Identification of the oosporein biosynthesis gene cluster in an entomopathogenic fungus Blackwellomyces cardinalis.

Blackwellomyces cardinalis (≡ Cordyceps cardinalis) is an entomopathogenic fungus that hosts lepidopteran insect larvae. Oosporein, produced by Bl. cardinalis, is a red secondary metabolite that is also produced by other entomopathogens and is known to contribute to entomopathogenic activity. In this study, a homologous region of the oosporein biosynthesis gene cluster (BcOpS cluster) was found from the genome sequence of Bl. cardinalis strain NBRC 103832. Within the cluster, a putative transcription factor gene BcOpS3 was deleted by homologous recombination. The deletion strain (ΔBcOpS3) did not produce oosporein. Real-time qPCR analysis showed that the expression of all genes was either lost or greatly reduced compared to the wild type strain (WT). Infection assay using silkworms showed that the virulence of the ΔBcOpS3 strain was not different from that of the WT strain. We compared the expression levels of antimicrobial peptide genes in silkworm infected with these strains, and found that the increased expression of the cecA gene in WT was not observed in the ΔBcOpS3 strain, suggesting that the immune response of the silkworm was altered.

Determination of Total Aflatoxins in Polished Rice by Liquid Chromatography-Fluorescence Detection with Multifunctional Column Cleanup and Precolumn Derivatization: Single-Laboratory and Inter-Laboratory Validation Studies.

BACKGROUND: Aflatoxins are toxic metabolites produced by Aspergillus spp. Because aflatoxins are potent carcinogens in humans and animals, many countries have set regulatory limits for aflatoxins in foods to prevent dietary exposure. From a global food safety perspective, in 2023, the Codex Alimentarius Commission established the maximum level (ML) of total aflatoxins in certain cereals and cereal-based products, including polished rice. Therefore, validated analytical methods for aflatoxin detection are necessary. OBJECTIVE: In this study, a high performance liquid chromatography (HPLC)-fluorescence method coupled with multifunctional column clean-up and trifluoroacetic acid derivatization was developed for the determination of aflatoxin levels in polished rice. METHODS: Our method was validated in a single laboratory study using aflatoxin-spiked materials, followed by an inter-laboratory validation study. Twelve laboratories participated in the inter-laboratory validation study, and five polished rice test samples artificially contaminated with aflatoxins were analyzed. RESULTS: In a single laboratory study, the ranges of mean recoveries of aflatoxin B1, B2, G1, G2, and total aflatoxins were 101%, 100-103%, 93-96%, 95-98%, and 97-99%, respectively. The relative standard deviations for within-day and between-day variations were all ≤ 4.4%. In the inter-laboratory validation study, the relative standard deviations for repeatability and reproducibility were from 0.7 to 2.7% and 3.3 to 8.9% for all analytes, respectively. CONCLUSION: In response to the Codex ML and method performance criteria for aflatoxins in polished rice, an analytical method based on HPLC-fluorescence detection was developed. All method performance parameters estimated from the testing results of the single-laboratory and inter-laboratory validation studies met the criteria required by the Codex. HIGHLIGHTS: Single- and inter-laboratory studies for the validation of an analytical method for aflatoxin level determination in polished rice were successfully performed. This analytical method will be suitable to determine aflatoxin levels around the Codex ML set for polished rice.

Oral Exposure to Low Concentration of Fumonisin B2, but Not Fumonisin B1, Significantly Exacerbates the Pathophysiology of Imiquimod-Induced Psoriasis in Mice.

This study aimed to determine whether oral fumonisin exposure contributes to the development of psoriasis. Oral administration of fumonisin B1 (FB1, 0.1 mg/kg) or fumonisin B2 (FB2, 0.1 mg/kg) was conducted for 10 days, in addition to the induction of psoriatic symptoms through topical application of 5% imiquimod cream from day 6 to day 10 (5 days) in female BALB/c mice. The results demonstrated that oral administration of FB2 significantly exacerbated psoriatic symptoms, including skin thickness, itching behavior, transepidermal water loss, immune cell infiltration in the dermis, and proinflammatory cytokine production. However, no changes were observed following exposure to FB1. Our results confirm that oral exposure to FB2 adversely affects the pathogenesis of psoriasis by increasing skin thickness and impairing barrier function.

