查找使用阿拉丁产品的科研文献

Inhibition of Aspergillus flavus growth and aflatoxins production on peanuts over α-Fe2O3 nanorods under sunlight irradiation

Di Sun,Jin Mao,Zhijian Wang,Hui Li,Liangxiao Zhang,Wen Zhang,Qi Zhang,Peiwu Li

Peanut is an important resource of edible oil and digestible protein in daily life, which is rich in the nutriments and antioxidants such as vitamins, minerals and polyphenols. However, peanut is susceptible to the contamination of Aspergillus flavus ( A. flavus ), which can produce highly carcinogenic toxins that brings serious threats to human health and food safety. Exploring green and effective methods to control A. flavus is meaningful. Herein, a green and economical way to control A. flavus on peanuts was demonstrated. It was found that the growth of A. flavus hyphae and germination of its spores could be inhibited in the presence of α-Fe 2 O 3 nanorods under sunlight irradiation according to the agar diffusion method , flat colony counting method and fluorescence-based live/dead test. The diameter of inhibition zone was 22.3 ± 0.2 mm and the inhibition rate of spores germination was about 60 ± 5%, when the concentration of α-Fe 2 O 3 was 10 mg/mL for 7 h sunlight irradiation. Most important, α-Fe 2 O 3 showed the photocatalytic inhibition of A. flavus on peanuts under sunlight irradiation with the inhibition rate of about 90 ± 5%, and the production of aflatoxin B 1 and aflatoxin B 2 were reduced by 90 ± 2% and 70 ± 3%, respectively. By comparing the fat contents, protein contents, acid value, peroxide value and antioxidative compositions of peanuts, it was found that there was no obvious effect on the quality of peanuts after inhibition treatment. The findings provide a green, safe and economical strategy to control A. flavus on peanuts, which may be as a promising way to be used in food and agro-food preservation.

PP2C phosphatases Ptc1 and Ptc2 dephosphorylate PGK1 to regulate autophagy and aflatoxin synthesis in the pathogenic fungus Aspergillus flavus

Zhuo Zhu,Mingkun Yang,Guang Yang,Bei Zhang,Xiaohong Cao,Jun Yuan,Feng Ge,Shihua Wang

Inhibition Mechanism of Cinnamomum burmannii Leaf Essential Oil Against Aspergillus flavus and Aflatoxins

Huanyan Liang,Feifei Lv,Mengting Xian,Chenghua Luo,Lei Zhang,Meihua Yang,Qian Li,Xiangsheng Zhao

This investigation evaluates the comparative efficacy ofCinnamomum burmanniileaf essential oil (YXYO) and its main active ingredients as a novel preservative to protect stored food commodities from fungal infestations, aflatoxin B1(AFB1) contamination caused byAspergillus flavus. Morphological observations utilizing SEM and TEM revealed significant alterations in treated samples, alongside a decrease in ergosterol content and a dose-dependent disruption of the antioxidant system and energy system. Transcriptomic analysis suggested that differentially expressed genes were predominantly associated with spore growth, the cell wall, the cell membrane, oxidative stress, energy metabolism, and aflatoxin biosynthesis. Solid-phase microextraction–gas chromatography–mass spectrometry (SPME-GC-MS) identified ten active ingredients in YXYO, including borneol,α-terpineol, terpinen-4-ol, etc. Moreover, an effective inhibition ofA. flavusinfection in peanuts was observed with the application of 30 μL/disc of YXYO and a blend of its active compounds.

Study on the Dynamic Changes in Fungal Communities During the Storage of Polygalae Radix and the Antifungal Effects of Peppermint Essential Oil

Hui Zhang,Yuying Su,Xinnan Wang,Ying Ren,Jinfeng Li,Jianping Han

Polygalae Radix, a traditional Chinese medicine for insomnia and memory disorders, is highly susceptible to fungal contamination and mycotoxin production (especially byAspergillus flavus) during storage, compromising its safety and efficacy. Therefore, in this study, high-throughput sequencing was employed to evaluate the dynamic changes in fungal communities during the storage of Polygalae Radix and to analyze common mycotoxin-producing genera. Furthermore, the inhibitory effects of peppermint essential oil (PEO) onA. flavuswere assessed through fumigation treatments, combined with colony counting and quantification of aflatoxins. Results showed the following: (1) Storage for 1–3 months significantly altered the fungal structure, promoting saprophytic and pathogenic fungi (e.g.,Wallemia,Paraphoma,Didymella,Cladosporium…) and increasing the relative abundance of mycotoxin producers likePenicillium,Aspergillus, andFusarium(notably,Penicilliumincreased from 0.28–2.33% to 5.39–80.43%). Additionally,A. flavus, capable of producing aflatoxins, was detected in samples stored for two months (RM2). (2) Antifungal tests demonstrated that PEO significantly inhibited the common fungi in Polygalae Radix. At 10 μL/g, it suppressed fungal growth and significantly reduced aflatoxin B1(AFB1) and total aflatoxins (AFT, including AFB1, AFB2, AFG1, and AFG2) levels (p< 0.05). At 10 μL/g, AFB1and AFT were reduced to undetectable levels. PEO can serve as a green and effective protective strategy to inhibitA. flavusduring the storage of Polygalae Radix and control aflatoxin contamination.

