is commonly regarded as the most "opportunistic" and ubiquitous group of sulfate reducers.6,7 There is an interesting literature on the inhibition of Desulfovibrio spp. by human saliva, the reason being quoted as salivary nitrate and nitrite.14 The mechanism behind the antimicrobial action of nitrate and nitrite is that they increase the oxidative stress on the bacteria.27 However, concentrations of salivary nitrate vary depending on the food intake, endogenous production, and salivary flow rate.28,29 Despite there exist natural inhibitors, the prevalence in oral cavity is high, 22% in healthy and 86% in patients associated with periodontitis.7 There is a predilection for the bacteria to grow when favorable conditions exist. Biofilms is one such favorable medium for the growth of SRB. Paster et al.26 identified SRB in biofilms of patients associated with refractory periodontitis, periodontitis, acute necrotizing ulcerative gingivitis (ANUG), and also in healthy subjects. Biofilm is a surface film composed of organic and inorganic saliva components that are colonized with microorganisms in extracellular polymeric substances adsorbed on all surfaces in the oral cavity.30 The oral biofilm formation is a complex process involving interspecies aggregation, which is surrounded by a cohesive matrix, forms a complex structure which in turn facilitates anaerobic growth. It is the intrinsic nature of oral biofilms which make the survival of facultative anaerobes such as SRB in the oral cavity possible. Literatures31-35 report that there are increased biofilm formations in orthodontic patients due to increased retentive areas caused by the brackets, ligatures, wires, mini implants, force components, and archwires. Bacteria in dental plaque function as a metabolically, functionally, and physically integrated community.36 The study by Mystkowska et al.37 mentioned that biofilm per se play a critical role in corrosion process by forming corrosive microcells. With time-dependent association, the microbes in the biofilm, along with saliva acting as an electrolyte and components from food, causes a decreased pH in the areas immediately under the biofilms. The decreased pH along with a change of oxygenation releases metal oxides and hydroxides from the metal surface ultimately leading to the corrosion of metallic structures.37-41 The initial roughness also acts in a vicious form promoting more biofilm adherence and the process repeats causing more corrosion. With the biofilm itself serving to initiate and propagate corrosion, the increased prevalence of SRB in patients associated with orthodontics treatment all the more increases the possibility of MIC of orthodontic materials.

Inhibition of Sulfate Reduction and Cell Division by Desulfovibrio desulfuricans Coated in Palladium Metal.

The growth of sulfate-reducing bacteria (SRB) and associated hydrogen sulfide production can be problematic in a range of industries such that inhibition strategies are needed. A range of SRB can reduce metal ions, a strategy that has been utilized for bioremediation, metal recovery, and synthesis of precious metal catalysts. In some instances, the metal remains bound to the cell surface, and the impact of this coating on bacterial cell division and metabolism has not previously been reported. In this study, Desulfovibrio desulfuricans cells (1g dry weight) enabled the reduction of up to 1500 mmol (157.5 g) palladium (Pd) ions, resulting in cells being coated in approximately 1 μm of metal. Thickly coated cells were no longer able to metabolize or divide, ultimately leading to the death of the population. Increasing Pd coating led to prolonged inhibition of sulfate reduction, which ceased completely after cells had been coated with 1200 mmol Pd g-1 dry cells. Less Pd nanoparticle coating permitted cells to carry out sulfate reduction and divide, allowing the population to recover over time as surface-associated Pd diminished. Overcoming inhibition in this way was more rapid using lactate as the electron donor, compared to formate. When using formate as an electron donor, preferential Pd(II) reduction took place in the presence of 100 mM sulfate. The inhibition of important metabolic pathways using a biologically enabled casing in metal highlights a new mechanism for the development of microbial control strategies. IMPORTANCE Microbial reduction of sulfate to hydrogen sulfide is highly undesirable in several industrial settings. Some sulfate-reducing bacteria are also able to transform metal ions in their environment into metal phases that remain attached to their outer cell surface. This study demonstrates the remarkable extent to which Desulfovibrio desulfuricans can be coated with locally generated metal nanoparticles, with individual cells carrying more than 100 times their mass of palladium metal. Moreover, it reveals the effect of metal coating on metabolism and replication for a wide range of metal loadings, with bacteria unable to reduce sulfate to sulfide beyond a specific threshold. These findings present a foundation for a novel means of modulating the activity of sulfate-reducing bacteria.