Atypical diarrhoeagenic Escherichia coli in milk related to a large foodborne outbreak.

A foodborne outbreak related to milk cartons served in school lunches occurred in June 2021, which involved more than 1,800 cases from 25 schools. The major symptoms were abdominal pain, diarrhoea, vomiting, and fever. Although major foodborne toxins and pathogens were not detected, a specific Escherichia coli strain, serotype OUT (OgGp9):H18, was predominantly isolated from milk samples related to the outbreak and most patients tested. The strains from milk and patient stool samples were identified as the same clone by core genome multilocus sequence typing and single-nucleotide polymorphism analysis. The strain was detected in milk samples served for two days related to the foodborne outbreak at a rate of 69.6% and levels of less than ten most probable number/100 mL but not on days unrelated to the outbreak. The acid tolerance of the strain for survival in the stomach was similar to that of enterohaemorrhagic E. coli O157:H7, and the same inserts in the chu gene cluster in the acid fitness island were genetically revealed. The pathogenicity of the strain was not clear; however, it was indicated that the causative pathogen was atypical diarrhoeagenic E. coli OUT (OgGp9):H18.

Chronic oral exposure to low-concentration fumonisin B2 significantly exacerbates the inflammatory responses of allergies in mice via inhibition of IL-10 release by regulatory T cells in gut-associated lymphoid tissue.

Contamination with fumonisins produced by Fusarium spp. is rapidly growing in both developing and developed countries. The purpose of this study was to determine whether oral exposure to fumonisin contributed to the development of allergic diseases. We initially examined the immunotoxic potential of short-term, oral administration of fumonisin B1 (FB1, 1 mg/kg) and fumonisin B2 (FB2, 1 mg/kg), both naturally occurring fumonisins, using a BALB/c mouse model of allergic contact dermatitis and Dermatophagoides farina-induced asthma. Using an NC/nga mouse model of atopic dermatitis (AD), we evaluated the adverse effects of subchronic oral exposure to low concentrations of FB2 (2 or 200 µg/kg). Finally, we explored the influence of FB2 on regulatory T cell proliferation and function in mesenteric lymph nodes after 1-week oral exposure to FB2 in BALB/c mice. Oral exposure to FB2 markedly exacerbated the symptoms of allergy, including skin thickness, histological evaluation, immunocyte proliferation, and proinflammatory cytokine production, although no change was observed following exposure to FB1. Furthermore, oral exposure to low concentrations of FB2 considerably exacerbated the AD scores, skin thickness, transepidermal water loss, histological features, and proinflammatory cytokine production. The aggravated allergic symptoms induced by oral exposure to FB2 could be attributed to the direct inhibition of IL-10 production by regulatory T cells in mesenteric lymph nodes. Our findings indicate that the recommended maximum fumonisin level should be reconsidered based on the potential for allergy development.

Determination of the biological origin of enzyme preparations using SDS-PAGE and peptide mass fingerprinting.

Enzymes are mainly extracted from the culture broth of microorganisms. Various commercially available enzyme preparations (EPs) are derived from different microorganisms, and the source of the EP should be the same as that mentioned in the manufacture's information. The development of analytical methods that can determine the origin of the final products is important for ensuring that the EPs are nontoxic, especially when used as food additives. In this study, various EPs were subjected to SDS-PAGE, and the main protein bands were excised. After in-gel digestion, the generated peptides were analysed using MALDI-TOF MS, and protein identification was performed by searching the set of peptide masses against protein databases. In total, 36 EPs including amylase, ß-galactosidase, cellulase, hemicellulase and protease were analysed, and the information about the enzyme sources was obtained for 30 EPs. Among these, the biological sources determined for 25 EPs were consistent with the manufacturer's information; for the remaining five, enzymes produced by closely-related species were shown as matching proteins due to high sequence similarity. Six enzymes derived from four microorganisms could not be identified because their protein sequences were not registered in the database. As these databases are expanded, this approach of using SDS-PAGE and peptide mass fingerprinting (PMF) can determine the biological origin of enzymes rapidly and contribute to ensuring the safety of EPs.

