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Bioleaching has been successfully used in commercial metal mining for decades. It uses microbes to biosolubilize metal-containing inorganic compounds such as metal oxides and sulfides. There is a growing interest in using bioleaching for bioremediation of solid wastes by removing heavy metals from ash and sewage sludge. This review presents the state of the art in bioleaching research for recovery of metals and bioremediation of solid wastes. Various process parameters such as reaction time, pH, temperature, mass transfer rate, nutrient requirement, pulp density and particle size are discussed. Selections of more effective microbes are assessed. Pretreatment methods that enhance bioleaching are also discussed. Critical issues in bioreactor scale-up are analyzed. The potential impact of advances in biofilm and microbiome is explained. [ABSTRACT FROM AUTHOR]

Corrosion of X80 pipeline steel under sulfate-reducing bacterium (SRB) biofilms, which formed in a culture medium at different times, in a simulated CO 2 -saturated oilfield produced water was investigated. Both planktonic and sessile SRB cells survived after 21 days of immersion in the water under carbon source starvation. The biofilms pre-cultured with a longer time increased the corrosion rate of the steel. At 37 °C, it took about 4 days for SRB to grow and then participate in the steel corrosion. The SRB also facilitated localized corrosion. The SRB biofilm, once deactivated, would no longer affect the steel corrosion. [ABSTRACT FROM AUTHOR]

In this work, a new correlation for the axial dispersion coefficient was obtained using experimental data in the literature for axial dispersion in fixed-bed columns packed with particles. The Chung and Wen correlation, the De Ligny correlation are two popular empirical correlations. However, the former lacks the molecular diffusion term and the latter does not consider bed voidage. The new axial dispersion coefficient correlation in this work was based on additional experimental data in the literature by considering both molecular diffusion and bed voidage. It is more comprehensive and accurate. The Peclet number correlation from the new axial dispersion coefficient correlation on the average leads to 12% lower Peclet number values compared to the values from the Chung and Wen correlation, and in many cases much smaller than those from the De Ligny correlation. [ABSTRACT FROM AUTHOR]

Corrosion inhibition by benzalkonium chloride (BKC) against anaerobic CO 2 corrosion and microbiologically influenced corrosion was studied using surface analysis, weight loss and electrochemical measurements. Results showed that the minimal bactericidal concentration of BKC against Desulfotomaculum nigrificans ( D. nigrificans ) was 40 mg L −1 . While at this concentration the planktonic D. nigrificans cell count could recover after 21-day incubation, it resulted in 4 log reduction in sessile D. nigrificans cell count. When 80 mg L −1 BKC was used, both planktonic and sessile D. nigrificans became undetectable. It was found that at these concentrations, BKC reduced both uniform corrosion and pitting corrosion. [ABSTRACT FROM AUTHOR]

In this work, the corrosion behavior and mechanism of carbon steel induced by extracellular polymeric substances (EPS) extracted from an iron-oxidizing bacterium culture were studied using surface analysis and electrochemical measurements in 3.5 wt% NaCl solutions. Results of electrochemical measurements showed that 7 day-old EPS at 240 mg L-1 inhibited the corrosion of carbon steel, especially after the EPS solution was heat treated to deactivate the enzymes in the EPS. However, 7 day-old EPS at much higher and much lower concentrations accelerated corrosion. Furthermore, 14 day-old EPS and 28 day-old EPS at 240 mg L-1 also accelerated corrosion. [ABSTRACT FROM AUTHOR]

Inhibition effect of an imidazoline derivative, dodecanoic acid and dodecylamine against CO 2 corrosion and microbiologically influence corrosion in a CO 2 -containing oilfield produced water was studied using surface analysis, weight loss and electrochemical measurements. Results indicated that dodecanoic acid could inhibit the adhesion of iron-oxidizing bacteria (IOB) significantly on carbon steel coupons, but had no effect on the planktonic IOB growth. Its inhibition efficiency reached 88.2% after 43 days of incubation. An imidazoline derivative was found to inhibit the adhesion of IOB on the steel surface, and contributed to lower inhibition effect. [ABSTRACT FROM AUTHOR]

In this paper, the effect of a magneticfield (MF) on biomineralization and corrosion behavior of Q235 carbon steel were studied using surface analysis, weight loss and electrochemical measurements. Experimental results showed that MF inhibited the growth of iron-oxidizing bacteria (IOB) and the corrosion of Q235 carbon steel. MF reduced the largest pit depth by half, while it reduced pit population density from 50 pits cm −2 to 10 pits cm −2 . MF also altered the morphology of biomineralization film, leading to the formation of a more compact biomineralization film which contributed to the lower corrosion rate. [ABSTRACT FROM AUTHOR]

The transition of the energy model dominated by centralized fossil energy use and the emergence of the Energy Internet and the Integrated Community Energy System (ICES) has gained attention. ICES involved the connection of electricity, heat, gas, and other kinds of energy, and was a significant form of the targeted transformation of conventional single energy networks. Within this system, the traditional demand response (DR) was transformed into an integrated demand response (IDR) in which all energy consumers could participate. The purpose of this study is to discuss the important technologies and models along with assessment and optimization strategies for the implementation of ICES and IDR, based on an extensive literature review. The analysis results show the "IDR + ICES" ecosystem proved to hold great potential for achieving renewable energy penetration, energy efficiency, and climate change control goals, while there are still many limitations in the coordination and reliability of the model and the design of the market mechanism. To conclude, the challenges and opportunities that ICES and IDR face were summarized, and future avenues for research are outlined. [ABSTRACT FROM AUTHOR]

