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ANTIBACTERIAL ANTIVIRAL

Polymer Blend Containing MoO3 Nanowires with Antibacterial Activity against Staphylococcus epidermidis ATCC 12228

Antibacterial activity of a polymer nanocomposite containing water-soluble poly(ethylene oxide) (PEO), water insoluble poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP), and MoO3 nanowires or MoO3 microparticles as antibacterial active substances is reported. The UV-vis absorption method was used for the illumination of dissolving of the MoO3 particles of different size and morphology in water. Dissolving of MoO3 nanowires (1 mg ml(-1)) decreases pH bellow 3.6 in only 3 min and below 3 in 15 min, while dissolving of the PEO/PVDF-HFP/MoO3 nanowires coating (5 mg ml(-1)) decreases pH bellow 3.6 in 90 min. These coatings completely destroy the Staphylococcus epidermidis ATCC 12228 bacterial strain within 3 h. The proposed applications are antibacterial protective coatings of contact surfaces.

U. G. Centa, P. Kocbek, 2A. Belcarz, S. D. Skapin, and M. Remskar,Polymer Blend Containing MoO3 Nanowires with Antibacterial Activity against Staphylococcus epidermidis ATCC 12228, Journal of Nanomaterials, 2020, |Article ID 9754024 | https://doi.org/10.1155/2020/9754024.

Effects of cerium and tungsten substitution on antiviral and antibacterial properties of lanthanum molybdate

Powders of cerium (Ce)-substituted and tungsten (W)-substituted La2Mo2O9 (LMO) were prepared using polymerizable complex method. Their antiviral and antibacterial performances were then evaluated using bacteriophage Qβ, bacteriophage Φ6, Escherichia coli, and Staphylococcus aureus. The obtained powders, which were almost single-phase, exhibited both antiviral and antibacterial properties. Effects of dissolved ions on their antiviral activity against bacteriophage Qβ were remarkable. A certain contribution of direct contact to the powder surface was also inferred along with the dissolved ion effect for antiviral activity against bacteriophage Φ6. Dissolved ion effects and pH values suggest that both Mo and W are in the form of polyacids. Antiviral activity against bacteriophage Φ6 was improved by substituting Ce for La in LMO. Similarly to LMO, Ce-substituted LMO exhibited hydrophobicity. Inactivation of alkaline phosphatase enzyme proteins was inferred as one mechanism of the antiviral and antibacterial activities of the obtained powders.

T. Matsumoto, K. Sunada, T. Nagai, T. Isobe, S. Matsushita, H. Ishiguro, and A. Nakajima,Effects of cerium and tungsten substitution on antiviral and antibacterial properties of lanthanum molybdate, Mater Sci Eng C Mater Biol Appl, 2020, 117, 111323.

             

Synergistic antibacterial activity of streptomycin sulfate loaded PEG-MoS2/rGO nanoflakes assisted with near-infrared

Synergistic antibacterial strategies have received growing attention due to their significantly enhanced antibacterial activity. Herein, we demonstrated a synergistic antibacterial strategy based on streptomycin sulfate (SS) loaded polyethylene glycol-MoS2/reduced graphene oxide (PEG-MoS2/rGO) nanoflakes assisted with near-infrared (NIR). The nanoflakes of PEG-MoS2/rGO were ultrasonically exfoliated well from the nanoflowers of PEG-MoS2/rGO fabricated by hydrothermal method, which was of antibacterial activity against Staphylococcus aureus and Escherichia coli after loading of SS. Under the irradiation of NIR, the antibacterial activity was significantly enhanced by the synergistic effects of physical damage, protein synthesis inhibition, thermal injury and oxidative stress. Moreover, the cytotoxicity of the nanoflakes was very low. The results suggest the great potential of PEG-MoS2/rGO-SS as a photothermal antibacterial agent.

X. Zhao, M. Chen, H. Wang, L. Xia, M. Guo, S. Jiang, Q. Wang, X. Li, and X. Yang,Synergistic antibacterial activity of streptomycin sulfate loaded PEG-MoS2/rGO nanoflakes assisted with near-infrared, Materials science & engineering. C, Materials for biological applications, 2020, 116, 111221.

             

Near-Infrared Regulated Nanozymatic/Photothermal/Photodynamic Triple-Therapy for Combating Multidrug-Resistant Bacterial Infections via Oxygen-Vacancy Molybdenum Trioxide Nanodots

Bacterial infections have become a major danger to public health because of the appearance of the antibiotic resistance. The synergistic combination of multiple therapies should be more effective compared with the respective one alone, but has been rarely demonstrated in combating bacterial infections till now. Herein, oxygen-vacancy molybdenum trioxide nanodots (MoO3–x NDs) are proposed as an efficient and safe bacteriostatic. The MoO3–x NDs alone possess triple-therapy synergistic efficiency based on the single near-infrared irradiation (808 nm) regulated combination of photodynamic, photothermal, and peroxidase-like enzymatic activities. Therein, photodynamic and photothermal therapies can be both achieved under the excitation of a single wavelength light source (808 nm). Both the photodynamic and nanozyme activity can result in the generation of reactive oxygen species (ROS) to reach the broad-spectrum sterilization. Interestingly, the photothermal effect can regulate the MoO3–x NDs to their optimum enzymatic temperature (50 °C) to give sufficient ROS generation in low concentration of H2O2 (100 µm). The MoO3–xNDs show excellent antibacterial efficiency against drug-resistance extended spectrum β-lactamases producing Escherichia coli and methicillin-resistant Staphylococcus aureus (MRSA). Animal experiments further indicate that the MoO3–x NDs can effectively treat wounds infected with MRSA in living systems.

Y. Zhang, D. Li, J. Tan, Z. Chang, X. Liu, W. Ma, and Y. Xu,Near-Infrared Regulated Nanozymatic/Photothermal/Photodynamic Triple-Therapy for Combating Multidrug-Resistant Bacterial Infections via Oxygen-Vacancy Molybdenum Trioxide Nanodots, Small, 2020, e2005739.

