Nanostructured Magnetic Particles for Removing Cyanotoxins: Assessing Effectiveness and Toxicity In Vitro.

The rise in cyanobacterial blooms due to eutrophication and climate change has increased cyanotoxin presence in water. Most current water treatment plants do not effectively remove these toxins, posing a potential risk to public health. This study introduces a water treatment approach using nanostructured beads containing magnetic nanoparticles (MNPs) for easy removal from liquid suspension, coated with different adsorbent materials to eliminate cyanotoxins. Thirteen particle types were produced using activated carbon, CMK-3 mesoporous carbon, graphene, chitosan, 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-oxidised cellulose nanofibers (TOCNF), esterified pectin, and calcined lignin as an adsorbent component. The particles' effectiveness for detoxification of microcystin-LR (MC-LR), cylindrospermopsin (CYN), and anatoxin-A (ATX-A) was assessed in an aqueous solution. Two particle compositions presented the best adsorption characteristics for the most common cyanotoxins. In the conditions tested, mesoporous carbon nanostructured particles, P1-CMK3, provide good removal of MC-LR and Merck-activated carbon nanostructured particles, P9-MAC, can remove ATX-A and CYN with high and fair efficacy, respectively. Additionally, in vitro toxicity of water treated with each particle type was evaluated in cultured cell lines, revealing no alteration of viability in human renal, neuronal, hepatic, and intestinal cells. Although further research is needed to fully characterise this new water treatment approach, it appears to be a safe, practical, and effective method for eliminating cyanotoxins from water.

First description of adenosine production by Gnomoniopsis smithogilvyi, causal agent of chestnut brown rot.

Gnomoniopsis smithogilvyi (Gnomoniaceae, Diaporthales) is the main causal agent of chestnut brown rot on sweet chestnut worldwide. The rotting of nuts leads to alterations in the organoleptic qualities and decreased fruit production, resulting in significant economic losses. In 2021, there was an important outbreak of chestnut rot in southern Galicia (Spanish northwest). The profile of secondary metabolites from G. smithogilvyi was studied, especially to determine its capability for producing mycotoxins, as happens with other rotting fungi, due to the possible consequences on the safety of chestnut consumption. Secondary metabolites produced by isolates of G. smithogilvyi growing in potato dextrose agar (PDA) medium were identified using liquid chromatography coupled with high-resolution mass spectrometry. Three metabolites with interesting pharmacological and phyto-toxicological properties were identified based on their exact mass and fragmentation patterns, namely adenosine, oxasetin, and phytosphingosine. The capacity of G. smithogilvyi to produce adenosine in PDA cultures was assessed, finding concentrations ranging from 176 to 834 µg/kg. Similarly, the production of mycotoxins was ruled out, indicating that the consumption of chestnuts with necrotic lesions does not pose a health risk to the consumer in terms of mycotoxins.

First report of Gnomoniopsis smithogilvyi causing chestnut brown rot on nuts and burrs of sweet chestnut in Spain.