Pharmacokinetics and 28-day repeated-dose toxicity of enniatin B after oral administration in mice.

Enniatins are emerging mycotoxins that contaminate foods. The present study investigated the oral pharmacokinetics and 28-day repeated-dose oral toxicity of enniatin B (ENNB) in CD1 (ICR) mice. In the pharmacokinetic study, male mice received a single oral or intravenous dose of ENNB [30 mg/kg body weight (BW) and 1 mg/kg BW, respectively]. After oral dosing, ENNB exhibited 139.9% bioavailability, a 5.1-h elimination half-life, 5.26% fecal excretion from 4 to 24 h post-dose, and upregulation of Cyp7a1, Cyp2a12, Cyp2b10, and Cyp26a1 in the liver 2 h post-dosing. In the 28-day toxicity study, ENNB was administered to male and female mice by oral gavage at 0, 7.5, 15, and 30 mg/kg BW/day. Females (7.5 and 30 mg/kg) showed dose-unrelated decreased food consumption without accompanying changes in clinical parameters. Males (30 mg/kg) showed low red blood cell counts and high blood urea nitrogen levels and absolute kidney weights; however, other related parameters including the histopathology of systemic organs/tissues were unchanged. These results suggest that ENNB may not induce toxicity after 28 days of oral administration in mice, despite high absorption. The no-observed-adverse-effect level of ENNB after 28 days of repeated oral doses was 30 mg/kg BW/day for both sexes of mice.

Free and Modified Mycotoxins in Organic and Conventional Oats (Avena sativa L.) Grown in Scotland.

Small grain cereals are frequently infected with mycotoxigenic Fusarium fungi. Oats have a particularly high risk of contamination with type A trichothecene mycotoxins; their glucoside conjugates have also been reported. Agronomy practices, cereal variety and weather conditions have been suggested to play a role in Fusarium infection in oats. The current study investigates concentrations of free and conjugated Fusarium mycotoxins in organic and conventional oats grown in Scotland. In 2019, 33 milling oat samples (12 organic, 21 conventional) were collected from farmers across Scotland, together with sample questionnaires. Samples were analysed for 12 mycotoxins (type A trichothecenes T-2-toxin, HT-2-toxin, diacetoxyscirpenol; type B trichothecenes deoxynivalenol, nivalenol; zearalenone and their respective glucosides) using LC-MS/MS. The prevalence of type A trichothecenes T-2/HT-2 was very high (100% of conventional oats, 83% of organic oats), whereas type B trichothecenes were less prevalent, and zearalenone was rarely found. T-2-glucoside and deoxynivalenol-glucoside were the most prevalent conjugated mycotoxins (36 and 33%), and co-occurrence between type A and B trichothecenes were frequently observed (66% of samples). Organic oats were contaminated at significantly lower average concentrations than conventional oats, whereas the effect of weather parameters were not statistically significant. Our results clearly indicate that free and conjugated T-2- and HT-2-toxins pose a major risk to Scottish oat production and that organic production and crop rotation offer potential mitigation strategies.

Trichoderma versus Fusarium-Inhibition of Pathogen Growth and Mycotoxin Biosynthesis.

This study evaluated the ability of selected strains of Trichoderma viride, T. viridescens, and T. atroviride to inhibit mycelium growth and the biosynthesis of mycotoxins deoxynivalenol (DON), nivalenol (NIV), zearalenone (ZEN), α-(α-ZOL) and ß-zearalenol (ß-ZOL) by selected strains of Fusarium culmorum and F. cerealis. For this purpose, an in vitro experiment was carried out on solid substrates (PDA and rice). After 5 days of co-culture, it was found that all Trichoderma strains used in the experiment significantly inhibited the growth of Fusarium mycelium. Qualitative assessment of pathogen-antagonist interactions showed that Trichoderma colonized 75% to 100% of the medium surface (depending on the species and strain of the antagonist and the pathogen) and was also able to grow over the mycelium of the pathogen and sporulate. The rate of inhibition of Fusarium mycelium growth by Trichoderma ranged from approximately 24% to 66%. When Fusarium and Trichoderma were co-cultured on rice, Trichoderma strains were found to inhibit DON biosynthesis by about 73% to 98%, NIV by about 87% to 100%, and ZEN by about 12% to 100%, depending on the pathogen and antagonist strain. A glycosylated form of DON was detected in the co-culture of F. culmorum and Trichoderma, whereas it was absent in cultures of the pathogen alone, thus suggesting that Trichoderma is able to glycosylate DON. The results also suggest that a strain of T. viride is able to convert ZEN into its hydroxylated derivative, ß-ZOL.

