Mycotoxins are toxic secondary metabolites produced by certain filamentous fungi (molds). These low molecular weight compounds (usually less than 1000 Daltons) are naturally occurring and practically ...unavoidable. They can enter our food chain either directly from plant-based food components contaminated with mycotoxins or by indirect contamination from the growth of toxigenic fungi on food. Mycotoxins can accumulate in maturing corn, cereals, soybeans, sorghum, peanuts, and other food and feed crops in the field and in grain during transportation. Consumption of mycotoxin-contaminated food or feed can cause acute or chronic toxicity in human and animals. In addition to concerns over adverse effects from direct consumption of mycotoxin-contaminated foods and feeds, there is also public health concern over the potential ingestion of animal-derived food products, such as meat, milk, or eggs, containing residues or metabolites of mycotoxins. Members of three fungal genera,
,
, and
, are the major mycotoxin producers. While over 300 mycotoxins have been identified, six (aflatoxins, trichothecenes, zearalenone, fumonisins, ochratoxins, and patulin) are regularly found in food, posing unpredictable and ongoing food safety problems worldwide. This review summarizes the toxicity of the six mycotoxins, foods commonly contaminated by one or more of them, and the current methods for detection and analysis of these mycotoxins.
The short‐lived hydrophobic gas nitric oxide (NO) is a broadly conserved signaling molecule in all domains of life, including the ubiquitous and versatile filamentous fungi (molds). Several studies ...have suggested that NO plays a vast and diverse signaling role in molds. In this review, we summarize NO‐mediated signaling and the biosynthesis and degradation of NO in molds, and highlight the recent advances in understanding the NO‐mediated regulation of morphological and physiological processes throughout the fungal life cycle. In particular, we describe the role of NO in molds as a signaling molecule that modulates asexual and sexual development, the formation of infection body appressorium, and the production of secondary metabolites (SMs). In addition, we also summarize NO detoxification and protective mechanisms against nitrooxidative stress.
NO signaling is initiated by binding of NO with soluble guanylyl cyclase (sGC). Upon the binding of NO, sGC catalyzes the conversion of GTP to cGMP followed by signal transduction. NO signaling affects diverse aspects of fungal development including conidiation, germination, formation of appressorium and sexual fruiting body. NO signaling is also involved, either as inducer or substrate, in fungal secondary metabolism.
Highlights ► Review updates genetic control of conidiation in two model filamentous fungi Aspergillus nidulans and Neurospora crassa . ► The velvet regulators contribute to the fecundity and fitness ...of fungi by coordinating differentiation and metabolism. ► Light is a key factor influencing the balance between sexual and asexual development and secondary metabolism in fungi.
Summary
The growing release of organic contaminants into the environment due to industrial processes has inevitably increased the incidence of their exposure to humans which often results in negative ...health effects. Microorganisms are also increasingly exposed to the pollutants, yet their diverse metabolic capabilities enable them to survive toxic exposure making these degradation mechanisms important to understand. Fungi are the most abundant microorganisms in the environment, yet less has been studied to understand their ability to degrade contaminants than in bacteria. This includes specific enzyme production and the genetic regulation which guides metabolic networks. This review intends to compare what is known about bacterial and fungal degradation of toxic compounds using benzo(a)pyrene as a relevant example. Most research is done in the context of using fungi for bioremediation, however, we intend to also point out how fungal metabolism may impact human health in other ways including through their participation in microbial communities in the human gut and skin and through inhalation of fungal spores.
In this review, we compare and contrast molecular and enzymatic mechanisms used by bacteria and fungi to degrade toxic compounds. By specifically focusing on degradation of the problematic contaminant benzo(a)pyrene, we highlight how metabolic strategies differ between these microbial kingdoms, as well as point out deficits in our current body of knowledge.
Consumers expect safe, healthy, natural, and sustainable food. Within the food industry, ingredient use is changing due to these consumer demands. While no single agreed‐upon definition of clean ...label exists, a “clean label” in the context of food refers to a product that has a simplified and transparent ingredient list, with easily recognizable and commonly understood components to the general public. Clean‐label products necessitate and foster a heightened level of transparency between companies and consumers. Dairy products are vulnerable to being contaminated by both pathogens and spoilage microorganisms. These microorganisms can be effectively controlled by replacing conventional antimicrobials with clean‐label ingredients such as protective cultures or bacterial/fungal fermentates. This review summarizes the perspectives of consumers and the food industry regarding the definition of “clean label,” and the current and potential future use of clean‐label antimicrobials in dairy products. A key goal of this review is to make the concept of clean‐label antimicrobial agents better understood by both manufacturers and researchers.
Here, a novel, versatile synthetic strategy to fabricate a yolk–shell structured material that can encapsulate virtually any functional noble metal or metal oxide nanocatalysts of any morphology in a ...free suspension fashion is reported. This strategy also enables encapsulation of more than one type of nanoparticle inside a single shell, including paramagnetic iron oxide used for magnetic separation. The mesoporous organosilica shell provides efficient mass transfer of small target molecules, while serving as a size exclusion barrier for larger interfering molecules. Major structural and functional advantages of this material design are demonstrated by performing three proof‐of‐concept applications. First, effective encapsulation of plasmonic gold nanospheres for localized photothermal heating and heat‐driven reaction inside the shell is shown. Second, hydrogenation catalysis is demonstrated under spatial confinement driven by palladium nanocubes. Finally, the surface‐enhanced Raman spectroscopic detection of model pollutant by gold nanorods is presented for highly sensitive environmental sensing with size exclusion.