About 60% of the nut production of sweet chestnut (Castanea sativa Mill.) in Europe originates in Spain (FAOSTAT, 2022), mostly (91%) in Galicia (NW Spain). In September 2021, premature fall of immature chestnut burrs and nuts of C. sativa was observed in eight orchards of Pontevedra and Ourense (provinces of Galicia). Chestnut green burrs had turned brown and fallen off, and the nuts showed brown lesions in kernels and embryos. Some nuts had become mummified. Symptomatic samples of burrs and nuts, including mummified fruits, were collected. Small pieces of samples were surface-disinfected with 2% sodium hypochlorite, and plated onto potato dextrose agar (PDA) plates. Colonies were creamy white to gray or light brown, and presented a woolly to felty mycelium with a dense development in concentric circles. Brownish to black conidiomata, produced abundantly, were globose to sub-globose. Conidia were hyaline, oval, obovoid, fusoid and multi-guttulate, and 6.6±0.78 [5.07 to 9.01] µm x 3.2±0.43 [2.41 to 4.38] µm in size. These features matched those described for Gnomoniopsis smithogilvyi (Shuttleworth et al. 2012), syn. G. castaneae (Visentin et al. 2012; Shuttleworth et al. 2015). Genomic DNA was extracted from mycelium developed in 22 burrs and nuts, and 30 pure cultures. The rDNA internal transcribed spacer (ITS), fragments of the ß-tubulin (TUB2) and the translation elongation factor-1α (TEF-1α) genes were amplified using ITS1F (Gardes and Bruns 1993) and ITS4 (White et al. 1990), T1/Bt2b (O'Donnell and Cigelnik 1997), and EF1-728F/EF1-986R (Carbone and Kohn 1999) primers, respectively. Two isolates (EFA 924A, EFA962.4A) were deposited in the Spanish Type Culture Collection (Paterna, Valencia), and their sequences submitted to GenBank (accession nos.: ITS: OM319846, OM319848; TUB2: OM417078, OM417080; TEF-1α: OM417081, OM417083). BLASTn analyses showed: for ITS and TEF-1α sequences, ≥99.7% identity to the ex-type of G. smithogilvyi (ITS: JQ910642, 474 matching bp; TEF-1α: JQ910645, 335-338 matching bp), and for TUB2 sequences, ≥99.1% identity to G. castaneae (LN999975, 446-453 matching bp). Pathogenicity tests were carried out on surface disinfected nuts of Castanea sativa `Raigona´. A superficial wound was made in the pericarp of each nut. A 2-mm mycelial plug of a 7-days-old culture of G. smithogilvyiwas then inoculated: twenty nuts with isolate EFA924A and twenty with isolate EFA962.4A. Twenty nuts inoculated with sterile agar were used as control. The holes were sealed with Parafilm®. Nuts were incubated in a moist chamber at 22±2°C. Two replicated tests were carried out. Four inoculated and four control nuts were inspected for the presence and progress of rot symptoms every seven days. Three weeks after inoculation, all remaining inoculated nuts were completely rotted, whereas all control nuts remained healthy. Gnomoniopsis smitholgilvyi was reisolated from all inoculated nuts, and it was not recovered from the controls. This pathogen causes chestnut brown rot on sweet chestnut worldwide (EPPO, 2022), causing also shoot cankers on chestnut (Lione et al, 2019). This is the first report of G. smithogilvyi causing chestnut brown rot on nuts and burrs of C. sativa in Spain. Future studies on the incidence of this pathogen and its impact on chestnut yield should be carried out in the main European producing countries, i.e. Spain, Italy, Portugal and Greece, where the disease has been detected and represents an emerging threat to chestnut production.

Occurrence of mycotoxins and mycotoxigenic fungi in silage from the north of Portugal at feed-out.

Maize and grass silages are important dietary components for ruminant livestock that influence the quality of animal products for human consumption, such as milk, in many parts of the world. Infection of plants by fungi able to produce mycotoxins, either in the field or post-harvest, can result in a decrease of silage nutritional quality and, consequently, in milk quality. In this study, 45 maize and grass silage samples were collected from 25 dairy farms located in the north of Portugal. The occurrence of fungi was evaluated in samples, the most frequently isolated species being Aspergillus fumigatus, Dipodascus geotrichum, Mucor circinelloides, Penicillium paneum, and Aspergillus flavus. The mycotoxigenic profile of the fungal species was studied using the ultra-high-performance liquid chromatography coupled to mass spectrometry-ion trap-time-of-flight (UHPLC-MS-IT-TOF) detection. In addition, a new method based on a QuEChERS extraction followed by the UHPLC- tandem mass spectrometry (UHPLC-MS/MS) detection was developed for simultaneous analysis of 39 mycotoxins in silage. A high co-occurrence of Fusarium mycotoxins was found, although at low levels of contamination. Deoxynivalenol and beauvericin were found in more than 82% of maize silage samples. It can be highlighted the low occurrence of Penicillium and Aspergillus toxins in the maize and grass silages studied despite the frequent detection of species of both genera.

Multianalyte method for the determination of regulated, emerging and modified mycotoxins in milk: QuEChERS extraction followed by UHPLC-MS/MS analysis.

A simple method for the quantification of 40 mycotoxins in milk was developed. This method is based on a QuEChERS extraction followed by the ultra-high liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) detection, and allows the simultaneous analysis of regulated, emerging, and modified mycotoxins. A sample treatment procedure was optimized to include a concentration step for the analysis of some compounds such as aflatoxin M1. The method was in-house validated in terms of limits of detection (LODs), limits of quantification (LOQs), linearity, recoveries, and precision. LOQs lower than 10 ng/mL were obtained, and recoveries ranged from 61% to 120% with a precision, expressed as the relative standard deviation, lower than 15%. Therefore, acceptable performance characteristics were obtained fulfilling European regulations. The method was successfully applied for the quantification of mycotoxins in raw milk. It can be highlighted high occurrence of beauvericin and enniatins were found in low amounts.

Magnetic nanostructures for marine and freshwater toxins removal.