Survival of SARS-CoV-2 and bovine coronavirus on common surfaces of living environments.

Aerosols or saliva containing severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can contaminate living environments, and viruses can be indirectly transmitted. To understand the survival potential of the virus, the viral titers of bovine coronavirus (BCoV), as a model virus, and SARS-CoV-2 were measured on porous and non-porous surfaces. The amount of infectious BCoV recovered remained relatively high on non-porous substrates. However, it quickly decreased on several non-porous surfaces such as nitrile rubber. The time taken to reach the limit of detection on non-woven masks, as a porous substrate, was longer than that of non-porous substrates. On porous substrates other than non-woven masks, the amount of virus recovered quickly decreased, and then remained at a low level. Representative substrates were tested with SARS-CoV-2. The decrease in the amount of infectious virus recovered was similar to that of BCoV, although that of SARS-CoV-2 was more rapid. RNA derived from SARS-CoV-2 was also detected using real-time PCR, and it remained on surfaces much longer than infectious virus, on all substrates. Therefore, it is important to measure the viral titer to avoid the overestimation of infectious virus contamination in the environments. Our results suggest that the surface structure was not directly related to viral survivability.

Cross-genus inhibitory activity of polyoxins against aflatoxin production by Aspergillus parasiticus and fumonisin production by Fusarium fujikuroi.

Co-exposure to aflatoxin and fumonisin is a health concern where corn is a staple food, and a method to prevent co-contamination of these mycotoxins in foods is urgently needed. Polyoxins are chitin synthase inhibitors produced by Streptomyces cacaoi var. asoensis. The aflatoxin production inhibitory activity of a commercially available polyoxin D and four polyoxins purified from polyoxin AL water-soluble powder, an agricultural chemical containing polyoxins, was tested. The five polyoxins dose-dependently inhibited aflatoxin production by Aspergillus parasiticus and the IC50 values of polyoxin A, B, D, K and L were 16, 74, 110, 9 and 280 µmol L-1, respectively. Polyoxins also inhibited fumonisin production by Fusarium fujikuroi, and the IC50 values of polyoxin B, D, K and L were 270, 42, 65 and 62 µmol L-1, respectively. Polyoxins repressed the transcription of genes encoding proteins required for aflatoxin biosynthesis in A. parasiticus and fumonisin biosynthesis in F. fujikuroi. Polyoxin K and D also inhibited conidiation in A. parasiticus and F. fujikuroi, respectively. These results suggest that a mixture of polyoxins may effectively prevent co-contamination of aflatoxin and fumonisin in foods.

Dynamics of Deoxynivalenol and Nivalenol Glucosylation in Wheat Cultivars Infected with Fusarium culmorum in Field Conditions─A 3 Year Study (2018-2020).

Fusarium head blight (FHB) caused by pathogenic species of Fusarium fungi is one of the most important diseases of cereal plants and a factor contributing to losses in plant production. The growth of FHB-associated species is often accompanied by biosynthesis of secondary metabolites─mycotoxins, which serve as a virulence factor. The aim of the study was to evaluate the ratios between deoxynivalenol (DON) and nivalenol (NIV) and their derivatives in the ears of six cultivars of winter wheat with varying resistance to FHB, taking into account a range of factors (weather conditions, location, cultivar, and year) after inoculation with Fusarium culmorum, during a 3 year field experiment, 2018-2020. The presence of toxins in the ears was measured within 21 days of inoculation. The toxins were found in the ears as soon as on the third day from the start of the experiment, whereas relative humidity higher than 80% was a decisive factor for FHB incidence. All wheat cultivars showed the ability to biotransform DON and NIV present in the ears to glucosides, that is, deoxynivalenol-3-glucoside (DON-3G) and nivalenol-3-glucoside (NIV-3G). The levels of these metabolites showed significant correlation with the levels of their basic analogues. In most cases, higher levels of DON and NIV in wheat ears and higher levels of their metabolites were observed, but the relative levels of DON-3G/DON and NIV-3G/NIV at relatively high levels of toxins were lower compared to the ear samples with relatively low toxin levels. The presented results are the first studies, which systematically correlate a variety of wheat cultivars with their extent to glucosylate trichothecenes.

