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Fusarium moniliforme (F. moniliforme) and its secondary metabolite fumonisin pose a severe threat to food safety, and searching for effective antimicrobial agents is a focus of current research. In this study, the secondary structure of Sub3 was analyzed by circular dichroism, meanwhile, the inhibition rate of Sub3 against F. moniliforme infection of maize was studied. To explore the possible inhibition mechanisms, morphological and structural changes of spores treated with Sub3 at 0, 1/2MIC and MIC were observed by scanning electron microscopy and transmission electron microscopy; the cell wall integrity, membrane integrity, reactive oxygen species, mitochondrial membrane potential, ATP synthase activity, redox reactions, and the nuclear damage of F. moniliforme were also investigated. The results showed that Sub3 was mostly in the state of random in deionized water, while mainly showed the β-sheet structure in the hydrophobic environment of 50% TFE solution, indicating that Sub3 might generate partial structure deformation when acting on the cell membrane; and its minimum inhibitory concentration (MIC) on F. moniliforme spores was 0.2 g/L. Under the 1/2MIC and MIC, the inhibition rates of Sub3 against F. moniliforme infected maize were 34.3% and 75.6%, respectively. The results of inhibition mechanisms revealed that the defective pathogenicity of F. moniliforme caused by Sub3 was attributed to damages on both the cell wall and the cell membrane, which might upset balance of intracellular redox system and mitochondrial energy metabolism and trigger nucleus damage, ultimately leading to cell death. The results provided direct evidence for inhibition of F. moniliforme infection of maize by Sub3, and useful knowledge applicable for food preservation.

Chemical control of fungal spoilage of postharvest cereal grains is an important strategy for the management of grain storage. Here, the potential antifungal activity of 1-nonanol, a main component of cereal volatiles, against Aspergillus flavus was studied. The growth of A. flavus was completely inhibited by 0.11 and 0.20 μL/mL 1-nonanol at vapor and liquid contact phases, respectively. Metabolomic analysis identified 135 metabolites whose expression was significantly different between 1-nonanol-treated and untreated A. flavus. These metabolites were involved in the tricarboxylic acid cycle, amino acid biosynthesis, protein degradation and absorption, aminoacyl-tRNA biosynthesis, mineral absorption, and in interactions with ABC transporters. Biochemical validation confirmed the disruptive effect of 1-nonanol on A. flavus growth, as indicated by the leakage of intracellular electrolytes, decreased succinate dehydrogenase, mitochondrial dehydrogenase, and ATPase activity, and the accumulation of reactive oxygen species. We speculated that 1-nonanol could disrupt cell membrane integrity and mitochondrial function and might induce apoptosis of A. flavus mycelia. Simulated grain storage experiments showed that 1-nonanol vapor, at a concentration of 264 μL/L, completely inhibited A. flavus growth in wheat, corn, and paddy grain with an 18% moisture content. This study provides new insights into the antifungal mechanism of 1-nonanol against A. flavus, indicating that it has a promising potential as a bio-preservative to prevent fungal spoilage of postharvest grains. KEY POINTS: • 1-Nonanol showed higher antifungal activity against A. flavus. • The antifungal mechanisms of 1-nonanol against A. flavus were revealed. • 1-Nonanol could damage cell membrane integrity and mitochondrial function.

Hexanal, a natural volatile organic compound, exerts antifungal activity against Aspergillus flavus; however, the mechanisms underlying these effects are unclear. In this study, we found that the growth of A. flavus mycelium was completely inhibited following exposure to 0.4 μL/mL hexanal (minimal inhibitory concentration). A detailed metabolomics survey was performed to identify changes in metabolite production by A. flavus cells after exposure to 1/2 the minimal inhibitory concentration of hexanal for 6 h, which revealed significant differences in 70 metabolites, including 20 upregulated and 50 downregulated metabolites. Among them, levels of L-malic acid, α-linolenic acid, phosphatidylcholine, D-ribose, riboflavin, D-mannitol, D-sorbitol, and deoxyinosine were significantly reduced. The metabolomics results suggest that the metabolites are mainly involved in the tricarboxylic acid cycle (TCA), ABC transport system, and membrane synthesis in A. flavus cells. Hexanal treatment reduced succinate dehydrogenase and mitochondrial dehydrogenase activity and stimulated superoxide anion and hydrogen peroxide accumulation in A. flavus mycelia. Increases in the electric conductivity and A260nm of the culture supernatant indicated cell membrane leakage. Therefore, hexanal appears to disrupt cell membrane synthesis, induce mitochondrial dysfunction, and increase oxidative stress in A. flavus mycelia. KEY POINTS: • Metabolite changes of A. flavus mycelia were identified after hexanal treatment. • Most differential metabolites were downregulated in hexanal-treated A. flavus. • An antifungal model of hexanal against A. flavus was proposed.

