Mercury-resistant Bacteria Research Articles

Simultaneous removal of elemental mercury and NO by mercury induced thermophilic community in membrane biofilm reactor

Thermophilic membrane biofilm reactor (TMBR) for elemental mercury (Hg0) and NO removal in simulated flue gas was investigated at oxygen content of 6% and 60 °C. The performance, the microbial community structures, gene function and the mechanism for Hg0 and NO removal in the TMBR were evaluated. TMBR achieved effective simultaneous Hg0 and NO removal in 210 days of operation, Hg0 and NO removal efficiency were up to 88.9% and 85.3%, respectively. Mercury induced thermophilic community had been formed significantly. Comamonas, Pseudomonas, Desulfomicrobium, Burkholderia and Halomonas were thermophilic mercury resistant bacteria. Brucella, Paracoccus, Tepidiphilus, Proteobacteria, Pseudomonas and Symbiobacterium were nitrifying/denitrifying genera, and had functional genes of mercury and nitrogen metabolism, as shown by16S rDNA and metagenomic sequencing. The biofilm in TMBR was characterized by XPS, HPLC. XPS and HPLC spectra indicate the formation of a mercuric species (Hg2+) from mercury oxidation. TMBR used oxygen as electron acceptor, NO and Hg0 as electron donor in nitrification; O2, NO and NO3− could be used as electron acceptor and Hg0 as electron donor in denitrification.

Isolation and characterization of mercury-resistant bacteria from wastewater sources in Egypt.

An important mechanism for microbial resistance to mercury is its reduction into elemental mercury (facilitated by the merA gene). Thirty-eight microbial isolates from a variety of wastewater sources in Egypt were collected. Approximately 14 of the 38 isolates exhibited not only a high degree of tolerance to mercury (up to 160 ppm) but also a high degree of resistance to other tested heavy metals (Cu, Co, Ni, and Zn). From these 14, the 10 most resistant isolates were selected for further study and were found to include 9 Gram-negative and 1 Gram-positive bacterial strains. Multi-antibiotic-resistance profiles were detected for 6 out of the 10 selected isolates. All the tested Gram-negative isolates (n = 9) harbored a plasmid-encoded merA gene. The mercury removal effectiveness for the 10 selected isolates ranged between 50% and 99.9%, among which Stenotrophomonas maltophilia ADW10 recorded the highest rate (99.9%; at an initial mercury concentration of 20 ppm). To the best of our knowledge, this is the first study to (i) demonstrate the presence of a multimetal-resistant S. maltophilia bacterium with a high mercury tolerance capacity that would make it a suitable candidate for future bioremediation efforts in heavy-metal-polluted areas in Egypt and (ii) report Pseudomonas otitidis as one of the mercury-resistant bacteria.

Isolation and characterization of mercury-resistant bacteria from industrial wastewater

Isolation and characterization of mercury-resistant bacteria from industrial wastewater

Potential of Organic Mercury-resistant Bacteria Isolated from Mercury Contaminated Sites for Organic Mercury Remediation.

Efforts at organic mercury detoxification can be carried out using resistant bacteria that can live in an environment contaminated with the compound. This study aimed at isolating and identifying resistant bacteria from mercury-contaminated environments and analysing their ability to detoxify organic mercury. Soil samples were obtained from 3 gold processing locations that make use of mercury in Tanoyan Village, Bolaang Mongondow district, North Sulawesi province. The identification was carried out on the mercury-resistant bacteria through morphological and molecular tests. Bacteria which were highly resistant to mercury were examined for their ability to detoxify phenyl mercury (organic mercury). The study showed that 8 mercury-resistant bacterial colonies could be isolated from the three soil samples. The bacteria were able to grow in LB broth containing 10 mg L-1 of phenyl mercury. Four isolates (AA, BB, CC and DD) were even able to grow in 40 mg L-1 of phenyl mercury. According to the identification tests, those bacteria were Pseudomonas sp. (AA, DD), Pseudomonas aeruginosa (BB) and Proteus mirabilis (CC). Testing of organic mercury against isolates of bacteria which are highly resistant to it in order to determine their detoxification capacity revealed that all four isolates could reduce levels of the compound in media, based on the results, starting from the highest was Pseudomonas sp. 74.99%, then Pseudomonas aeruginosa 60.23% and Proteus mirabilis 47.59% after 24 h of incubation. The study suggested that there are four bacteria that have potentials to remediate organic mercury contamination sites.