Abstract: The study of microbiologically influenced corrosion (MIC) has long been plagued by a lack of clear understanding of MIC mechanisms. In this work, bioenergetics was used to explain why and when sulfate-reducing bacteria (SRB) became aggressive toward carbon steel. Fe2+/Fe0 and acetate + (lactate) have similar reduction potentials at pH 7 (−447 mV vs. −430 mV). Bioenergetically, Fe0 oxidation releases more energy than lactate oxidation, but Fe0 cannot provide organic carbons needed for growth. If there is insufficient carbon source that can diffuse from the bulk fluid to an iron surface, sessile cells at the bottom of an SRB biofilm on the surface may suffer from local carbon source starvation. In this work, mature Desulfovibrio vulgaris (ATCC 7757) biofilms initially grown in ATCC 1249 culture medium on C1018 carbon steel coupons were subjected to starvation by switching to fresh culture media with 0% (control), 90%, 99% and 100% less organic carbon, respectively. It was found that 90% and 99% carbon reductions increased weight loss significantly. Experimental data also showed that 90% carbon reduction caused a 10 μm maximum pit depth, largest among all other cases, while 99% carbon reduction yielded the highest specific weight loss of 0.0019 g/cm2. [Copyright &y& Elsevier]

Abstract: This work presents a systematic procedure for using the general rate model to predict experimental chromatograms. The model considered axial dispersion, interfacial film mass transfer and intraparticle diffusion with parameters that have been intensively investigated in classical chemical engineering mass-transfer research. Theoretical equations, mass-transfer correlations and experimental procedures for obtaining bed voidage, particle porosity, mass-transfer parameters and Langmuir isotherm parameters are described. Three simple experiments were used to obtain system delay volume, bed voidage and particle porosity, respectively. Mass-transfer parameters were estimated using existing correlations in the literature without the need for additional experiments. A complete example was used to illustrate the approach. The model satisfactorily predicted the partial breakthrough curve of bovine serum albumin on a chromatography column packed with large anion-exchange particles with a nominal diameter of 90μm. A parameter sensitivity analysis indicated the importance of accurate intraparticle diffusion modeling and demonstrated that lumped-particle models would be inadequate for understanding chromatographic behavior of large particles. [Copyright &y& Elsevier]

Abstract: Cored beads (also known as pellicular, superficially porous, and fused-cored beads or particles) offer advantages over fully porous beads in reduced diffusional mass transfer resistances in particle macropores and separation times in liquid chromatography (LC). They are also used to regulate bead densities. The core of a bead has a relatively small volume and yet presents a large linear distance for diffusional mass transfer inside particle macropores. Using a non-porous inert core, intraparticle diffusional mass transfer resistance can be reduced with a relatively small loss in binding capacities. In multicompnent isocratic elution chromatography, cored beads are a compromise between fully porous beads and non-porous beads. Non-porous beads completely eliminate intraparticle diffusion, providing sharp elution peaks with the shortest retention times. However, they do not provide a sufficient retention time range for peaks to separate in preparative LC because of their limited binding capacities. At the other end, fully porous beads offer the largest retention time differences, but suffering from excessive band broadening. For a particular multicomponent elution system, core radius fraction can be optimized to take the advantages of both fully porous beads and non-porous beads. This work presented a general rate model for cored beads and its numerical solution strategy. The model considered axial dispersion, interfacial mass transfer, intraparticle diffusion, and multicomponent Langmuir isotherm. Computer simulation was used to study the effects of core radius fraction on breakthrough curves and elution peaks. The model was used to optimize the core radius fraction for a preparative ternary elution system as an example case. [Copyright &y& Elsevier]

Liquid-liquid equilibrium (LLE) occurs at a subzero temperature for the acetonitrile-water binary system. When the equilibrium temperature is below its LLE critical temperature of - 1.32°C, the top phase is acetonitrile-rich and the bottom phase water-rich. It was observed that a human growth hormone analog with 191 amino acids partitioned exclusively into the bottom phase and its bioactivity was retained. This suggests that the liquid-liquid partition system can be used for bioseparations. The new system gives a different selectivity and the low temperature environment offers better stabilities for biomolecules compared to conventional solvent extraction systems. This work presented the partition coefficients of some biomolecules including trypsin, thyroglobulin, transferrin, ribonuclease A; L-phenylalanine, L-tryptophan; val-ala-ala-phe, phe-gly-gly-phe; erythromycin, chloramphenicol, vancomycin, spiramycin, gramicidin D, cycloheximide, fusidic acid, antimycin and tetracycline. Temperature and pH effects, as well as partition mechanisms were probed. [ABSTRACT FROM AUTHOR]

Abstract: Ganoderic acids are valuable bioactive secondary metabolites produced by a traditional medicinal mushroom Ganoderma lucidum (“Ling-zhi” in Chinese and “Reishi” in Japanese). In this work, a fast and efficient method for the recovery and purification of ganoderic acid T (GA-T) and ganoderic acid Me (GA-Me) from triterpene-enriched extracts of G. lucidum mycelia was developed by using reversed phase HPLC (RP-HPLC) on a C18 column with an acidified methanol–water mobile phase in combination with ultraviolet (UV) detection and electrospray ionization mass spectrometry (ESI-MS). The presence of each targeted GA (GA-T and GA-Me) in its corresponding peak was easily identified and confirmed by UV and MS. The chemical structures of the purified GA-T and GA-Me were further confirmed by 1H NMR. The retention behaviors of the two GAs over a temperature range of 15–55°C were also investigated. From the retention time data, van’t Hoff plots were obtained. The estimated enthalpy (ΔH) and entropy (ΔS) data suggest that the retention time difference between GA-T and GA-Me might be driven by an enthalpy difference. Furthermore, a semi-preparative HPLC purification was achieved on a semi-preparative C18 column using the conditions optimized for the analytical column. The method presented in this work can be a valuable tool for the rapid semi-preparative purification of targeted GAs, and it may also be applicable to some other natural products. [Copyright &y& Elsevier]

The flexible and automatic monitoring and control of a 22  L B. Braun Biostat C fermenter using LabVIEW software were achieved by establishing a serial interface between the fermenter's control unit and a personal computer. This setup was also used for the on-line monitoring of the DO change in a custom-made 50  L airlift bioreactor. [ABSTRACT FROM AUTHOR]