The prevention of fungal spoilage is an essential consideration in wheat storage. Recent studies have revealed that volatile organic compounds (VOCs), possibly with natural fungicidal properties, could be produced from stored wheat grains. In this study, the antifungal effect of hexanal, a main component of VOCs from stored wheat, against spoilage fungi on agar plate and in high-moisture wheat grains were investigated via the gas fumigation method. And the impact of hexanal fumigation on grain quality was evaluated through analysis of the malondialdehyde content, fatty acid values, germination percentages and vigor of 16% and 18% moisture wheat grains fumigated with 1.66, 2.49, and 3.31 mmol/L hexanal vapor. The results of in vitro antifungal experiments on agar plates revealed that the minimum inhibitory concentration and minimum fungicidal (fatal) concentration of hexanal against the five fungi were 4–14 folds and 4–7 folds lower than those of propionic acid, respectively. The fungal spoilage of high-moisture wheat grains inoculated with pure fungal spores and with naturally occurring fungi could be completely inhibited by 1.66 mmol/L hexanal vapor. During 5-week storage of high-moisture wheat grains fumigated with 1.66, 2.49, and 3.31 mmol/L hexanal vapor, the malondialdehyde content in high-moisture wheat grains did not change significantly in all samples, and fatty acid values were slightly higher in 18% moisture wheat than in 16% moisture wheat. The germination percentages and vigor of wheat samples decreased with increased hexanal vapor concentrations and moisture content. These results indicated that hexanal fumigation could be used as an alternative chemical control method to prevent the fungal spoilage of postharvest wheat.

Plant-derived substances as antifungal agents have received considerable attention in recent years to reduce the use of chemical fungicides in food preservatives. In this study, honokiol, a type of phenolic compound in Magnolia officinalis, was found to inhibit spore germination and mycelia growth of Aspergillus flavus at 100 μg/mL. In addition, a pathogenicity assay showed that honokiol had potent antifungal activity against A. flavus in corn flour by suppressing conidia production. Fluorescence staining, transmission electron microscopy and biochemical assays were performed to explore its possible inhibition mechanisms against A. flavus. The results showed that the destructive effect of honokiol on A. flavus appeared to be related to increased plasma membrane permeability, the inhibition of ATPase activity, mitochondrial dysfunction and the accumulation of reactive oxygen species. Furthermore, a transcriptomic analysis showed that honokiol treatment resulted in 1578 different expressed genes. Gen Ontology and Kyoto Encyclopedia of Genes and Genomes analysis revealed that some genes of A. flavus related to spore development, integrity of the cell wall and membrane, oxidative stress and energy metabolism were significantly downregulated. In addition, RNA-seq results were validated by quantitative real-time polymerase chain reactions. Our finding enhanced the understanding of the antifungal activity of honokiol and underlying mechanisms of action at the molecular level, supporting honokiol as a potential agent in preventing contamination by A. flavus.

Single-walled carbon nanotubes (SWCNTs) have attracted great interest regarding drug-delivery applications. However, their application has been limited by some inherent disadvantages. In this study, raw SWCNTs were purified with different oxidizing acids, and the resulting shortened CNTs were conjugated with poly(ethylene glycol) (PEG) and polyethylenimine (PEI). The different nanocarriers, that is, CNTs-COOH (CNTs), CNTs-PEG and CNTs-PEG-PEI, were systematically characterized and evaluated in terms of drug loading, in vitro release, cytotoxicity towards MCF-7 cells and cellular uptake. The results showed that all CNT carriers had a high drug loading capacity. In comparison with CNTs-COOH and CNTs-PEG, CNTs-PEG-PEI showed a more rapid drug release under acidic conditions and a higher antitumor activity. Furthermore, fluorescence detection and flow cytometry (FCM) analysis results indicated that the internalization into cells of CNTs-PEG-PEI was significantly enhanced, thus inducing tumor cell death through apoptosis more efficiently. The above series of benefits of CNTs-PEG-PEI may be attributed to their good dispersibility and comparably higher affinity to tumor cells due to the difunctionalization. In summary, the PEG- and PEI-conjugated CNTs may be used as novel nanocarriers and the findings will contribute to the rational design of multifunctional delivery vehicles for anticancer drugs.