             

MoO3 ANTIBACTERIAL

In-vitro toxicity of molybdenum trioxide nanoparticles on human keratinocytes

Molybdenum trioxide (MoO3) nanoparticles (NPs) embedded in polymer films have been proposed as a cheap way of producing antibacterial coatings on external surfaces. Recently, we synthesized MoO3 nanowires in a unique shape and degree of anisotropy, which enables their fast water dissolution and quick antimicrobial reaction. Potential human health risks following the exposure to MoO3 NPs however need to be assessed prior their wide use. We therefore, investigated the biological effect of these newly synthesized MoO3 NPs on the human keratinocyte cell line HaCaT, used here as a model for the human skin. Exposure of HaCaT cells to 1 mg/mL MoO3 NPs concentration for 1 h showed no effect on cell survival, had no influence on reactive oxygen species production, expression of proteins involved in antioxidant defense, secretion of pro-inflammatory cytokines, nor induced DNA damage. Interestingly however, ERK and p38 MAP kinases were activated, and upon longer time exposure, induced a moderate release of the pro-inflammatory cytokine interleukin 6, increased DNA damage and increased the level of caspase independent cell death. Our study indicates that exposing HaCaT cells to antibacterial MoO3 NPs water-based solution in durations less than 1 h exhibits no cytotoxicity, but rather triggers cell signalling involved in cell survival and inflammation; which should be taken into consideration when evaluating MoO3 NPs for medical applications.

K. Božinović, D. Nestić, U. G. Centa, A. Ambriović-Ristov, A. Dekanić, L. de Bisschop, M. Remškar, and D. Majhen,In-vitro toxicity of molybdenum trioxide nanoparticles on human keratinocytes, Toxicology, 2020, 444, 152564.

 

ANIMALS

Some toxic metals (Al, As, Mo, Hg) from cow's milk raised in a possibly contaminated area by different sources

Milk can be considered as an indicator of the degree of environmental contamination of the place where it is produced and this is especially important when assessing its content in toxic metals. Therefore, 36 bovine milk samples from 7 farms with a semi-extensive grazing system were analysed, located in Asturias (Spain), in an area with high probability of being highly contaminated due to a mining zone, with important industrial activity and near high-density highway traffic. The samples were lyophilised to achieve total dehydration, further analysed using inductively coupled plasma mass spectrometry (ICP-MS). The metals titrated were aluminium (Al), arsenic (As), moybdenum (Mo) and mercury (Hg) in the lyophilised samples and subsequently extrapolated their values to whole milk. All samples analysed showed levels of Al and Mo above the limit of detection, with mean values of Al of 140.89 +/- 157.07 in liquid milk and 1065.76 +/- 1073.45 in lyophilised milk and Mo of 20.72 +/- 14.61 mug/kg and 152.26 +/- 96.82 mug/kg in whole and lyophilised milk. Only As was detected in four samples with mean values of 18.45 +/- 6.89 and 166.45 +/- 42.30 mug/kg in liquid and lyophilised milk, respectively, and no Hg was found in any of them. In no case do the values found indicate a significant hazard to the population and are in agreement with those found in other investigations. Although the various anthropogenic activities of the area (industrial, mining, traffic density) could, a priori, indicate a possibly contaminated area.

J. R. Gonzalez-Montana, E. Senis, A. J. Alonso, M. E. Alonso, M. P. Alonso, and J. C. Dominguez,Some toxic metals (Al, As, Mo, Hg) from cow's milk raised in a possibly contaminated area by different sources, Environmental science and pollution research international, 2019, 26, 28909-28918.

               

In vivo assessment of moybdenum and cadmium co-induced the mRNA levels of heat shock proteins, inflammatory cytokines and apoptosis in shaoxing duck (Anas platyrhyncha) testicles

Cadmium (Cd) and high dietary intake of moybdenum (Mo) can lead to adverse reactions on animals, but the combined impacts of Mo and Cd on testicle are not clear. To investigate the co-induced toxic effects of Mo and Cd in duck testicles on the mRNA levels of heat shock proteins (HSPs), inflammatory cytokines, and apoptosis. A total of sixty 11-day-old male Shaoxing ducks (Anas platyrhyncha) were randomly divided into 6 groups and testicles were collected on day 120. The mRNA levels of HSPs (HSP60, HSP70, HSP90), inflammatory cytokines (TNF-alpha, NF-kappaB, COX-2), and apoptosis genes (Bcl-2, Bak-1, Caspase-3) were determined by real-time quantitative polymerase chain reaction (RT-qPCR), meanwhile the changes of ultrastructural were evaluated. The results showed HSPs mRNA levels were increased in high Mo and Cd groups, however, they were decreased in high dose Mo and Cd co-treated group. In all treatment groups, the mRNA levels of Bak-1 and Caspase-3 were upregulated, and Bcl-2 mRNA level was downregulated, especially in combination groups. The TNF-alpha, NF-kappaB, and COX-2 expression in co-exposure groups were higher than those in single groups. Furthermore, the ultrastructural changes showed nuclear deformation, mitochondria hyperplasia and cristaes rupture, and vacuolation in combination groups. Changes of all above factors indicated a possible synergistic relationship between the two elements, and the high expression of HSPs and inflammatory cytokines may play a role in the resistance of testicles toxicity induced by Mo or Cd or both.

X. Dai, G. Nie, H. Cao, C. Xing, G. Hu, and C. Zhang,In vivo assessment of moybdenum and cadmium co-induced the mRNA levels of heat shock proteins, inflammatory cytokines and apoptosis in shaoxing duck (Anas platyrhyncha) testicles, Poultry science, 2019, 98, 5424-5431.

