One-step preparation of nano-Fe3O4 modified inactivated yeast for the adsorption of patulin

Current insights into yeast application for reduction of patulin contamination in foods: A comprehensive review

Patulin, a fungal secondary metabolite with multiple toxicities, is widely existed in a variety of fruits and their products. This not only causes significant economic losses to the agricultural and food industries but also poses a serious threat to human health. Conventional techniques mainly involved physical and chemical methods present several challenges include incomplete patulin degradation, high technical cost, and fruit quality decline. In comparison, removal of mycotoxin through biodegradation is regarded as a greener and safer strategy which has become popular research. Among them, yeast has a unique advantage in detoxification effect and application, which has attracted our attention. Therefore, this review provides a comprehensive account of the yeast species that can degrade patulin, degradation mechanism, current application status, and future challenges. Yeasts can efficiently convert patulin into nontoxic or low-toxic substances through biodegradation. Alternatively, it can use physical adsorption, which has the advantages of safety, high efficiency, and environmental friendliness. Nevertheless, due to the inherent complexity of the production environment, the sole utilization of yeast as a control agent remains inherently unstable and challenging to implement on a large scale in a practical manner. Integration control, enhancement of yeast resilience, improvement of yeast cell wall adsorption capacity, and research on additional patulin-degrading enzymes will facilitate the practical application of this approach. Furthermore, we analyzed the feasibility of the yeast commercial application in patulin reduction and provided suggestions on how to enhance its commercial value, which is of great significance for the control of mycotoxins in food products.

Optimization of Seleno-chitosan-phytic acid nanocomplex for efficient removal of patulin from apple juice

A novel and effective adsorbent known as Seleno-chitosan-phytic acid nanocomplex (Se-CS-PA) has been developed specifically for efficiently removing patulin (PAT) from a simulated juice solution. The synthesis of Se-CS-PA nanocomplex was confirmed through Fourier transform infrared (FT-IR), scanning electron microscopy (SEM), and energy dispersive X-Ray (EDX) analyses. Response surface methodology (RSM) was employed using central composite design (CCD) to examine the impact of four independent variables (PA concentration, amount of nano-complex, duration of interaction between PAT and nano-complex, and initial concentration of PAT) on the removal of PAT. PA concentration of 0.1 % with 2.1 g Se-CS-PA nanocomplex according to RSM polynomial equation and apple juice with 25 μg.L-1 PAT yielded a remarkable adsorption rate of 94.23 % and 87.52 % respectively after 7 h. The process of PAT adsorption was explained using the pseudo-first-order model (R2 = 0.8858) for the kinetic model and the Freundlich isotherm (R2 = 0.9988) for the isotherm model.

Microbial Composition of Water Kefir Grains and Their Application for the Detoxification of Aflatoxin B1

Water kefir grains (WKGs), the starter used to develop a traditional beverage named water kefir, consist of a symbiotic mixture of probiotics with diverse bioactivities, but little is known about their abilities to remove mycotoxins that have serious adverse effects on humans and animals. This study investigated the ability of WKGs to remove aflatoxin B1 (AFB1), one of the most toxic mycotoxins, under different settings, and determined the mechanism of absorption mediated by WKGs and the effect of WKGs on the toxicity induced by AFB1 and the reduction in AFB1 in cow milk and tea soups. The results showed the WKGs used herein were dominated by Lactobacillus, Acetobacter, Phenylobacterium, Sediminibacterium, Saccharomyces, Issatchenkia, and Kodamaea. HPLC analysis demonstrated that the WKGs effectively removed AFB1 at concentrations ranging from 1 to 5 µg/mL, pH values ranging from 3 to 9, and temperatures ranging from 4 to 45 °C. Additionally, the removal of AFB1 mainly depended on absorption, which was consistent with the Freundlich and pseudo-second-order kinetic models. Moreover, only 49.63% of AFB1 was released from the AFB1-WKG complex after four washes when the release of AFB1 was non-detectable. Furthermore, WKG treatment caused a dramatic reduction in the mutagenicity induced by AFB1 according to an Ames test and reduced more than 54% of AFB1 in cow milk and three tea soups. These results suggested that WKGs can act as a potential bio-absorbent with a high binding ability to detoxify AFB1 in food and feed via a chemical action step and multi-binding sites of AFB1 absorption in a wide range of scenarios.

