APPLIED MICROBIOLOGY AND BIOTECHNOLOGY
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2024
·Vol. 108
·期 1
·1-11
·
IF 3.9
Li Na,Wang Yuan,Meng Yinyin,Lv Yangyong,Zhang Shuaibing,Wei Shan,Ma Pingan,Hu Yuansen,Lin Hui
Abstract Old yellow enzymes (OYEs) have been proven as powerful biocatalysts for the asymmetric reduction of activated alkenes. Fungi appear to be valuable sources of OYEs, but most of the fungal OYEs are unexplored. To expand the OYEs toolbox, a new thermophilic-like OYE ( Af OYE1) was identified from Aspergillus flavus strain NRRL3357. The thermal stability analysis showed that the T 1/2 of Af OYE1 was 60 °C, and it had the optimal temperature at 45 °C. Moreover, Af OYE1 exhibited high reduction activity in a wide pH range (pH 5.5–8.0). Af OYE1 could accept cyclic enones, acrylamide, nitroalkenes, and α, β-unsaturated aldehydes as substrates and had excellent enantioselectivity toward prochiral alkenes (> 99% ee). Interestingly, an unexpected ( S )-stereoselectivity bioreduction toward 2-methylcyclohexenone was observed. The further crystal structure of Af OYE1 revealed that the “cap” region from Ala132 to Thr182, the loop of Ser316 to Gly325, α short helix of Arg371 to Gln375, and the C-terminal “finger” structure endow the catalytic cavity of Af OYE1 quite deep and narrow, and flavin mononucleotide (FMN) heavily buried at the bottom of the active site tunnel. Furthermore, the catalytic mechanism of Af OYE1 was also investigated, and the results confirmed that the residues His211, His214, and Tyr216 compose its catalytic triad. This newly identified thermophilic-like OYE would thus be valuable for asymmetric alkene hydrogenation in industrial processes. Key points
A new thermophilic-like OYE AfOYE1 was identified from Aspergillus flavus, and the T 1/2 of AfOYE1 was 60 °C
AfOYE1 catalyzed the reduction of 2-methylcyclohexenone with (S)-stereoselectivity
The crystal structure of AfOYE1 was revealedv
研究领域:
生物化学
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工业酶学
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结构生物学
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JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY
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2022
·
IF 5.895
Xiancai Li,Liyuan Yao,Binghong Xiong,Yaodan Wu,Shaohua Chen,Zhifang Xu,Sheng-Xiang Qiu
Control of Aspergillus flavus is beneficial for the agricultural economy and food safety. Stilbenes exhibit antifungal properties through an unknown mechanism. Here, six stilbenes isolated from Cajanus cajan were screened for anti-A. flavus activity. Among them, pinosylvin monomethyl ether (PME) showed the strongest anti-A. flavus activity and has a broad antifungal spectrum with negligible hemolysis within the concentration range measured. PME inhibited the spore germination of A. flavus and the accumulation of aflatoxin B1. Mechanistic studies showed that PME could bind the cell membrane phospholipids, resulting in increased permeability and decreased fluidity. Further metabolic analysis showed that PME caused the lysis of cell membranes and subsequent collapse of spores, which resulted in a cell wall autolysis-like phenotype. Structure–activity relationship analysis revealed the importance of maintaining amphiphilicity harmony by substituent groups for the antifungal activity of stilbenes. Together, natural stilbenes are promising antifungal lead compounds worthy of further exploration and research for potential application in the food, pharmaceutical, and agricultural industries.
研究领域:
微生物学
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药理学
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农业科学
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食品科学
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植物科学
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INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
·
2024
·
IF 7.7
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.
研究领域:
食品科学
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微生物学
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BIOPROCESS AND BIOSYSTEMS ENGINEERING
·
2018
·Vol. 41
·期 4
·511-518
·
IF 2.139
Ning Cheng,Qingyun Li,Aixing Tang,Wei Su,Youyan Liu
Aspergillus flavus : fungal strain A5p1 is reported here to decolorize a variety of dyes under broad environmental conditions. For the 15 dyes tested, the decolorization efficiencies ranged from 61.7 to 100.0% at an initial concentration of 100 mg/L. Direct Blue 71 (DB71), Direct Blue 86 (DB86), and Reactive Blue 19 (RB19) were selected as models for comparing decolorization performance. The results show that biosorption and biodegradation work together in the strain to remove the pigments; the effect of biosorption was stronger for DB71 and DB86, whereas the effect of biodegradation was stronger for RB19. For DB71 and DB86, the decolorization rate surpassed 90% with inactivated biomass under acidic conditions and with living biomass under alkaline conditions. DB19 achieved the highest removal rate of 90% under neutral conditions. The strain could effectively decolorize high concentrations of dyes up to 1000 mg/L, which was achieved mainly via biosorption at concentrations below 500 mg/L and via biodegradation at concentrations above 500 mg/L. The findings suggest that A5p1 has a strong adaptability to different dye types and environmental conditions and can, therefore, be potentially used in biological processes for the treatment of dye-containing wastewater.