Adsorption toward Cu(II) and inhibitory effect on bacterial growth occurring on molybdenum disulfide-montmorillonite hydrogel surface

Novel molybdenum disulfide-montmorillonite (MoS2)@2DMMT) hydrogels for Cu(II) removal and inhibition on bacterial growth were successfully prepared.MoS2 was first in-situ growth onto 2DMMT platelet through hydrothermal method and then cross-linked with organic reagents to form hydrogels. The flower-like structure of synthesizedMoS2 could be clearly observed inMoS2@2DMMT by SEM. The synthesized hydrogels possessed a three-dimensional macroporous structure, offering a free access for contaminants to get inside and combine with the active sites. Adsorption tests revealed that efficient Cu(II) removal (65.75 mg/g) could be achieved within a short time (30 min) at pH 5. The pseudo-second-order kinetics model and Langmuir isotherm model indicated the existence of chemisorption and monolayer absorption for Cu(II) ontoMoS2@2DMMT hydrogels. Characterizations of EDS and XPS indicated that Cu(II) reacted with groups of carboxyl, hydroxyl and amidogen. Bacteriostatic tests revealed that almost a complete bacteriostatic was achieved with just small dosage (0.8 mg/mL) ofMoS2@2DMMT hydrogels after the Cu(II) removal under the normal illumination. The mechanism was ascribed to the destructive effect of Cu(II) to the cytomembrane and the damage of reactive oxygen species (ROS) to the DNA. Such hydrogel not only provided insights for treating co-existing contaminates, but also guides for designing novel polymer materials from two-dimensional (2D) nano-materials.

W. Wang, T. Wen, H. Bai, Y. Zhao, J. Ni, L. Yang, L. Xia, and S. Song,Adsorption toward Cu(II) and inhibitory effect on bacterial growth occurring on molybdenum disulfide-montmorillonite hydrogel surface, Chemosphere, 2020, 248, 126025.

Unvealing the role of beta-Ag2MoO4 microcrystals to the improvement of antibacterial activity

Crystal morphology with different surfaces is important for improving the antibacterial activity of materials. In this experimental and theoretical study, the antibacterial activity of beta-Ag2MoO4 microcrystals against the Gram-positive bacteria, namely, methicillin-resistant Staphylococcus aureus (MRSA), and the Gram-negative bacteria, namely, Escherichia coli (E. coli), was investigated. In this study, beta-Ag2MoO4 crystals with different morphologies were synthesized by a simple co-precipitation method using three different solvents. The antimicrobial efficacy of the obtained microcrystals against both bacteria increased according to the solvent used in the following order: water < ammonia < ethanol. Supported by experimental evidence, a correlation between morphology, surface energy, and antibacterial performance was established. By using the theoretical Wulff construction, which was obtained by means of density functional calculations, the morphologies with large exposition of the (001) surface exhibited superior antibacterial activity. This study provides a low cost route for synthesizing beta-Ag2MoO4 crystals and a guideline for enhancing the biological effect of biocides on pathogenic bacteria by the morphological modulation.

C. C. De Foggi, R. C. De Oliveira, M. Assis, M. T. Fabbro, V. R. Mastelaro, C. E. Vergani, L. Gracia, J. Andres, E. Longo, and A. L. Machado,Unvealing the role of beta-Ag2MoO4 microcrystals to the improvement of antibacterial activity, Materials Science & Engineering C-Materials for Biological Applications, 2020, 111, 110765.

 

BACTERIA

BACTERIAL AND ANTIBACTERIAL

Biocompatible MoS2/PDA-RGD coating on titanium implant with antibacterial property via intrinsic ROS-independent oxidative stress and NIR irradiation

To inhibit bacterial infection in situ and improve osseointegration are essentially important for long-term survival of an orthopedic implant, in particular for infection-associating revision surgery. Herein, we fabricate a functional moybdenum disulfide (MoS2)/polydopamine (PDA)-arginine-glycine-aspartic acid (RGD) coating on titanium (Ti) implant to address above concerns simultaneously. The coating not only improved the osteogenesis of mesenchymal stem cells (MSCs), but also endowed Ti substrates with effective antibacterial ability when exposing to near-infrared (NIR) irradiation. It accelerated glutathione (GSH) oxidation via photothermal energy and induced intrinsic ROS-independent oxidative stress damage deriving from MoS2 nanosheets. The results displayed that RGD-decorated MoS2 nanosheets significantly increased the cellular osteogenic behaviors of MSCs via up-regulating osteogenesis-related genes (ALP, Runx2, Col I and OCN) in vitro. Moreover, the functionalized Ti substrates demonstrated great antibacterial efficiency of over 92.6% inhibition for S. aureus and E. coli under NIR-irradiation. Hyperthermia induced by photothermal effect accelerated the GSH consumption and ROS-independent oxidative stress destroyed the integrity of bacteria membranes, which synergistically led to protein leakage and ATP decrease. Furthermore, co-culture experiment showed that S. aureus contamination was efficiently cleaned from MoS2/PDA-RGD surface after NIR photothermal treatment, while MSCs adhered and proliferated on the MoS2/PDA-RGD surface. In an S. aureus infection model in vivo, MoS2/PDA-RGD modified Ti rods killed bacteria with an efficiency of 94.6% under NIR irradiation, without causing damage to normal tissue. More importantly, the MoS2/PDA-RGD modified Ti implants accelerated new bone formation in comparison with TNT implants in vivo.

Z. Yuan, B. Tao, Y. He, J. Liu, C. Lin, X. Shen, Y. Ding, Y. Yu, C. Mu, P. Liu, and K. Cai,Biocompatible MoS2/PDA-RGD coating on titanium implant with antibacterial property via intrinsic ROS-independent oxidative stress and NIR irradiation, Biomaterials, 2019, 217, 119290.

               

Antibacterial activity and cytotoxicity of novel silkworm-like nisin@PEGylated MoS2

Recently, moybdenum disulfide functionalized with poly-ethylene glycol (PEGylated MoS2) has been widely used as a new drug delivery vehicle in biomedical field. However, the weak antibacterial activity of PEGylated MoS2 limits its application as an antibacterial agent. In this work, a novel silkworm-like conjugate of nisin loaded PEGylated MoS2 (nisin@PEGylated MoS2) was developed for antibacterial application. The morphology and structure of PEGylated MoS2 were strongly dependent on the Mo/S molar ratio of precursors during the solvothermal process. The silkworm-like skeleton was well kept after loading with nisin. A high level of reactive oxygen species (ROS) induced by the conjugate was an important cause of bacteria death. Due to the different structure of cell membranes, the sharp edges could more easily puncture into Escherichia coli (E. coli) as compared with Staphylococcus aureus (S. aureus) and produced more intracellular ROS, which improved the antibacterial activity of nisin against E. coli. As a result, nisin@PEGylated MoS2 displayed the antibacterial activity against both gram-positive and gram-negative bacteria. Furthermore, the toxicity of the conjugate was very low. Therefore, the target conjugate of nisin@PEGylated MoS2 may have great potential application as an antibacterial agent.

