Recent trends in detecting, controlling, and detoxifying of patulin mycotoxin using biotechnology methods

A novel multimodal aptasensor for Patulin detection in fruit products based on high-performance RuMOF@hydrogel and versatile pericarp-derived carbonized polymer dots

Patulin (PAT) is a widespread fruit toxin. Trace-level PAT exposure can cause serious harm to human health. Herein, a multimodal PAT aptasensor was designed based on Ru(bpy)32+-based metal organic framework composited hydrogel (RuMOF@hydrogel) and versatile banana peel-derived carbonized polymer dots (BPPDs). RuMOF@hydrogel modified magnetic-electrode exhibited excellent anodic and cathodic electrochemiluminescence (ECL) emission and stability. Meanwhile, the BPPDs could enhance anodic ECL of RuMOF@hydrogel, and also show excellent fluorescence (FL) and photothermal (PT) properties. With the aid of PAT-triggered hybridization chain reaction and magnetic separation, ECL, FL, and PT responses could be recorded concurrently. The detection limit can reach as low as 0.25 fg mL-1. The ratiometric ECL quantitation ensured the sensitivity and accuracy of this assay. And visual FL and portable PT modes contributed to the utility. Furthermore, this aptasensor demonstrated better performances than HPLC in fruit products and the protocol can be extended to determine various contaminants in foods.

New Family of Benzimidazole-Based Chitosan Derivatives against Penicillium expansum

Penicillium expansum is the major fungus that causes blue mold and produces patulin, threatening human health. Due to health and environmental pollution concerns, chitosan (CS) has attracted more and more attention as a safer alternative to synthetic fungicides for the control of blue mold. In the present study, four different benzimidazole groups were introduced onto CS by the acylation reaction to obtain benzimidazole-based chitosan derivatives (R1b-R4b). After being well-characterized with Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible spectroscopy (UV-vis spectra), and nuclear magnetic resonance (NMR), their antifungal activities against P. expansum were screened. Results showed that the inhibitory effects of chitosan derivatives against the pathogen were significantly correlated with chitosan derivatives' concentration and their structures. R4b was shown as optimum with good solubility and antifungal activity with a minimum inhibitory concentration (MIC) value of 0.5 mg/mL and a minimum fungicidal concentration (MFC) value of 2.0 mg/mL. The remarkable antifungal efficiency of R4b against P. expansum was further demonstrated in terms of spore germination, mycelial growth, patulin production, and the preliminary antifungal mechanism. R4b exhibited significant inhibition of patulin production, while its antifungal mechanism was revealed by destroying cell membrane integrity and inducing membrane depolarization. Furthermore, R4b treatment could significantly reduce the incidence of blue mold rot in apple fruit, and the MTT assay showed the nontoxicity of R4b against Raw 264.7, HBZY-1, and Caco-2 cells. Altogether, these results indicate that it is promising to be used as a fruit preservative in the future.

Immobilization of aldo-keto reductase on dopamine/polyethyleneimine functionalized magnetic cellulose nanocrystals to enhance the detoxification of patulin in fresh pear juice

Patulin (PAT) is a highly toxic mycotoxin, which can contaminate fruits and their products and cause harm to human health. Cellulose nanocrystals (CNCs) were functionalized by magnetite nanoparticles, dopamine (DA) and polyethyleneimine (PEI) to form a multifunctional nanocarrier (DA/PEI@Fe3O4/CNCs) for immobilizing aldo-keto reductase (MgAKR) to degrade PAT. The MgAKR-DA/PEI@Fe3O4/CNCs were reusable and environmentally friendly due to its surface area, high magnetization value, and oxygen/amine function. The immobilization method significantly improved reusability, resistance to proteolysis, temperature stability and storage stability of MgAKR-DA/PEI@Fe3O4/CNCs. With NADPH as a coenzyme, the detoxification rate of MgAKR-DA/PEI@Fe3O4/CNCs on PAT reached 100 % in phosphate buffer and 98 % in fresh pear juice. The quality of fresh pear juice was unaffected by MgAKR-DA/PEI@Fe3O4/CNCs and could be quickly separated by magnet after detoxification, which was convenient for recycling. It has broad application prospects in the control of PAT contamination in beverage products containing fruit and vegetable ingredients.

A novel g-C3N4-SH@konjac glucomannan composite aerogel for patulin removal from apple juice and its photocatalytic regeneration

Patulin (PAT) is a hazardous mycotoxin frequently occurs in fruit industry. A reusable g-C3N4-SH@KG composite aerogel for PAT removal in a novel "dark adsorption-light regeneration" mode was prepared by thiol(-SH) functionalization and konjac glucomannan (KG) immobilization. The g-C3N4-SH@KG was characterized by SEM, FT-IR, XPS and UV-Vis DRS, and its PAT adsorption and photocatalytic regeneration behaviors and mechanisms were investigated. The g-C3N4-SH@KG exhibited good regeneration performance, maintaining 83% of PAT initial adsorption capacity (0.92 mg/g) after 5 "adsorption-regeneration" cycles. The adsorption process was endothermic and spontaneous. •OH and h+ generated by photocatalysis were the main substances that degraded PAT into two products and regenerated -SH. The g-C3N4-SH@KG could effectively remove PAT without negative impact on juice quality. The study provided a new strategy for the regeneration of thiol-functionalized PAT adsorbents, and a new idea for the application of non-selective photocatalysis in the control of food contaminations.