Affinity chromatography uses biospecific binding usually between an antibody and an antigen, an enzyme and a substrate or other pairs of key-lock type of matching molecules. Due to its high selectivity, it is able to purify proteins and other macromolecules from very dilute solutions. In this work, a general rate model for affinity chromatography was used for scale-up studies. Parameters for the model were estimated from existing correlations, or from experimental results obtained on a small column with the same packing material. As an example, Affi-Gel with 4.5 μmol cm−3 Cibacron Blue F-3GA as immobilized ligands covalently attached to cross-linked 6% agarose was used for column packing. Cibacron Blue F-3GA was also used as a soluble ligand in the elution stage. Two separate cases were studied. One involved a bovine serum albumin solution, and the other hen egg white lysozyme solution. Satisfactory scale-up predictions were obtained for a 98.2 ml column and a 501 ml column based on a few experimental data obtained on a 7.85 ml small column. [Copyright &y& Elsevier]

Engineering living functional biofilms offers an ecofriendly and efficient technique for the corrosion protection of metallic materials in marine environments. Its firm attachment to the metal surface is a key step to effectively improve the corrosion protection. Herein, engineered Escherichia coli biofilm with strong metal binding ability is constructed by genetically appending a metal binding domain (MBD) to extracellular amyloids. The engineered living biofilm improved the corrosion resistance of X70 carbon steel. Moreover, a biofilm‐induced mineralization layer, mainly composed of calcite, is formed on the X70 surface, which provided a stable corrosion barrier. At the end of 7‐days immersion, the icorr decreased from 5.1 ± 0.4 µA cm−2 without biofilm to 0.5 ± 0.1 µA cm−2 with E. coli MBD biofilm, resulting in a corrosion inhibition efficiency of 90.2%. It also demonstrated the corrosion protection effect for 304 stainless steel, suggesting possible broad applications of the engineered biofilm. The application of synthetic biology offers a novel approach in the development of anti‐corrosion technologies in water environments. [ABSTRACT FROM AUTHOR]

• Nitrate reducing Pseudomonas aeruginosa corrodes galvanized steel significantly. • The corrosion mechanism is film damage-microbiologically influenced corrosion. • 30 ppm (w/w) trehalase reduces sessile cell count by 0.8-log and weight loss by 14%. • Trehalase enhances 30 ppm THPS with fewer sessile cells and lower weight loss. • This work uses a mini-electrochemical glass cell to minimize chemical consumption. Pseudomonas aeruginosa is a facultative bacterium that is pathogenic. It is ubiquitous in the environment including air handling systems. It causes microbiologically influenced corrosion (MIC) aerobically and anaerobically. In this work, P. aeruginosa was grown as a nitrate reducing bacterium (NRB) in Luria-Bertani medium with KNO 3 at 37 °C. Trehalase, an enzyme which plays a crucial role in biofilm formation was found to enhance the treatment of P. aeruginosa biofilm and its MIC against galvanized steel by tetrakis-hydroxymethyl phosphonium sulfate (THPS) green biocide. After a 7-d incubation, 30 ppm (w/w) trehalase reduced sessile cell count by 0.8-log, and it also reduced galvanized steel weight loss by 14%, compared to 2.3-log and 39%, respectively for the 30 ppm THPS treatment. The combination of 30 ppm THPS + 30 ppm trehalase reduced sessile cell count further by 0.1-log and weight loss by 13% compared to using THPS alone. Electrochemical corrosion measurements supported weight loss results. The injection of 20 ppm riboflavin into a 3-d P. aeruginosa broth failed to accelerate the corrosion rate, suggesting that nitrate reducing P. aeruginosa MIC of galvanized steel did not belong to extracellular electron transfer-MIC, because Zn was hydrolyzed after the microbe damaged the passive film. [ABSTRACT FROM AUTHOR]

Stress corrosion cracking (SCC) is a serious problem threatening structural integrity and safety. Metal corrosion pits can develop into more harmful cracks under mechanical stress. It is known in abiotic corrosion that fast corrosion does not necessarily cause more severe SCC. This is because fast corrosion can prevent or dissolve crack tips and convert them into less harmful pits if the uniform corrosion rate is fast enough. This work experimentally proved the hypothesis that the same phenomenon occurs in biotic corrosion. It was found that a highly corrosive SRB (sulfate reducing bacterium) strain, namely Desulfovibrio ferrophilus (strain IS5), caused fast uniform corrosion and dull pits, but no SCC cracks against X80 carbon steel U-bend coupons (stressed). In comparison, Desulfovibrio vulgaris , a far less corrosive SRB strain caused less corrosion, but generated sharp pits and SCC cracks in a 3-month lab test. This work also revealed that the X80 U-bend had a 44% higher sessile cell count and 34% higher weight loss after a 14-d D. ferrophilus incubation in deoxygenated enriched artificial seawater culture medium at 28 °C when compared with the (flat) square coupons (no stress). This weight loss trend was corroborated by transient electrochemical measurements. [Display omitted] [ABSTRACT FROM AUTHOR]

In recent decades, urban energy consumption and carbon emissions have expanded rapidly on a global scale. Building sector, in particular, accounts for approximately 40% of overall energy use. Urban planners and decision-makers have a significant responsibility to achieve sustainable energy and climate objectives. Urban building energy modeling (UBEM) has increased in popularity in recent years as a tool for calculating urban-scale energy use in buildings with limited resources, and that facilitated the formulation of new energy policies. However, published studies of UBEM methodologies and tools lack comprehensive examinations of the potential limitations of research and the prospects of future opportunities. This paper provides a complete conceptual framework for UBEM based on extensive literature reviews and prior researchers’ work. In addition to providing a comprehensive understanding of the various UBEM approaches and tools, future research directions are explored. The results demonstrate that earlier researches did not adequately account for input uncertainty and lacked proper simulation and calibration control for algorithms/models. These challenges not only increased the workload and computational burden of modelers but also diminished the precision of model calculations. In response, this paper provides targeted recommendations for each essential phase of the present UBEM workflow, namely model input, model development, and model calibration, to address these limitations, as well as a comprehensive analysis of future prospects. The main aim of the research is to further UBEM development as a faster, more accurate and multiscale supportive tool and establish a framework for future UBEM methods. [ABSTRACT FROM AUTHOR]