Kinetic process of the biosorption of Cu(II), Ni(II) and Cr(VI) by waste Pichia pastoris cells

Waste biomass of Pichia pastoris (P.pastoris) cells from the fermentation industry is an environmentally friendly biosorption material. The present study aimed to explore the biosorption behaviour of waste P.pastoris cells for Cu(II), Ni(II) and Cr(VI) in aqueous solution conditions. The results showed that the adsorption kinetics of three kinds of metals were well-fitted with lineared Elovich, pseudo-second-order kinetics models, non-linear kinetics and adsorption isotherms. The effective biosorption rates for Cu(II), Ni(II) and Cr(VI) removal were 71.3%, 59.7% and 16.25% respectively. The maximum Cu(II) adsorption capacity of waste P.pastoris was 40 mg/g at pH = 4 and 225 mg/L of solute concentration for 0.4 g biomass, better than that of the living yeasts. The pattern of Fourier transform infrared (FTIR) indicated that functional groups such as -NH, -OH, Si-O, P-O-C were involved in Cu(II) adsorption process. The analysis of SEM-EDS, XRD and TEM-EDS can be concluded that Cu(II) occupied Ca(II) binding sites by ion exchange mechanism to remove flocculation, and Cu(II) adsorbed onto the diatomite containing in the industrial waste P.pastoris. Thus the adsorption mechanism of the industrial waste P.pastoris was proposed taking Cu(II) as the example. And consecutive biosorption/desorption cycles were used for the evaluation of the regeneration efficiency, suggesting the good regeneration and reusability of waste P.pastoris.

Role of nano-Fe3O4 particle on improving membrane bioreactor (MBR) performance: Alleviating membrane fouling and microbial mechanism

This study would investigate the effect of nano-Fe3O4 particles on the performance of membrane bioreactor (MBR), including membrane fouling, membrane rejection and microbial community. It can effectively alleviate membrane fouling and improve the effluent quality in MBR by bio-effect rather than nanoparticle adsorption. The lowest membrane fouling resistance was achieved at R4-MBR (sludge and membrane surface with nano-Fe3O4), which decreased by 46.08%. Meanwhile, R3-MBR (sludge with nano-Fe3O4) had the lowest concentration of COD in effluent which was below 20 mg/L in the stable phase of MBR operation. After applying nano-Fe3O4, the content of extracellular polymeric substances (EPS) and soluble microbial products (SMP) were both reduced with a lower molecular weight. From the microbial community analysis, the abundance of Proteobacteria increased from 25.06 to 45.11% at the phylum level in R3-MBR. It contributed to removing organic substances in MBRs. Moreover, the nano-Fe3O4 restricted Bacteroidetes growth, especially in R4-MBR, leading to a more excellent performance of membrane flux. Besides, the applied nano-Fe3O4 promoted the abundance of Quorum Quenching (QQ) microorganism, and declined the percentage of Quorum Sensing (QS) bacteria. Then, a lower content of N-Acyl-l-Homoserine Lactones (AHLs) in containing nano-Fe3O4 sludge. That was also prone to control membrane fouling. Overall, this study indicates the nano-Fe3O4 particle is appropriate for elevating MBR performance, such as membrane fouling and effluent quality, by bio-effect.

Interaction of plastic particles with heavy metals and the resulting toxicological impacts: a review

Interactions of plastic particles with different organic/inorganic pollutants including heavy metals impact their ecotoxicological potential, and proper understanding in this regard is important for their ecological risk assessment. However, many studies have reported the interactions between micro-/nanoplastics (MNPs) and heavy metals (HMs), but the most prevalent interactive forces and factors monitoring their interactions are still not clear. So, the present review represents the mechanisms of interactions with special emphasis on major interactive forces and biophysicochemical and environmental factors influencing trace element's adsorption onto the surface of MNPs. Electrostatic interaction and pore-filling mechanism can best explain the HMs adsorption to MNPs. A number of biophysicochemical factors (such as biofilm, size, crystallinity, and surface charge) and environmental factors (such as pH, salt, and temperature) act together for mediating interactions and ecotoxicities of MNPs and HMs in the real environment. From a toxicological point of view, the synergistic mode of action may be more active in animals, whereas the antagonistic activity may be prevalent in plants. Besides polymer density, biofilm formation and agglomeration property of MNPs can control the vertical distribution of MNPs along the water column. Finally, the ecotoxicological potential of MNPs in the natural environment can be considered as a function of spatiotemporal variation in abiotic (including MNPs and heavy metals) and biotic components. This review will be helpful in the detail understanding of ecotoxicological risk assessment of MNPs in relation to their interaction with heavy metals.