Integrated Photoelectrochemical-SERS Platform Based on Plasmonic Metal-Semiconductor Heterostructures for Multidimensional Charge Transfer Analysis and Enhanced Patulin Detection

Comprehending the charge transfer mechanism at the semiconductor interfaces is crucial for enhancing the electronic and optical performance of sensing devices. Yet, relying solely on single signal acquisition methods at the interface hinders a comprehensive understanding of the charge transfer under optical excitation. Herein, we present an integrated photoelectrochemical surface-enhanced Raman spectroscopy (PEC-SERS) platform based on quantum dots/metal-organic framework (CdTe/Yb-TCPP) nanocomposites for investigating the charge transfer mechanism under photoexcitation in multiple dimensions. This integrated platform allows simultaneous PEC and SERS measurements with a 532 nm laser. The obtained photocurrent and Raman spectra of the CdTe/Yb-TCPP nanocomposites are simultaneously influenced by variable bias voltages, and the correlation between them enables us to predict the charge transfer pathway. Moreover, we integrate gold nanorods (Au NRs) into the PEC-SERS system by using magnetic separation and DNA biometrics to construct a biosensor for patulin detection. This biosensor demonstrates the voltage-driven ON/OFF switching of PEC and SERS signals, a phenomenon attributed to the plasmon resonance effect of Au NRs at different voltages, thereby influencing charge transfer. The detection of patulin in apples verified the applicability of the biosensor. The study offers an efficient approach to understanding semiconductor-metal interfaces and presents a new avenue for designing high-performance biosensors.

Analysis of Mycotoxins and Cytotoxicity of Airborne Molds Isolated from the Zoological Garden-Screening Research

OBJECTIVE

The objective of this paper was to assess the airborne mold contamination, secondary metabolite profiles, and cytotoxicity of the dominant fungal species isolated from the air in selected rooms at a Zoological Garden.

MATERIALS AND METHODS

Fungal concentrations were measured with MAS-100 air samplers. The collected airborne fungi were identified using a combination of morphological and molecular methods. The cytotoxicity of 84 strains belonging to two Penicillium and Aspergillus genera was determined using the quantitative colorimetric MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium salt) assay. The mycotoxins were detected using high-performance liquid chromatography (HPLC) with a mass spectrometry detector.

RESULTS

The ITS gene was amplified and sequenced to identify the 132 species. For mycotoxicological and cytotoxicity analyses, 52 Penicillium isolates and 32 Aspergillus representatives were selected. Cytotoxicity was confirmed in 97.6% of cases analyzed. Using the LC-MS/MS method, 42 out of 84 strains produced at least one of the following toxins: ochratoxin A, ochratoxin B, patulin, gliotoxin, roquefortine C, griseofulvin, sterigmatocystin, fumonisin B2, moniliformin, and mycophenolic acid.

CONCLUSIONS

Analytical methods for assessing the presence of mycotoxins in fungal isolates collected directly from the air have proven to be an effective tool. Our research provides new information on the occurrence of potentially toxin-producing molds within a zoo.

Biodegradation of patulin in fresh pear juice by an aldo-keto reductase from Meyerozyma guilliermondii

Bio-enzymes have shown broad application prospects in controlling mycotoxins due to their strong specificity, fast reaction rate and mild reaction conditions. However, the number of enzymes isolated, purified and characterized to degrade patulin (PAT) is limited. We expressed an aldo-keto reductase (MgAKR) from Meyerozyma guilliermondii in Escherichia coli. The results demonstrated that the purified MgAKR could convert PAT into ascladiol in vitro with NADPH serving as a coenzyme. Adding 300 μg/mL MgAKR resulted in an 88 % reduction of PAT in fresh pear juice without affecting its quality in the biodegradation process. The site-directed mutagenesis suggested that the interaction between MgAKR and PAT occurred through the active sites of Lys242 and Leu240. This study serves as a valuable theoretical reference for the development of enzymes aimed at detoxifying PAT in fruit and their derivatives.

Structural switching aptamer-based electrochemical sensor for mycotoxin patulin detection

In this study, an electrochemical and aptamer-based aptasensor was developed for the sensitive detection of patulin, a mycotoxin commonly found in fruits and fruit-based products. The aptasensor used an innovative structural switching signal-off platform for detecting patulin. The aptamer immobilization on screen-printed carbon electrodes was achieved through Au electrodeposition and thiol group (-SH) route. Response surface methodology was used to determine the optimal incubation times for the aptamer, blocking agent, and target molecule, which were found to be 180 min, 40 min, and 89 min, respectively. The response of the aptamer to different concentrations of patulin was measured using square wave voltammetry by exploiting the structural switching mechanism. The sensor response was determined by quantifying differences in the aptasensor's background current. The aptasensor exhibited a linear working range of 1-25 μM and a low detection limit of 3.56 ng/mL for patulin. The aptasensor's relative standard deviation and accuracy were determined to be 0.067 and 94.4%, respectively. A non-specific interaction was observed at low concentrations of two other mycotoxins, ochratoxin A and zearalenone. The interference from ochratoxin A in the measurements was below 10%. In real sample tests using apple juice, interference, particularly at low concentrations, had changed the recovery of patulin negatively with a significant effect on the structural switching behavior. Nevertheless, at a concentration of 25 ng/mL, the interference effect was eliminated, and the recovery standard deviation improved to 6.6%. The aptasensor's stability was evaluated over 10 days, and it demonstrated good performance, retaining 13.12% of its initial response. These findings demonstrate the potential of the developed electrochemical aptasensor for the sensitive detection of patulin in fruit-based products, with prospects for application in food safety and quality control.