Thermosensitive liposome-based drug delivery systems (DDS) are powerful tools for site-specific delivery of chemotherapeutics, especially when combined with regional hyperthermia. The objective of this work was to develop a novel thermosensitive liposomal DDS loaded with lomustine, a chemotherapeutic compound, and iohexol, a contrast medium for visualization by CT. Thermosensitive compound liposomes (TSCLs) composed of DPPC were prepared by reverse-phase evaporation and investigated for encapsulation efficiency, temperature-sensitivity, release kinetics, and In Vivo pharmacokinetics. The size and zeta-potential of TSCLs ranged from 250 to 300 nm and −15 to −30 mV, respectively. At 41 °C, TSCLs were shown to release over 90% of iohexol and lomustine within 4 h. The in vitro release profiles of iohexol and lomustine at 41 °C conformed to first-order kinetics and Weibullmodel, respectively. Phase-transition did not occur after incorporation of cholesterol and soybean phospholipids. In Vivo evaluation performed with C6 glioma model rats proved the prolonged half-lives and improved bioavailability by liposomal encapsulation for both compounds under mild local hyperthermia. The TSCLs used in this study may offer a clinically promising mean of increasing efficacy and controlling toxicity.

Aspergillus flavus contaminates crops and produces carcinogenic aflatoxins that pose severe threat to food safety and human health. To identify potential targets to control aflatoxin contamination, we characterized a novel Afper1 protein, which regulates cell development and secondary metabolite biosynthesis in A. flavus. Afper1 is localized in the nucleus and is required for hyphal growth, conidial and sclerotial production, and responses to osmotic stress and essential oils such as cinnamaldehyde and thymol. More importantly, aflatoxin production was impaired in the Afper1 deletion mutant. Proteomics analysis revealed that extracellular hydrolases and proteins involved in conidial development, endoplasmic reticulum (ER) homeostasis, and aflatoxin biosynthesis were differentially regulated in ΔAfper1. Unexpectedly, enzymes participated in reactive oxygen species (ROS) scavenging, including catalase (catA, catB) and superoxide dismutase (sodM) were significantly downregulated, and the ROS accumulation and sensitivity to hydrogen peroxide were confirmed experimentally. Additionally, Afper1 deletion significantly upregulated heterochromatin protein HepA and downregulated acetyltransferases involved in heterochromatin formation. Accompanying ROS accumulation and chromatin remodeling, proteins related to aflatoxins, ustiloxin B and gliotoxin were downregulated. These results implied that Afper1 deletion affected chromatin remodeling and disturbed ER homeostasis, leading to ROS accumulation, and ultimately resulting in defective growth and impaired secondary metabolite biosynthesis.

Lysine 2-hydroxyisobutyrylation (K

Endo-1,4-β-mannosidases catalyze the cleavage of the β-d-1,4-mannopyranosyl linkage in mannan and have potential biotechnological applications in biofuel production, manno-oligosaccharide production, cleansing, and food and feed industries. In this study, an endo-1,4-β-mannosidase gene (TaMan3A) from wheat (Triticum aestivum) was successfully expressed in Pichia pastoris, and the antifungal effectiveness and manno-oligosaccharide production of the enzyme were evaluated. The purified TaMan3A exhibited a molecular weight of approximately 43 kDa, and its highest enzyme activity at pH 4.0 and 40 °C. Comparisons with other β-mannanases showed that TaMan3A had a conserved mannan-binding V-shaped groove, catalytic acid/base residue (E179), and nucleophilic residue (E297). Antifungal assays for TaMan3A against seven fungi commonly associated with wheat kernels showed that this enzyme had higher inhibitory effects on hyphal growth of the field fungi Fusarium graminearum and Alternaria sp. in comparison with that of storage fungi. TaMan3A could hydrolyze mannan polymers of galactomannan and Konjac glucomannan to mannobiose, mannotriose, and mannotetraose as the main products. Overall, these results showed the potential of TaMan3A for enhancing host resistance against fungal pathogens in wheat and manno-oligosaccharide production in the feed and food industries.

