Role of Visible Light-Activated Photocatalyst on the Reduction of Anthrax Spore-Induced Mortality in Mice

BACKGROUND: Photocatalysis of titanium dioxide (TiO(2)) substrates is primarily induced by ultraviolet light irradiation. Anion-doped TiO(2) substrates were shown to exhibit photocatalytic activities under visible-light illumination, relative environmentally-friendly materials. Their anti-spore activity against Bacillus anthracis, however, remains to be investigated. We evaluated these visible-light activated photocatalysts on the reduction of anthrax spore-induced pathogenesis. METHODOLOGY/PRINCIPAL FINDINGS: Standard plating method was used to determine the inactivation of anthrax spore by visible light-induced photocatalysis. Mouse models were further employed to investigate the suppressive effects of the photocatalysis on anthrax toxin- and spore-mediated mortality. We found that anti-spore activities of visible light illuminated nitrogen- or carbon-doped titania thin films significantly reduced viability of anthrax spores. Even though the spore-killing efficiency is only approximately 25%, our data indicate that spores from photocatalyzed groups but not untreated groups have a less survival rate after macrophage clearance. In addition, the photocatalysis could directly inactivate lethal toxin, the major virulence factor of B. anthracis. In agreement with these results, we found that the photocatalyzed spores have tenfold less potency to induce mortality in mice. These data suggest that the photocatalysis might injury the spores through inactivating spore components. CONCLUSION/SIGNIFICANCE: Photocatalysis induced injuries of the spores might be more important than direct killing of spores to reduce pathogenicity in the host

Monitoring of Aflatoxin M1 in Various Origins Greek Milk Samples Using Liquid Chromatography Tandem Mass Spectrometry

Aflatoxin M1(AFM1), a major metabolite of Aflatoxin B1(AFB1), has been identified as a potential contaminant in dairy products. Because of its possible carcinogenicity, the legislation limits as set by Commission Regulation (EC) No. 1881/2006 are very strict, namely 0.050 µg kg−1 in milk and 0.025 µg kg−1 in infant formulas. To meet these requirements, a sensitive and accurate method was developed, employing liquid chromatography tandem mass spectrometry (UPLC-MS/MS). Immunoaffinity columns (R-Biopharm) were used for sample purification and preconcentration of the analyte of interest. The quantification of AFM1 was conducted using fortified milk samples, while Aflatoxin B2 (AFB2) was used as an internal standard (IS). The method was validated in terms of linearity, precision, trueness, limits of detection and quantification and uncertainty. The performance criteria for the method were evaluated based on European Commission Regulation (EC) No. 401/2006 and its most recent amendment, as well as the suggested criteria for revision by the EU Reference Laboratory for Mycotoxins and Plant Toxins. The recovery was in the range of 77.9–81.0% for all fortification levels (0.025–0.050–0.075 µg kg−1 ), with RSDR values (Relative Standard Deviation of intermediate precision) ranging from 6.1% to 12%. The method’s detection and quantification limits were 0.0027 µg kg−1 and 0.0089 µg kg−1, respectively. The occurrence of AFM1 was investigated in 40 samples of different animal origin (cow, goat and sheep milk) provided by Greek producers. © 2022 by the authors. Licensee MDPI, Basel, Switzerland

Determination of 56 per- and polyfluoroalkyl substances in top predators and their prey from Northern Europe by LC-MS/MS