Marine and freshwater toxins contaminate water resources, shellfish and aquaculture products, causing a broad range of toxic effects in humans and animals. Different core-shell nanoparticles were tested as a new sorbent for removing marine and freshwater toxins from liquid media. Water solutions were contaminated with 20 µg/L of marine toxins and up to 50 µg/L of freshwater toxins and subsequently treated with 250 or 125 mg/L of nanoparticles. Under these conditions, carbon nanoparticles removed around 70% of saxitoxins, spirolides, and azaspiracids, and up to 38% of diarrheic shellfish poisoning toxins. In the case of freshwater toxins, the 85% of microcystin LR was eliminated; other cyclic peptide toxins were also removed in a high percentage. Marine toxins were adsorbed in the first 5 min of contact, while for freshwater toxins it was necessary 60 min to reach the maximum adsorption. Toxins were recovered by extraction from nanoparticles with different solvents. Gymnodinium catenatum, Prorocentrum lima, and Microcystis aeruginosa cultures were employed to test the ability of nanoparticles to adsorb toxins in a real environment, and the same efficacy to remove toxins was observed in these conditions. These results suggest the possibility of using the nanotechnology in the treatment of contaminated water or in chemical analysis applications.

Detoxification agents based on magnetic nanostructured particles as a novel strategy for mycotoxin mitigation in food.

Mycotoxins are toxic compounds that can be present in feed, food and beverages. In this work, 25 magnetic nanostructured materials were developed to remove the main types of mycotoxins from liquid food matrices. The efficiency for binding mycotoxins from contaminated aqueous solutions was studied. Nanocomposites (diameters lower to 15 µm) composed of mixtures of activated carbon, bentonite and aluminium oxide were able to eliminate up to 87% of mycotoxins with an adsorption efficiency of 450 µg/g. On the other hand, spheres with sizes below 3 mm and composed by biopolymers and activated carbon or graphene oxide removed up to 70% of mycotoxins (adsorption of 598 ng/g). These particles were tested for beer detoxification, and spheres composed of alginate and activated carbon or pectin maintain the ability to eliminate toxins from this beverage. Hence, this technology could be a useful tool for the food industry.

First report of Fusarium foetens as a mycotoxin producer.

Fusarium foetens, a pathogen of Begonia plants, has been recently described as a new fungal species. This Fusarium species causes a destructive vascular wilt disease which leads to the death of the plant. Moreover, Fusarium species are known to produce a huge variety of secondary metabolites such as mycotoxins and phytotoxins. Here, we studied the toxicogenic profile of one F. foetens strain, isolated from maize, employing two methods based on the use of ultra-performance liquid chromatography coupled to mass spectrometry-ion trap-time of flight detection. The mycotoxins beauvericin and fusaric acid were detected in a pure culture of F. foetens. In addition, four fusaric acid analogs (10,11-dihidroxyfusaric acid, hydroxyfusaric acid, dehydrofusaric acid, and a hydroxylated unsaturated fusaric acid analog) were tentatively identified on the basis of their accurate mass and fragmentation patterns. Therefore, these preliminary data indicate that F. foetens isolated from maize is able to produce Fusarium mycotoxins including beauvericin and fusaric acid.

A QuEChERS based extraction procedure coupled to UPLC-MS/MS detection for mycotoxins analysis in beer.

A new method based on a QuEChERS extraction followed by the ultra-high liquid chromatography tandem mass spectrometry (UPLC-MS/MS) detection has been developed for the analysis of mycotoxin in beer. The method allows the identification and quantification of 23 mycotoxins with different chemical characteristic including regulated, emerging and masked compounds. A sample treatment procedure involving a QuEChERS extraction and dispersive solid-phase clean-up steps was applied. This protocol involves a new approach based on a sample concentration before the extraction. The method was in-house validated in terms of limits of detection (LODs), limits of quantification (LOQs), linearity, repeatability and recoveries. For most compounds, recoveries ranged from 70% to 110% with LOQs (from 0.038 to 30.43 µg/L) lower than the maximum residue levels established in European regulations. In general, acceptable performance characteristics were obtained fulfilling the current legislation. Therefore, the proposed method is appropriate for routine analysis of beer.

Detection of new emerging type-A trichothecenes by untargeted mass spectrometry.

Mycotoxins occur naturally as agricultural contaminants all over the world. The toxic effects of some of their metabolites are known and their presence regulated in food and feed. This paper describes two methods for the detection of toxins of type-A trichothecenes group, and their modified forms, using mass spectrometry. Ultra-performance liquid chromatography coupled to mass spectrometry-ion trap-time of flight (UPLC-MS-IT-TOF) was employed to characterize the fragmentation pathways of 10 type-A trichothecenes, and characteristic ions were tentatively identified in scan mode through their accurate masses. Unknown signals were detected in a F. sporotrichioides extract, which afterwards were identified as seven modified forms of neosolaniol (NEO) and T-2 toxin. Then, UPLC coupled to tandem mass spectrometry (MS/MS) was employed to develop a precursor ion scanning method that can be used as a screening tool to detect any modified type-A trichothecenes.

UPLC-MS-IT-TOF Identification of Circumdatins Produced by Aspergillus ochraceus.