Infiltration of porcine pancreatic lipase into magnetic hierarchical mesoporous UiO-66-NH2 metal-organic frameworks for efficient detoxification of patulin from apple juice

Patulin (PAT) is a mycotoxin known to globally contaminate fruits. The economic losses and health hazards caused by PAT desires a safe and efficient strategy for detoxifying PAT. Here, a magnetic core-shell hierarchical mesoporous metal-organic framework (Fe3O4@HMUiO-66-NH2) was synthesized via a salt-assisted nanoemulsion guided assembly method. This mesoporous structure (centered at 4.25 nm) allowed porcine pancreatic lipase (PPL) to infiltrate into the MOF shell at an immobilized amount of 255 mg/g, providing protection for PPL and enabling rapid separation and recovery. Compared with free PPL, PPL/Fe3O4@HMUiO-66-NH2 at 70 °C possessed 4.7 folds improved thermal stability in terms of half-life. The detoxification rates of immobilized enzyme for PAT in neutral water, acidic water, and apple juice were 99.6%, 60.9%, and 52.6%, respectively. Moreover, the so designed PPL/Fe3O4@HMUiO-66-NH2 showed extraordinary storage stability, reusability, and biocompatibility. Crucially, the quality of apple juice did not change significantly after PPL/Fe3O4@HMUiO-66-NH2 treatment, which facilitated its application in apple juice. The magnetic core-shell mesoporous structure along with the revealed mechanism of immobilized enzyme detoxification of PAT provide tremendous opportunity for designing a safe and efficient PAT detoxification method.

Visualization detection of mycotoxin patulin in fruit juices by a small-molecule fluorescent probe

The mycotoxin patulin is a common contaminant in rotten fruits, posing severe food safety risks and threats to human health. Developing a convenient, sensitive and reliable method for patulin detection is of utmost importance but remains challenging. In this study, we have successfully designed and synthesized a small-molecule fluorescent probe, FITC-Lys, which demonstrates good sensitivity in detecting patulin. Upon contact with patulin, the terminal Lys group of the FITC-Lys probe reacts with patulin, resulting in the formation of the fluorescein dimer that subsequently quenches fluorescence. This variation of fluorescence enables the visualization and sensitive detection of patulin. The probe exhibits good sensitivity with a low LOD of 8 ng mL-1 for the fluorescence spectrum method and a LOD of 12 ng mL-1 for the fluorescence imaging method. Moreover, we have validated the probe's capability for patulin detection in apple and pear juices, achieving good recoveries ranging from 98.60% to 103.80%. Notably, the probe FITC-Lys is the first small-molecule fluorescent probe that has proven successful in visualizing patulin in juices derived from decayed apples and pears. Consequently, this probe holds great potential as a practical tool for monitoring patulin in foodstuffs, thereby contributing to enhanced food safety standards.

DNA-bridged double gold nanoparticles-based immunochromatography for dual-mode detection of ochratoxin A

A novel immunochromatography strip (ICS) based on the DNA-bridged double gold nanoparticles was established and evaluated for the dual-mode detection of ochratoxin A (OTA). For this purpose, the streptavidin was coupled with the big size of gold nanoparticle (40 nm, AuNP), the OTA monoclonal antibody and biotinylated DNA-SH were simultaneously immobilized on the small size of AuNP (20 nm), and then the enhanced ICS was self-assembled and evaluated. The dual-mode detection of semi-quantification and quantification had been achieved and performed by the proposed ICS. The LOD for semi-quantification (semi-Q-LOD) was 0.06 ng/mL by the directly naked eye (eightfold enhanced than conventional ICS). By the on-site reader, the LOD for quantification (Q-LOD) was 0.03 ng/mL (threefold enhanced), with the detection range between 0.03 and 1.2 ng/mL. The specificity, reliability, and practicability had been well represented. Furthermore, the OTA-positive results of the enhanced ICS method correlated well with those obtained by the referenced HPLC-MS/MS for the market samples. This study provided a new ICS pattern of semi-quantification and quantification for OTA contamination, which could be used as a valuable reference for improving the ICS technology and enhancing the sensitivity.

Molecular Response of Meyerozyma guilliermondii to Patulin: Transcriptomic-Based Analysis

Patulin (PAT), mainly produced by Penicillium expansum, is a potential threat to health. In recent years, PAT removal using antagonistic yeasts has become a hot research topic. Meyerozyma guilliermondii, isolated by our group, produced antagonistic effects against the postharvest diseases of pears and could degrade PAT in vivo or in vitro. However, the molecular responses of M. guilliermondii over PAT exposure and its detoxification enzymes are not apparent. In this study, transcriptomics is used to unveil the molecular responses of M. guilliermondii on PAT exposure and the enzymes involved in PAT degradation. The functional enrichment of differentially expressed genes indicated that the molecular response mainly includes the up-regulated expression of genes related to resistance and drug-resistance, intracellular transport, growth and reproduction, transcription, DNA damage repair, antioxidant stress to avoid cell damage, and PAT detoxification genes such as short-chain dehydrogenase/reductases. This study elucidates the possible molecular responses and PAT detoxification mechanism of M. guilliermondii, which could be helpful to further accelerate the commercial application of antagonistic yeast toward mycotoxin decontamination.