P. Wang, H. Wang, X. Zhao, L. Li, M. Chen, J. Cheng, J. Liu, and X. Li,Antibacterial activity and cytotoxicity of novel silkworm-like nisin@PEGylated MoS2, Colloids and surfaces. B, Biointerfaces, 2019, 183, 110491.

Bacteria and antibacterial

MoS2 antibacterial phototherapy

Enhancing the antibacterial efficacy of low-dose gentamicin with 5 minute assistance of photothermy at 50 degrees C

Implant materials are prone to bacterial infections and cause serious consequences, while traditional antibiotic therapy has a long treatment cycle and even causes bacterial resistance. In this work, a photothermal therapy (PTT) assisted drug release system has been developed on the implant surface for in situ rapid disinfection under 808 nm light irradiation within a short time, in which gentamicin (Gent) is loaded by polyethylene glycol (PEG) modified molybdenum disulfide (MoS2) on Ti surface, and then encapsulated with chitosan (CS) (CS/Gent/PEG/MoS2-Ti). The hyperthermia produced by the coatings irradiated by 808 nm near-infrared (NIR) light can not only accelerate the local release of Gent, but also reduce the activity of bacteria, which makes it easy for these locally released drugs to enter the interior of the bacteria to inhibit the protein synthesis and destroy the cell membrane. When maintained at 50 degrees C for 5 min under NIR irradiation, this system can achieve an antibacterial efficacy of 99.93% and 99.19% against Escherichia coli and Staphylococcus aureus, respectively. By contrast, even after treatment for 120 min, only a 93.79% antibacterial ratio can be obtained for Gent alone. This is because hyperthermia produced from the coatings during irradiation can assist antibiotics in killing bacteria in a short time. Even under a low dose of 2 g mL(-1), the photothermal effect assisted gentamicin can achieve an antibacterial efficacy of 96.86% within 5 min. In vitro cell culture shows that the modified surface can facilitate cell adhesion, spreading and proliferation. The 7 day subcutaneous infection model confirms that the prepared surface system can exhibit a much faster sterilization and tissue reconstruction than the control group with light assistance. Compared with the traditional drug release system, this photothermy controlled drug-loaded implant surface system can not only provide rapid and high-efficiency in situ sterilization, but also offer long-term prevention of local bacterial infection.

M. X. Ma, X. M. Liu, L. Tan, Z. D. Cui, X. J. Yang, Y. Q. Liang, Z. Y. Li, Y. F. Zheng, K. W. K. Yeung, and S. L. Wu,Enhancing the antibacterial efficacy of low-dose gentamicin with 5 minute assistance of photothermy at 50 degrees C, Biomaterials Science, 2019, 7, 1437-1447.

 

Antibacterial Nanomaterials Review

Nanomaterials with a photothermal effect for antibacterial activities: an overview

Nanomaterials and nanotechnologies have been expected to provide innovative platforms for addressing antibacterial challenges, with potential to even deal with bacterial infections involving drug-resistance. The current review summarizes recent progress over the last 3 years in the field of antibacterial nanomaterials with a photothermal conversion effect. We classify these photothermal nanomaterials into four functional categories: carbon-based nanoconjugates of graphene derivatives or carbon nanotubes, noble metal nanomaterials mainly from gold and silver, metallic compound nanocomposites such as copper sulfide and molybdenum sulfide, and polymeric as well as other nanostructures. Different categories can be assembled with each other to enhance the photothermal effects and the antibacterial activities. The review describes their fabrication processes, unique properties, antibacterial modes, and potential healthcare applications.

J. W. Xu, K. Yao, and Z. K. Xu,Nanomaterials with a photothermal effect for antibacterial activities: an overview, Nanoscale, 2019, 11, 8680-869.

 

MoS2

ANTIBACTERIAL

High antibacterial activity of chitosan - molybdenum disulfide nanocomposite

Bacterial infections have evolved as a life-threatening problem afflicting people due to the abuse of antibiotics and emergence of drug-resistant bacteria. Thus developing novel antibacterial materials is an urgent need. Herein, chitosan-MoS2 (CS-MoS2) nanocomposite was synthesized through thiol ligand functionalization and chemical modification to achieve more efficient bactericidal activity. CS-MoS2 exhibited synergistic remarkable bactericidal capability against Gram-positive Staphylococcus aureus (S. aureus) and Gram-negative Escherichia coli (E.coli), where bacterial viabilities were significantly reduced. After treatment with 10 mug/mL of CS-MoS2, 100% and 98.1% of S. aureus and E.coli cells were killed respectively. A mechanism study revealed that the positively charged CS-MoS2 could interact with cell membrane, then cause damage to the membrane and cellular constituents by generation of reactive oxygen species (ROS) and glutathione (GSH) oxidation, finally inhibit bacterial growth. The CS-MoS2 could be an attractive antibacterial agent with improved efficiency and provide more strategies for application of MoS2.

W. Cao, L. Yue, and Z. Wang,High antibacterial activity of chitosan - molybdenum disulfide nanocomposite, Carbohydrate polymers, 2019, 215, 226-234.

               

               

 

               

BACTERIA

Production of Molybdenum blue by two novel molybdate reducing bacteria belonging to the genus Raoultella isolated from Egypt and Iraq

AIM: The aim of this study was to isolate potential molybdate reducing bacteria to be used for bioremediation. METHODS AND RESULTS: Two molybdate reducing bacteria (Mo1 and MoI) were isolated from polluted soil samples from Ismailia Canal, Egypt and Sallah Elddin Governorate, Iraq respectively. The isolates exhibited dark blue colonies when grown on solid medium containing sodium molybdate which indicated the reduction of molybdate to molybdenum blue. The absorbance at 865 nm were (0.743 +/- 0.007) and (0.453 +/- 0.005) for Mo1 and MoI, respectively. The molybdenum blue produced showed characteristic absorption spectrum peak at 865 nm and a shoulder at 700 nm. The isolates were identified by 16S rRNA genes sequencing and were submitted to GenBank as Raoultella ornithinolytica strain Mo1 and Raoultella planticola strain MoI. The optimum conditions were glucose as electron donor, initial pH of 6 and incubation temperature of 30 degrees C. Scanning electron micrographs were taken for both isolates in presence and absence of molybdate source.