Summary: Biocorrosion first surfaced in the scientific literature when Richard H. Gaines associated corrosion with bacterial activities in 1910. It is also known as microbiologically influenced corrosion (MIC). In general, it covers two scenarios. One is that microbes cause corrosion directly, which usually means microbes secrete corrosive metabolites or microbes harvest electrons from a metal for respiration to produce energy. In the second scenario, microbes are behind the initiation or acceleration of corrosion caused by a pre‐existing corrosive agent such as water and CO2, by compromising the passive film (often a metal oxide film on a metal). MIC is caused by microbial biofilms. It is everywhere around us. This work dissects some notable examples with perspectives. [ABSTRACT FROM AUTHOR]

The extracellular electron transfer (EET) mechanism for corrosion of EH36 steel (with copper) and Q235 steel (without copper) caused by Halomonas titanicae was investigated. Due to copper cytotoxicity, the sessile H. titanicae cells on the EH36 surface was only 18% of that on Q235. This led to its lower EET rate, resulting in EH36 corrosion being 0.67 times of Q235 corrosion. The EET corrosion mechanism was further proven by the increased corrosion of the two steels after injection to the H. titanicae broth of 20 ppm (w/w) (in the broth) riboflavin, an electron mediator known to accelerate EET. • H. titanicae causes EH36 and Q235 MIC in anaerobic environments. • EH36 ship steel is more resistant to nitrate reducing H. titanicae than Q235 steel. • Copper cytotoxicity on EH36 leads to a much lower sessile cell count. • Fewer sessile H. titanicae cells on EH36 leads to less severe MIC. • MIC mechanism is confirmed as extracellular electron transfer-MIC using riboflavin. [ABSTRACT FROM AUTHOR]

A super-hydrophobic (SH) CuO surface was prepared on copper using chemical etching followed by fluorination treatment. The relationship between surface morphology and hydrophobicity was investigated. When the etching time varied from 5 to 120 min, morphology changed from sparse sharp needles to dense sharp needles, and then to a stamen-like structure with flower-like clusters. All these surfaces were SH with the dense micro-needle surface (10 min etching) the best. This SH surface made salt (NaCl) particles deliquesce and roll away. Electrochemical tests showed that it reduced corrosion in a 3.5% (w/w) NaCl solution by more than 10 2 times. [ABSTRACT FROM AUTHOR]

Biocorrosion is also known as microbiologically influenced corrosion (MIC). Most anaerobic MIC cases can be classified into two major types. Type I MIC involves non-oxygen oxidants such as sulfate and nitrate that require biocatalysis for their reduction in the cytoplasm of microbes such as sulfate reducing bacteria (SRB) and nitrate reducing bacteria (NRB). This means that the extracellular electrons from the oxidation of metal such as iron must be transported across cell walls into the cytoplasm. Type II MIC involves oxidants such as protons that are secreted by microbes such as acid producing bacteria (APB). The biofilms in this case supply the locally high concentrations of oxidants that are corrosive without biocatalysis. This work describes a mechanistic model that is based on the biocatalytic cathodic sulfate reduction (BCSR) theory. The model utilizes charge transfer and mass transfer concepts to describe the SRB biocorrosion process. The model also includes a mechanism to describe APB attack based on the local acidic pH at a pit bottom. A pitting prediction software package has been created based on the mechanisms. It predicts long-term pitting rates and worst-case scenarios after calibration using SRB short-term pit depth data. Various parameters can be investigated through computer simulation. [ABSTRACT FROM AUTHOR]

High metal ion concentrations and low pH cause severely inhibit the activity of an acidophilic microbial consortium (AMC) in bioleaching. This work investigated the effects of exogenous spermine on biofilm formation and the bioleaching efficiency of LiCoO2 by AMC in 9K medium. After the addition of 1 mM spermine, the activities of glutathione peroxidase and catalase increased, while the amount of H2O2, intracellular reactive oxygen species (ROS) and malondialdehyde in AMC decreased. These results indicated that the ability of AMC biofilm to resist oxidative stress introduced by 3.5 g/L Li+ and 30.1 g/L Co2+ was improved by spermine. The activity of glutamate decarboxylase was promoted to restore the intracellular pH buffering ability of AMC. Electrochemical measurements showed that the oxidation rate of pyrite was increased by exogenous spermine. As a result, high bioleaching efficiencies of 97.1% for Li+ and 96.1% for Co2+ from a 5.0% (w v−1) lithium cobalt oxide powder slurry were achieved. This work demonstrated that Tafel polarization can be used to monitor the AMC biofilm’s ability of uptaking electrons from pyrite during bioleaching. The corrosion current density increased with 1 mM spermine, indicating enhanced electron uptake by the biofilm from pyrite. [ABSTRACT FROM AUTHOR]

The corrosion behavior of carbon steel was investigated in the presence of SRB and IOB separately in their respective culture media and in the mixed culture of SRB and IOB in artificially produced water with 4.2 mg/L dissolved oxygen. The results showed that IOB inhibited the growth of planktonic SRB, but promoted the growth of sessile SRB when SRB was cultured together with IOB. The mixture of SRB and IOB had a synergistic effect enhancing the pitting corrosion of the coupons. The limited amount of dissolved oxygen played a key role in the formation of corrosion products. [ABSTRACT FROM AUTHOR]

Desulfovibrio ferrophilus (IS5) corrosion of X65 carbon steel was impacted by gravity. Six o'clock position (6P) had the highest sessile count due to gravity assisting planktonic cell settling in early biofilm formation, leading to most severe static corrosion followed by 9P and 12P. The 7-d weight loss at 6P was 49.6 ± 4.4 mg/cm2 (3.3 mm/a in uniform corrosion rate) followed by 9P with 35.7 ± 2.6 mg/cm2 (2.4 mm/a) and 12P with 20.5 ± 5.5 mg/cm2 (1.4 mm/a). The trend was supported by electrochemical measurements. The weight loss differences reduced considerably when there was agitation, supporting the gravity hypothesis. • Early SRB biofilm growth is impacted by gravity, favoring 6 o'clock position (6P). • The biofilm sessile cell count sequence is 6P > 9P (side way) >12P (face down). • Weight loss and pit depth sequences after 7-day SRB incubation are 6P > 9P > 12P. • 6P has a uniform corrosion rate of 3.3 mm/a vs. 1.4 mm/a for 12P for 7-d incubation. • Agitation lowered weight loss differences, supporting gravity impact hypothesis. [ABSTRACT FROM AUTHOR]