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JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY
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2024
·
IF 5.7
Jing Liu,Hao Chen,Yan Lv,Huixiang Wu,Li-jun Yang,Jiahui Zhang,Jianying Huang,Wenjie Wang
Aspergillus flavus contamination in agriculture and food industries poses threats to human health, leading to a requirement of a safe and effective method to control fungal contamination. Chitosan-based nitrogen-containing derivatives have attracted much attention due to their safety and enhanced antimicrobial applications. Herein, a new benzimidazole-grafted chitosan (BAC) was synthesized by linking the chitosan (CS) with a simple benzimidazole compound, 2-benzimidazolepropionic acid (BA). The characterization of BAC was confirmed by Fourier transform infrared (FTIR) spectroscopy and nuclear magnetic resonance spectroscopy (1H and 13C NMR). Then, the efficiency of BAC against A. flavus ACCC 32656 was investigated in terms of spore germination, mycelial growth, and aflatoxin production. BAC showed a much better antifungal effect than CS and BA. The minimum inhibitory concentration (MIC) value was 1.25 mg/mL for BAC, while the highest solubility of CS (16.0 mg/mL) or BA (4.0 mg/mL) could not completely inhibit the growth of A. flavus. Furthermore, results showed that BAC inhibited spore germination and elongation by affecting ergosterol biosynthesis and the cell membrane integrity, leading to the permeabilization of the plasma membrane and leakage of intracellular content. The production of aflatoxin was also inhibited when treated with BAC. These findings indicate that benzimidazole-derived natural CS has the potential to be used as an ideal antifungal agent for food preservation.
研究领域:
材料科学
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微生物学
·
食品科学
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LWT-FOOD SCIENCE AND TECHNOLOGY
·
2024
·
IF 6
Yanli Xin,Wei Zhang,Yang Lei,Shan Wei,Shuaibing Zhang,Na Li,Yuansen Hu,Yangyong Lv
The inhibition of fungal contamination of food by natural plant essential oils is receiving widespread attention. In this study, 1 μL/mL p -anisaldehyde showed remarkable antifungal ability against Aspergillus flavus spore germination and mycelium growth. Experiments of peanut seeds infection showed that 4 μL/mL p -anisaldehyde inhibited the development of A. flavus spores on peanuts by 95.5% and the production of aflatoxin B1 production by 69.4%. Transcriptome analysis suggested that differentially expressed genes were primarily associated with spore growth, cell wall, cell membrane, oxidative stress, and energy metabolism. Physiological and biochemical experiments as well as scanning electron microscopy, fluorescence staining, and enzyme activity assay, further confirmed that p -anisaldehyde destroyed the cell wall, permeability, and ergosterol biosynthesis of the cell membrane and led to decreased mitochondrial membrane potential and accumulated reactive oxygen species. This study provided new knowledge on the antifungal activity of p -anisaldehyde and its mechanism of action, as well as theoretical support for p -anisaldehyde as a possible antifungal agent for the control of A. flavus contamination of food crops.
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JOURNAL OF FOOD QUALITY
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2020
·
IF 1.763
Shiqi Xia,Hong Lin,Peilin Zhu,Peiling Wang,Shengliang Liao,Shangxing Chen,Zongde Wang,Guorong Fan
Aspergillus flavus (A. flavus) is a frequent harmful fungal pathogen. It can infect traditional Chinese medicine materials and release aflatoxin, to cause both economic and human health effects. By comparing the inhibitory potential of Litsea cubeba oil and its active components to A. flavus CGMCC 3.4408, citral was confirmed to be the main component that inhibits the growth of A. flavus CGMCC 3.4408, and the EC50 was 163.65 mg L−1. The inhibitory effect of citral on A. flavus CGMCC 3.4408 was studied for colony growth rate, mycelium biomass, aflatoxin production, and microstructure. Citral slowed down the growth rate of colonies and reduced mycelium biomass and toxin production. Moreover, citral altered the morphology of fungal spores and mycelium. In addition, citral also has the inhibitory effects on the isolates of A. flavus from moldy traditional Chinese medicinal materials. Thus, citral can be used as a potential agent to check the growth of A. flavus or related fungal strains.