Electrochemical analysis of specific catalase activity during development of Aspergillus flavus and its correlation with aflatoxin B1 production

Yanjing Yun,Zhisong Lu,Jing Yang,Taotao Liang,Gang Xiao,Yan Qiao,Yang Liu

Aflatoxin B 1 (AFB 1 ) contamination causes huge economic losses. To explore the correlation between catalase (CAT) and AFB 1 production during fungal development, we fabricated an electrochemical CAT-activity sensor by measuring residual H 2 O 2 after enzymatic degradation. The sensor made by palladium nanoparticles/carbonized bacterial cellulose nanocomposites exhibits a linear range over 0.5–3.5 U/mL and a detection limit of 0.434 U/mL. Both dry weight and CAT activity of mycelia continuously increase. But, the latter shows a greater increase than the former after three days. Specific CAT activity in crude enzyme extract of A. flavus was quantified. It maintains at ~25.00 U/mg for 3 days and enhances to 28.91 and 45.30 U/mg, respectively, on days 4 and 5. AFB 1 production follows the same trend. On days 4 and 5, AFB 1 concentration reaches 201.35 and 767.9 ng/mL, respectively. The positive correlation between specific CAT activity and AFB 1 production suggests that CAT is involved in AFB 1 biosynthesis.

A novel sample pretreatment of nanofiber-packed solid-phase extraction of aflatoxin B1, B2, G1 and G2 in foods and simultaneous determination with HPLC

Yunzheng Wang,Lanling Chu,Jiansong Qu,Bo Ding,Xuejun Kang

A novel analytical method based on nanofiber-packed solid-phase extraction (PFSPE) combined with HPLC-FLD has been successfully developed and applied to determine aflatoxin B1, B2, G1, G2 in foods. In order to effectively adsorb analytes from complex food matrices, four types of nanofibers based on skeleton of polystyrene–polyvinyl pyrrolidone were prepared by electrospinning and applied as adsorbent to home-made solid-phase extraction device. The effects of type of nanofibers, pH of sample, type and concentration of salt ion, type of activation solvent, type and volume of eluent, amount of nanofibers, and extraction time on the adsorption/desorption were investigated and optimized. Under optimal conditions, the method showed satisfactory linear relationship, with limits of detection (LODs) of 0.07–0.17 ng g −1 , intra-day and inter-day RSDs for spiked samples of 1.3–8.0 % and 1.9–5.8 %, and absolute recoveries in the range of 60.1–98.4 %. The results presented the great potential to be utilized to determine AFs in foodstuffs.

Synergistic effect of acetic acid and chitosan against Aspergillus flavus

Jing Liu,Hao Chen,Yan Lv,Lijun Yang,Wenjie Wang,Jianying Huang,Dandan Zhang

The mycotoxin-producing fungi contamination of foodstuffs and agricultural commodities is a serious problem. In this study, the efficacy of acetic acid (AcA), chitosan (CS), and CS with extra AcA (CS/extra AcA) against Aspergillus flavus ( A. flavus ) in vitro and in vivo were investigated. Results showed that CS/extra AcA strongly inhibited the mycelial growth and aflatoxins production of A. flavus at lower concentrations than CS (MIC > 16.0 mg/mL) or AcA (MIC: 0.31 %). Significant inhibition was achieved in the presence of 4.0/0.12 and 8.0/0.08 CS (mg/mL)/extra AcA (%). CS/extra AcA exhibited remarkable antifungal activities based on the results of spore germination inhibition, abnormalities of spore morphology, disruption of cell membrane, mitochondrial dysfunction, and induction of apoptosis of hyphae. Moreover, pathogenicity test in peanut kernels showed that 8.0/0.16 CS (mg/mL)/extra AcA (%) could effectively inhibit the fungal infection and aflatoxin B 1 production. The efficacy of CS/extra AcA is possibly due to the synergy of the antifungal property of CS, and undissociated AcA. The findings referred that CS/extra AcA is safe, efficient, and economical, and it could be used as a promising way to control A. flavus contamination in agro-foods preservation.