The microbiologically influenced corrosion (MIC) of copper via extracellular electron transfer (EET) caused by Halomonas titanicae was investigated using two different methods. Copper corrosion in enriched seawater was accelerated by H. titanicae and was further promoted by riboflavin (RF), an electron mediator that can accelerate EET. Within minutes of 20 ppm RF injection, the copper corrosion started to increase. The copper weight loss for 100% carbon source reduction was 1.4 times that of 0% carbon source reduction. The RF injection data together with carbon starvation data indicate that H. titanicae utilized elemental copper as an electron source to cause EET-MIC. [Display omitted] • Nitrate reducing H. titanicae can utilize rather noble copper as an electron donor. • Copper MIC rate starts to increase within minutes after riboflavin injection. • Riboflavin can be used as a probe to confirm EET-MIC by nitrate reducing bacteria. [ABSTRACT FROM AUTHOR]

Headspace to liquid volumetric ratio can impact bacterial activity, which affects the metabolic process and extracellular electron transportation (EET) of microbial biofilms. In this work, the ratio of headspace volume to culture medium volume was varied to investigate the behavior of Cu microbiologically influenced corrosion (MIC) by P. aeruginosa as a nitrate reducing bacterium (NRB). This NRB produced ammonia as a toxic metabolite that inhibited its growth in anaerobic bottles. The results showed that a larger headspace volume led to lower ammonium concentration in the liquid phase (due to escape of ammonia to the headspace), higher planktonic and sessile cell counts, deeper pits and higher uniform corrosion rate. With a fixed culture medium volume of 200 mL, the weight loss of Cu coupons corresponding to 500 mL and 200 mL headspace volumes were approximately 1.9-fold and 1.5-fold larger than that for 50 mL headspace volume, respectively, with corresponding pit depth increased by 2.6 times and 1.7 times, respectively. Ammonia acted as a complexing agent, not an oxidant (electron acceptor) in the system. The terminal electron acceptor was nitrate. The reduction of nitrate in the cytoplasm of P. aeruginosa using extracellular electrons released by Cu oxidation is thermodynamically favorable. Thus, Cu corrosion by the nitrate reducing P. aeruginosa biofilm belongs to EET-MIC. • Nitrate reduction coupled with Cu oxidation is thermodynamically favorable. • NH 4 + in P. aeruginosa broth inhibits sessile cell growth and thus impacts MIC. • Increased headspace leads to higher sessile cell count and more severe Cu MIC. • Localized corrosion and general corrosion are observed in 14-day tests. • Data support the mechanism for Cu MIC with electron uptake by the nitrate reducer. [ABSTRACT FROM AUTHOR]

Cu-bearing antibacterial stainless steels have been gaining popularity in recent years due to their strong antibacterial performances. However, only a few studies were reported for their actual performances against microbiologically influenced corrosion (MIC). In this study, electrochemical methods and surface analytical techniques were applied to study the MIC resistance characteristics of a 304L-Cu stainless steel (SS) against Escherichia coli in comparison with 304L SS as control. Corrosion tests for specimens after a 21-day exposure to a Luria–Bertani (LB) culture medium with E. coli demonstrated that the 304L-Cu SS considerably reduced the maximum MIC pit depth and the specific weight loss compared with 304L SS (8.3 μm and 0.2 mg/cm 2 vs. 13.4 μm and 0.6 mg/cm 2 ). Potentiodynamic polarization tests showed that the corrosion current density of the 304L-Cu SS was as much as 4 times lower than that of the 304L SS, indicating that the 304L-Cu SS is a better choice for applications in MIC-prone environments. [ABSTRACT FROM AUTHOR]

Oceanic facilities and equipment corrosion present considerable economic and safety concerns, predominantly due to microbial corrosion. Early detection of corrosive microbes is pivotal for effective monitoring and prevention. Yet, traditional detection methods often lack specificity, require extensive processing time, and yield inaccurate results. Hence, the need for an efficient real-time corrosive microbe monitoring technology is evident. Pseudomonas aeruginosa , a widely distributed microorganism in aquatic environments, utilizes its production of quinone-like compounds, specifically pyocyanin (PYO), to corrode metals. Here, we report a novel fiber optic surface plasmon resonance (SPR) sensor modified by the C-terminal of BrlR protein (BrlR-C), which is a specific receptor of PYO molecule, to detect P. aeruginosa in aquatic environments. The results showed that the sensor had a good ability to recognize PYO in the concentration range of 0–1 μg/mL, and showed excellent sensing performance in real-time monitoring the growth status of P. aeruginosa. With a strong selectivity of PYO, the sensor could clearly detect P. aeruginosa against other bacteria in seawater environment, and exhibited excellent anti-interference ability against variations in pH, temperature and pressure and other interfering substances. This study provides a useful tool for monitoring corrosive P. aeruginosa biofilm in aquatic environments, which is a first of its kind example that serves as a laboratory model for the application of fiber optic technology in real-world scenarios to monitoring biofilms in microbial corrosion and biofouling. [ABSTRACT FROM AUTHOR]