Matrix-Assisted Laser Desorption and Ionization Time-of-Flight Mass Spectrometry Analysis for the Direct Detection of SARS-CoV-2 in Nasopharyngeal Swabs.

The most common diagnostic method used for coronavirus disease-2019 (COVID-19) is real-time reverse transcription polymerase chain reaction (PCR). However, it requires complex and labor-intensive procedures and involves excessive positive results derived from viral debris. We developed a method for the direct detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in nasopharyngeal swabs, which uses matrix-assisted laser desorption and ionization time-of-flight mass spectrometry (MALDI-ToF MS) to identify specific peptides from the SARS-CoV-2 nucleocapsid phosphoprotein (NP). SARS-CoV-2 viral particles were separated from biological molecules in nasopharyngeal swabs by an ultrafiltration cartridge. Further purification was performed by an anion exchange resin, and purified NP was digested into peptides using trypsin. The peptides from SARS-CoV-2 that were inoculated into nasopharyngeal swabs were detected by MALDI-ToF MS, and the limit of detection was 106.7 viral copies. This value equates to 107.9 viral copies per swab and is approximately equivalent to the viral load of contagious patients. Seven NP-derived peptides were selected as the target molecules for the detection of SARS-CoV-2 in clinical specimens. The method detected between two and seven NP-derived peptides in 19 nasopharyngeal swab specimens from contagious COVID-19 patients. These peptides were not detected in four specimens in which SARS-CoV-2 RNA was not detected by PCR. Mutated NP-derived peptides were found in some specimens, and their patterns of amino acid replacement were estimated by accurate mass. Our results provide evidence that the developed MALDI-ToF MS-based method in a combination of straightforward purification steps and a rapid detection step directly detect SARS-CoV-2-specific peptides in nasopharyngeal swabs and can be a reliable high-throughput diagnostic method for COVID-19.

4-O-Glucosylation of Trichothecenes by Fusarium Species: A Phase II Xenobiotic Metabolism for t-Type Trichothecene Producers.

The t-type trichothecene producers Fusarium sporotrichioides and Fusarium graminearum protect themselves against their own mycotoxins by acetylating the C-3 hydroxy group with Tri101p acetylase. To understand the mechanism by which they deal with exogenously added d-type trichothecenes, the Δtri5 mutants expressing all but the first trichothecene pathway enzymes were fed with trichodermol (TDmol), trichothecolone (TCC), 8-deoxytrichothecin, and trichothecin. LC-MS/MS and NMR analyses showed that these C-3 unoxygenated trichothecenes were conjugated with glucose at C-4 by α-glucosidic linkage. As t-type trichothecenes are readily incorporated into the biosynthetic pathway following the C-3 acetylation, the mycotoxins were fed to the ΔFgtri5ΔFgtri101 mutant to examine their fate. LC-MS/MS and NMR analyses demonstrated that the mutant conjugated glucose at C-4 of HT-2 toxin (HT-2) by α-glucosidic linkage, while the ΔFgtri5 mutant metabolized HT-2 to 3-acetyl HT-2 toxin and T-2 toxin. The 4-O-glucosylation of exogenously added t-type trichothecenes appears to be a general response of the ΔFgtri5ΔFgtri101 mutant, as nivalenol and its acetylated derivatives appeared to be conjugated with hexose to some extent. The toxicities of 4-O-glucosides of TDmol, TCC, and HT-2 were much weaker than their corresponding aglycons, suggesting that 4-O-glucosylation serves as a phase II xenobiotic metabolism for t-type trichothecene producers.