A method based on the combined use of ultraperformance liquid chromatography coupled to mass spectrometry-ion trap-time-of-flight (UPLC-MS-IT-TOF) detection was employed to identify the metabolite production of Aspergillus ochraceus, which is the major cause of food and feed contamination due to ochratoxin A. Under the proposed chromatographic conditions, seven metabolites belonging to the family of circumdatins were separated and identified. Their initial identification was performed through the exact molecular formula, as a function of their accurate mass. Collision-induced dissociation was applied to predict precursor and product ions, and the elemental composition of each compound was obtained. The elimination of nitrogenous groups followed by successive losses of carbonyl groups is the common fragmentation pathway of circumdatins. With the fragmentation data obtained, an UPLC-MS/MS method was created and optimized to detect circumdatins in corn samples.

Triacylglyceride, antioxidant and antimicrobial features of virgin Camellia oleifera, C. reticulata and C. sasanqua Oils.

Virgin oils obtained from seeds of Camellia oleifera (CO), Camellia reticulata (CR) and Camellia sasanqua (CS) were studied for their triacylglyceride composition, antioxidant and antimicrobial activities. Levels of fatty acids determined by ¹H-nuclear magnetic resonance analysis were similar to those reported for olive oils (82.30%-84.47%; 5.69%-7.78%; 0.26%-0.41% and 8.04%-11.2%, for oleic, linoleic, linolenic and saturated acids, respectively). The CR oil showed the best antioxidant potential in the three in vitro models tested. With regard to EC50 values (µg/mL), the order in DPPH radical-scavenging was CR (33.48) < CO (35.20) < CS (54.87). Effectiveness in reducing power was CR (2.81) < CO (3.09) < CS (5.32). IC50 for LPO inhibition were 0.37, 0.52 and 0.75 µg/mL for CR, CO and CS, respectively. All the oils showed antimicrobial activity, and exhibited different selectivity and MICs for each microorganism tested (E. coli, B. cereus and C. albicans). B. cereus was the less sensitive species (MIC: 52.083 ± 18.042 for CO; 41.667 ± 18.042 for CR; 104.167 ± 36.084 for CS mg/mL) and the E. coli was the most sensitive to camellia oil's effect. The standard gentamicin presented higher MIC for E. coli (4.2) than the CR (MIC= 2.6) and CO (MIC = 3.9) oils.

¹H-nuclear magnetic resonance analysis of the triacylglyceride composition of cold-pressed oil from Camellia japonica.

Camellia japonica (CJ) has oil-rich seeds, but the study of these oils has received little attention and has mainly focused only on their health properties. In the present work the relative composition of the fatty acid (FA) components of the triglycerides in cold-pressed oil from CJ is studied by ¹H-NMR. The results obtained were: 75.75%, 6.0%, 0.17% and 18.67%, for oleic, linoleic, linolenic and saturated FA respectively. Levels of C18 unsaturated FA found in CJ oil were similar to those reported for olive oils. We also checked the possibility of using ¹³C-NMR spectroscopy; however, the results confirmed the drawback of ¹³C over ¹H-NMR for the study of FA components of CJ triglycerides due to its low gyromagnetic ratio and its very low natural abundance.

In vitro selection of an effective fungicide against Armillaria mellea and control of white root rot of grapevine in the field.

Armillaria mellea (Vahl ex Fr) Kummer is an aggressive pathogen which causes white root rot in a wide range of hosts. Most chemicals tested so far against Armillaria, both in vitro and in the field, have not been effective in reducing fungal growth and/or preventing plant decline and mortality. In the present work the effects of four DMI (sterol demethylation inhibitor) fungicides, cyproconazole, hexaconazole, propiconazole and tetraconazole, and another six downwardly mobile systemic chemicals, azoxystrobin, cubiet (copper bis(ethoxy-dihydroxy-diethylamino)sulfate), fosetyl-Al, potassium phosphite, sodium tetrathiocarbonate (STTC) and 2-(thiocyanomethylthio)benzothiazole (TCMTB), on the mycelial growth of A. mellea were compared and evaluated; the product yielding the best results in in vitro experiments was selected to determine its efficacy in preventing decline and mortality of grapevines in the field. Best results on in vitro fungal growth reduction were obtained with the four azoles tested, in particular with cyproconazole and hexaconazole, achieving 67-72% mycelial growth inhibition at the lowest dose. Results obtained in the field showed that a dose of 50 mg AI litre(-1) of cyproconazole once or twice a year was efficient in controlling the disease even in vines seriously affected by the pathogen. However, further research is required to study minimum effective doses, residual effects and the convenience of the application of annual dressings in damaged vineyards, so as to gradually reduce the pathogen inoculum potential in soil and control the disease while reducing chemical residues in the plant and preventing development of fungal resistance.