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Effects of different substrates and oils on aflatoxin B1 production by Aspergillus parasiticus

Ma Huihui,Zhang Niya,Sun Lvhui,Qi Desheng

Aflatoxin contamination levels vary from crop to crop, suggesting that it is of great significance to explore the effects of different substrates on aflatoxins production. In this study, the effects of corn, wheat, peanut, and soybean on aflatoxin B 1 (AFB 1 ) production by Aspergillus parasiticus were investigated, and the effects of corn germ, wheat germ, soybean, and peanut oils on the production of AFB 1 by A . parasiticus in the corresponding defatted substrates were evaluated at the rates of 2, 5, 10, and 15 g/100 g of substrate. The effects of the combinations of different oils with different defatted substrates on the accumulation of AFB 1 by A . parasiticus were also studied. AFB 1 concentration was determined by HPLC. The results indicated that high-lipid substrates of soybean and peanut had significantly higher AFB 1 production than low-fat substrates of wheat and corn throughout the entire incubation period (15 days) in both autoclaved and non-autoclaved grains. Corn germ, wheat germ, soybean, and peanut oils with different doses could effectively stimulate AFB 1 accumulation, and AFB 1 production was determined by the oil content of the substrates. Our results suggest that the oil content of substrates is one of the factors affecting AFB 1 production by A . parasiticus and that the composition and content of the substrates may also play a role.

Restoration of Choujiu Koji and evaluation of its brewing performance

Jing Zhang,Kairu Liu,Xiaojuan Duan,Xuhao Wang,Wupeng Ge,Wenping Jin

Koji is used as a fermentation starter in Choujiu manufacture in northwestern China. Traditional natural Koji (NK) cultivates in open environments, which probably leads to diverse microflora, causes inconsistent quantities in Koji, then results in instable qualities of Choujiu. A native Choujiu producer has been purchasing NK from local workshop, while their Choujiu qualities fluctuate by the stability of NK. As a request from the producer, this study aimed for stable Koji and inheriting sensory traits of current products. Strains of mold, yeast, and LAB, separated from NK, were selected for Restored Koji (RK) making. Brewing performance of RK and NK were compared by analysis of the physicochemical properties and volatile flavor compounds (VFCs) in fermented mash, combined with sensory evaluation in corresponding Choujiu. Pure Koji from individual strains was separately cultured at 28 °C for 48 h, and then reconstituted for RK II at the proportion of mold Koji (M7 Koji): yeast Koji (Y3 Koji: Y4 Koji = 1:1): LAB Koji (L1 Koji) = 1:1:1, where M7 was Rhizopus oryzae , Y3 was Saccharomyces cerevisiae , Y4 was Saccharomycopsis fibuligera , and L1 was Pediococcus pentosaceus . Results showed RK II could meet the desired purpose of this study.

Investigations on the Antifungal Effect of Nerol against Aspergillus flavus Causing Food Spoilage

Jun Tian,Xiaobin Zeng,Hong Zeng,Zhaozhong Feng,Xiangmin Miao,Xue Peng

The antifungal efficacy of nerol (NEL) has been proved against Aspergillus flavus by using in vitro and in vivo tests. The mycelial growth of A. flavus was completely inhibited at concentrations of 0.8 μL/mL and 0.1 μL/mL NEL in the air at contact and vapor conditions, respectively. The NEL also had an evident inhibitory effect on spore germination in A. flavus along with NEL concentration as well as time-dependent kinetic inhibition. The NEL presented noticeable inhibition on dry mycelium weight and synthesis of aflatoxin B1 (AFB1) by A. flavus, totally restraining AFB1 production at 0.6 μL/mL. In real food system, the efficacy of the NEL on resistance to decay development in cherry tomatoes was investigated in vivo by exposing inoculated and control fruit groups to NEL vapor at different concentration. NEL vapors at 0.1 μL/mL air concentration significantly reduced artificially contaminated A. flavus and a broad spectrum of fungal microbiota. Results obtained from presented study showed that the NEL had a great antifungal activity and could be considered as a benefit and safe tool to control food spoilage.