Characterizing the roles of pretreatment methods for model suspensions in the membrane fouling process: The case of yeast and kaolin

Model suspensions are important substances for characterizing fouling processes to study the mechanism of membrane fouling, thus, choosing a suitable standard suspension is critical for researches on membrane fouling processes. The pretreatment methods of model suspensions have long been neglected, which can alter the physical and chemical properties and affect fouling results. This study compared four different pretreatment methods (centrifuging and drying, magnetic stirring, ultrasonic processing, and dissolving in buffer solution) and found effects on size distribution, dispersion stability, pH variation over time, and fouling properties. Among the characterization of model suspensions, different pretreatment methods led to various changes in physical and chemical properties in this study. Membrane filtration experiments showed that these four pretreatments changed the rate of membrane fouling. The results of the analysis of filtration flux for suspensions indicated that for ultrasonic processing of all suspensions and magnetic stirring of kaolin suspensions, pore blocking was the main mechanism, while cake formation was dominant for the others. Therefore, special attention should be placed on different pretreatment methods and selecting appropriate model foulants. Finally, some guidance on selecting appropriate model foulants was given in the study.

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.

Aerogel doped by sulfur-functionalized graphene oxide with convenient separability for efficient patulin removal from apple juice

Patulin (PAT) contaminant causes severe food safety issue throughout apple industry. Although adsorption is the feasible approach to remove PAT, the limited adsorption capacity and separation difficulty of most adsorbent is the major drawback that remains to be overcome. Here GO-SH doped aerogel was prepared and used for removal PAT from apple juice. The intrinsic porous of the aerogel and abundant active sites including -COOH, -NH₂ and -SH offered the PAT adsorption capacity of 24.75 μg/mg that superior to most reported adsorbents. Furthermore, it could reduce 89 ± 1.23% PAT in real apple juice without juice quality deterioration and cytotoxicity. Importantly, the aerogel with good mechanical strength and structure stability could endure the complex juice solution so that there was no any residue after convenient separation of the aerogel, which proved that the proposed aerogel was a promising adsorbent to be applied to apple juice industry for PAT removal.

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

Patulin (PAT) is a mycotoxin that can contaminate many foods and especially fruits and fruit-based products. Therefore, accurate and effective testing is necessary to enable producers to comply with regulations and promote food safety. Traditional approaches involving the use of chemical compounds or physical treatments in food have provided practical methods that have been used to date. However, growing concerns about environmental and health problems associated with these approaches call for new alternatives. In contrast, recent advances in biotechnology have revolutionized the understanding of living organisms and brought more effective biological tools. This review, therefore, focuses on the study of biotechnology approaches for the detection, control, and mitigation of PAT in food. Future aspects of biotechnology development to overcome the food safety problem posed by PAT were also examined. We find that biotechnology advances offer novel, more effective, and environmental friendly approaches for the control and elimination of PAT in food compared to traditional methods. Biosensors represent the future of PAT detection and use biological tools such as aptamer, enzyme, and antibody. PAT prevention strategies include microbial biocontrol, the use of antifungal biomolecules, and the use of microorganisms in combination with antifungal molecules. PAT detoxification aims at the breakdown and removal of PAT in food by using enzymes, microorganisms, and various adsorbent biopolymers. Finally, biotechnology advances will be dependent on the understanding of fundamental biology of living organisms regarding PAT synthesis and resistance mechanisms.

Core-Shell Molecularly Imprinted Polymers on Magnetic Yeast for the Removal of Sulfamethoxazole from Water

In this work, magnetic yeast (MY) was produced through an in situ one-step method. Then, MY was used as the core and the antibiotic sulfamethoxazole (SMX) as the template to produce highly selective magnetic yeast-molecularly imprinted polymers (MY@MIPs). The physicochemical properties of MY@MIPs were assessed by Fourier-transform infrared spectroscopy (FT-IR), a vibrating sample magnetometer (VSM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), specific surface area (S_BET) determination, and scanning electron microscopy (SEM). Batch adsorption experiments were carried out to compare MY@MIPs with MY and MY@NIPs (magnetic yeast-molecularly imprinted polymers without template), with MY@MIPs showing a better performance in the removal of SMX from water. Adsorption of SMX onto MY@MIPs was described by the pseudo-second-order kinetic model and the Langmuir isotherm, with maximum adsorption capacities of 77 and 24 mg g^-1 from ultrapure and wastewater, respectively. Furthermore, MY@MIPs displayed a highly selective adsorption toward SMX in the presence of other pharmaceuticals, namely diclofenac (DCF) and carbamazepine (CBZ). Finally, regeneration experiments showed that SMX adsorption decreased 21 and 34% after the first and second regeneration cycles, respectively. This work demonstrates that MY@MIPs are promising sorbent materials for the selective removal of SMX from wastewater.