CONCLUSION: To the best of our knowledge this is the first recordation of molybdate reduction by Raoultella sp. isolated from Egypt and Iraq.

SIGNIFICANCE AND IMPACT OF STUDY: The isolated bacteria belonging to the Raoultella could be used in in situ bioremediation. This article is protected by copyright. All rights reserved.

A. M. Saeed, E. E. Shatoury, and R. Hadid,Production of Molybdenum blue by two novel molybdate reducing bacteria belonging to the genus Raoultella isolated from Egypt and Iraq, Journal of applied microbiology, 2019. https://doi.org/10.1111/jam.14254

ANTIBACTERIAL

The antimicrobial effect of metal substrates on far food pathogens

The development of surfaces as antimicrobial materials is important to the food industry. This study investigated the antimicrobial potential of a range of metal coated surfaces including silver, titanium, copper, iron,  molybdenum , zinc and silicon (control) against Staphylococcus aureus, Escherichia coli and Listeria monocytogenes. The leaching potential of the metals were measured by inductively coupled plasma-atomic adsorption spectroscopy and were compared to the antibacterial activity of the metals using a nitroblue tetrazolium assay and an adapted BS ISO 22196:2011 standard. Leaching into solution from the coatings alone was not related to the antimicrobial activity of the coatings. Copper and zinc showed the greatest propensity to leach from the coatings; silver, titanium, iron and  molybdenum  leached at lower rates and silicon showed no leaching. Copper demonstrated the greatest antimicrobial potential followed by silver and zinc. Titanium displayed the least antimicrobial potential, however using the standard method in humid conditions resulted in increased growth of Listeria. This study provides evidence of the efficacy of copper and silver as effective antimicrobial metal surface coatings, however use of titanium under humid conditions suggest that surfaces for use in the food industry needs to be given careful consideration before application. (C) 2018 The Authors. Published by Elsevier B.V. on behalf of Institution of Chemical Engineers.

I. D. Akhidime, F. Saubade, P. S. Benson, J. A. Butler, S. Olivier, P. Kelly, J. Verran, and K. A. Whitehead,The antimicrobial effect of metal substrates on far food pathogens, Food and Bioproducts Processing, 2019, 113, 68-76.

 

               

Antibacterial properties and modulation analysis of antibiotic activity of NaCe( MoO4)2 microcrystals

This study reports the antibacterial properties and modulation analysis of antibiotic activity by NaCe( MoO4)2 microcrystals as well as their structural and morphological characterization. Evaluation of the antibacterial and antibiotic-modulating activity was carried out using the broth microdilution method. The Minimum Inhibitory Concentrations (MICs) of the compounds were expressed as the geometric mean of the triplicate values obtained through the use of Resazurin. Compound concentrations in the plates ranged from 512 to 0.5 mu g/mL. Regarding its direct antibacterial activity, NaCe( MoO4)2 had a MIC >= 1024 mu g/mL against all studied strains. As for its modulatory effect, it presented synergism with the antibiotic Gentamicin against the S. aureus strain and with Norfloxacin against E. coil, causing a reduction of 75% and 60%, respectively, in the antibiotic quantity required to have the same effect on the strain in study.

J. V. B.  Moura, T. S. Freitas, R. P. Cruz, R. L. S. Pereira, A. R. P. Silva, A. T. L. Santos, J. H. da Silva, C. Luz-Lima, and H. D. M. Coutinho,Antibacterial properties and modulation analysis of antibiotic activity of NaCe( MoO4)2microcrystals, Microbial Pathogenesis, 2019, 126, 258-262.

 

               

Highly efficient of  molybdenum  trioxide-cadmium titanate nanocomposites for ultraviolet light photocatalytic and antimicrobial application: Influence of reactive oxygen species

In the present work we report the enhanced UV light photocatalytic performance of cadmium titanate photo-catalyst by  MoO3 for Drug pollutant degradation. The nano photocatalyst sample was synthesized employing the Pechini-ultrasonic-hydrothermal route. Therefore, the nano photocatalyst were characterized by various analytical devices. The wide scan X-ray photoelectron spectral study confirmed the  MoO3 in the CdTiO3 matrix. The crystallite size calculated with the Debye-Scherrer equation (55.4, 57.0, 61.2 and 63.1 nm for pure CdTiO3,  MoCdTi-0,  MoCdTi-1, and  MoCdTi-2 nanocomposites, respectively). SEM micrographs revealed nanowire morphology indicated the crystalline nature of the sample. The  MoO3-CdTiO3 photocatalyst degraded the aspirin pollutant in 90 min under UV light which was higher and efficient than the pristine cadmium titanate. The enhanced photocatalytic efficiency can be attributed to the significant decrease in the band gap energy relative to the pristine cadmium titanate coupled with larger surface area morphology. The actual band gap values calculated were 2.95 to 2.66 eV ranges. The antifungal efficiency of the CdTiO3, and  MoO3-CdTiO3 was examined against Aspergillus flavus, and Trigoderma veride and their antibacterial efficiency was examined against Escherichia coli, and streptococcus pyogenes. The  MoO3-CdTiO3 with high ratio of  MoO3 has suitable to good activity compared with pure CdTiO3 and other  MoO3-CdTiO3 samples.

J. M. Zhu, M. Hosseini, A. Fakhri, S. S. Rad, T. Hadadi, and N. Nobakht,Highly efficient of  molybdenum  trioxide-cadmium titanate nanocomposites for ultraviolet light photocatalytic and antimicrobial application: Influence of reactive oxygen species, Journal of Photochemistry and Photobiology B-Biology, 2019, 191, 75-82.