A New Laccase of Lac 2 from the White Rot Fungus Cerrena unicolor 6884 and Lac 2-Mediated Degradation of Aflatoxin B1

Zhimin Zhou,Renkuan Li,Tzi Bun Ng,Yunyun Lai,Jie Yang,Xiuyun Ye

Aflatoxin B1(AFB1) is a known toxic human carcinogen and can be detoxified by laccases, which are multicopper oxidases that convert several environmental pollutants and toxins. In this study, a new laccase that could catalyze AFB1degradation was purified and identified from the white-rot fungusCerrena unicolor6884. The laccase was purified using (NH4)2SO4precipitation and anion exchange chromatography, and then identified as Lac 2 through zymogram and UHPLC-MS/MS based on the Illumina transcriptome analysis ofC. unicolor6884. Six putative laccase protein sequences were obtained via functional annotation. Thelac 2cDNA encoding a full-length protein of 512 amino acids was cloned and sequenced to expand the fungus laccase gene library for AFB1detoxification. AFB1degradation by Lac 2 was conducted in vitro at pH 7.0 and 45 °C for 24 h. The half-life of AFB1degradation catalyzed by Lac 2 was 5.16 h. Acetosyringone (AS), Syrinagaldehyde (SA) and [2,2′ -azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid)] (ABTS) at 1 mM concentration seemed to be similar mediators for strongly enhancing AFB1degradation by Lac 2. The product of AFB1degradation catalyzed by Lac 2 was traced and identified to be Aflatoxin Q1(AFQ1) based on mass spectrometry data. These findings are promising for a possible application of Lac 2 as a new aflatoxin oxidase in degrading AFB1present in food and feeds.Keywords:laccase;Cerrena unicolor;aflatoxin B1;biodegradation;detoxification;product;transcriptomeKey Contribution:A product identified to be AFQ1was found from Lac 2-mediated AFB1degradation, indicating that AFB1would be transformed during Lac 2-mediated AFB1degradation.

A label-free fluorescent aptasensor for AFB1 and AFM1 based on the aptamer tailoring strategy and synergistic signal amplification of HCR and MoS2 nanosheets

Yifeng Lan,Yingqi Ma,Yingwen Xu,Yuan Zhang,Rujia Deng,Lulu Liu,Boya Hou,Haiyan Cui,Keming Yun,Zhiwen Wei,Yanli Wei

Effective truncation and mutation can obtain highly active nucleic acid aptamers for the target, especially avoiding non-specific binding, uncertainty to the tertiary structure and low binding affinity of the lengthy aptamer. In this work, a new aptamer, T-AF28 (28 nt) with better affinity to AFB1 was obtained by truncating 22 bases and mutating 3 bases of the reported AFB1 aptamer (50 nt), and the thermodynamic information, structural changes and binding domains of aptamer T-AF28 in the presence of AFB1 or AFM1 were further investigated by isothermal titration calorimetry, circular dichroism, and molecular dynamics. On this basis, Using optimized aptamers as recognition elements, a novel label-free and enzyme-free fluorescent aptasensor for AFB1 and AFM1 was developed by synergistic amplification effect of hybridization chain reaction (HCR) coupled molybdenum disulfide nanosheets and copper nanoparticles in situ synthesized (CuNPs) on an extra-long double-stranded template generated by HCR as the fluorescent probe. Under the optimal experimental conditions, sensitive and selective fluorescent detection of AFB1 and AFM1 was achieved with wide linear detection ranges of 0.030 ng/mL-46.8 ng/mL and 0.030 ng/mL-32.8 ng/mL, respectively. And this aptasensor can be applied to accurate detection of AFB1 and AFM1 in grains, edible oil, tea, and milk with the recovery in the range of 85.20 %-117.0 %. This work not only provides a theoretical basis for the design of AFB1 and AFM1 aptasensors and expands the application of AFB1 aptasensors in the field of food safety, but also breaks a new path for the development of HCR-MoS 2 Ns CuNPs aptasensors.