Overexpression of the SDR gene improves the ability of Meyerozyma guilliermondii to degrade patulin in pears and juices

The intracellular enzymes of antagonistic yeast are effective in controlling patulin (PAT) contamination. However, countless enzymes that have been revealed remain functionally uncharacterized. The study built on previous transcriptomic data obtained by our research group to amplify and express a gene encoding a short-chain dehydrogenase/reductase (SDR) in Meyerozyma guilliermondii. Overexpression of SDR increased the tolerance of M. guilliermondii to PAT and the ability to degrade PAT of the intracellular enzymes. Furthermore, MgSDR-overexpressed M. guilliermondii showed higher PAT degradation in juices (apple and peach) and controlled the blue mold of pears at 20 °C and 4 °C while significantly reduced the content of PAT and the biomass of Penicillium expansum in decayed tissues than wild-type M. guilliermondii. This study provides theoretical references for the subsequent heterologous expression, formulation, and application of the SDR protein from M. guilliermondii and contributes to elucidating the PAT degradation mechanism of antagonistic yeasts.

An Overview of Biosensors for the Detection of Patulin Focusing on Aptamer-Based Strategies

Patulin is a low molecular weight mycotoxin and poses a global problem, especially threatening food safety. It is also resistant to processing temperatures and is commonly found in fruits and vegetables. Studies have shown that it has toxic effects on animals and humans and the severity of patulin toxicity depends on the amount ingested. Therefore, the consumption of contaminated products, especially in infants and children, is important. The maximum daily intake of PAT that can be tolerated is found to be 0.4 µg/kg body weight to prevent chronic effects and the maximum residue limits in food samples were given as 50 ng/g (∼320 nM). Conventional methods for the detection of PAT have many disadvantages such as the use of expensive equipment, the need for trained personnel, and complicated sample preparation steps. To this extent, various numbers of research have been conducted on selective and sensitive detection of patulin using biosensor platforms in various media. This review presents an overview of the current literature dealing with the studies to develop patulin-specific aptamer-based biosensors and adapts various immobilization methods to increase the sensor response using different nanomaterials. Furthermore, a comparison of biosensors with conventional methods is presented using analytical performance parameters and their practicality for the detection of patulin.

Detoxification of Fumonisins by Three Novel Transaminases with Diverse Enzymatic Characteristics Coupled with Carboxylesterase

Fumonisin (FB) is one of the most common mycotoxins contaminating feed and food, causing severe public health threat to human and animals worldwide. Until now, only several transaminases were found to reduce FB toxicity, thus, more fumonisin detoxification transaminases with excellent catalytic properties required urgent exploration for complex application conditions. Herein, through gene mining and enzymatic characterization, three novel fumonisin detoxification transaminases-FumTSTA, FumUPTA, FumPHTA-were identified, sharing only 61-74% sequence identity with reported fumonisin detoxification transaminases. Moreover, the recombinant proteins shared diverse pH reaction ranges, good pH stability and thermostability, and the recombinant protein yields were also improved by condition optimum. Furthermore, the final products were analyzed by liquid chromatography-mass spectrometry. This study provides ideal candidates for fumonisin detoxification and meets diverse required demands in food and feed industries.

Phenolic compounds as natural microbial toxin detoxifying agents

Despite the abundance of promising studies, developments, and improvements about the elimination of microbial toxins from food matrices, they are still considered as one of the major food safety problems due to the lack of their complete avoidance even today. Every year, many crops and foodstuffs have to be discarded due to unconstrained contamination and/or production of microbial toxins. Furthermore, the difficulty for the detection of toxin presence and determination of its level in foods may lead to acute or chronic health problems in many individuals. On the other hand, phenolic compounds might be considered as microbial toxin detoxification agents because of their inhibition effect on the toxin synthesis of microorganisms or exhibiting protective effects against varying damaging mechanisms caused by toxins. In this study, the effect of phenolic compounds on the synthesis of bacterial toxins and mycotoxins is comprehensively reviewed. The potential curing effect of phenolic compounds against toxin-induced damages has also been discussed. Consequently, phenolic compounds are indicated as promising, and considerable natural preservatives against toxin damages and their detoxification potentials are pronounced.

Comprehensive review on patulin and Alternaria toxins in fruit and derived products

Mycotoxins are toxic secondary metabolites produced by certain fungi, which can contaminate various food commodities, including fruits and their derived products. Patulin and Alternaria toxins are among the most commonly encountered mycotoxins in fruit and their derived products. In this review, the sources, toxicity, and regulations related to these mycotoxins, as well as their detection and mitigation strategies are widely discussed. Patulin is a mycotoxin produced mainly by the fungal genera Penicillium, Aspergillus, and Byssochlamys. Alternaria toxins, produced by fungi in the Alternaria genus, are another common group of mycotoxins found in fruits and fruit products. The most prevalent Alternaria toxins are alternariol (AOH) and alternariol monomethyl ether (AME). These mycotoxins are of concern due to their potential negative effects on human health. Ingesting fruits contaminated with these mycotoxins can cause acute and chronic health problems. Detection of patulin and Alternaria toxins in fruit and their derived products can be challenging due to their low concentrations and the complexity of the food matrices. Common analytical methods, good agricultural practices, and contamination monitoring of these mycotoxins are important for safe consumption of fruits and derived products. And Future research will continue to explore new methods for detecting and managing these mycotoxins, with the ultimate goal of ensuring the safety and quality of fruits and derived product supply.