Aspergillus flavus infection is a major issue for safe food storage. In this study, we constructed an efficient prokaryotic expression system for puroindoline B (PINB) protein to detect its antifungal activity. The Puroindoline b gene was cloned into pET-28a (+) vector and expressed in Escherichia coli. Treatment with fusion PINB revealed that it inhibits mycelial growth of A. flavus, a common grain mold. Moreover, fusion PINB-treated A. flavus mycelium withered and exhibited a sunken spore head. As fusion PINB concentration increased, electrical conductivity in mycelium also increased, indicative of cell membrane damage. Furthermore, intracellular malate dehydrogenase and succinate dehydrogenase activity decreased, revealing a disruption in the tricarboxylic acid cycle. Moreover, the dampened activity of the ion pump Na+K+-ATPase negatively affected the intracellular regulation of both ions. Catalase and superoxide dismutase activity decreased, thus reducing antioxidant capacity, a result confirmed with an increase in malondialdehyde content. Changes to the GSH/GSSG ratio indicated a shift to an intracellular oxidative state. At the same time, laser scanning confocal microscopy assay showed the accumulation of reactive oxygen species and nuclear damage. Therefore, the PINB fusion protein may have the potential to control A. flavus in grain storage and food preservation.

Surfactin is a promising microbial lipopeptide with wide applications in food, environmental, agricultural, and pharmaceutical fields. However, its high cost caused by low productivity largely limits the commercial application. In this study, genome shuffling was employed to improve surfactin production in Bacillus velezensis strain LM3403 via recursive protoplast fusion. RT-qPCR analysis was employed to evaluate the transcriptional variance of surfactin synthase genes and surfactin efflux gene to insight into the variance underlying the recombinant strain. After three rounds of genome shuffling, a high-yield and genetic stable recombinant F34 was obtained, exhibiting dramatic improvement in surfactin production (from 229.60 ± 7.10 mg/L to 908.15 ± 5.65 mg/L) with high proportion of long carbon chain homologues. Scale-up fermentation confirmed that F34 had good growth performance and reached the yield of 917.05 ± 10.25 mg/L in a 30 L fermenter, which was 3.99-fold that of the initial strain. RT-qPCR analysis showed that the transcriptional levels of surfactin synthase genes srfAA and sfp, and surfactin efflux gene swrC in F34 were 8.12-fold, 9.27-fold, and 8.45-fold higher than those of LM3403, respectively. The upregulation of genes were consistent with the high surfactin yield in F34, indicating the increased capability of surfactin biosynthesis and transmember efflux in F34. To our knowledge, this is the first attempt to employ genome shuffling to breeding a B. velezensis strain to improve surfactin yield. The research helps us to understand the mechanisms underlying surfactin overproduction and provide references for further rational strain improvement.

Aspergillus flavus is a notorious saprophytic fungus that compromises the quantity and quality of postharvest grains and produces carcinogenic aflatoxins. The natural compound hexanal disrupts cell membrane synthesis and mitochondrial function and induces apoptosis in A. flavus; here, we investigated the molecular mechanisms underlying these effects. The minimum inhibition and fungicidal concentration (MIC and MFC) of hexanal against A. flavus spores were 3.2 and 9.6 μL/mL, respectively. Hexanal exposure resulted in abnormal spore morphology and early spore apoptosis. These changes were accompanied by increased reactive oxygen species production, reduced mitochondrial membrane potential, and DNA fragmentation. Transcriptomic analysis revealed that hexanal treatment greatly altered the metabolism of A. flavus spores, including membrane permeability, mitochondrial function, energy metabolism, DNA replication, oxidative stress, and autophagy. This study provides novel insights into the mechanism underlying the antifungal activity of hexanal, suggesting that hexanal can be used an anti-A. flavus agent for agricultural applications. • Hexanal exposure resulted in abnormal spore morphology. • The apoptotic characteristics of A. flavus were induced after hexanal treatment. • Hexanal could change the expression of key A. flavus growth-related genes.