Quinone-mediated Sb removal from sulfate-rich wastewater by anaerobic granular sludge: Performance and mechanisms

Antimony (Sb) is a typical pollutant in sulfate-rich industrial wastewater. This study investigated the Sb removal efficiency in sulfate-rich water by anaerobic granular sludge (AnGS) and the stimulation of amended anthraquinone-2-sulfonate (AQS). Results showed that 89.0% of 5 mg/L Sb(V) was reduced by AnGS within 24 h, along with the observed first accumulation (up to 552.2 μg/L) and then precipitation of Sb(Ш); coexistence of 2 g/L sulfate inhibited the removal of Sb(V) by 71.4% within 24 h, along with gradual accumulation of Sb(Ш) by 3257.4 μg/L, indicating the potential competition of adsorption sites and electron donors between Sb(V) and sulfate. Amendment of 31 mg/L AQS successfully removed the inhibition from sulfate, contributing to 99.5% Sb(V) removal and minimum Sb(Ш) accumulation in Sb(V) + sulfate+AQS group. Further test results suggested that Sb(V) removal by AnGS was mainly through dissimilatory reduction instead of bio-sorption, while Sb(Ш) removal mainly relied on instant bio-sorption by AnGS followed by precipitation in the form of Sb2O3 and Sb2S3. Extracellular Polymeric Substances (EPS) characterization showed that AQS promoted the accumulation of Sb(V) and Sb(Ш) in EPS. High-throughput sequencing analysis showed the enrichment of sulfate-reducing bacteria (SRB) in Sb(V) + sulfate group and suppressed SRB growth in Sb(V) + sulfate+AQS group.

Effects of cadmium sulfide nanoparticles on sulfate bioreduction and oxidative stress in Desulfovibrio desulfuricans

Sulfate-containing wastewater has a serious threat to the environment and human health. Microbial technology has great potential for the treatment of sulfate-containing wastewater. It was found that nano-photocatalysts could be used as extracellular electron donors to promote the growth and metabolic activity of non-photosynthetic microorganisms. However, nano-photocatalysts could also induce oxidative stress and damage cells. Therefore, the interaction mechanism between photosynthetic nanocatalysts and non-photosynthetic microorganisms is crucial to determine the regulatory strategies for microbial wastewater treatment technologies. In this paper, the mechanism and regulation strategy of cadmium sulfide nanoparticles (CdS NPs) on the growth of sulfate-reducing bacteria and the sulfate reduction process were investigated. The results showed that the sulfate reduction efficiency could be increased by 6.4% through CdS NPs under light conditions. However, the growth of Desulfovibrio desulfuricans C09 was seriously inhibited by 55% due to the oxidative stress induced by CdS NPs on cells. The biomass and sulfate reduction efficiency could be enhanced by 6.8% and 5.9%, respectively, through external addition of humic acid (HA). At the same time, the mechanism of the CdS NPs strengthening the sulfate reduction process by sulfate bacteria was also studied which can provide important theoretical guidance and technical support for the development of microbial technology combined with extracellular electron transfer (EET) for the treatment of sulfate-containing wastewater.Graphical

Recovery of anaerobic system treating sulfate-rich wastewater using zero-valent iron

The anaerobic digestion (AD) process often fails in treating wastewater containing high levels of sulfate because sulfate-reducing bacteria (SRB) can reduce sulfate to sulfide and compete with methane-producing archaea (MPA) for their common substrates. The sulfide produced from the sulfate reduction could inhibit both MPA and SRB. In this study, we investigated the application of zero-valent iron (ZVI) to recover the growth and activities of MPA and SRB in an AD process treating wastewater with a relatively low ratio of chemical oxygen demand (COD) to sulfate ratio (SO42-) (9,000 mg COD/L glucose and 4,500 mg/L SO42-). The one-time addition of 210 g ZVI increased the CH4 production rates from near zero to 0.54 ± 0.15 L/L·d. An electron flow analysis (in terms of COD) demonstrated that the CH4-COD was approximately eight times higher than the COD contributed by ZVI electrons. The results indicated that ZVI not only provided extra electrons for use in hydrogenotrophic methanogenesis, but also provided ferrous ions that could co-precipitate with sulfides and reduced the inhibition of acetoclastic methanogens from undissociated H2S. ZVI helped recover the acetoclastic activity of the biomass to approximately the same level as the activity of the inoculum before being inhibited by sulfides and improved the hydrogenotrophic activity by over 72 times. In addition, ZVI had different effects on the acetoclastic activities of the culture attached to ZVI and the suspended culture. The acetoclastic activity of the culture attached to ZVI (0.446 ± 0.003 g COD/g COD·d) was only approximately half of that of the suspended culture (1.056 ± 0.070 g COD/g COD·d).