Ultraviolet Applications to Control Patulin Produced by Penicillium expansum CMP-1 in Apple Products and Study of Further Patulin Degradation Products Formation and Toxicity

Patulin is a mycotoxin whose presence in apple-derived products and fruit juices is legally regulated, being its maximum limits established in the legislation of multiple countries. However, the management of contaminated batches is still an issue for producers. This investigation aims to evaluate ultraviolet light (254 nm, UV-C254nm) irradiation to find solutions that can be applied at different stages of the apple juice production chain. In this regard, 8.8 (UV-1) and 35.1 (UV-2) kJ m−2 treatments inactivated spores of Penicillium expansum CMP-1 on the surface of apples. Although the same treatments applied to wounded apples (either before the infection or after the infection, immediately or when the lesion had appeared) did not show any effect on the growth rate of P. expansum during storage (up to 14 days, at 4 or 25 °C), they reduced patulin content per lesion size in apples treated after the infection had occurred (patulin decreased from 2.24 (control) to 0.65 µg kg−1 cm−2 (UV-2 treated apples)). Additionally, the treatment of juice with patulin with ultraviolet light up to 450.6 kJ m−2 resulted in more than 98 % reduction of patulin. Degradation products of patulin after UV-C254nm treatments were tentatively identified by HPLC–MS, and toxicity and biological activities were assessed in silico, and results indicated that such products did not pose an increased risk when compared to patulin.

Unveiling ochratoxin a controlling and biodetoxification molecular mechanisms: Opportunities to secure foodstuffs from OTA contamination

Anarchic growth of ochratoxin A (OTA) producing fungi during crop production, prolonged storage, and processing results in OTA contamination in foodstuffs. OTA in food exacerbates the risk of health and economic problems for consumers and farmers worldwide. Although the toxic effects of OTA on human health have not been well established, comprehensive preventive and remedial measures will be essential to eliminate OTA from foodstuffs. Strict regulations, controlling OTA at pre- or post-harvest stage, and decontamination of OTA have been adopted to prevent human and animal OTA exposure. Biological control of OTA and bio-decontamination are the most promising strategies due to their safety, specificity and nutritional value. This review addresses the current understanding of OTA biodegradation mechanisms and recent developments in OTA control and bio-decontamination strategies. Additionally, this review analyses the strength and weaknesses of different OTA control methods and the contemporary approaches to enhance the efficiency of biocontrol agents. Overall, this review will support the implementation of new strategies to effectively control OTA in food sectors. Further studies on efficacy-related issues, production issues and cost-effectiveness of OTA biocontrol are to be carried out to improve the knowledge, develop improved delivery technologies and safeguard the durability of OTA biocontrol approaches.

Label-free fluorescence aptasensor for the detection of patulin using target-induced DNA gates and TCPP/BDC-NH2 mixed ligands functionalized Zr-MOF systems

Patulin (PAT) is an unsaturated lactone mycotoxin primarily produced by Penicillium expansum and Aspergillus clavatus. Given the potential health risks and economic losses associated with PAT, the rapid detection of PAT using fluorescent aptasensors is of significant importance in evaluating food safety. However, it easily increases the cost and complexity caused by signal labeling. We combined TCPP/BDC-NH₂ mixed ligands functionalized Zr metal-organic frameworks (Zr-MOF_mix) and terminated three-stranded DNA gates (ttsDNA gates) to fabricate a label-free fluorescent aptasensor for PAT detection. The Zr-MOF_mix system was synthesized via a one-pot strategy and could be used to address the problem of pore size limitation and increase the loading amounts of dyes. TtsDNA gate was integrated into the Zr-MOF_mix system to control the release of dyes, exhibiting a high signal-to-background ratio. The single-stranded aptamer region in ttsDNA gate situated away from the surface of the Zr-MOF_mix, resulting in a natural release of dyes in the absence of PAT. While binding to PAT resulted in target-induced conformational changes that helped form the hairpin structure of the aptamer. This structure hindered the release of dyes from the pores of Zr-MOF_mix, thus reducing the fluorescence signals intensity. The stimuli-responsive DNA-gated material provides a platform for PAT analysis under conditions of a low limit of detection (0.871 pg/mL). Furthermore, the excellent specificity and anti-interference of the fluorescent aptasensor make the system suitable for the analysis of apple juice samples. This label-free strategy is cheaper and simper compared with labeled detection, especially for the development of multi-target-detection.

Ultrasensitive fluorometric oligonucleotide immunoassay for the simultaneous and efficient detection of two mycotoxins in agricultural products

An ultrasensitive fluorometric oligonucleotide immunoassay (UFOIA) based on a fluorometric oligonucleotide and magnetic separation was proposed for the simultaneous detection of two mycotoxins. Two kinds of magnetic nanoparticle (MNP) probes and their corresponding fluorometric oligonucleotide probes were prepared. After the immune reaction, Cy5-linked and 6-FAM-linked oligonucleotides were dissociated and applied to detect fluorescence signals simultaneously. Under optimal conditions, the detection ranges of the UFOIA were in the range of 0.654-1438.8 pg mL^-1 for zearalenone (ZEN) and 0.215-3190.1 pg mL^-1 for aflatoxin B₁ (AFB₁). The limits of detection (LODs) were 0.378 pg mL^-1 for ZEN and 0.043 pg mL^-1 for AFB₁, which showed improved sensitivities of 529-fold and 112-fold compared to those from the ELISA. The positive results of the UFOIA for authentic agricultural products were highly correlated with those from LC-MS/MS. The specificity, accuracy, precision and reliability of the UFOIA are well demonstrated. The proposed UFOIA method achieved the simultaneous and ultrasensitive detection of mycotoxins at the pg mL^-1 level, which was a considerable improvement. This study might provide an alternative approach for detecting multi-component contamination equipped with the notable highlights of ultrasensitivity, simultaneity, simplicity, high efficiency and a low background signal.