Mesoporous silica nanoparticles (MSNs) and liposomes are inorganic and organic nano-vehicles that are widely used for drug delivery, respectively, however, their application as drug carriers have been limited by some of their inherent defects. In this study, mesoporous silica nanoparticle-supported lipid bilayers (LMSNs) were developed with doxorubicin (DOX) used as the model drug to be loaded. The different nanocarriers, including MSNs, amino-modified MSNs (MSNs-NH2 and MSNs-PEI), as well as LMSNs were systematically characterized and evaluated comparatively in terms of in vitro release, cytotoxicity towards MCF-7 cells, cellular internalization and cellular uptake mechanism. The results indicated that LMSNs had the more effective drug encapsulation, and various nanocarriers exhibited a pH-responsive release feature and the coverage of the lipid bilayer would retard the release of DOX to reach the sustained release effect. Facilitated by the lipid membrane affinity and improved stability supplied by PEGylated lipids, in comparison with both the bare and amino-modified MSNs, the internalization efficiency into cells and cytotoxicity of LMSNs was significantly enhanced. Further study results of the cellular uptake mechanism supported that LMSNs could be internalizated by cells through caveolae mediated endocytosis and macropinocytosis pathway, and these more efficient uptake pathway was probably the important cause for their higher cell internalization and delivery capacity. In summary, the LMSNs were the potent nanocarriers with promising properties and the findings will contribute to the rational design of multifunctional nano-drug carriers for efficient delivery and therapy.

Polysaccharide produced from medicinal endophytic fungus not only has applications in foods, but also exhibits multiple biological activities. In this work, an endophytic fungus Chaetomium globosum CGMCC 6882 could use corn stover to produce a polysaccharide (GCP-SC) by consolidated bioprocess and the titer of GCP-SC reached 3.2 g/L. The transcriptional levels of genes related to cellulose degradation (cbh, cdh, glu and egl) in C. globosum CGMCC 6882 were 4.38, 3.85, 3.13, and 2.17 folds compared to the control group when corn stover was used as the sole carbon source. Moreover, GCP-SC showed a time- and dose-dependent manner of inhibitory effect on A549 cells and the inhibitory rate reached 93.3%. This work provides meaningful data on agricultural residues utilization and facilitation of future relative resource conversion studies. Keywords: Corn stover, Chaetomium globosum CGMCC 6882, Polysaccharide

The quality of wheat deteriorates naturally during long-term storage. In this study, to evaluate the quality changes of stored wheat, an artificial aging treatment was applied to accelerate the deterioration of wheat grain. The germination rate, free fatty acid content, malondialdehyde (MDA) content, and embryo and endosperm microstructures were examined in the wheat cultivars Zhengmai-103 and Zhengmai-379. In both wheat cultivars, seed germination almost completely ceased during storage for 10 months, whereas the contents of free fatty acids and MDA increased significantly. The variance analysis results showed that the accelerated deterioration process had significant effects on the free fatty acid, MDA, and superoxide radical contents. Further, the storage time was well correlated with the germination rate, free fatty acid content, and MDA content, and there was significant correlation between the free fatty acid and MDA contents (p

In Aspergillus flavus, laeA affects cell morphology and contributes to the production of secondary metabolites (SMs) production including aflatoxin, cyclopiazonic acid, and aflatrem. Here, we investigated the function of this transcription factor by performing proteomics analysis of the wild-type (WT) and ΔlaeA mutant growing on corn. Notably, our proteomics profile confirmed the functions of extracellular hydrolases, conidial hydrophobin, and response to oxidative stress during the induction of aflatoxin biosynthesis regulated by laeA. Unexpectedly, deletion of laeA resulted in the significant upregulation of the NAD+-dependent histone deacetylase sirA involved in silencing SM clusters via chromatin remodeling. Accompanying the chromatin modification, enzymes participating in SM, including aflatoxin and cyclopiazonic acid biosynthesis, were drastically decreased. Another unexpected finding was that enzymes in the recently identified ustiloxin B biosynthesis pathway might be regulated by laeA. These data provided novel insights into the complex regulation of laeA and suggested a potential link between laeA deletion, NAD+-dependent histone deacetylation, and SM production in A. flavus.