Simultaneous mercury oxidation and NO reduction in a membrane biofilm reactor

This work demonstrates bacterial oxidation of mercury (Hg0) coupled to nitric oxide (NO) reduction in a denitrifying membrane biofilm reactor (MBfR). In 93 days' operation, Hg0 and NO removal efficiency attained 90.7% and 74.1%, respectively. Thauera, Pseudomonas, Paracoccus and Pannonibacter played dual roles as Hg0 oxidizers and denitrifiers simultaneously. Denitrifying bacteria and the potential mercury resistant bacteria dominated the bacterial community. Denitrification-related genes (norB, norC, norD, norE, norQ and norV) and enzymatic Hg0 oxidation-related genes (katG, katE) were responsible for bacterial oxidation of Hg0 and NO reduction, as shown by metagenomic sequencing. XPS, HPLC-ICP-MS and SEM-EDS indicated the formation of a stable mercuric species (Hg2+) reasulting from Hg0 oxidation in the biofilm. Bacterial oxidation of Hg0 was coupled to NO reduction in which Hg0 served as the initial electron donor while NO served as the terminal electron acceptor and thereby redox between Hg0 and NO was formed. MBfR was capable of both Hg0 bio-oxidation and denitrifying NO reduction. This research opens up new possibilities for application of MBfR to simultaneous flue gas demercuration and denitration.

The potential of mercury resistant purple nonsulfur bacteria as effective biosorbents to remove mercury from contaminated areas

Abstract This study aimed to investigate the possibility to remove mercury (Hg) using the live or dead biomass of Hg resistant purple nonsulfur bacteria (PNSB) for their potential application to clean up shrimp ponds and during cultivation. The efficiency of Hg2+ removal by three PNSB strains; Rhodovulum sulfidophilum SRW1–5, and Afifella marina strains SSS2-1 and SSW15-1, grown with 2 different growth conditions (microaerobic light and aerobic dark conditions) were tested (2 mg/L HgCl2, 4.5 mg dry cell weight/mL, 30 min). It was found that the efficiency to remove Hg2+ by the dead cells of all strains was significantly higher than for live cells; and the most effective strain was SSS2-1. The highest Hg2+ removal under the optimum conditions using a 4 mg/L initial HgCl2 concentration by live and dead cells grown with both incubation conditions were approximately 87% and 95%, respectively. Under both incubation conditions, Hg2+ biosoption by strain SSS2-1 fitted the Freundlich model for live cells and the Langmuir model for dead cells. The kinetics of Hg2+ biosorption by both cell types of strain SSS2-1 suggests the process as a pseudo-second order kinetic model. This study demonstrates that biomass of the strain SSS2-1 has great potential for its biosorption to remove Hg2+ from contaminated areas like shrimp ponds.

Profil Protein Isolat Bakteri Resisten Merkuri Dari Pertambangan Emas Rakyat Di Desa Pongkor, Bogor-Jawa Barat, Indonesia

Mercury pollution due to gold mining at Pongkor Village can threaten the life of organisms because mercury is toxic. Bioremediation can be considered to reduce mercury concentration in the water. The mercury-resistant bacteria can be isolated from the area and may be developed as mercury bioremediation agents. This study aims to isolate mercury-resistant bacteria, test their resistance to mercury, and conduct protein profile studies after mercury induction. The mercury-resistant bacteria were isolated from soil samples in the Pongkor Village gold mining area and the isolate resistance to HgCl2 was measured based on the Minimum Inhibitory Concentration (MIC) value. The protein profile was analyzed using SDS PAGE gel electrophoresis. The results showed that two of the most resistant bacterial isolates to mercury were HgP1 and HgP2 with MIC value was 575 ppm. The protein profile showed that mercury induced decreased protein synthesis under normal conditions and increased synthesis of one protein suspected to play a role in the mechanism of bacterial resistance to mercury.