Highly efficient removal of patulin using immobilized enzymes of Pseudomonas aeruginosa TF-06 entrapped in calcium alginate beads

Patulin is a toxic secondary metabolite produced by several moulds, which contaminates fruits and their products posing serious threats to human health. Though several microorganisms and enzymes have been reported to effectively degrade patulin, separation of them from fruit juice challenges the commercial applications. Here, a Pseudomonas aeruginosa strain TF-06 was isolated, its patulin degradation mechanism and optimum conditions for enzyme immobilization were investigated. The results indicated that TF-06 could degrade patulin into non-cytotoxic E/Z-ascladiol mainly by the activity of intracellular enzymes. For easy separation of enzymes, calcium alginate was selected for immobilization of intracellular enzymes from TF-06. The immobilized enzyme beads were effective in detoxification of patulin in apple juice. The mitigation rate was reached 95%, while there was no negative effect on juice quality. The study provides a promising way to resolve the issue of enzyme separation during mycotoxin biological detoxification in fruit juice.

Effects of Selenium Nanoparticles on Preventing Patulin-Induced Liver, Kidney and Gastrointestinal Damage

Patulin (PAT) is a toxic fungal metabolite, and oxidative damage was proved to be its important toxicity mechanism. Selenium nanoparticles (SeNPs) were prepared by reducing sodium selenite with chitosan as a stabilizer and used for preventing PAT-induced liver, kidney and gastrointestinal damage. SeNPs have good dispersibility, in vitro antioxidant activity, and are much less cytotoxic than sodium selenite. Cell culture studies indicated that SeNPs can effectively alleviate PAT-induced excessive production of intracellular ROS, the decline of glutathione peroxidase activity, and the suppression of cell viability. Evaluation of serum biochemical parameters, histopathology, oxidative stress biomarkers and activities of antioxidant enzymes in a mouse model showed that pre-treatment with SeNPs (2 mg Se/kg body weight) could ameliorate PAT-induced oxidative damage to the liver and kidneys of mice, but PAT-induced gastrointestinal oxidative damage and barrier dysfunction were not recovered by SeNPs, possibly because the toxin doses suffered by the gastrointestinal as the first exposed tissues exceeded the regulatory capacity of SeNPs. These results suggested that a combination of other strategies may be required to completely block PAT toxicity.

Toxic Mechanism and Biological Detoxification of Fumonisins

Food safety is related to the national economy and people's livelihood. Fumonisins are widely found in animal feed, feed raw materials, and human food. This can not only cause economic losses in animal husbandry but can also have carcinogenicity or teratogenicity and can be left in animal meat, eggs, and milk which may enter the human body and pose a serious threat to human health. Although there are many strategies to prevent fumonisins from entering the food chain, the traditional physical and chemical methods of mycotoxin removal have some disadvantages, such as an unstable effect, large nutrient loss, impact on the palatability of feed, and difficulty in mass production. As a safe, efficient, and environmentally friendly detoxification technology, biological detoxification attracts more and more attention from researchers and is gradually becoming an accepted technique. This work summarizes the toxic mechanism of fumonisins and highlights the advances of fumonisins in the detoxification of biological antioxidants, antagonistic microorganisms, and degradation mechanisms. Finally, the future challenges and focus of the biological control and degradation of fumonisins are discussed.

Improvement of the enzymatic detoxification activity towards mycotoxins through structure-based engineering

Mycotoxin contamination of food and feed is posing a serious threat to the global food safety and public health. Biological detoxification mediated by enzymes has emerged as a promising approach, as they can specifically degrade mycotoxins into non-toxic ones. However, the low degradation efficiency and stability limit their further application. To optimize the enzymes for mycotoxin removal, modification strategies that combine computational design with their structural data have been developed. Accordingly, this review will comprehensively summarize the recent trends in structure-based engineering to improve the enzyme catalytic efficiency, selectivity and stability in mycotoxins detoxification, which also provides perspectives in obtaining innovative and effective biocatalysts for mycotoxins degradation.