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

Development and validation of a sensitive and simple LC-MS/MS method for simultaneous quantitation of valsartan, sacubitril and sacubitrilat in pediatric population

Quancheng Yang,Peng Cao,Yi Lv,Hua Peng,Xuejia Zhai

Pediatric heart failure (HF) is an important clinical disease with high hospitalization rates, morbidity, mortality and medical costs. Sacubitril/valsartan (also known as Entresto), was approved for the treatment of adult HF and is recently used in pediatrics. However, clinical therapy on children is more challenging than adults, and the pharmacokinetics of Entresto in children are still largely unknown and urgently needed. Herein, we aim to develop a simple and sensitive analytic method to monitor Entresto in pediatric patients, which is of great importance for individualized safe medication in children. Specifically, a liquid chromatography tandem mass spectrometry method for simultaneously quantification of valsartan, sacubitril and its bio-active metabolite sacubitrilat in human plasma has been developed and validated in pediatric patients. Plasma samples were pretreated with acetonitrile for protein precipitation. Elution was performed on X Select HSS T3 column (2.1 × 100 mm, 5 µm; Waters) column using an isocratic mobile phase process consisting of 0.1% formic acid aqueous solution and 0.1% formic acid acetonit rile with a total run time of 3.0 min. Valsartan-d3, sacubitrilin-d4 and sacubitrilat-d4 were used as the corresponding deuterium internal standards. According to the Bioanalytical Method Validation Guidance for Industry, the method was validated in the range of 0.5–5000 ng/mL. Intra- and inter-day accuracy of sacubitril,valsartan and sacubitrilat ranged from 93%− 108%, 98%− 109%, 91%− 102%, respectively, with relative standard deviation of precision ranging from 2.0% to 5.1%, 2.4%− 7.5%, 1,3%− 7.4%. The proposed method demonstrated good accuracy, precision and linearity. The matrix factors normalized by internal standard meet the acceptance criteria. The method was fully validated and applied in 39 children. Trough concentration of the three substances to be measured were: valsartan (11.3–938.0 ng/mL), sacubitril (0.5–395.5 ng/mL) and sacubitrilat (522.1–4890.0 ng/mL). Overall, this is the first study to simultaneously determined the plasma valsartan, sacubitril and sacubitrilat concentrations in children, which is believed to facilitate the clinical management of pediatric HF.

Effect of Peony (Paeonia ostii) Seed Meal Supplement on Enzyme Activities and Flavor Compounds of Chinese Traditional Soybean Paste during Fermentation

Weiqi Fu,Jiamin Ren,Shuwen Li,Dirong Ren,Xixi Li,Chenghuan Ren,Xueru Zhao,Jiaying Li,Fengjuan Li

Peony seed meal (PSM) is the by-product obtained from peony seeds after oil extraction. In this study, PSM was incorporated into traditional koji-making, and its impacts on koji enzyme activities and flavor compounds in final products were investigated. In the process of koji fermentation, the optimal addition ratio of PSM to soybean was determined as 7:3. Under this ratio, the maximum enzyme activities of neutral protease, amylase, and glucoamylase were 1177.85, 686.58, and 1564.36 U/g, respectively, and the koji obtained was subjected to maturation. During post-fermentation, changes in the fermentation characteristics of the paste samples were monitored, and it was found that compared to the soybean paste without PSM, the enzyme activities maintained at a relatively good level. The PSM soybean paste contained a total of 80 flavor compounds and 11 key flavor compounds (OAV ≥ 1), including ethyl isovalerate, isovaleric acid, hexanal, phenylacetaldehyde, 3-Methyl-1-butanol 4-heptanone, 2-pentylfuran, methanethiol ester caproate, isoamyl acetate, 3-methyl-4-heptanone, and isovaleraldehyde. These findings could be used to improve the quality of traditional fermented paste, enrich its flavor, and simultaneously promote PSM as a valuable resource for fermented foods.Keywords:peony seed meal;fermented soybean paste;enzyme activity;koji making;flavor compounds

Liquid Crystal Elastomer Actuators Enhanced by Tapered Optical Fibers for Controllable Bending Directions and Amplitudes