A facile and reproducible method was proposed to synthesize ZnO nano-cages (ZNC) using zeolitic imidazolate framework-8 (ZIF-8) as precursor. The ZNCs were in situ formed taking advantage of the uniform shape of the ZIF-8. The shape, size, crystal structure and composition of the ZNCs were confirmed with scanning/transmission electron microscope, X-ray diffraction, and X-ray photoelectron spectroscopy, which indicates the structural qualities of the ZNCs is highly sensitive to the conversion heating process. In addition, based on the microplate alamar blue assay technique, the ZNC-400 shows the optimized effects on inhibiting the growth of M. tuberculosis. The minimum inhibitory concentration could be measured as 12.5 μg/mL, which is similar with the effect of the commercial organic medicines, indicating the novel ZNC has great potential to function as positive candidate for the organic medicines to combat tuberculosis disease.

Fungal contamination poses a threat to agriculture, food production and human health, and a safe and effective method to limit fungal contamination is still needed. In this study, the inhibitory potency of heptanal, a natural volatile chemical, against Aspergillus flavus growth was evaluated, and its mechanism of action was explored. The minimum inhibitory concentrations (MICs) of heptanal vapor fumigation and liquid contact culture were 0.085 and 0.8 μL/mL, respectively. A total of 79 significant differentially abundant metabolites, including 37 upregulated and 42 downregulated ones, were identified in A. flavus mycelia after exposure to 0.8 μL/mL heptanal for 6 h. Metabolomics analysis revealed that heptanal had destructive effects on plasma integrity and mitochondrial function in mycelia. Biochemical analysis confirmed that heptanal caused intracellular substance leakage and resulted in reduced intracellular ATP content, reactive oxygen species (ROS) accumulation, and lower mitochondrial dehydrogenase and ATPase activities. Evaluation of the control efficacy of heptanal fumigation on wheat grain under simulated storage conditions revealed that 225.0 μL/L heptanal vapor could inhibit A. flavus growth under 19% moisture. These results provide insights into the antifungal mechanism of heptanal against A. flavus growth as a promising bio-preservative.

Thermosensitive liposome-based drug delivery systems (DDS) are powerful tools for site-specific delivery of chemotherapeutics, especially when combined with regional hyperthermia. The objective of this work was to develop a novel thermosensitive liposomal DDS loaded with lomustine, a chemotherapeutic compound, and iohexol, a contrast medium for visualization by CT. Thermosensitive compound liposomes (TSCLs) composed of DPPC were prepared by reverse-phase evaporation and investigated for encapsulation efficiency, temperature-sensitivity, release kinetics, and

Background Aspergillus flavus, a saprophytic fungus, is regularly detected in oil-enriched seeds. During colonization, this organism releases aflatoxins that pose a serious risk to food safety and human health. Therefore, an eco-friendly biological approach to inhibit the pathogen is desirable. Results Experimental results indicated that A. flavus spores could not germinate in potato dextrose broth culture medium, when the concentration of Sub3 exceeded 0.15 g L-1 . Morphological evaluation performed by flow cytometry and scanning electron microscopy indicated that spores were shrunken and pitted following Sub3 exposure. Physiological assessment using propidium iodide, 5,5',6,6'-tetrachloro-1,1',3,3'-tetraethylbenzimidazolocarbocyanine iodide, 2,7-dichlorodihydrofluorescein diacetate and 4',6-diamidino-2-phenylindole staining revealed damaged cell membranes, decreased mitochondrial membrane potential, increased intracellular reactive oxygen species levels, and elevated large nuclear condensation and DNA fragmentation. Moreover, mitochondrial dehydrogenase activity was reduced by 29.42% and 45.48% after treatment with 0.1 and 0.15 g L-1 Sub3, respectively. Additionally, colonization capacity in peanut was significantly decreased, and the number of spores on seeds treated with Sub3 was decreased by 26.86% (0.1 g L-1 ) and 77.74% (0.15 g L-1 ) compared with the control group. Conclusion Sub3 likely inhibits A. flavus by crossing the cell wall and targeting the cell membrane, disrupting mitochondrial energy metabolism, and inducing DNA damage, leading to spore death. Thus, Sub3 may provide a useful biocontrol strategy to control A. flavus growth in peanuts. © 2020 Society of Chemical Industry.