 

Photogenerated Charge Carriers in  molybdenum  Disulfide Quantum Dots with Enhanced Antibacterial Activity

Molybdenum  disulfide ( MoS2) nanosheets have received considerable interest due to their superior physicochemical performances to graphene nanosheets. As the lateral size and layer thickness decrease, the formed  MoS2 quantum dots (QDs) show more promise as photocatalysts, endowing them with potential antimicrobial properties under environmental conditions. However, studies on the antibacterial photodynamic therapy of  MoS2 QDs have rarely been reported. Here, we show that  MoS2 QDs more effectively promote the creation and separation of electron-hole pair than  MoS2 nanosheets, resulting in the formation of multiple reactive oxygen species (ROS) under simulated solar light irradiation. As a result, photoexcited  MoS2 QDs show remarkably enhanced antibacterial activity, and the ROS-mediated oxidative stress plays a dominant role in the antibacterial mechanism. The in vivo experiments showed that  MoS2 QDs are efficacious in wound healing under simulated solar light irradiation and exert protective effects on normal tissues, suggesting good biocompatibility properties. Our findings provide a full description of the photochemical behavior of  MoS2 QDs and the resulting antibacterial activity, which might advance the development of  MoS2-based nanomaterials as photodynamic antibacterial agents under environmental conditions.

X. Tian, Y. Sun, S. Fan, M. D. Boudreau, C. Chen, C. Ge, and J. J. Yin,Photogenerated Charge Carriers in  molybdenum  Disulfide Quantum Dots with Enhanced Antibacterial Activity, ACS Appl Mater Interfaces, 2019, 11, 4858-4866.

antibacterial activity

               

Bacteria

BACTERIA

Cyanobacteria

Impact of ageing on the fate of molybdate-zerovalent iron nanohybrid and its subsequent effect on cyanobacteria (microcystis aeruginosa) growth in aqueous media

Nanoscale zerovalent iron (nZVI) has been proposed to remediate heavy metal ions in the subsurface. However, the fate of metal-nZVI hybrid has not been fully investigated. In this study, we investigated (1) the long-term removal performance of nZVI for molybdate (Mo(VI)); (2) the relationship between the ageing of Mo-nZVI hybrid in specific solution chemistries and the remobilization of Mo(VI) from the hybrid; and (3) the effects of Mo-nZVI hybrid on cyanobacteria (Microcystis aeruginosa). Results showed that although common ions have limited influence on the removal ratio of Mo(VI) by nZVI, they do impact the structure evolution and transformation of the Mo-nZVI nanohybrid formed thereafter. Ageing time was crucial for the chemical stabilization of Mo-nZVI hybrid, but common groundwater ions retarded the stabilizing process, which may lead to a significant remobilization of Mo(VI) from the hybrid after exposure to water bodies. While low levels of Mo(VI) ions could stimulate the growth of M. aeruginosa, aged Mo-nZVI hybrid inhibited the growth of M. aeruginosa, except when ageing occurred in the presence of HPO42-/CO32- (which also retarded hybrid stabilization). This study shows that nZVI can immobilize Mo(VI) ions in groundwater, and the derived metal-nZVI hybrid can effectively suppress the potential growth of M. aeruginosa in river water.

Y. Su, D. Qian, A. S. Adeleye, J. Zhang, X. Zhou, D. Jassby, and Y. Zhang, Impact of ageing on the fate of molybdate-zerovalent iron nanohybrid and its subsequent effect on cyanobacteria (microcystis aeruginosa) growth in aqueous media, Water Res, 2018, 140, 135-147.

 

The toxicity of molybdate to freshwater and marine organisms. III. Generating additional chronic toxicity data for the refinement of safe environmental exposure concentrations in the US and Europe

The freshwater and marine long-term ecotoxicity datasets used in the European REACH registration dossiers for molybdenum and molybdenum compounds resulted in the derivation of a HC5,50%,freshwater (38.2mgMo/L) and HC5,50%,marine (5.70mgMo/L) by means of the statistical extrapolation method. Both datasets, however, did not meet the US-EPA information requirements for deriving Final Chronic Values (FCV) that were based on chronic data. US-EPA compliance was achieved by generating chronic no-effect data for the freshwater benthic amphipod Hyalella azteca and the marine inland silverside fish Menidia beryllina, using sodium molybdate dihydrate as test substance. A 42d-EC10 of 44.6mgMo/L for reproduction was determined in a water-only exposure with H. azteca. For M. beryllina, a 37d-NOEC of 139mg mMo/L for standard length and blotted wet weight was found. Other endpoints (e.g., survival, hatching success) proved to be less sensitive. Data were added to the existing chronic toxicity datasets, together with new long-term no-effect values that were identified in open literature for brown trout Salmo trutta, the marine alga Isochrysis galbana, the marine snail Nassarius dorsatus and the marine barnacle Amphibalanus amphitrite. The updated data sets resulted in a freshwater and marine HC5,50% of 35.7 and 6.85mgMo/L, respectively. The same data sets were also used for the determination of US-EPA FCVs, where the FVCfreshwater was 36.1mg/L, and the FCVmarine was 3.85mgMo/L. As the Final Plant Values for both aquatic environments were higher than their respective FCVs, the Criterion Continuous Concentration (CCC) for molybdenum is equal to the FCV.

Heijerick, D. G., and Carey, S.,The toxicity of molybdate to freshwater and marine organisms. III. Generating additional chronic toxicity data for the refinement of safe environmental exposure concentrations in the US and Europe, The Science of the total environment, 2017, 609, 420-428.

 

Precision editing of the gut microbiota ameliorates colitis

Inflammatory diseases of the gastrointestinal tract are frequently associated with dysbiosis(1-8), characterized by changes in gut microbial communities that include an expansion of facultative anaerobic bacteria of the Enterobacteriaceae family (phylum Proteobacteria). Here we show that a dysbiotic expansion of Enterobacteriaceae during gut inflammation could be prevented by tungstate treatment, which selectively inhibited molybdenum-cofactor-dependent microbial respiratory pathways that are operational only during episodes of inflammation. By contrast, we found that tungstate treatment caused minimal changes in the microbiota composition under homeostatic conditions. Notably, tungstate-mediated microbiota editing reduced the severity of intestinal inflammation in mouse models of colitis. We conclude that precision editing of the microbiota composition by tungstate treatment ameliorates the adverse effects of dysbiosis in the inflamed gut.