Bioremediation of hexavalent-chromium contaminated groundwater: Microcosm, column, and microbial diversity studies

Sulfate reducing bacteria (SRB) have the capability of bioreducing hexavalent chromium [Cr(VI)] to trivalent chromium [Cr(III)] under sulfate-reducing conditions for toxicity reduction. However, a high amount of sulfate addition would cause elevated sulfide production, which could inhibit the growth of SRB and result in reduced Cr(VI) bioreduction efficiency. A slow release reagent, viscous carbon and sulfate-releasing colloidal substrates (VCSRCS), was prepared for a long-lasting carbon and sulfate supplement. In the column study, VCSRCS was injected into the column system to form a VCSRCS biobarrier for Cr(VI) containment and bioreduction. A complete Cr(VI) removal was observed via the adsorption and bioreduction mechanisms in the column with VCSRCS addition. Results from X-ray diffractometer analyses indicate that Cr(OH)3(s) and Cr2O3(s) were detected in precipitates, indicating the occurrence of Cr(VI) reduction followed by Cr(III) precipitation. Results from the Fourier-transform infrared spectroscopy analyses show that cell deposits carried functional groups, which could adsorb Cr. Addition of VCSRCS caused increased populations of total bacteria and dsrA, which also enhanced Cr(VI) reduction. Microbial diversity results indicate that VCSRCS addition resulted in the growth of Cr(VI)-reducing bacteria including Exiguobacterium, Citrobacter, Aerococcus, and SRB. Results of this study will be helpful in developing an effective and green VCSRCS biobarrier for the bioremediation of Cr(VI)-polluted groundwater.

Anti-corrosion, antiscalant and anti-microbial performance of some synthesized trimeric cationic imidazolium salts in oilfield applications

In this study, two trimeric cationic imidazolium salts (APMI and APBI) were synthesized, characterized, and evaluated as tri-functional chemicals i.e. anti-microbial, antiscalant, and anti-corrosion for N80 type steel in oilfield formation water to simulate the oilfield produced water reinjection conditions for enhanced oil recovery (EOR). The results of the EIS method revealed that the corrosion inhibition efficiencies, for APMI and APBI were 86.79 % and 90.47 % at 200 ppm, respectively. The potentiodynamic polarization method (PDP) showed that the two salts acted as mixed type inhibitors. The investigated imidazolium salts obeyed Langmuir adsorption isotherm. SEM and EDX analyses provided the appearance of an inhibitor layer encapsulating the surface of N80 type steel. In addition, the anti-scale property of the prepared imidazolium salts against CaCO3 and CaSO4 was also investigated via static scale precipitation tests. The data revealed that the scale inhibition effectiveness improved by increasing the doses of these imidazolium salts. The imidazolium salts were evaluated for their antibacterial activities and exhibited good biological performance against the growth of sulfate-reducing bacteria (SRB) during petroleum processing operations. Finally, the results obtained from theoretical calculations support our experimental studies.

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.

Review on Microbial Enhanced Oil Recovery and Controlling Its Produced Hydrogen Sulfide Effects on Reservoir and Transporting Pipelines

Using viable microbial cultures within hydrocarbon reservoirs so as to enhancement of oil recovery through metabolic activities is exactly what we recognize as Microbial enhanced oil recovery (MEOR). In similar with many other process in industries, there are some cons and pros following with MEOR. The creation of sulfides such as hydrogen sulfide as a result of injecting the sulfate-containing seawater into hydrocarbon reservoirs in order to maintain the required reservoir pressure, leads to produce and growth of Sulfate Reducing Bacteria (SRB) approximately near the injection wells, turning the reservoir into sour, however SRB is not considered as the only microbial process stimulating the formation of sulfides. Along with SRB, thermochemical sulfate reduction or thermal redox reaction (TSR) is also known to be highly effective at resulting in having extremely concentrated zones of 𝐻2S in the reservoir fluids eligible to cause corrosion. Owing to extent of the topic, more information on formation of 𝐻2S are going to be put finger on. Besides, confronting the undesirable production of sulfide species in the reservoirs can lead to serious operational, environmental and financial problems in particular the transporting pipelines. Consequently, conjuring up reservoir souring control strategies on the way production of oil and gas is the only way to prevent possible damages in terms of environment, finance and man power which requires determining the compound’s reactivity, origin and partitioning behavior. This article is going to provide a comprehensive review on progress made in this field and the possible advent of new strategies in this technologically advanced world of petroleum industry.