研究领域:
微生物学
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药理学
·
食品科学
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TheScientificWorldJOURNAL
·
2013
·
IF 1.73
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.
研究领域:
微生物学
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食品安全
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植物化学
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JOURNAL OF BASIC MICROBIOLOGY
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2022
·Vol. 62
·期 12
·1457-1466
·
IF 2.65
Minghua Li,Binbin Yao,Xiumei Meng
Phenyllactic acid (PLA) has gained a lot of attention due to its broad antimicrobial activity, but the mechanism of its antifungal action has been barely reported until now. Herein, the inhibitory activity of PLA against Aspergillus flavus spore germination and its mechanism were preliminarily investigated. Results indicated that PLA had a strong antifungal activity against A. flavus with the minimal inhibitory concentration (MIC) and minimal fungicidal concentration (MFC) of 6 and 12 mg/ml, respectively. As observed by scanning electron microscopy (SEM), the A. flavus spores displayed wrinkled and shrunken appearance after treatment with PLA. In addition, the permeability and integrity of A. flavus cell membrane were changed obviously after PLA treatment as indicated by the propidium iodide (PI) staining results, which was further confirmed by a rise in electric conductivity and increased leakage of intracellular protein and nucleic acid. Furthermore, reduced activities of mitochondrial ATPase and dehydrogenases caused by PLA were also observed in A. flavus spores, with a result of remarkable decrease in ATP synthesis. Therefore, it could be concluded that PLA was effective in inhibiting spore germination of A. flavus mainly by disrupting cell membrane and interfering with mitochondrial energy metabolism.
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Iranian Journal of Biotechnology
·
2020
·
IF 0.973
Shuang Feng Li,Huai Wang,Jia Li Chen,Hui Xia Zhu,Ri-Sheng Yao,Huan Wu
Background: Lignin is the largest natural aromatic polymer in nature and is also a unique aromatic-based biopolymer, accountingfor nearly 30% of the earth’s organic carbon. Generally, lignin is regarded as waste and is mainly used as a low- valuefuel that is burned to generate heat and energy to solve the problem of biomass waste; for this obstacle of lignin,highly efficient biodegradation plays a critical role in developing an environmentally friendly technique for lignin biotransformation. Objectives: This study intends to isolate and purify several microbial strains from nature. It also explores how their lignin degradationis able to enhance the biodegradation and recycling of biomass and the reclamation of lignin in wastewater from pulp and paper mills. Materials and Methods: Lignin-degrading microbial strains were isolated from soil using medium containing sodium lignosulphonate as the sole carbonsource. They were then screened by aniline blue and guaiacol plate, and then the best strain was chosen and identified.The conventional one-factor method was used to optimize various parameters that affect lignin’s degradation ability. Results: The strain possessing the highest lignin biodegradation ability was identified and denominated as Aspergillus Flavus F-1. After optimization, the maximum degradation rate of lignin, 44.6% within 3 days, was obtained at pH 7.0, 30 ℃, 2.5 g·L -1 ammoniumsulfate, 2 g·L -1 lignin and 0.5 g·L -1 glucose. The results show the LiP and Lac secreted from Aspergillus Flavus F-1 played the main role in the degradation of lignin. Conclusion: One microbial strain, Aspergillus Flavus F-1, was successfully isolated with a lignin-degrading abilitythat can cut the lignin into fragments. This provides a promising candidate for the transformation and utilization of crop waste biomass for various industrial purposes.
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RSC Advances
·
2017
·Vol. 7
·期 37
·23021-23026
·
IF 3.108
Jing Zhao,Ling Wang,Dan Xu,Zhisong Lu
Silver nanoparticles (AgNPs) have been extensively studied as antimicrobial materials, but their capability of suppressing aflatoxin production has not been investigated. In this work, AgNPs with an average size of 4.5 nm were synthesized to inhibit the growth of Aspergillus flavus (A. flavus). Based on the anti-fungal assay, the concentration of 5 μg mL−1 was chosen to study the direct inhibiting effects of AgNPs on aflatoxin production. Results show that AgNP treatment could significantly decrease secretion of aflatoxin B1 from A. flavus. Real-time measurements of O2− with an electrochemical sensor reveal that the AgNPs could trigger the release of O2− from fungal mycelia. A mechanism involving O2− release is proposed to explain AgNP-caused depression of aflatoxin production from A. flavus. This is the first attempt to study AgNP-induced inhibition on aflatoxin generation and its possible mechanisms.
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Foods
·
2025
·Vol. 14
·期 4
·682
·
IF 5.1
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.
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