A newly developed yolk–shell structure encapsulates functional nanoparticles of complex morphology to enable efficient localized photothermal heating, hydrogenation catalysis under spatial confinement, and ultrasensitive environmental sensing based on surface‐enhanced Raman spectroscopy. The mesoporous organosilica shell facilitates selective transport of target reactant and analyte from bulk phase to the inner reaction compartment, while rejecting interfering species via size exclusion.
The most common, toxic, and carcinogenic mycotoxins found in human food and animal feed are the aflatoxins (AFs). The United States is a leading exporter of various nuts, with a marketing value of ...$9.1 billion in 2019; the European Union countries are the major importers of U.S. nuts. In the past few years, border rejections and notifications for U.S. tree nuts and peanuts exported to the E.U. countries have increased due to AF contamination. In this work, we analyzed notifications from the "Rapid Alert System for Food and Feed (RASFF)" on U.S. food and feed products contaminated with mycotoxins, primarily AFs, for the 10-year period 2010-2019. Almost 95% of U.S. mycotoxin RASFF notifications were reported for foods and only 5% for feeds. We found that 98.9% of the U.S. food notifications on mycotoxins were due to the AF contamination in almond, peanut, and pistachio nuts. Over half of these notifications (57.9%) were due to total AF levels greater than the FDA action level in food of 20 ng g
. The Netherlands issued 27% of the AF notifications for U.S. nuts. Border rejection was reported for more than 78% of AF notifications in U.S. nuts. All U.S. feed notifications on mycotoxins occurred due to the AF contamination. Our research contributes to better understanding the main reasons behind RASFF mycotoxins notifications of U.S. food and feed products destined to E.U. countries. Furthermore, we speculate possible causes of this problem and provide a potential solution that could minimize the number of notifications for U.S. agricultural export market.
Compared to the traditional heterogeneous assays, a homogeneous immunoassay is a preferred format for its simplicity. By cloning and isolating luminescent proteins from bioluminescent organisms, ...bioluminescence has been widely used for various biological applications. In this study, we present the development of a homogeneous luminescence immunoassay (FNanoBiT assay) for detection of fumonisin B1 (FB1), based on the binding of two subunits of an engineered luminescent protein (NanoLuc). For the detection of the mycotoxin FB1 in foods, the anti-fumonisin antibody was conjugated to the large subunit of NanoLuc (FLgBiT), and the FB1 was conjugated to the small subunit (FSmBiT). The conjugates were used for the detection of FB1 in a competitive immunoassay format without the need of a secondary antibody, or washing steps. The developed FNanoBiT assay revealed high specificity toward FB1 with no cross-reactivity with other mycotoxins, and it demonstrated acceptable recovery (higher than 94%) and relative standard deviation from spiked maize samples. Further, the assay was successfully applied for the detection of FB1 in naturally contaminated maize, with a dynamic range of 0.533–6.81 ng mL-1 and a detection limit of 0.079 ng mL-1. The results derived with FNanoBiT assay of all spiked samples showed a strong correlation to those obtained by the High-performance liquid chromatography method. Thus, the FNanoBiT based homogeneous immunoassay could be used as a rapid, and simple tool for the analysis of mycotoxin-contaminated foods.
•The FNanoBiT is the first luminescent technology developed for fumonisin B1 quantification in food.•The binding of the FLgBiT and FSmBiT pair provides a sensitive and rapid detection of fumonisin B1 in food.•The NanoBiT technology is versatile and powerful tool for rapid analysis of contaminants in food samples.
Trehalose is a compatible osmolyte produced by bacteria, fungi, insects and plants to protect the integrity of cells against various environmental stresses. Spores, the reproductive, survival and ...infection bodies of fungi require high amounts of trehalose for long-term survival. Here, via a gain-of-function genetic screen, we identify the novel regulator VosA that couples the formation of spores and focal trehalose biogenesis in the model fungus Aspergillus nidulans. The vosA gene is expressed specifically during the formation of both sexual and asexual spores (conidia). Levels of vosA mRNA and protein are high in both types of spore. The deletion of vosA results in the lack of trehalose in spores, a rapid loss of the cytoplasm, organelles and viability of spores, and a dramatic reduction in tolerance of conidia to heat and oxidative stress. Moreover, the absence of vosA causes uncontrolled activation of asexual development, whereas the enhanced expression of vosA blocks sporulation, suggesting that VosA also functions in negative-feedback regulation of sporogenesis. VosA localizes in the nucleus of mature conidia and its C-terminal region contains a potential transcription activation domain, indicating that it may function as a transcription factor primarily controlling the late process of sporulation including trehalose biogenesis. VosA is conserved in most fungi and may define a new fungus-specific transcription factor family.
We report an electrochemical immunosensing method for rapid and sensitive detection of two mycotoxins, fumonisin B1 (FB1) and deoxynivalenol (DON). A disposable screen-printed carbon electrode (SPE) ...was used as sensing platform. The working electrode part of SPE was modified by gold nanoparticles (AuNPs) and polypyrrole (PPy)-electrochemically reduced graphene oxide (ErGO) nanocomposite film for effective anti-toxin antibody immobilization, enhanced electrical conductivity, and biocompatibility. Under optimized test conditions, the limit of detection and linear range achieved for FB1 were 4.2ppb and 0.2 to 4.5ppm (%RSD=4.9%); and the corresponding values for DON were 8.6ppb and 0.05 to 1ppm (%RSD=5.7%). The immunosensor can specifically detect the target toxin in co-existing toxins environment. The sensor exhibited high sensitivity and low matrix interference when tested using extracts obtained from spiked corn samples. Hence, our electrochemical immunosensing scheme can be adopted for highly sensitive and rapid detection of multiple co-contaminant mycotoxins in food and feed products.
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