Thiol-functionalized inactivated yeast embedded in agar aerogel for highly efficient adsorption of patulin in apple juice

The issue of patulin (PAT) contamination in apple juice has attracted widespread concern. Recently, inactivated yeast based biosorbents have shown great advantages in the removal of toxic contaminants. However, the traditional yeast adsorbents have disadvantages of a limited adsorption capacity in juice and separation difficulty. In the present work, five chemical thiol-functionalization methods were used to increase the PAT adsorption efficiency of yeast cells in apple juice. Thereinto, glutaraldehyde cross-linking increased the thiol (-SH) content of yeast cells to 1.26 mmol g^-1 and improved the PAT adsorption capacity of inactivated yeast in apple juice by 150 times. The covalent bonding of -SH and PAT played an important role in the improvement of adsorption capacity. The as-prepared thiol-modification yeast (Y-SH(Gl)) was then embedded in the agar aerogel to obtain Y-SH(Gl)@Agar free of separation. PAT adsorption of Y-SH(Gl)@Agar was consistent with the Freundlich model and the pseudo-second-order kinetic model. Moreover, Y-SH(Gl)@Agar was competent for PAT removal in apple juice and manifested negligible effects on juice quality. Cytotoxicity investigation indicated its good biocompatibility and ignorable food safety risk, thereby demonstrating that Y-SH(Gl)@Agar may be a promising adsorbent material for the control of PAT contaminant in juice.

Combined effects of polystyrene microplastics and natural organic matter on the accumulation and toxicity of copper in zebrafish

As emerging contaminants, microplastics (MPs) are predicted to act as vectors for other contaminants and their combined effects are largely unknown. In this study, the combined effects of MPs and natural organic matter (NOM) on the accumulation and toxicity of copper (Cu) in zebrafish (Danio rerio) were investigated. As a result, small-size MPs could absorb more Cu than large-size MPs. The presence of NOM promoted Cu adsorption on MPs in the pH range of 6-8. Our results demonstrate that the combination of MPs and NOM increased Cu accumulation in the livers and guts in a size-depended manner. Correspondingly, the results of biochemical test showed that MPs and NOM could aggravate Cu-toxicity in the livers and guts, which is manifested in the increased levels of malonaldehyde (MDA) and metallothionein (MT) and decreased levels of superoxide dismutase (SOD). Furthermore, the results of transcriptomic analysis suggested that such aggravation of toxicity was mainly attributed to the inhibition of Cu-ion transport and the enhanced oxidative stress. Since the co-existence of MPs and NOM in the environment is inevitable, their enhancement effects on the bioaccumulation and toxicity of other pollutants such as heavy metals deserve more attention.

Mycotoxin patulin in food matrices: occurrence and its biological degradation strategies

Patulin is a mycotoxin produced by a number of filamentous fungal species. It is a polyketide secondary metabolite which can gravely cause human health problems and food safety issues. This review deals with the occurrence of patulin in major food commodities from 2008 to date, including historical aspects, source, occurrence, regulatory limits and its toxicity. Most importantly, an overview of the recent research progress about the biodegradation strategies for contaminated food matrices is provided. The physical and chemical approaches have some drawbacks such as safety issues, possible losses in the nutritional quality, chemical hazards, limited efficacy, and high cost. The biological decontamination based on elimination or degradation of patulin using yeast, bacteria, and fungi has shown good results and it seems to be attractive since it works under mild and environment-friendly conditions. Further studies are needed to make clear the detoxification pathways by available potential biosorbents and to determine the practical applications of these methods at a commercial level to remove patulin from food products with special reference to their effects on sensory characteristics of foods.

Efficient removal of ethidium bromide from aqueous solution by using DNA-loaded Fe3O4 nanoparticles