Removal of contaminants of emerging concern (CECs) and antibiotic resistant bacteria in urban wastewater using UVA/TiO2/H2O2 photocatalysis

The dispersion of pollutants and proliferation of antibiotic resistant bacteria in the aquatic environment are an emerging health concern worldwide. In this sense, it is essential to develop new technologies to increase the quality of wastewater treatment, which is spread throughout the environment. The present study has demonstrated evidence of the existence of antibiotic and mercury-resistant bacteria in the aquatic environment. The application of heterogeneous photocatalysis with UVA/TiO2 P25 slurry (200 mg L−1), UVA/TiO2-immobilized, and UVA/TiO2-immobilized/H2O2 were evaluated for the simultaneous elimination of a mixture of contaminants of emerging concern (acetamiprid (ACP), imazalil (IMZ) and bisphenol A (BPA)) and inactivation of antibiotic and mercury-resistant bacteria (Pseudomonas aeruginosa and Bacillus subtilis). UVA/TiO2-immobilized/H2O2 increased the inactivation and elimination of the contaminants. After the combined treatment, the mixture of BPA, IMZ and ACP decreased 62%, 21% and <5%, respectively, after 300 min at 13.10 kJ L−1 of accumulated UV energy. The Pseudomonas aeruginosa strain was inactivated after 120 min using 5.24 kJ L−1 of accumulated UV energy, whereas the Bacillus subtilis strain was shown to be extremely resistant, with a capacity to develop mechanisms to avoid the oxidation process.

Assessment of the bioremediation efficacy of the mercury resistant bacterium isolated from the Mithi River

Abstract The contamination of natural resources with mercury has gained attention due to its high toxicity to all life forms. Bioremediation of mercury using bacteria is a useful technique to remediate mercury contamination. In the present study mercury resistant bacteria (MRB) were isolated from Mithi River water samples. Total heterotrophic bacteria (THB) and MRB present in the Mithi river water samples were enumerated. The count for THB was found to be 3.7 × 106 CFU/ml. MRB enumerated in the nutrient agar medium with mercury concentrations of 50, 100 and 150 ppm had counts of 2.8 × 106, 9.1 × 105 and 5.8 × 104 CFU/ml, respectively. The minimum inhibitory concentration (MIC) of the isolated bacterium was found to be around 500 ppm of mercury, and it was selected for further analysis. The bacterial isolate was found to tolerate a wide range of salt concentrations from 5 to 35 ppt of NaCl. The bacterial isolate was characterized by using standard biochemical tests and identified by using the 16S rDNA technique. Homology analysis of the 16S rDNA gene has confirmed the identity of the bacterium as Bacillus thuringiensis strain RGN1.2 with NCBI accession no. KX832953.1. It could remove 96.72%, 90.67% and 90.10% of mercury in 48 hours at 10, 25 and 50 ppm of mercury.

Mercury bioremediation by mercury resistance transposon-mediated in situ molecular breeding.

Mercury-resistant (HgR) bacteria occur in various bacterial species from a wide variety of environmental sources. Resistance is conferred by a set of operon genes termed the mer operon. Many HgR bacteria have been isolated from diverse environments and clinical samples, and it is recognized that mer operons are often localized on transposons. Previous research reports have suggested that HgR transposons participate in the horizontal gene transfer of mer operons among bacteria. This was confirmed by a study that found that mer operons were distributed worldwide in Bacilli with dissemination of TnMERI1-like transposons. In this mini review, possible strategies for transposon-mediated in situ molecular breeding (ISMoB) of HgR bacteria in their natural habitat are discussed. In ISMoB, the target microorganisms for breeding are indigenous bacteria that are not HgR but that are dominant and robust in their respective environments. Additionally, we propose a new concept of bioremediation technology for environmental mercury pollution by applying transposon-mediated ISMoB for environmental mercury pollution control.

Biochemical Properties of Mercuric Reductase from Local Isolate of Bacillus sp for Bioremediation Agent

Mercuric reductase is the important enzyme which catalyzes a reduction of a toxic Hg2+ to non-toxic Hg0. The enzyme which has been potentially used as mercury bioremediation agent is produced by mercury resistant bacteria. These research aims are to determinate the resistance level of a local Bacillus sp to HgCl2 in media, to determine the mercuric reductase activity from the bacteria, and to determine the biochemical properties of the mercuric reductase. The Bacillus sp was grown in the Nutrient Broth media with various of 0; 20; 40; 60; 120; and 160 µM HgCl2 to know the response of the bacteria against mercury, The cell growth of Bacillus sp was measured by optical density (OD) method of at λ 600 nm. The mercuric reductase activity was assayed in the solution of MRA (Mercury Reductase Assay), then the oxidized NADPH was observed by the spectrophotometry method at λ340 nm. The result showed that the Bacillus sp has been resistant to media containing mercury at 120 µM, but the microbial growth was decreased by 50% in media containing mercury 80 µM. The Bacillus sp could produce highly the mercuric reductase enzyme at 16 hours of growth time with enzyme activity as 0.574 Unit/µg. The mercuric reductase from the bacteria has an optimum activity at pH 6 and temperature 37 °C

