Mesoporous silica nanoparticles adsorb aflatoxin B1 and reduce mycotoxin-induced cell damage.

The present study examined the effects of mesoporous silica nanoparticles (MSNs) on its adsorption capacity of aflatoxin B1 (AFB1). Moreover, the study evaluated the toxicity of MSNs with AFB1 using NIH3T3 cells and hemolysis test. The obtained MSNs were spherical, irregular-like in shape, having a mean size of 39.97 ± 7.85 nm and a BET surface area of 1195 m2/g. At 0.1 mg mL-1 concentration of MSN, the AFB1 adsorption capacity was 30%, which reached 70% when the MSN concentration increased to 2.0 mg mL-1. Our findings showed that AFB1 was adsorbed (∼67%) in the first few minutes on being in contact with MSNs, reaching an adsorption capacity of ∼70% after 15 min. Thereafter, the adsorption capacity remained constant in solution, demonstrating that the MSNs adsorbed toxins even beyond overnight. MSN treatment (0.5-2.0 mg mL-1) using NIH3T3 cells did not result in any reduction in cell viability. In addition, MSN treatment completely reversed the cytotoxic effect of AFB1 at all concentrations. Hemolysis test also revealed no hemolysis in MSNs evaluated alone and in those combined with AFB1. To the best of our knowledge, this study is the first to demonstrate that MSN can reduce cell toxicity produced by AFB1 due to its potential to adsorb mycotoxins.

Mesoporous silica nanoparticles incorporated with zinc oxide as a novel antifungal agent against toxigenic fungi strains.

Developing environmentally friendly alternative strategies to reduce the damage caused by fungi in agriculture has been widely investigated. In this study, we evaluated using mesoporous silica nanoparticles (MSNs) incorporated with zinc oxide (MSNs-ZnO) as a potential antifungal agent against Fusarium graminearum and Aspergillus flavus strains, as well as their antimycotoxin properties. The MSNs that synthesized and characterized could release abundant ZnO in the first 24 h. Subsequently, the ZnO release became slower, providing greater durability of the antifungal effect. Significant (P < 0.001) growth reductions in F. graminearum (81%) and A. flavus (65%) compared to the control were obtained at a high concentration of the MSNs-ZnO (1.0 mg mL-1). Moreover, the MSNs-ZnO treatment at a high concentration (1.0 mg mL-1) caused morphology alteration in both fungi, showing ruptures and deformations in the fungal hyphae, affecting their growth and toxin production. A significant reduction (P < 0.001) in the productions of deoxynivalenol (89%) and aflatoxin B1 (58%) by F. graminearum and A. flavus were also observed. These findings imply that using MSNs as the carriers of zinc compounds, such as ZnO, could be investigated as a safe alternative for effectively controlling toxigenic fungi in agriculture.

Wild rice (O. latifolia) from natural ecosystems in the Pantanal region of Brazil: Host to Fusarium incarnatum-equiseti species complex and highly contaminated by zearalenone.

We assessed the mycobiota diversity and mycotoxin levels present in wild rice (Oryza latifolia) from the Pantanal region of Brazil; fundamental aspects of which are severely understudied as an edible plant from a natural ecosystem. We found multiple fungal species contaminating the rice samples; the most frequent genera being Fusarium, Nigrospora and Cladosporium (35.9%, 26.1% and 15%, respectively). Within the Fusarium genus, the wild rice samples were mostly contaminated by the Fusarium incarnatum-equiseti species complex (FIESC) (80%) along with Fusarium fujikuroi species complex (20%). Phylogenetic analysis supported multiple FIESC species and gave support to the presence of two putative new groups within the complex (LN1 and LN2). Deoxynivalenol (DON) and zearalenone (ZEN) chemical analysis showed that most of the isolates were DON/ZEN producers and some were defined as high ZEN producers, displaying abundant ZEN levels over DON (over 19 times more). Suggesting that ZEN likely has a key adaptive role for FIESC in wild rice (O. latifolia). Mycotoxin determination in the rice samples revealed high frequency of ZEN, and 85% of rice samples had levels >100 µg/kg; the recommended limit set by regulatory agencies. DON was only detected in 5.2% of the samples. Our data shows that FIESC species are the main source of ZEN contamination in wild rice and the excessive levels of ZEN found in the rice samples raises considerable safety concerns regarding wild rice consumption by humans and animals.

Microbiological evaluation of bristles of frequently used toothbrushes / Avaliação microbiológica das cerdas de escovas dentárias de uso frequente

INTRODUCTION: Brushing teeth is probably the practice of oral hygiene most common in the world; however, inadequate use can become a risk to the population health, once they may be contaminated with various microorganisms. OBJECTIVE: The aim of this study was to evaluate the bacterial contamination on toothbrush bristles using different methodologies. METHOD: We used 40 toothbrushes from healthy individuals aged 3 to 58 years. The samples were grown in test tubes containing trypticase soy broth sterile, and with the help of a tracking 0.1 μl samples were placed on plates containing sheep blood agar 5% and MacConkey agar then the samples were stored in a bacteriological incubator at 37°C for 24 hours for later analysis. It was counted the colony forming units and bacteria identification present in the brush. RESULTS: On the microbiological analysis, there was a growth of Escherichia coli, Klebsiella pneumoniae, Streptococcus pyogenes and Staphylococcus coagulase negative. CONCLUSION: According to the results presented in this study, we observed a high incidence of bacterial contamination in the brushes analyzed. The most frequent microorganisms were members of the Enterobacteriaceae. The usage time of toothbrushes may be related to contamination found and, therefore, not only good hygiene ensures the reduction of microbial load, but replacing the toothbrush can also ensure individuals better oral health.

INTRODUÇÃO: a escovação de dentes é, provavelmente, a prática de higiene bucal mais comumente realizada no mundo; entretanto, o acondicionamento inadequado pode se transformar em um risco para a saúde da população, uma vez que podem estar contaminadas com vários tipos de microrganismos. OBJETIVO: o objetivo desse estudo foi avaliar a contaminação bacteriana de cerdas de escovas dentais através de diferentes métodos. MÉTODOS: foram utilizadas 40 escovas de dentes provenientes de indivíduos sadios, com idade entre 3 a 58 anos. As amostras foram semeadas em tubo de ensaio contendo caldo tripticaseína de soja (TSB) estéril e, com o auxílio de uma alça de 0,1μl, as amostras foram semeadas em placas contendo ágar sangue de carneiro a 5% e ágar MacConkey. Em seguida foram armazenadas em estufa bacteriológica a 37°C por 24hs para posterior análise. Foi realizada a contagem das unidades formadora de colônias (UFC) e a identificação das bactérias presentes nas escovas. RESULTADOS: nas análises microbiológicas, houve crescimento de Escherichia coli, Klebsiella pneumoniae, Streptococcus pyogenes e Staphylococcus coagulase negativas. Conclusões: de acordo com os resultados apresentados nesse trabalho, verificamos que houve alta incidência de contaminação bacteriana nas escovas analisadas. Os microrganismos com maior frequência foram membros da família Enterobacteriaceae. O tempo de uso das escovas dentárias pode estar relacionado à contaminação encontrada e, por isso, não só uma boa higienização garantirá a redução da carga microbiana, mas a troca da escova dentária também pode garantir melhor saúde bucal aos indivíduos.