• Rough surface finish on a coupon facilitates early biofilm development. • Highly-corrosive D. ferrophilus IS5 provides large weight losses. • 36 grit has higher sessile cell count and higher weight loss than 600 grit at 7 d. • These differences wane over time as suggested by 30 d data. • Electrochemical data support weight loss data with additional transient information. Carbon steel microbiologically influenced corrosion (MIC) by sulfate reducing bacteria (SRB) is known to occur via extracellular electron transfer (EET). A higher biofilm sessile cell count leads to more electrons being harvested for sulfate reduction by SRB in energy production. Metal surface roughness can impact the severity of MIC by SRB because of varied biofilm attachment. C1018 carbon steel coupons (1.2 cm2 top working surface) polished to 36 grit (4.06 μm roughness which is relatively rough) and 600 grit (0.13 μm) were incubated in enriched artificial seawater inoculated with highly corrosive Desulfovibrio ferrophilus IS5 at 28 ℃ for 7 d and 30 d. It was found that after 7 d of SRB incubation, 36 grit coupons had a 11% higher sessile cell count at (2.0 ± 0.17) × 108 cells/cm2, 52% higher weight loss at 22.4 ± 5.9 mg/cm2 (1.48 ± 0.39 mm/a uniform corrosion rate), and 18% higher maximum pit depth at 53 μm compared with 600 grit coupons. However, after 30 d, the differences diminished. Electrochemical tests with transient information supported the weight loss data trends. This work suggests that a rougher surface facilitates initial biofilm establishment but provides no long-term advantage for increased biofilm growth. [ABSTRACT FROM AUTHOR]

Metal ions stress will inhibit the oxidation capacity of iron and sulfur of an acidophilic microbial consortium (AMC), which leads to reduced bioleaching efficiency. This work explored the impacts of Li+ and Co2+ on the composition and function of AMC biofilms with a multi-scale approach. At the reactor scale, the results indicated that the oxidative activity, the adsorption capacity, and the biofilm formation ability of AMC on pyrite surfaces decreased under 500 mM Li+ and 500 mM Co2+. At the biofilm scale, the electrochemical measurements showed that Li+ and Co2+ inhibited the charge transfer between the pyrite working electrode and the biofilm, and decreased the corrosion current density of the pyrite working electrode. At the cell scale, the content of proteins in extracellular polymers substrate (EPS) increased as the concentrations of metal ions increased. Moreover, the adsorption capacity of EPS for Li+ and Co2+ increased. At the microbial consortium scale, a BugBase phenotype analysis showed that under 500 mM Li+ and 500 mM Co2+, the antioxidant stress capacity and the content of mobile gene elements in AMC increased. The results in this work can provide useful data and theoretical support for the regulation strategy of the bioleaching of spent lithium-ion batteries to recover valuable metals. [Display omitted] • Metal ions stress leads to decreased oxidation activities and biofilm formation. • It inhibits electron transfer between acidophilic microbial consortium biofilm and pyrite. • Biofilm EPS composition changes to adsorb more metal ions for self-defense. • Biofilm consortium diversity change enhances its resistance to metal ion stress. • Electrochemical measurements can monitor biofilm oxidation ability in bioleaching. [ABSTRACT FROM AUTHOR]

Bifunctional antibacterial and anticorrosive broad-spectrum rosin thiourea iminazole quaternary ammonium salt (RTIQAS) was investigated to inhibit microbiologically influenced corrosion (MIC) caused by anaerobic gram-negative sulfate reducing bacterium (SRB) Desulfovibrio vulgaris against X80 carbon steel and aerobic gram-positive bacterium Bacillus licheniformis against 316L stainless steel. It also indicated that RTIQAS was more effective than common commercial biocides THPS (tetrakis hydroxymethyl phosphonium sulfate) and glutaraldehyde at the same concentration against X80 carbon steel corrosion by D. vulgaris. In the molecular simulation, the interaction energy confirmed the favorable adsorption of RTIQAS on the metal surfaces, indicating its potential as an effective corrosion inhibitor. • A bifunctional antibacterial and anticorrosive inhibitor RTIQAS was synthesized. • RTIQAS had antibacterial performances against anaerobic Desulfovibrio vulgaris on X80 carbon steel. • RTIQAS presented antibacterial abilities against aerobic Bacillus licheniformis on 316 L stainless steel. • RTIQAS showed better inhibition effect than two common commercial biocides against D. vulgaris. • RTIQAS molecules were adsorbed on iron surface based on molecular [ABSTRACT FROM AUTHOR]

Abstract: Generally speaking, a much higher concentration of biocide is needed to treat biofilms compared to the dosage used to for planktonic bacteria. With increasing restrictions of environmental regulations and safety concerns on large-scale biocide uses such as oil field applications, it is highly desirable to make more effective use of biocides. In this paper a green biocide enhancer ethylenediaminedisuccinate (EDDS) that is a biodegradable chelator, was found to enhance the efficacy of glutaraldehyde in its treatment of sulfate-reducing bacteria (SRB) biofilms. Experiments were carried out in 100 ml anaerobic vials with carbon steel coupons. The ATCC 14563 strain of Desulfovibrio desulfuricans was used. Biofilms on coupon surfaces were visualized using scanning electron microscopy (SEM). Experimental results showed that EDDS reduced the glutaraldehyde dosages considerably in the inhibition of SRB biofilm establishment and the treatment of established biofilms on carbon steel coupon surfaces. [Copyright &y& Elsevier]

The kinetics of cell growth and protein production for the recombinant Aspergillus niger strain AB4.1[pgpdAGLAGFP]#11 were investigated. An unstructured kinetic model was developed to describe the cell growth and product formation mathematically. The dynamics of glucose consumption and biomass production can be well-described by the model. The assumption that the degradation of GFP by proteases is a first-order reaction can express the trend of the GFP profile reasonably well. The dynamics of protease production is also described reasonably well by considering the inhibition effect of glucose on protease production. Because of the high initial glucose concentration and keeping the pH value of the broth at 6, the protease activity could be kept low most of the time during the fermentation. The increase of protease activity near the end of the culture might be caused by cell lysis because the intracellular protease activity was much higher than the extracellular activity. [ABSTRACT FROM AUTHOR]