Transformation of Selected Fusarium Toxins and Their Masked Forms during Malting of Various Cultivars of Wheat.

This study investigated the impact of malting of six wheat cultivars inoculated with Fusarium culmorum on the dynamics of content changes of selected Fusarium toxins. The grains of all the tested cultivars showed a high content of deoxynivalenol (DON), zearalenone (ZEN), and their derivatives, whereas nivalenol (NIV) and its glucoside were found only in the Legenda cultivar. Our experiments confirmed that the malting process of wheat grain enables the secondary growth of Fusarium, and mycotoxin biosynthesis. The levels of toxins in malt were few-fold higher than those in grain; an especially high increase was noted in the case of ZEN and its sulfate as the optimal temperature and pH conditions for the biosynthesis of these toxins by the pathogen are similar to those used in the grain malting process. This is the first paper reporting that during the malting process, biosynthesis of ZEN sulfate occurs, instead of glycosylation, which is a typical modification of mycotoxins by plant detoxication enzymes.

Disruption of postnatal neurogenesis and adult-stage suppression of synaptic plasticity in the hippocampal dentate gyrus after developmental exposure to sterigmatocystin in rats.

Exposure to sterigmatocystin (STC) raises concerns on developmental neurological disorders. The present study investigated the effects of maternal oral STC exposure on postnatal hippocampal neurogenesis of offspring in rats. Dams were exposed to STC (1.7, 5.0, and 15.0 ppm in diet) from gestational day 6 until day 21 post-delivery (weaning), and offspring were maintained without STC exposure until adulthood on postnatal day (PND) 77, in accordance with OECD chemical testing guideline Test No. 426. On PND 21, 15.0-ppm STC decreased type-3 neural progenitor cell numbers in the subgranular zone (SGZ) due to suppressed proliferation. Increased γ-H2AX-immunoreactive (+) cell numbers in the SGZ and Ercc1 upregulation and Brip1 downregulation in the dentate gyrus suggested induction of DNA double-strand breaks in SGZ cells. Upregulation of Apex1 and Ogg1 and downregulation of antioxidant genes downstream of NRF2-Keap1 signaling suggested induction of oxidative DNA damage. Increased p21WAF1/CIP1+ SGZ cell numbers and suppressed cholinergic signaling through CHRNB2-containing receptors in GABAergic interneurons suggested potential neurogenesis suppression mechanisms. Multiple mechanisms involving N-methyl-d-aspartate (NMDA) receptor-mediated glutamatergic signaling and various GABAergic interneuron subpopulations, including CHRNA7-expressing somatostatin+ interneurons activated by BDNF-TrkB signaling, may be involved in ameliorating the neurogenesis. Upregulation of Arc, Ptgs2, and genes encoding NMDA receptors and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors suggested synaptic plasticity facilitation. On PND 77, ARC+ granule cells decreased, and Nos2 was upregulated following 15.0 ppm STC exposure, suggesting oxidative stress-mediated synaptic plasticity suppression. Inverse pattern in gene expression changes in vesicular glutamate transporter isoforms, Slc17a7 and Slc17a6, from weaning might also be responsible for the synaptic plasticity suppression. The no-observed-adverse-effect level of maternal oral STC exposure for offspring neurogenesis was determined to be 5.0 ppm, translating to 0.34-0.85 mg/kg body weight/day.

A 28-day repeated oral dose toxicity study of enniatin complex in mice.

Enniatins are so-called "emerging mycotoxins" that commonly occur in milligrams per kilogram levels in grains and their derived products, as well as in fish, dried fruits, nuts, spices, cocoa, and coffee. The present study investigated the 28-day repeated oral dose toxicity of enniatin complex in CD1(ICR) mice. Enniatin B, enniatin B1, and enniatin A1 at a ratio of 4:4:1 were administered to male and female mice at doses of 0 (vehicle controls), 0.8, 4, and 20 mg/kg body weight/day. In life parameters did not change during the study period, with the exception of slight reductions in food consumption in male mice administered 4 and 20 mg/kg and in female mice administered 20 mg/kg. Body and organ weights did not change, and no alterations in hematology, blood biochemistry, or histopathology parameters were observed at the end of the administration period. Thus, we determined that the no-observed-adverse-effect level of enniatin complex was 20 mg/kg/day for both sexes under the present experimental conditions.