Ethidium bromide (EtBr) is widely used as DNA-staining dyes for the detection of nucleic acids in laboratories and known to be powerful mutagens and carcinogens. In the present paper, the removal of EtBr from aqueous solutions in a batch system using DNA-loaded Fe₃O₄ nanoparticles as a simple and efficient method was investigated. DNA was covalently loaded on the surface of Fe₃O₄ magnetic nanoparticles, which was confirmed by FT-IR analysis and zeta potential measurements. The morphology and crystal structure were characterized by SEM, TEM, and XRD. The influence factors on the removal efficiency such as initial EtBr concentration, contact time, adsorbent dose, pH, and temperature were also studied. The removal process of EtBr can be completed quickly within 1 min. The removal efficiency was more than 99% while the EtBr concentration was routinely used (0.5 mg L^-1) in biology laboratories and the dosages of nanoparticles were 1 g L^-1. For the different EtBr concentrations from 0.5 to 10 mg L^-1 in aqueous solution, the goal of optimized removal was achieved by adjusting the dosage of DNA-loaded Fe₃O₄ nanoparticles. The optimum pH was around 7 and the operational temperature from 4 to 35 °C was appropriate. Kinetic studies confirmed that the adsorption followed second-order reaction kinetics. Thermodynamic data revealed that the process was spontaneous and exothermic. The adsorption of EtBr on DNA-loaded Fe₃O₄ nanoparticles fitted well with the Freundlich isotherm model. These results indicated that DNA-loaded Fe₃O₄ nanoparticles are a promising adsorbent for highly efficient removal of EtBr from aqueous solution in practice.

Equilibrium modeling of selenium binding from aqueous solutions by Candida utilis ATCC 9950 yeasts

The study investigated the effectiveness of selenium binding from its salt solution by Candida utilis ATCC 9950 yeast biomass cultured on a medium prepared from the agro-food industry wastes, containing an available source of carbon and nitrogen. Selenium binding by C. utilis yeast strain after 48 h of culturing at 28 °C from aqueous solutions with the addition of 30 mg Se/L reached a value of 2.28 mg Se/g of yeast biomass. The kinetics of selenium binding by the yeasts showed a better fit for the pseudo-second-order kinetic model compared to the pseudo-first-order one. Accumulation stability data were analyzed using the Freundlich and Langmuir isotherm models. The presence of competing anions such as SO 4 2 - , and HPO 4 2 - at a concentration of 0.5 mM resulted in about 35% reduction of selenium binding by the examined C. utilis strain. FTIR analysis showed that sulfur compounds were involved in selenium biosorption by the yeast. Compounds containing ammonium groups appeared to be very important for selenium binding. The results of the study demonstrated that the yeast can be used to effectively bind selenium from aqueous solution. At the same time, it gives the opportunity to obtain a biomass rich in this deficient element, which can also be used in dietary supplement production.

Effective Adsorption of Patulin from Apple Juice by Using Non-Cytotoxic Heat-Inactivated Cells and Spores of Alicyclobacillus Strains

Patulin (PAT) is a major threat to many food products, especially apple and apple products, causing human health risks and economic losses. The aim of this study was to remove PAT from apple juice by using the heat-inactivated (HI) cells and spores of seven Alicyclobacillus strains under controlled conditions. The HI cells and spores of seven strains adsorbed PAT effectively, and the HI cells and spores of Alicyclobacillus acidocaldarius DSM 451 (A51) showed maximum PAT adsorption capacity of up to 12.621 μg/g by HI cells and 11.751 μg/g by HI spores at 30 °C and pH 4.0 for 24 h. Moreover, the PAT adsorption process followed the pseudo-first order kinetic model and the Freundlich isotherm model; thermodynamic parameters revealed that PAT adsorption is a spontaneous exothermic physisorption process. The results also indicated that PAT adsorption is strain-specific. The HI cells and spores of Alicyclobacillus strains are non-cytotoxic, and the bioadsorption of PAT did not affect the quality of the juice. Furthermore, the cell wall surface plays an important role in the adsorption process.

Patulin removal from apple juice using a novel cysteine-functionalized metal-organic framework adsorbent

Patulin (PAT) is one of the most common toxic contaminants of apple juice, which causes severe food safety issues throughout the apple industry. In order to remove PAT efficiently, a metal-organic framework-based adsorbent (UiO-66(NH₂)@Au-Cys) was successfully synthesized and used for PAT removal from juice-pH simulation solution and real apple juice. Batch adsorption experiments were systematically performed to study the adsorption behavior for PAT. The results showed that adsorption process could be well described by the Pseudo-second order model and Freundlich isotherm model. The maximum adsorption capacity (4.38 µg/mg) was 10 times higher than the microbe-based biosorbents. Thermodynamic investigation demonstrated that adsorption process was spontaneous and endothermic. Furthermore, no marked cytotoxicity on NIH 3T3 cell lines was observed when the concentration of the adsorbent was lower than 10 μg/mL. Therefore, UiO-66(NH₂)@Au-Cys is a potential adsorbent for PAT removal from apple juice with little quality changes.