Estragole Inhibits Growth and Aflatoxin Biosynthesis of Aspergillus flavus by Affecting Reactive Oxygen Species Homeostasis

Liuke Liang,Wei Zhang,Jing Hao,Yanyu Wang,Shan Wei,Shuaibing Zhang,Yuansen Hu,Yangyong Lv

A variety of essential oils and edible compounds have been widely recognized for their antifungal activity in recent years. In this study, we explored the antifungal activity of estragole from Pimenta racemosa against Aspergillus flavus and investigated the underlying mechanism of action. The results showed that estragole had significant antifungal activity against A. flavus, with a minimum inhibitory concentration of 0.5 μL/mL against spore germination. Additionally, estragole inhibited the biosynthesis of aflatoxin in a dose-dependent manner, and aflatoxin biosynthesis was significantly inhibited at 0.125 μL/mL. Pathogenicity assays showed that estragole had potential antifungal activity against A. flavus in peanut and corn grains by inhibiting conidia and aflatoxin production. Transcriptomic analysis showed that the differentially expressed genes (DEGs) were mainly related to oxidative stress, energy metabolism, and secondary metabolite synthesis following estragole treatment. Importantly, we experimentally verified reactive oxidative species accumulation following downregulation of antioxidant enzymes, including catalase, superoxide dismutase, and peroxidase. These results suggest that estragole inhibits the growth and aflatoxin biosynthesis of A. flavus by modulating intracellular redox homeostasis. These findings expand our knowledge on the antifungal activity and molecular mechanisms of estragole, and provide a basis for estragole as a potential agent against A. flavus contamination.IMPORTANCE Aspergillus flavus contaminates crops and produces aflatoxins, carcinogenic secondary metabolites which pose a serious threat to agricultural production and animal and human health. Currently, control of A. flavus growth and mycotoxin contamination mainly relies on antimicrobial chemicals, agents with side effects such as toxic residues and the emergence of resistance. With their safety, environmental friendliness, and high efficiency, essential oils and edible compounds have become promising antifungal agents to control growth and mycotoxin biosynthesis in hazardous filamentous fungi. In this study, we explored the antifungal activity of estragole from Pimenta racemosa against A. flavus and investigated its underlying mechanism. The results demonstrated that estragole inhibits the growth and aflatoxin biosynthesis of A. flavus by modulating intracellular redox homeostasis.

Aflatoxin contamination and aflatoxin-producing strain screening in dried red chili peppers from different origins

Yaoyao Su,Jun Huang,Xiaoman Chen,Gang Yang,Kewei Chen,Muying Du,Zsolt Zalán,Ferenc Hegyi,Sameh Awad,Jianquan Kan

The contamination of spices with aflatoxin (AF) raises concerns regarding its health risks. In this study, 51 samples of dried red chili peppers (including 10 varieties collected from three regions) were used to investigate the AF contamination of dried red chili peppers sold in China, and the toxigenic characteristics of Aspergillus flavus strains isolated from chili peppers. AFs were identified using immunoaffinity column purification, derivatization, and high-performance liquid chromatography with fluorescence detection. The AF content in various types of dried red chili peppers sold in the Chinese market was generally low (≤ 7.19 µg/kg), below the limit of the relevant standard (10 µg/kg). The frequency of suspected A. flavus strains isolated from chili peppers was high (24/51), with a high toxigenic strain ratio of 29.17%. Further investigation revealed that 25–30 ℃ was the optimal temperature for toxin production by these toxigenic strains. This indicated that dried chilled peppers have a significant risk of AF contamination. Therefore, the findings of this study suggest that long-term storage of dried chili peppers should be conducted at temperatures below 25 ℃ or above 37 ℃ to mitigate the problem of AF contamination exceeding the levels allowed by the standards, providing new insights for the prevention and control of AF contamination of dried red chili peppers.

A fluorescent aptasensor based on functional graphene oxide and FRET strategy simultaneously detects aflatoxins B1 and aflatoxins M1

Yuzheng CAI,Ge GUO,Yankun FU,Xianqing HUANG,Tianlin WANG,Tiange LI

Simultaneous and rapid detection of various mycotoxins in food holds significant practical importance in the field of food processing and safety. In this study, a fluorescent aptasensor based on functionalized graphene oxide (FGO) is developed for simultaneous detection of aflatoxin B 1 (AFB 1 ) and aflatoxin M 1 (AFM 1 ). The two aptamers specific to AFB 1 and AFM 1 are labeled with Cy3 and Cy5 respectively. Both the aptamers can be adsorbed onto the surface of FGO through π - π stacking, resulting in fluorescence resonance energy transfer (FRET) between the fluorophore and FGO. The absence of target leads to quenching of fluorescence while presence of either aflatoxin causes interaction between corresponding aptamer and target, leading to release from FGO surface thereby turning on fluorescence signal. The limit of detection (LOD) for AFB 1 is determined as 8.7 pg/mL whereas for AFM 1 it is found to be 20.1 pg/mL, demonstrating fast and sensitive detection capability using this approach. Furthermore, the aptasensor exhibits good specificity and selectivity even under influence from other common interfering toxins. With its simplicity in operation and portability features, this sensor has potential applications for establishing sensitive and portable on-site detection methods for various mycotoxins.