Yongcheng He,Haojun Liu,Jiajia Luo,Nuo Li,Zhishen Zhang,Jiulin Gan,Zhongmin Yang

Liquid crystal elastomer (LCE) photoactuators offer a versatile platform for executing complicated tasks through precisely controlled bending directions and amplitudes. Optical waveguides assist photoactuators to perform tasks unimpededly. While most existing optical waveguide actuators are limited to unidirectional bending, limiting their versatility. Here, a LCE actuator integrated with a tapered optical fiber with controllable bending directions and amplitudes is presented. The LCE actuator displays bending motions induced by uneven shrinkage due to the off-center fiber. The bending directions are parallel to the previous uniaxial alignment of the LCE film, which can be adjusted to an arbitrary angle with the tapered optical fiber. The LCE actuators exhibit adaptable bending directions at 0°, 45°, and 90°, representing the possible bending motions. The bending amplitudes are regulated by infrared laser power. A hook-like LCE actuator with 0° bending direction carried the handle of a basket. In addition, a 90° bending direction LCE actuator displays the shrinkage behavior, showing a special bending motion control. Moreover, a bionic hand, comprising five LCE actuators with various bending directions, exhibited diverse gestures with precise control. The controllable bending motions in optical waveguide actuators expand the promising applications in complicated scenarios, such as catheters or other medical devices.

Tactile Electronic Skin With Curved Surface Compensation by In Situ Curvature Self-Sensing

Xiangyu Meng,Hongyao Tang,Xiaozhou Lü,Yaoguang Shi,Weimin Bao

Tactile electronic skins with flexibility and good conformability have good application prospects in wearable electronics. However, pseudo-signals are generated when the electronic skin is attached to a curved surface, which affects the pressure detection performance of the electronic skin and limits its application. In this article, we developed a tactile electronic skin that compensates for curved surfaces through in situ curvature sensing and established a pressure, curvature-current model for the compensation of the curvature effect of the electronic skin. The electronic skin can compensate for the measured pressure according to the model and realizes a high-precision sensing capability. It consists of Ag/Ecoflex electrodes, pressure-sensitive materials, and a support layer. The Ag/Ecoflex electrodes with curvature sensing were prepared using screen printing and prestretching. The pressure insensitivity mechanism of the electrodes was analyzed. The effects of curvature on the measurement error of electronic skin were investigated. Experimental results suggest that Ag/Ecoflex electrodes with 80% prestretch have a 21.6/cm−1 curvature sensitivity coefficient and insensitivity to pressure at 0–200 kPa. The measurement errors introduced by curvature can be reduced by compensation. As an application, the skin is attached to the human arm for pressure measurement, through which its great potential is therefore highlighted in curved scenarios such as human prostheses, robots, and flexible airplane skins.

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.

Screening a Strain of Aspergillus niger and Optimization of Fermentation Conditions for Degradation of Aflatoxin B1

Wei Zhang,Beibei Xue,Mengmeng Li,Yang Mu,Zhihui Chen,Jianping Li,Anshan Shan

Aflatoxin B1, a type of highly toxic mycotoxin produced by some species belonging to theAspergillusgenus, such asAspergillus flavusandAspergillus parasiticus, is widely distributed in feed matrices. Here, coumarin was used as the sole carbon source to screen microorganism strains that were isolated from types of feed ingredients. Only one isolate (ND-1) was able to degrade aflatoxin B1after screening. ND-1 isolate, identified as a strain ofAspergillus nigerusing phylogenetic analysis on the basis of 18S rDNA, could remove 26.3% of aflatoxin B1after 48 h of fermentation in nutrient broth (NB). Optimization of fermentation conditions for aflatoxin B1degradation by selectedAspergillus nigerwas also performed. These results showed that 58.2% of aflatoxin B1was degraded after 24 h of culture under the optimal fermentation conditions. The aflatoxin B1degradation activity ofAspergillus nigersupernatant was significantly stronger than cells and cell extracts. Furthermore, effects of temperature, heat treatment, pH, and metal ions on aflatoxin B1degradation by the supernatant were examined. Results indicated that aflatoxin B1degradation ofAspergillus nigeris enzymatic and this process occurs in the extracellular environment.Keywords:Aspergillus niger;coumarin;aflatoxin B1;degradation

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.