Abstract: A microbial fuel cell (MFC) is a bioreactor that converts chemical energy in the chemical bonds in organic compounds to electrical energy through catalytic reactions of microorganisms under anaerobic conditions. It has been known for many years that it is possible to generate electricity directly by using bacteria to break down organic substrates. The recent energy crisis has reinvigorated interests in MFCs among academic researchers as a way to generate electric power or hydrogen from biomass without a net carbon emission into the ecosystem. MFCs can also be used in wastewater treatment facilities to break down organic matters. They have also been studied for applications as biosensors such as sensors for biological oxygen demand monitoring. Power output and Coulombic efficiency are significantly affected by the types of microbe in the anodic chamber of an MFC, configuration of the MFC and operating conditions. Currently, real-world applications of MFCs are limited because of their low power density level of several thousand mW/m2. Efforts are being made to improve the performance and reduce the construction and operating costs of MFCs. This article presents a critical review on the recent advances in MFC research with emphases on MFC configurations and performances. [Copyright &y& Elsevier]

Abstract: Filamentous fungi have long been used for the production of metabolites and enzymes. With developments in genetic engineering and molecular biology, filamentous fungi have also achieved increased attention as hosts for recombinant DNA. However, the production levels of non-fungal proteins are usually low. Despite the achievements obtained using molecular tools, the heterologous protein loss caused by extracellular fungal protease degradation persists. This review provides an overview of the potential bioprocessing strategies that can be applied to inhibit protease activity thereby enhancing heterologous protein production. [Copyright &y& Elsevier]

Microbiologically influenced corrosion (MIC) is one of the major corrosion threats in the oil and gas industry. It is caused by environmental biofilms. Glutaraldehyde is a popular green biocide for mitigating biofilms and MIC. This work investigated the efficacy of glutaraldehyde enhancement by food-grade green chemical d-limonene in the biofilm prevention and MIC mitigation using a mixed-culture oilfield biofilm consortium. After 7 days of incubation at 37 °C in enriched artificial seawater in 125 mL anaerobic vials, the 100 ppm (w/w) glutaraldehyde + 200 ppm d-limonene combination treatment reduced the sessile cell counts on C1018 carbon steel coupons by 2.1−log, 1.7−log, and 2.3−log for sulfate reducing bacteria, acid producing bacteria, and general heterotrophic bacteria, respectively in comparison with the untreated control. The treatment achieved 68% weight loss reduction and 78% pit depth reduction. The 100 ppm glutaraldehyde + 200 ppm d-limonene combination treatment was found more effective in biofilm prevention and MIC mitigation than glutaraldehyde and d-limonene used individually. Electrochemical tests corroborated weight loss and pit depth data trends. [ABSTRACT FROM AUTHOR]

A segregated model was proposed to investigate the inherent relationships between growth, substrate consumption, cell differentiation and product formation in a Bacillus subtilis fermentation producing heterologous amylase in a 22-l bioreactor. The segregated model includes three distinguishable cell states and the transition from vegetative phase to sporangium and finally to mature spore. An age-based population balance model was applied to describe the maturity of sporangium toward the formation of spores. Parameters in the model were determined by fitting the model with experimental data. The model was able to predict the transient behavior of B. subtilis in both batch and fed-batch cultures. [Copyright &y& Elsevier]

Three types of stainless steel (304 SS, 410 SS, and 2205 SS) were evaluated for their corrosion behaviors in microbiologically influenced corrosion (MIC) by Desulfovibrio ferrophilus strain IS5, a relatively new and very corrosive sulfate-reducing bacteria (SRB) strain. The incubation lasted for 7 days in enriched artificial seawater at 28°C and the results showed that 410 SS had a rather large weight loss (6.2 mg/cm2) and a maximum pit depth (118 µm), but 2205 SS and 304 SS did not suffer from significant weight loss or pitting. Electrochemical tests indicated that 2205 SS was slightly more resistant to SRB MIC than 304 SS, while 410 SS was far less resistant. [ABSTRACT FROM AUTHOR]

During bioleaching of Cobalt from waste lithium-ion batteries, the biooxidation activity of acidophilic bacteria is inhibited by a high concentration of Co ion in the liquid phase. However, the mechanism for Co2+ toxicity to acidophilic bacteria has not been fully elucidated. In this study, the effects of Co2+ concentration on the biooxidation activity for Fe2+, intracellular reactive oxygen species (ROS) level and antioxidant defense systems in a mixed-culture of acidophilic bacteria (MCAB) were investigated. The results showed that the biooxidation activity of the MCAB was inhibited by Co2+. Furthermore, it was indicated that the intracellular ROS contents of the MCAB under conditions of 0.4 M and 0.6 M Co2+ were 2.60 and 3.34 times higher than that under the condition of 0 M Co2+. The increase in intracellular malondialdehyde content indicated that the oxidative damage was induced by Co2+. Moreover, the antioxidant systems in MCAB were affected by Co2+. It was observed that the Co2+ exposure increased the catalase and glutathione peroxidase activities while reducing the superoxide dismutase activity and the intracellular glutathione (GSH) content. It was found that an exogenous GSH supplementation eliminated excess intracellular ROS and improved the biooxidation activity of the MCAB. [ABSTRACT FROM AUTHOR]

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. Unlabelled Image • Pseudomonas aeruginosa biofilm accelerates the corrosion of 304L stainless steel. • Salvia officinalis extract effectively prevents the P. aeruginosa biofilm formation. • S. officinalis extract successfully removes the mature P. aeruginosa biofilm. • S. officinalis compounds adsorb on the 304L SS and form a protective layer. • Experimental data confirm the MIC mitigation by the extract. [ABSTRACT FROM AUTHOR]

Sulfate-reducing bacterium Desulfovibrio vulgaris promoted the microbiologically influenced corrosion (MIC) of CoCrFeMnNi high entropy alloy (HEA) and led to pitting corrosion. D. vulgaris caused the formation of metal sulfides and thinning of passive film. The corrosion resistance decreased, and pit depths increased when the carbon source reduced to 40%. The relative expression of hydrogenase genes hydA and hydB in the biofilms under 40% carbon source significantly increased, indicating that the indirect electron transfer mediated by 2H+/H 2 might play an important role in promoting the HEA MIC by D. vulgaris under starvation. • Desulfovibrio vulgaris promotes CoCrFeMnNi HEA MIC and causes pitting corrosion. • The presence of D. vulgaris causes the thinning of HEA passive film. • In the starved 40% carbon source level, D. vulgaris leads to more aggressive HEA MIC. • Two hydrogenase genes (hydA and hydB) upregulate in the starvation condition. • The indirect electron transfer mediated by 2H+/H 2 may play an important role in starvation. [ABSTRACT FROM AUTHOR]