Per- and polyfluoroalkyl substances (PFAS) are a group of emerging substances that have proved to be persistent and highly bioaccumulative. They are broadly used in various applications and are known for their long-distance migration and toxicity. In this study, 65 recent specimens of a terrestrial apex predator (Common buzzard), freshwater and marine apex predators (Eurasian otter, harbour porpoise, grey seal, harbour seal) and their potential prey (bream, roach, herring, eelpout) from northern Europe (United Kingdom, Germany, the Netherlands and Sweden) were analyzed for the presence of legacy and emerging PFAS, employing a highly sensitive liquid chromatography electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) method. 56 compounds from 14 classes were measured; 13 perfluoroalkyl carboxylic acids (PFCAs), 7 perfluoroalkyl sulphonic acids (PFSAs), 3 perfluorooctane sulfonamides (FOSAs), 4 perfluoroalkylphosphonic acids (PFAPAs), 3 perfluoroalkylphosphinic acids (PFPi's), 5 telomer alcohols (FTOHs), 2 mono-substituted polyfluorinated phosphate esters (PAPs), 2 di-substituted polyfluorinated phosphate esters (diPAPs), 6 saturated fluorotelomer acids (FTAS), 3 unsaturated fluorotelomer acids (FTUAs), 2 N-Alkyl perfluorooctane sulfonamidoethanols (FOSEs), 3 fluorotelomer sulphonic acids (FTSAs), 2 perfluoroether carboxylic acids (PFECAs) and 1 chlorinated perfluoroether sulphonic acid (Cl-PFESA). All samples were lyophilized before analysis, in order to enhance extraction efficiency, improve the precision and achieve lower detection limits. The analytes were extracted from the dry matrices through generic methods of extraction, using an accelerated solvent extraction (ASE), followed by clean-up through solid phase extraction (SPE). Method detection limits and method quantification limits ranged from 0.02 to 1.25 ng/g wet weight (ww) and from 0.05 to 3.79 ng/g (ww), respectively. Recovery ranged from 40 to 137%. Method precision ranged from 3 to 20 %RSD. The sum of PFAS concentration in apex predators livers ranged from 0.2 to 20.2 μg/g (ww), whereas in the fish species muscle tissues it ranged from 16 to 325 ng/g (ww). All analyzed specimens were primarily contaminated with PFOS, while the three PFPi's included in this study exhibited frequency of appearance (FoA) 100 %. C9 to C13 PFCAs were found at high concentrations in apex predator livers, while the overall PFAS levels in fish fillets also exceeded ecotoxicological thresholds. The findings of our study show a clear association between the PFAS concentrations in apex predators and the geographical origin of the specimens, with samples that were collected in urban and agricultural zones being highly contaminated compared to samples from pristine or semi-pristine areas. The high variety of PFAS and the different PFAS composition in the apex predators and their prey (AP&P) samples is alarming and strengthens the importance of PFAS monitoring across the food chain. © 2021 Elsevier Lt

Three years of wastewater surveillance for new psychoactive substances from 16 countries

The proliferation of new psychoactive substances (NPS) over recent years has made their surveillance complex. The analysis of raw municipal influent wastewater can allow a broader insight into community consumption patterns of NPS. This study examines data from an international wastewater surveillance program that collected and analysed influent wastewater samples from up to 47 sites in 16 countries between 2019 and 2022. Influent wastewater samples were collected over the New Year period and analysed using validated liquid chromatography – mass spectrometry methods. Over the three years, a total of 18 NPS were found in at least one site. Synthetic cathinones were the most found class followed by phenethylamines and designer benzodiazepines. Furthermore, two ketamine analogues, one plant based NPS (mitragynine) and methiopropamine were also quantified across the three years. This work demonstrates that NPS are used across different continents and countries with the use of some more evident in particular regions. For example, mitragynine has highest mass loads in sites in the United States, while eutylone and 3-methylmethcathinone increased considerably in New Zealand and in several European countries, respectively. Moreover, 2F-deschloroketamine, an analogue of ketamine, has emerged more recently and could be quantified in several sites, including one in China, where it is considered as one of the drugs of most concern. Finally, some NPS were detected in specific regions during the initial sampling campaigns and spread to additional sites by the third campaign. Hence, wastewater surveillance can provide an insight into temporal and spatial trends of NPS use. © 2023 The Author(s

Thuricin CD, a posttranslationally modified bacteriocin with a narrow spectrum of activity against Clostridium difficile

The last decade has seen numerous outbreaks of Clostridium difficile-associated disease (CDAD), which presented significant challenges for healthcare facilities worldwide. We have identified and purified thuricin CD, a two-component antimicrobial that shows activity against C. difficile in the nanomolar range. Thuricin CD is produced by Bacillus thuringiensis DPC 6431, a bacterial strain isolated from a human fecal sample, and it consists of two distinct peptides, Trn-α and Trn-β, that act synergistically to kill a wide range of clinical C. difficile isolates, including ribotypes commonly associated with CDAD (e.g., ribotype 027). However, this bacteriocin thuricin CD has little impact on most other genera, including many gastrointestinal commensals. Complete amino acid sequencing using infusion tandem mass spectrometry indicated that each peptide is posttranslationally modified at its respective 21st, 25th, and 28th residues. Solution NMR studies on [13C,15N] Trn-α and [13C,15N]Trn-β were used to characterize these modifications. Analysis of multidimensional NOESY data shows that specific cysteines are linked to the α-carbons of the modified residues, forming three sulfur to α-carbon bridges. Complete sequencing of the thuricin CD gene cluster revealed genes capable of encoding two S′-adenosylmethionine proteins that are characteristically associated with unusual posttranslational modifications. Thuricin CD is a two-component antimicrobial peptide system with sulfur to α-carbon linkages, and it may have potential as a targeted therapy in the treatment of CDAD while also reducing collateral impact on the commensal flora