W. H. Zhu, M. G. Winter, M. X. Byndloss, L. Spiga, B. A. Duerkop, E. R. Hughes, L. Buttner, E. D. Romao, C. L. Behrendt, C. A. Lopez, L. Sifuentes-Dominguez, K. Huff-Hardy, R. P. Wilson, C. C. Gillis, C. Tukel, A. Y. Koh, E. Burstein, L. V. Hooper, A. J. Baumler, and S. E. Winter,Precision editing of the gut microbiota ameliorates colitis, Nature, 2018, 553, 208-+.

               

Self-Healing, antibacterial and sensing nanoparticle coating and its excellent optical applications

Self-healing, antibacterial and metal-ion sensing coatings with nanoparticles were developed using layer-by-layer (LbL) self-assembly technique via host-guest interaction. The coatings consist of MoS2 nanosheets, beta-cyclodextrin (beta-CD)-modified poly (ethylenimine) (PEI) and adamantane (AD)modified poly (acrylic acid) (PAA). Damages to conventional coatings results in cracking and affects the coatings' ability to maintain antibacterial and sensing qualities. The prepared MoS2/beta-CD-PEI/AD-PAA self-healing coatings are not only able to greatly suppress bacterial adhesion and have excellent antibacterial property, particularly under UV light irradiation, but also have a longtime service time. Moreover, the self-healing coatings first applied the fluorescence quenching for detecting heavy metals (Co2+). Fluorescence spectra demonstrated that a linear relationship existed between the fluorescence intensity and the Co2+ concentration with 0 similar to 0.1 µg/mL and the detection limit of Co2+ is 0.018 mg/mL. Therefore, the nanoparticle multilayer polyelectrolyte hybrid coatings have a potential application in food industries. (C) 2017 Elsevier B.V. All rights reserved.

H. Y. Xuan, W. Dai, Y. X. Zhu, J. Y. Ren, J. H. Zhang, and L. Q. Ge,Self-Healing, antibacterial and sensing nanoparticle coating and its excellent optical applications, Sensors and Actuators B-Chemical, 2018, 257, 1110-1117.

 

MoS2-TiO2 Nanocomposite with Excellent Adsorption Performance and High Antibacterial Activity

The need of multifunctional advanced materials, facilitating clean and sustainable environment is the key issue from the perspective of materials scientists. This study demonstrates facile and scalable synthesis of MoS2-TiO2 nanocomposites and their excellent performance as nanoadsorbents and antibacterial agent. The synthesized composites, with different loading of MoS2 and TiO2, were examined by XRD, XPS, RAMAN, FESEM and HRTEM for structural, chemical and morphological details. The MoS2-TiO2 nanocomposite displays adsorption capacity as high as 364.56mg.g(-1) for methylene blue (MB) at room temperature and the kinetic data reveal that the adsorption process of MB is well-matched with the pseudo-first-order model. The MoS2-TiO2 nanocomposites, with different morphology, have shown their capability as an organic dye scavenger with high speed and efficiency. Moreover the composites execute considerable antibacterial activity against Gram positive Staphylococcus aureus and Gram negative Escherichia coli bacteria. Thus the presented MoS2-TiO2 nanocomposite, with synergistic performance, shows huge potential in the search of multifunctional smart materials for future technology to address environment issues.

A. Pal, T. K. Jana, T. Roy, A. Pradhan, R. Maiti, S. M. Choudhury, and K. Chatterjee, MoS2-TiO2 Nanocomposite with Excellent Adsorption Performance and High Antibacterial Activity, Chemistryselect, 2018, 3, 81-90.

 

Bacteria MoS2 toxicity

Comparative toxicity of Cd, Mo, and W sulfide nanomaterials toward E-coli under UV irradiation

In this study, the phototoxicity of cadmium sulfide (CdS), molybdenum disulfide (MoS2), and tungsten disulfide (WS2) nanoparticles (NPs) toward Escherichia coil (E. coli) under UV irradiation (365 nm) was investigated. At the same mass concentration of NPs, the toxicity of three NPs decreased in the order of CdS > MoS2 > WS2. For example, the death rates of E. coil exposed to 50 mg/L CdS, MoS2, and WS2 were 96.7%, 38.5%, and 31.2%, respectively.
Transmission electron microscope and laser scanning confocal microscope images of E. coli exposed to three NPs showed the damage of cell walls and release of intracellular components. The CdS-treated cell wall was more extensively damaged than those of MoS2 treated and WS2-treated bacteria.
WS2 and MoS2 generated superoxide radical (O2.—), singlet oxygen 1O2, and hydroxyl radical under UV irradiation, CdS produced only O2- and 1O2. CdS and WS2 released ions under UV irradiation, while MoS2 did not. Reactive oxygen species (ROS) generation and toxic ion release jointly resulted in the antibacterial activities of CdS and WS2. ROS generation was the dominant toxic mechanism of MoS2 toward the bacteria. This study highlighted the importance of considering the hazardous effect of sulfide NPs after their release into natural waters under light irradiation condition. (C) 2017 Elsevier Ltd. All rights reserved.

Shang, E. X., Niu, J. F., Li, Y., Zhou, Y. J., and Crittenden, J. C.,Comparative toxicity of Cd, Mo, and W sulphide nanomaterials toward E-coli under UV irradiation, Environmental Pollution, 2017, 224, 606-614.