Mercuric resistant bacteria Aeromonas exhibits neurologic toxic effects on the developmental motor reflexes, and brain oxidative stress in mice offspring

Mercury and its derivatives even in small concentration may cause a major human health problem. Though not reported in detail, there are various aquatic bacterial species that produce small quantities of methyl mercury (MM) growing under aerobic conditions. Consumption of food derived from sources contaminated with such bacteria within therapeutic doses and exposure to different forms of MM compounds through such sources may induce substantial toxic effects. In the present study, the perinatal oral exposure of pregnant mice to two strains of mercury resistant bacteria (MRB), Aeromonas KSU5 MRB and KSU6 MRB resulted in a significant reduction in postnatal body weight gain, delays in the opening of the eyes and appearance in the body hair fuzz, and deficits in the developing sensory motor reflexes in the mice pups during their weaning period on post-natal day (PD)7, PD14 and PD21. A significant and MM producing concentration-dependent disturbance in the levels of neurotransmitters like dopamine (DA) and serotonin (5-HT); non-enzymatic oxidative stress (OS) indices like thiobarbituric acid-reactive substances (TBARS) and total reduced glutathione (GSH); and enzymatic OS indices like glutathione S-transferase (GST), catalase (CAT), and superoxide dismutase (SOD) were observed in the forebrain region of the offspring at weaning period (PD7, PD14, and PD21), at adolescent age (PD30), and at adult age (PD36). Thus, perinatal exposure to MRB can affect developing fetus, raising the concerns for it's potential neurotoxic hazards. A reduced exposure to mercury during pregnancy is of crucial importance in preventing mercury-induced neurotoxicity in the offspring.

Functional efficiency of MerA protein among diverse mercury resistant bacteria for efficient use in bioremediation of inorganic mercury

MerA protein of mer operon in mercury resistant bacteria influences transformation of Hg2+ to Hg0. Both in-silico and in-vivo studies have been carried out and MerA sequences, conserved motifs for mercury binding and NADPH (GCVPSK and LSCCA) varied widely in both Gram-positive and Gram-negative bacteria. As MerA-NADPH-FAD complex plays an important role in mercury volatilization, molecular interaction studies between MerA, NADPH, FAD and Hg2+ was carried out to study the efficiency of transformation of Hg2+ to Hg0 in mercury resistant bacteria. After the prediction of suitable models and molecular interaction analysis, the potential energies in the selected bacteria were as follows: Bacillus thuringiensis (NADPH: −5.15 kcal/mol and FAD: −9.63 kcal/mol), Pseudomonas aeruginosa (NADPH: −3.8 kcal/mol and FAD: −8.56 kcal/mol), Exiguobacterium sp. (NADPH: −3.37 kcal/mol and FAD: −8.42 kcal/mol), Vibrio sp. (NADPH: −3.3 kcal/mol and FAD: −6.7 kcal/mol) and Escherichia coli (NADPH: −3.28 kcal/mol and FAD: −5.69 kcal/mol). Additionally, the binding scores between MerA and Hg2+ followed the similar trend and found higher in B. thuringiensis (3.79) followed by P. aeruginosa (3.57), Exiguobacterium sp. (2.37), Vibrio sp. (1.47) and E. coli (1.07). ANOVA (2-way) result showed the significant (P < 0.05) variation among the energy values obtained after interaction studies. In-vivo analysis of expression of merA gene and Hg2+ removal efficiency also followed the same pattern with a highly significant correlation (P < 0.001) between the binding energy, binding score and expression pattern of merA gene as well as Hg2+ volatilization. Thus, the mercury removal efficiency of bacteria is genera specific which is correlated with the binding efficiency between MerA-NADPH complex and Hg2+ in mer operon mediated mercury resistant bacteria.

Expression and Purification of Transmembrane Protein MerE from Mercury-Resistant Bacillus cereus.