Mycotoxins detection: view in the lens of molecularly imprinted polymer and nanoparticles

Molecularly imprinted polymers (MIPs) are tailor-made functional composites which selectively recognize and bind the target molecule of interest. MIP composites are products of the massively cross-linked polymer matrices, generated via polymerization, with bio-inspired recognition cavities that are morphologically similar in size, shape and spatial patterns to the target conformation. These features have enabled researchers to expand the field of molecular recognition, more specifically for target with peculiar requirements. Nevertheless, MIPs alone are characterized with weak sensitivity. Besides, nanoparticles (NPs) are remarkably sensitive but also suffer from poor selectivity. Intriguingly, the combination of the two results in a highly sensitive and selective MIP composite. For instance, the conjugation of different functional NPs with MIPs can generate new flexible target capture tools, either a dynamic sensor or a novel drug delivery system. In this regard, although the technology is considered an established and feasible approach, it is still perceived as a burgeoning technology for various fields, which makes it unceasingly worthy reviewing. Therefore, in this review, we attempt to give an update on various custom-made biosensors based on MIPs in combination with various NPs for the detection of mycotoxins, the toxic secondary metabolites of fungi. We first summarize the classification, prevalence, and toxicological characteristics of common mycotoxins. Next, we provide an overview of MIP composites and their characterization, and then segment the role of NPs with respect to common types of MIP-based sensors. At last, conclusions and outlook are discussed.

Antifungal Activity of Lactobacillus plantarum ZZUA493 and Its Application to Extend the Shelf Life of Chinese Steamed Buns

Lactic acid bacteria (LAB) can produce many kinds of antifungal substances, which have been widely proven to have antifungal activity. In this study, 359 strains of LAB were screened for antifungal activity against Aspergillus niger (A. niger) using the 96-well microtiter plate method, and three showed strong activity. Of these, ZZUA493 showed a broad-spectrum antifungal ability against A. niger, Aspergillus oryzae, Trichoderma longibrachiatum, Aspergillus flavus and Fusarium graminearum. ZZUA493 was identified as Lactobacillus plantarum. Protease treatment, the removal of hydrogen peroxide with catalase and heat treatment had no effect on the antifungal activity of the cell-free supernatant (CFS) of ZZUA493; organic acids produced by ZZUA493 appeared to have an important role in fungal growth inhibition. The contents of lactic acid, acetic acid and phenyllactic acid in the CFS tended to be stable at 48 h, and amounted to 28.5, 15.5 and 0.075 mg/mL, respectively. In addition, adding ZZUA493, as an ingredient during their preparation, prolonged the shelf life of Chinese steamed buns. Overall, ZZUA493 appears to have good potential as a fungal inhibitor for food preservation.

Influence of processing steps on the fate of ochratoxin A, patulin, and alternariol during production of cloudy and clear apple juices

Mycotoxins are frequently found in fruits and fruit juices. However, data about occurrence and fate of mycotoxins along the fruit juice processing chain are currently insufficient. Herein, a liquid chromatographic/tandem mass spectrometric (LC–MS/MS) multi-mycotoxin method was developed and applied to investigate the effect of technological unit operations on the fate of three of the most relevant mycotoxins along the processing chain for cloudy and clear apple juice, namely patulin (PAT), ochratoxin A (OTA), and alternariol (AOH). Raw juice obtained directly after dejuicing was spiked with the aforementioned mycotoxins at pilot-plant scale prior to subjecting it to different technological unit operations. Regarding clear apple juice production treatment with a pectinolytic enzyme preparation, and pasteurization were insignificant for mycotoxin reduction, but fining with subsequent filtration was effective, although the mycotoxins showed different affinity towards the tested agents. The most effective fining agent was activated charcoal/bentonite in combination with ultrafiltration, which removed OTA (54 µg/L) and AOH (79 µg/L) to not quantifiable amounts (limit of quantification (LOQ) 1.4 and 4.6 µg/L, respectively), while PAT was reduced only by 20% (from 396 to 318 µg/L). Regarding cloudy apple juice production, all studied processing steps such as centrifugation and pasteurization were ineffective in reducing mycotoxin levels. In brief, none of the common steps of clear and cloudy apple juice production represented a fully effective safety step for minimizing or even eliminating common mycotoxins. Thus, ensuring the sole use of sound apples should be of utmost importance for processors, particularly for those manufacturing cloudy juices.

Recent advances in Penicillium expansum infection mechanisms and current methods in controlling P. expansum in postharvest apples

One of the most significant challenges associated with postharvest apple deterioration is the blue mold caused by Penicillium expansum, which leads to considerable economic losses to apple production industries. Apple fruits are susceptible to mold infection owing to their high nutrient and water content, and current physical control methods can delay but cannot completely inhibit P. expansum growth. Biological control methods present promising alternatives; however, they are not always cost effective and have application restrictions. P. expansum infection not only enhances disease pathogenicity, but also inhibits the expression of host-related defense genes. The implementation of new ways to investigate and control P. expansum are expected with the advent of omics technology. Advances in these techniques, together with molecular biology approaches such as targeted gene deletion and whole genome sequencing, will lead to a better understanding of the P. expansum infectious machinery. Here, we review the progress of research on the blue mold disease caused by P. expansum in apples, including physiological and molecular infection mechanisms, as well as various methods to control this common plant pathogen.

Recent Achievements in Electrochemical and Surface Plasmon Resonance Aptasensors for Mycotoxins Detection

Mycotoxins are secondary metabolites of fungi that contaminate agriculture products. Their release in the environment can cause severe damage to human health. Aptasensors are compact analytical devices that are intended for the fast and reliable detection of various species able to specifically interact with aptamers attached to the transducer surface. In this review, assembly of electrochemical and surface plasmon resonance (SPR) aptasensors are considered with emphasis on the mechanism of signal generation. Moreover, the properties of mycotoxins and the aptamers selected for their recognition are briefly considered. The analytical performance of biosensors developed within last three years makes it possible to determine mycotoxin residues in water and agriculture/food products on the levels below their maximal admissible concentrations. Requirements for the development of sample treatment and future trends in aptasensors are also discussed.