 

Optimization and maximization of hexavalent molybdenum reduction to Mo-blue by SERRATIA SP strain MIE2 using response surface methodology

Molybdenum has long been known to be toxic to ruminants, but not to humans. However, more recently it has been increasingly reported that molybdenum shows toxic effects to reproductive organs of fish, mouse and even humans. Hence, its removal from the environment is highly sought after. In this study, response surface methodology (RSM) was successfully applied in the optimization and maximization of Mo6+ reduction to Mo-blue by Serratia sp. MIE2 for future bioremediation application. The optimal conditions predicted by RSM were 20 mM molybdate, 3.95 mM phosphate, pH 6.25 and 25 g l-1 sucrose with absorbance of 19.53 for Mo-blue production measured at 865 nm. The validation experimental run of the predicted optimal conditions showed that the maximum Mo-blue production occurred at absorbance of 20.87, with a 6.75 % deviation from the predicted value obtained from RSM. Molybdate reduction was successfully maximized using RSM with molybdate reduction before and after optimization using RSM showing Mo-blue production starting at the absorbance value of 10.0 at 865 nm going up to an absorbance value above 20.87. The modelling kinetics of Mo6+ reduction showed that Teissier was the best model, with calculated P-max, K-s and K-i values of 1.97 Mo-blue per hour, 5.79 mM and 31.48 mM, respectively.

bin Halmi, M. I. E., Abdullah, S. R. S., Wasoh, H., Johari, W. L. W., Ali, M. S. B., Shaharuddin, N. A., and Shukor, M. Y.,Optimization and maximization of hexavalent molybdenum reduction to Mo-blue by Serratia sp strain MIE2 using response surface methodology, Rendiconti Lincei-Scienze Fisiche E Naturali, 2016, 27, 697-709.

Modelling the kinetics of hexavalent molybdenum (Mo6+) reduction by the SERRATIA sp strain MIE2 in batch culture

In the present work, the kinetics of hexavalent molybdenum reduction by the Serratia sp. strain MIE2 were investigated using several kinetic models, such as Monod, Haldane, Teissier, Aiba, Yano, Han and Leven-spiel and Luong. The statistical analysis showed that the best model was Teissier, which had the lowest RMSE and AICc values, the highest adjusted R-2 values, and an F test and with a bias factor and an accuracy factor nearest to unity (1.0). The calculated value for the Teissier constants, such as p(max), K-s and K-i, was 0.506 mu mol Mo-blue h(-1), 6.53 mM and 29.41 mM, respectively. The effect of heavy metals showed that hexavalent molybdenum reduction by the strain MIE2 was inhibited by silver, mercury and copper with a total inhibition of 96, 97, and 45 %, respectively, at a concentration of 1 ppm. Otherwise, the Mo-reducing enzyme was inhibited by mercury and zinc with an inhibition of 88 and 65 %, respectively. Most of the respiratory inhibitors did not inhibit the Mo-reducing enzyme activity, indicating that the respiratory system in this bacterium is not the site of the hexavalent molybdenum reduction. The results obtained from this study could be useful for estimating the relationship between molybdenum-blue production and the molybdate concentration, which may be important during the up scaling of the molybdenum bioremediation process.

Halmi, M. I. E., Abdullah, S. R. S., Johari, W. L. W., Ali, M. S. M., Shaharuddin, N. A., Khalid, A., and Shukor, M. Y.,Modelling the kinetics of hexavalent molybdenum (Mo6+) reduction by the Serratia sp strain MIE2 in batch culture, Rendiconti Lincei-Scienze Fisiche E Naturali, 2016, 27, 653-663.

NEGATIVE STAINING and Transmission Electron Microscopy of Bacterial Surface Structures

Negative staining is an essential and versatile staining technique in transmission electron microscopy that can be employed for visualizing bacterial cell morphology, size, and surface architecture at high resolution. Bacteria are usually transferred by passive electrostatic adsorption from suspensions in physiological saline onto suitable hydrophilic support films on electron microscopic grids. There they are contrasted, or "stained," by heavy metal ions in solution such as tungsten, uranyl, molybdate, or vanadate compounds. Here, I describe how to visualize the interaction between the bacterial M1 protein and complement factors C1q and C3 on the surface of group A streptococcus by negative staining with uranyl formate on carbon support films. The methodology should be generally applicable to the study of a large number of other bacteria-protein interactions.

Morgelin, M.,Negative Staining and Transmission Electron Microscopy of Bacterial Surface Structures, Methods in molecular biology (Clifton, N.J.), 2017, 1535, 211-217.

Investigating the Influence of MoS2 Nanosheets on E-COLI from Metabolomics Level

Molybdenum disulfide, a type of two-dimensional layered material with unique properties, has been widely used in many fields. However, an exact understanding of its toxicity remains elusive, let alone its effects on the environmental microbial community. In this study, we utilized metabolomics technology to explore the effects of different concentrations of molybdenum disulfide nanosheets on Escherichia coli for the first time. The results showed that with increasing concentration of molybdenum disulfide nanosheets, the survival rate of Escherichia coli was decreased and the release of lactic dehydrogenase was increased. At the same time, intracellular concentrations of reactive oxygen species were dramatically increased. In addition, metabolomics analysis showed that high concentrations of molybdenum disulfide nanosheets (100, 1000 mu g/mL) could significantly affect the metabolic profile of Escherichia coli, including glycine, serine and threonine metabolism, protein biosynthesis, urea cycle and pyruvate metabolism. These results will be beneficial for molybdenum disulfide toxicity assessment and further applications.

Wu, N., Yu, Y. D., Li, T., Ji, X. J., Jiang, L., Zong, J. J., and Huang, H.,Investigating the Influence of MoS2 Nanosheets on E-coli from Metabolomics Level, Plos One, 2016, 11.

 

IMOA Toxicological Testing Programme: Bacteriaa
SubstanceToxicity/ mg/l
Acute bacterial growth inhibitionAcute bacterial respiratory inhibition
EC10b3 h EC50c
Molybdenum trioxide (pure) d 820
Molybdenum trioxide (tech) d 3000
Ammonium dimolybdate 13  
Sodium molybdate 50  

Notes

a There are no EC criteria for bacterial toxicity. It is however factored into the German Water Hazard Classification. Under the German classification scheme, which takes into account fish, mammal and bacterial toxicity, the materials tested would give a maximum Water Hazard Classification of 1(weak hazard for waters).

b The EC10 is the concentration that causes a 10% reduction in turbidity. Test culture incubated with various concentrations of test substance for 18 hours. Turbidity measured by light transmission.

c The EC50 is the concentration that causes a 50% reduction in respiration. Test culture and test substance were left in contact for 30 minutes and three hours. At the end of each time period the dissolved oxygen content of the solution was measured.

d Growth inhibition is determined by the decrease in turbidity of test solution. Therefore, this method cannot be used on insolubles.

Users of the Database should be aware that inclusion of an abstract in the Database does not imply any IMOA endorsement of the accuracy or reliability of the reported data or the quality of a publication.