Mercury-resistant (HgR) bacteria were isolated from heavy metal polluted wastewater and soil collected near to tanneries of district Kasur, Pakistan. Bacterial isolates AZ-1, AZ-2 and AZ-3 showed resistance up to 40 μg/ml against mercuric chloride (HgCl2). 16S rDNA ribotyping and phylogenetic analysis were performed for the characterization of selected isolates as Bacillus sp. AZ-1 (KT270477), Bacillus cereus AZ-2 (KT270478) and Bacillus cereus AZ-3 (KT270479). Phylogenetic relationship on the basis of merA nucleotide sequence confirmed 51- 100% homology with the corresponding region of the merA gene of already reported mercuryresistant Gram-positive bacteria. The merE gene involved in the transportation of elemental mercury (Hg0) via cell membrane was cloned for the first time into pHLV vector and transformed in overexpressed C43(DE3) E. coli cells. The recombinant plasmid (pHLMerE) was expressed and the native MerE protein was obtained after thrombin cleavage by size exclusion chromatography (SEC). The purification of fusion/recombinant and native protein MerE by Ni-NTA column, dialysis and fast protein liquid chromatography (FPLC/SEC) involved unfolding/refolding techniques. A small-scale reservoir of wastewater containing 30 μg/ml of HgCl2 was designed to check the detoxification ability of selected strains. It resulted in 83% detoxification of mercury by B. cereus AZ-2 and B. cereus AZ-3, and 76% detoxification by Bacillus sp. AZ-1 respectively (p < 0.05).

Screening of mercury‐resistant and indole‐3‐acetic acid producing bacterial‐consortium for growth promotion of Cicer arietinum L.

Mercury resistant (HgR ) bacteria were screened from industrial effluents and effluents-polluted rhizosphere soils near to districts Kasur and Sheikhupura, Pakistan. Out of 60 isolates, three bacterial strains, Bacillus sp. AZ-1, Bacillus cereus AZ-2, and Enterobacter cloacae AZ-3 showed Hg-resistance as 20 μg ml-1 of HgCl2 and indole-3-acetic acid (IAA) production as 8-38 μg ml-1 . Biochemical and molecular characterization of selected bacteria was confirmed by 16S ribotyping. Mercury resistant genes merA, merB, and merE of mer operon in Bacillus spp. were checked by PCR amplification. The merE gene involved in the transportation of elemental mercury (Hg0 ) via cell membrane was first time cloned into pHLV vector and transformed in C43(DE3) Escherichia coli cells. The recombinant plasmid (pHLMerE) was expressed and purified by nickel (Ni+2 ) affinity chromatography. Chromatographic techniques viz. thin layer chromatography (TLC), high performance liquid chromatography (HPLC), and Gas chromatography-mass spectrometry (GC-MS) confirmed the presence of Indole-3-acetic acid (IAA) in supernatant of selected bacteria. The strain E. cloacae AZ-3 detoxified 88% of mercury (Hg+2 ) from industrial effluent (p < 0.05) after immobilization in Na-alginate beads. Finally, Hg-resistant and IAA producing bacterial consortium of two strains, Bacillus sp. AZ-1 and E. cloacae AZ-3, inoculated in mercury amended soil with 20 μg ml-1 HgCl2 resulted 80, 22, 64, 116, 50, 75, 30, and 100% increase as compared to control plants in seed germination, shoot and root length, shoot and root fresh weight, number of pods per plant, number of seeds and weight of seeds, respectively, of chickpea (Cicer arietinum L.) in pot experiments (p < 0.05).

RESISTANCE LEVEL OF Pseudomonas stutzeri AGAINST MERCURY AND ITS ABILITY IN PRODUCTION OF MERCURY REDUCTASE ENZYME

Mercury reductase is an enzyme that is able to reduce Hg2+ to Hg0 non toxic. This enzyme is usually produced by mercury resistant bacteria. The research wanted to determine the resistance of indigenous Pseudomonas stutzeri isolate toward mercury and to explore the mercury reductase activity which is produced by the bacteria. The results of resistance assay of the Pseudomonas stutzeri toward mercury ion showed that the isolate could survive in media containing HgCl2 up to a concentration of 80 µM. The bacteria could produce mercury reductase optimally at the 24th of fermentation time. The enzyme showed optimum activity at pH 7 and temperature of 45 oC

Aktivitas Reduksi Merkuri pada Bakteri yang Diisolasi dari Air dan Sedimen di Sungai Musi

This study aims to isolate mercury resistant bacteria from water and sediment in Pulau Salah Nama which located on the River Musi Palembang, characterized mercury resistant bacteria growing at the highest concentration of HgCl2 and test the power of these bacteria in reducing mercury. The research was conducted from June 2015 until September 2015 using experimental methods laboris and descriptive data analysis. Reasecrh consissted of several stages, including sampling, bacterial isolation, characterization to determine the type of bacteria and mercury reducing power of bacteria. Isolation of bacteria produced 10 isolates. A1 was bacteria isolated from water and A2 was bacteria isolated from sediment. From 10 isolates selected 2 isolates of the higest concentration of HgCl2. Selected isolate A1 have the lowest mercury reduction power of 39.26% and selected isolate A2 have the highest mercury reduction power of 65.93%. In control medium without inoculant a decline in mercury concentration of 39.44%. Based on the characterization of the bacteria biochemical activity known A1 and A2 were Bacillus subtilis