In this work, microbial corrosion behavior of Ti-6Al-4V (TC4) alloy caused by electroactive Desulfovibrio ferrophilu s biofilm in enriched artificial seawater containing soluble electron shuttle was investigated. The addition of riboflavin-shuttle did not significantly change the planktonic and sessile cell counts but accelerated the microbiologically influenced corrosion of TC4 alloy. The Hilbert-Huang transform revealed the evolution of corrosion pits and the maximum pit depth enhanced with the increase of electron shuttle concentration. Electrochemical measurements proved that riboflavin-shuttle decreased the shuttled electron barrier and increased the anodic dissolution rate. Phase, organization and grain size of alloy were influenced by the MIC. • Ti-6Al-4 V (TC4) is not immune to Desulfovibrio ferrophilus. • Electron shuttle advances the transition of TC4 corrosion pits from metastable to stable state. • Rapid response of D. ferrophilus biofilms to riboflavin shuttle injection. • SRB-MIC decreases the α phase of the alloy. [ABSTRACT FROM AUTHOR]

• More Fe2+ leads to better planktonic and sessile Desulfovibrio vulgaris growth. • More Fe2+ increases dissolved H 2 S concentration despite increased FeS precipitation. • More Fe2+ in the culture medium increases carbon steel weight loss and pit depth. • With more Fe2+, increased corrosion is primarily attributed to more sessile cells. • Electrochemical measurements corroborate weight loss and pit depth data. Ferrous ion (Fe2+) in a sulfate reducing bacteria (SRB) culture medium is known to enhance microbiologically influenced corrosion (MIC) of carbon steel, but the underlining mechanism is controversial. This work showed that it was due to better sessile cell growth that was likely attributed to Fe2+ detoxification of H 2 S. Two hundred ppm (w/w) initial Fe2+ in the ATCC 1249 medium achieved a 4.7 times higher Desulfovibrio vulgaris sessile cell count and 5.0 times higher C1018 carbon steel weight loss, compared to 20 ppm. Linear polarization resistance, electrochemical impedance spectroscopy and potentiodynamic polarization measurements corroborated weight loss and pitting data trends. [ABSTRACT FROM AUTHOR]

Highlights • B-PAMFC fulfills wastewater treatment, CO 2 sequestration and bioenergy production. • B-PAMFC performed better than PAMFC in power density and CO 2 fixation rate. • Algal biofixation combined with solution absorption enhances CO 2 sequestration. • Urea as nitrogen source promoted the power generation and CO 2 sequestration. • B-PAMFC is an energy-positive system with a maximum net energy of 1.824 kWh m−3. Abstract This study developed a bubbling-type photosynthetic algae microbial fuel cell (B-PAMFC) to treat synthetic wastewater and capture CO 2 using Chlorella vulgaris with simultaneous power production. The performance of B-PAMFC in CO 2 fixation and bioenergy production was compared with the photosynthetic algae microbial fuel cell (PAMFC) and bubbling photobioreactor. Different nitrogen sources for C. vulgaris growth, namely sodium nitrate, urea, ammonium acetate and acetamide were studied. The maximum CO 2 fixation rate in B-PAMFC with 2.8 g L−1 urea reached 605.3 mg L−1 d−1, 3.86-fold higher than that in PAMFC. Urea also enhanced the solution absorption of CO 2. Furthermore, the B-PAMFC reached a high lipid productivity of 105.9 mg L−1 d−1. An energy balance analysis indicated that B-PAMFC had a maximum net energy of 1.824 kWh m−3, making it a lab-scale energy-positive system. The B-PAMFC with urea as nitrogen source would provide an attractive strategy for simultaneous CO 2 sequestration and bioenergy production. [ABSTRACT FROM AUTHOR]

Highlights • D. vulgaris is pre-grown on C1018 carbon steel coupons before the starvation test. • Carbon source starvation weakens the SRB biofilm but still increases weight loss. • Weight loss is 6.6 mg/cm2 for 20% carbon source vs. 3.3 mg/cm2 for 100% after 10 d. • Pit depth and electrochemical measurement data corroborate weight loss trend. • Iron corrosion by SRB belongs to extracellular electron transfer MIC (EET-MIC). Abstract Microbiologically influenced corrosion (MIC) of carbon steel by sulfate reducing bacterium (SRB) Desulfovibrio vulgaris under organic carbon starvation was investigated using electrochemical methods to support weight loss and pitting data. 20% carbon source led to the highest weight loss (6.6 mg/cm2), while 100% had the lowest (3.3 mg/cm2) after 10 days. Linear polarization resistance and electrochemical impedance spectrometry data confirmed the weight loss and pitting data trends. The data in this work support the theory that carbon steel corrosion by SRB is due to electron harvest from extracellular iron oxidation by SRB, which belongs to extracellular electron transfer MIC (EET-MIC). [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Molecular simulation confirms that sodium pyrithione (SPT) inhibits iron corrosion. • SPT is found to inhibit planktonic and sessile sulfate reducing bacteria (SRB). • SRB corrosion rate in simulated oilfield produced water is reduced by SPT. • SRB corrosion weight loss data are corroborated by electrochemical measurements. Abstract Anti–bacterial and anti–corrosion properties of sodium pyrithione (SPT) were studied using experimental methods and quantum chemical calculations. SPT at 80 mg/L reduced planktonic and sessile sulfate reducing bacteria (SRB) on X80 carbon steel to undetectable levels. The corrosion inhibition efficiency of SPT against microbiologically influenced corrosion exceeded 80% based on weight loss, which was corroborated by electrochemical data. Molecular modeling showed that SPT molecule provided electrons to the unoccupied orbitals of the Fe surface with a large binding energy of SPT on the Fe (1 1 0) plane, which favored SPT adsorption on the carbon steel. [ABSTRACT FROM AUTHOR]