Quorum sensing (QS) is of crucial importance for the formation and performance of biofilms adhered to aerated membranes. In this study, the QS-related genes in membrane-aerated biofilm reactors (MABR) for phenolic wastewater treatment were investigated through high-throughput metagenomic sequencing. Results showed that numerous regulatory QS-related genes were associated with the production of signals including acyl-homoserine lactones (AHLs) and diguanylate monophosphate (c-di-GMP), indicating that the biofilms were potentially regulated by the AHL-mediated QS and c-di-GMP-mediated QS systems. Species and functional contribution analysis demonstrated that Pseudomonas, Achromobacter, Rhodococcus, Granulicoccus and Thauera were the key QS-related gene carriers. Redundancy analysis and Spearman correlation analysis showed that high influent phenolic loading gave rise to a high relative abundance of QS bacteria within the biofilm community. Thus, QS-related genes likely play an important role in strengthening biofilm resistance to phenolics, as well as the removal of phenolic contaminants.

Ultra-thin hydrogenated black TiO2 sheets with rich surface disorders were prepared by a facile hydrogenation of submicrometer sized TiO2 sheets. Due to the reduced band gap of 2.81 eV, the light harvesting ability of black TiO2 sheets is enhanced in the visible range. In addition, the rich surface disorder reduces the primary particle-size and increases the surface area from 20.9 to 46.2 m2g-1, which enhances the population of active catalytic sites and substantially improves the photocatalytic activities both under visible light and full spectrum solar light. The mechanism tests indicate the black TiO2 sheets triggered photodegradation is a hole mediated process. Moreover, the catalyst shows long-term stability, which permits its potential application in the real waste water treatment.

Aspergillus flavus contamination is of great concern to food safety. Our previous studies demonstrated that recombinant Puroindoline B protein (rPINB) has an inhibitory effect on A. flavus mycelium development. However, fungal contamination often begins with spore germination within food shelf life. Here, rPINB was evaluated for its antifungal properties against A. flavus spores in vivo and in vitro. The results showed that rPINB could inhibit spore formation and aflatoxin B1 of A. flavus on maize. In vitro analysis revealed its dose-dependent antifungal effect on spore germination and germ tube growth of A. flavus. Scanning electron microscopy revealed that rPINB exposure altered spore morphology, indicating it damaged the cell wall. Transmission electron microscopy and the inhibition of ergosterol synthesis further revealed that rPINB exposure significantly damaged the cell membrane. The mitochondrial membrane potential decreased, and DNA fragments were scattered in the cytoplasm as detected using 5,5′,6,6′-tetrachloro-1,1′,3,3′-tetraethylbenzimidazolocarbocyanine iodide and 4′,6-diamidino-2-phenylindole staining. The direct antifungal activity of rPINB observed both in vivo and in vitro suggests that rPINB may be used to prevent fungal contamination of stored foods and agricultural products in the future.

We compared physiochemical changes in wheat cultivars of different hardnesses during long-term storage. Respiration, ATP content, germination ability, expansin gene expression, and the activities of dehydrogenase, catalase, and peroxidase were studied in soft wheat (‘Zhengmai 004’), medium hard wheat (‘Aikang 58’), and hard wheat (‘Zhengmai 9023’). Wheat cultivars were stored under natural conditions for one year or harvested fresh and then stored for eight weeks either naturally or with artificial aging. Enzymatic activities decreased about 10% during one year of natural storage. Physiochemical properties of fresh and naturally aged wheats did not change significantly in eight weeks of further storage at 12% moisture content (MC) and 30 °C, which suggests that wheat stores well. However, physiochemical quality deteriorated rapidly in artificially aged wheat stored at 12% MC and 30 °C. Changes were relatively small in the soft wheat cultivar, with low basal metabolism and slow reduction of physiological enzymes indicating that soft wheat may have better storage tolerance than harder cultivars. This study provides important data for determining storage tolerances of different wheat cultivars.

The prevention of fungal growth is of great importance for the safe storage of wheat. Previous studies have shown that soft wheat is more resistant to the xerophilic fungus Aspergillus glaucus than hard wheat during storage under the same conditions. We conducted a comparative proteomic analysis of embryos of soft wheat cv. Yangmai 15 and of hard wheat cv. Yangmai 16 to identify specific differentially expressed proteins. Dot-blot analysis of embryo lysates revealed 65 and 15 specific differential protein spots from Yangmai 15 and Yangmai 16, respectively. Four specific differential protein spots were revealed from Yangmai matched antifungal proteins, including a peroxidase, endogenous alpha-amylase/subtilisin inhibitor, xylanase inhibitor protein 1, and puroindoline B, while spots from Yangmai 16 did not match any antifungal proteins. This proteomic study provided novel insights to investigate the discrepancy of storage tolerances among different wheat varieties.