Transformation of Selected Trichothecenes during the Wheat Malting Production.

The transformation of deoxynivalenol (DON), nivalenol (NIV), and their glucosides (DON3G and NIV3G) during the malting of grains of two wheat varieties was studied. The concentration of DON3G and NIV3G started to increase significantly before the concentration of DON and NIV increased. This may reflect the transformation of the parent mycotoxin forms into their glucosides due to xenobiotic detoxification reactions. After a sharp rise during the last 2 days of the process (day 6 and 7), the DON concentration reached 3010 ± 338 µg/kg in the Legenda wheat-based malt and 4678 ± 963 µg/kg in the Pokusa wheat-based malt. The NIV concentration, at 691 ± 65 µg/kg, remained the same as that in the dry grain. The concentration of DON3G in the Legenda and Pokusa wheat-based malt was five and three times higher, respectively, than that in the steeped grain. The concentration of NIV3G in the Legenda wheat-based malt was more than twice as high as that in the steeped grain. The sharp increase in the concentration of DON at the end of the malting process reflected the high pathogen activity. We set aside some samples to study a batch that was left undisturbed without turning and aeration, for the entire period of malting. The concentration of DON in the malt produced from the latter batch was 135% and 337% higher, for Legenda and Pokusa, respectively, than that in the malt produced from the batch that was turned and aerated. The NIV concentration was 22% higher in the latter batch.

[Discovery of Putative Anti-Kudoa septempunctata Chemical Agents by Comprehensive Assay].

We screened 360 chemicals and discovered that 71 chemicals had anti-Kudoa septempunctata effect. Especially 19 and seven of 71 chemicals were antibiotics and antibacterial agents/disinfectants, respectively. The other 45 chemicals were pesticides, natural toxins, industrial chemicals and medicines for non-infectious diseases. Nineteen antibiotics that possessed anti-Kudoa effect contained four tetracyclines, one steroid, two macrolides, one aminoglycoside, three ß-lactams, one quinolone, two rifamycines, one polyene, one novobiocine, one sulfonamide and two nitroimidazoles. To use these drugs for prevention of Kudoa infection, the further study is need for the determination of effective dose.

Prevalent Human Gut Bacteria Hydrolyse and Metabolise Important Food-Derived Mycotoxins and Masked Mycotoxins.

Mycotoxins are important food contaminants that commonly co-occur with modified mycotoxins such as mycotoxin-glucosides in contaminated cereal grains. These masked mycotoxins are less toxic, but their breakdown and release of unconjugated mycotoxins has been shown by mixed gut microbiota of humans and animals. The role of different bacteria in hydrolysing mycotoxin-glucosides is unknown, and this study therefore investigated fourteen strains of human gut bacteria for their ability to break down masked mycotoxins. Individual bacterial strains were incubated anaerobically with masked mycotoxins (deoxynivalenol-3-ß-glucoside, DON-Glc; nivalenol-3-ß-glucoside, NIV-Glc; HT-2-ß-glucoside, HT-2-Glc; diacetoxyscirpenol-α-glucoside, DAS-Glc), or unconjugated mycotoxins (DON, NIV, HT-2, T-2, and DAS) for up to 48 h. Bacterial growth, hydrolysis of mycotoxin-glucosides and further metabolism of mycotoxins were assessed. We found no impact of any mycotoxin on bacterial growth. We have demonstrated that Butyrivibrio fibrisolvens, Roseburia intestinalis and Eubacterium rectale hydrolyse DON-Glc, HT-2 Glc, and NIV-Glc efficiently and have confirmed this activity in Bifidobacterium adolescentis and Lactiplantibacillus plantarum (DON-Glc only). Prevotella copri and B. fibrisolvens efficiently de-acetylated T-2 and DAS, but none of the bacteria were capable of de-epoxydation or hydrolysis of α-glucosides. In summary we have identified key bacteria involved in hydrolysing mycotoxin-glucosides and de-acetylating type A trichothecenes in the human gut.