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.

Newly imine-azo dicationic amphiphilic for corrosion and sulfate-reducing bacteria inhibition in petroleum processes: Laboratory and theoretical studies

Oil and gas process faces a large dilemma during the acidizing job. So, dicationic surfactant namely; 1-dodecyl-3-((E)-(4-(((E)-(1-dodecylpyridin-1-ium-4-yl) methylene)amino)-2-hydroxyphenyl) diazenyl)pyridin-1-iumdibromide (SDCAC) was synthesized. Spectroscopic and CHN elemental analysis studies confirmed the SDCAC structure. SDCAC has Surface active properties. The anticorrosion performance of SDCAC for carbon steel (CS) in 1.0 M HCl has been validated gravimetrically and electrochemically accompanied with surface analysis studies. SDCAC enhances the resistance of CS corrosion by 98%. Tafel data classify SDCAC as a hybrid anticorrosive substance. Adsorption of SDCAC is more fitted to the Langmuir adsorption isotherm model. Theoretical indices of SDCAC affirm its tendency toward adsorption. The activity of SDCAC against sulfate reducing bacteria (SRB) has been examined and promising outcomes have been achieved. According to the findings of this investigation, the SDCAC can reduce SRB growth from 107 to102 cell/ml.

Effect of magnetic field on stress corrosion cracking induced by Sulfate-reducing bacteria

Buried pipes are often affected by microorganisms and magnetic fields. In this paper, the stress corrosion cracking (SCC) behavior of X80 steel under the combined effect of magnetic field (MF) and sulfate-reducing bacteria (SRB) was studied by electrochemical and slow strain rate tensile testing. The synergistic effect of MF and SRB on SCC was expounded for the first time. Results confirmed that the sensitivity of SCC increased under 0~20 mT, which was attributable to the fact that the MF promoted the entry of diamagnetic corrosion anions into the corrosion pit and accelerated the paramagnetic Fe2+ to detach from the steel surface. MF and SRB not only independently improved the stress corrosion sensitivity of steel, but also had a synergistic effect. MF changed the arrangement of the biofilm. At 30 mT, the sensitivity of SCC decreased, which was due to the excessive MF inhibited the growth of SRB.

ESTIMATION OF BACTERICIDAL EFFICIENCY OF THE «UNIKO-N» REAGENT REGARDING SULPHATE REDUCING BACTERIA IN OIL FIELD WATERS

The article presents the results of a study of the effectiveness of the new generation UNIKO-N-60 reagent and its modifications which do not contain salts of quaternary ammonium compounds (QAC), for inactivation of sulfate-reducing bacteria (SRB) in the pumped liquid at the ASHIT Oil and Gas Production Department-1 of JSC «Belkamneft» named by A.A. Volkov. Comparative data have been obtained on the assessment of the effectiveness when changing the dosage of the reagent on SRB cultures of two field facilities of the UKPN ASH IT and RVS-13 UKPN ASHIT. The obtained data indicate that the samples of the UNIKO-N exhibit high efficiency. The suppression of the growth of SRB by the samples of UNIKO-N occurs at a low dosage of 5 g/m3. The effectiveness of the reagent was not changed when the dosage was increased to 100 g/m3. Their higher efficiency is shown in comparison with the base reagent. It is noted that reagents of the UNIKO-N series based on high molecular weight polymer compounds have biocidal activity against all types of bacteria, including SRB, viruses and fungi, while simultaneously exhibiting the properties of corrosion inhibitors. It has been established that UNIKO-N polymer compositions protect St3 steel from general corrosion in mineralized water in the absence of hydrogen sulfide at a minimum dosage of 0,4 to 4,0 mg/l. Modifications of the UNIKO-N reagent have been developed and tested, having different freezing points, concentrations of active components and various functional additives, depending on the needs of a particular consumer. The usage of reagents of new generation for inactivation of SRB in petroleum production engineering not containing in its composition QAC permits to eliminate their negative influence on state of equipment and pipelines.