Identification by MALDI-TOF Mass Spectrometry of Mercury-resistant Bacteria Associated with the Rhizosphere of an Apple Orchard

ABSTRACTIn this work, mercury-resistant bacterial strains were isolated from the rhizosphere of an apple orchard, growing in a soil with high levels of mercury (Nuevo San Joaquin, Queretaro State, Mexico). Analysis of the soil in this region by the Cold Vapor Atomic Absortion Spectroscopy method showed that it contained 637 ± 51 mg mercury per kg. Mercury accumulation by fresh apples from this orchard amounted to 15.44 ± 4.33 mg/kg. The bacterial isolates were identified by application of proteomic technique of matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). They were found to be strains of Bacillus muralis and Bacillus simplex. All strains showed the ability to catalyze the volatilization of Hg as measured via the nonradioactive X-ray method. In all strains merR and merA genes were detected by polymerase chain reaction. Nucleotide sequence analysis showed that merR from B. simplex was 435 bp in length and that its sequence was similar to merR sequences reported for other bacteria such as Cupriavidus, Ralstonia, Pseudomonas and Serratia. To our knowledge, this is the first report of mercury-resistant Bacillus strains isolated from the rhizosphere of an apple orchard and the first merR gene sequence from such Bacilli.

Mercury resistance transposons in Bacilli strains from different geographical regions.

A total of 65 spore-forming mercury-resistant bacteria were isolated from natural environments worldwide in order to understand the acquisition of additional genes by and dissemination of mercury resistance transposons across related Bacilli genera by horizontal gene movement. PCR amplification using a single primer complementary to the inverted repeat sequence of TnMERI1-like transposons showed that 12 of 65 isolates had a transposon-like structure. There were four types of amplified fragments: Tn5084, Tn5085, Tn(d)MER3 (a newly identified deleted transposon-like fragment) and Tn6294 (a newly identified transposon). Tn(d)MER3 is a 3.5-kb sequence that carries a merRETPA operon with no merB or transposase genes. It is related to the mer operon of Bacillus licheniformis strain FA6-12 from Russia. DNA homology analysis shows that Tn6294 is an 8.5-kb sequence that is possibly derived from Tn(d)MER3 by integration of a TnMERI1-type transposase and resolvase genes and in addition the merR2 and merB1 genes. Bacteria harboring Tn6294 exhibited broad-spectrum mercury resistance to organomercurial compounds, although Tn6294 had only merB1 and did not have the merB2 and merB3 sequences for organomercurial lyases found in Tn5084 of B. cereus strain RC607. Strains with Tn6294 encode mercuric reductase (MerA) of less than 600 amino acids in length with a single N-terminal mercury-binding domain, whereas MerA encoded by strains MB1 and RC607 has two tandem domains. Thus, Tn(d)MER3 and Tn6294 are shorter prototypes for TnMERI1-like transposons. Identification of Tn6294 in Bacillus sp. from Taiwan and in Paenibacillus sp. from Antarctica indicates the wide horizontal dissemination of TnMERI1-like transposons across bacterial species and geographical barriers.

A Kamikaze Approach for Capturing Hg(2+) Ions through the Formation of a One-Dimensional Metal-Organometallic Polymer.

Efficient uptake of Hg(2+) ions in mercury-resistant bacteria is attributed to the presence of cysteine thiolates in the Mer proteins. In this work, a pyridine-appended pyridine-fused imidazolyl-2-thione scaffold was used as a mimic for the cysteinyl residues for efficient binding of the Hg(2+) ions. In the presence of Hg(2+) ions, an aryl C-H bond of the ligand is activated. The sulfur and nitrogen donors on the other end of the ligand coordinate with a second Hg(2+) ion. This motif in the presence of acetate ions forms a one-dimensional polymeric crystalline network characterized by singal-crystal X-ray diffraction studies. The formation of this polymeric structure leads to efficient removal (∼99%) of Hg(2+) ions from aqueous solutions through an underexplored "kamikaze" approach involving a small-molecule ligand as a sacrificial agent for trapping the ion.