Critical Assessment of Mycotoxins in Beverages and Their Control Measures

Mycotoxins are secondary metabolites of filamentous fungi that contaminate food products such as fruits, vegetables, cereals, beverages, and other agricultural commodities. Their occurrence in the food chain, especially in beverages, can pose a serious risk to human health, due to their toxicity, even at low concentrations. Mycotoxins, such as aflatoxins (AFs), ochratoxin A (OTA), patulin (PAT), fumonisins (FBs), trichothecenes (TCs), zearalenone (ZEN), and the alternaria toxins including alternariol, altenuene, and alternariol methyl ether have largely been identified in fruits and their derived products, such as beverages and drinks. The presence of mycotoxins in beverages is of high concern in some cases due to their levels being higher than the limits set by regulations. This review aims to summarize the toxicity of the major mycotoxins that occur in beverages, the methods available for their detection and quantification, and the strategies for their control. In addition, some novel techniques for controlling mycotoxins in the postharvest stage are highlighted.

Patulin in food: A mycotoxin concern for human health and its management strategies

The mycotoxin patulin is primarily produced as a secondary metabolite by numerous fungal species and predominantly by Aspergillus, Byssochlamys, and Penicillium species. It is generally associated with fungal infected food materials. Penicillium expansum is considered the only fungal species liable for patulin contamination in pome fruits, especially in apples and apple-based products. This toxin in food poses serious health concerns and economic threat, which has aroused the need to adopt effective detection and mitigation strategies. Understanding its origin sources and biosynthetic mechanism stands essential for efficiently designing a management strategy against this fungal contamination. This review aims to present an updated outline of the sources of patulin occurrence in different foods and their biosynthetic mechanisms. It further provides information regarding the detrimental effects of patulin on human and agriculture as well as its effective detection, management, and control strategies.

Prevention and detoxification of patulin in apple and its products: A review

Patulin-producing fungi pose an unavoidable problem for apple and its product quality, thereby threatening human and/or animal health. Studies on controlling the patulin-producing fungal growth and patulin contamination in apple and its products by physical methods, chemical fungicides, and biological methods have been performed for decades, but patulin contamination has not been addressed. Here, the important of studying regulation mechanism of patulin production in apple at the protein expression and metabolism levels is proposed, which will facilitate the development of controlling patulin production by using physical, chemical, and biological methods. Furthermore, the advantages or disadvantages and effects or mechanisms of using physical, chemical, biological methods to control the decay caused by Penicillium expansum and to remove patulin in food was discussed. The development of physical methods to remove patulin depends on the development of special equipment. Chemical methods are economical and efficient, if we have ensured that there are no unknown reactions or toxic by-products by using these chemicals. The biological method not only effectively controls the decay caused by Penicillium espansum, but also removes the toxins that already exist in the food. Degradation of patulin by microorganisms or biodegradation enzymes is an efficient and promising method to remove patulin in food if the microorganisms used and the degradation products are completely non-toxic.

Leuconostoc mesenteroides subsp. mesenteroides LB7 isolated from apple surface inhibits P. expansum in vitro and reduces patulin in fruit juices

This research aimed to isolate lactic acid bacteria (LAB) from apple surface and to reveal their potential to inhibit the growth of Penicillium expansum. Besides, their ability to detoxify fruit juices contaminated with mycotoxin patulin, produced by this fungi, was also studied. The isolation was performed on a typical MRS medium under ambient conditions. The molecular identification of the strains was done by sequencing the 16S rRNA genes. Antifungal activities of the isolated strains have been evaluated using dual agar plate assay protocol. A total of 11 LAB isolates was obtained from apples. These isolates showed phenotypic traits consistent with the genera of LAB. They have been identified as Leuconostoc mesenteroides subsp. mesenteroides and Weissella paramesenteroides. Among them, the strain LB7 showed exciting inhibitory activities in vitro against P. expansum. LB7 also successfully detoxified homemade and commercial fruit juices contaminated with patulin. Further research will bring the application prospects of these LABs in food biocontrol and biopreservation strategies.

Protection of Citrus Fruits from Postharvest Infection with Penicillium digitatum and Degradation of Patulin by Biocontrol Yeast Clavispora lusitaniae 146

Fungal rots are one of the main causes of large economic losses and deterioration in the quality and nutrient composition of fruits during the postharvest stage. The yeast Clavispora lusitaniae 146 has previously been shown to efficiently protect lemons from green mold caused by Penicillium digitatum. In this work, the effect of yeast concentration and exposure time on biocontrol efficiency was assessed; the protection of various citrus fruits against P. digitatum by C. lusitaniae 146 was evaluated; the ability of strain 146 to degrade mycotoxin patulin was tested; and the effect of the treatment on the sensory properties of fruits was determined. An efficient protection of lemons was achieved after minimum exposure to a relatively low yeast cell concentration. Apart from lemons, the yeast prevented green mold in grapefruits, mandarins, oranges, and tangerines, implying that it can be used as a broad-range biocontrol agent in citrus. The ability to degrade patulin indicated that strain 146 may be suitable for the control of further Penicillium species. Yeast treatment did not alter the sensory perception of the aroma of fruits. These results corroborate the potential of C. lusitaniae 146 for the control of postharvest diseases of citrus fruits and indicate its suitability for industrial-scale fruit processing.