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Pre-ozonation can enhance the removal of algae in source water during cyanobacterial blooms; however, little is known about the influence of the co-existing allochthonous natural organic matter (NOM) on algal removal and algal organic matter (AOM) behavior during ozonation. This study aims to elucidate in the presence and absence of allochthonous NOM and the effects of varying ozone doses on Synechococcus sp. cell removal, membrane integrity, and dissolved organic matter (DOM) release and removal. The results indicate that ozone effectively disrupted algal cell membranes, reducing algal density; however, the presence of allochthonous NOM delayed cell rupture by competing for ozone due to aromatic humic-like substances. Pterin-like and protein-like fluorescent compounds were released upon cell disruption. Due to that, excess ozone led to the oxidation of the released pterin-like compounds, with characteristic fluorescence changes correlating to ozone dosage; these changes are potential to be used as an indicator to determine the optimized ozone dosage, avoiding more adverse release of intracellular AOM to form disinfection byproducts. [ABSTRACT FROM AUTHOR]

Currently, bacterial inoculant technology focuses on improving long-term storage conditions to ensure adequate rhizobia numbers and their effectiveness as plant growth promoters. This study aimed to investigate whether storage at 4 °C for four years of alginate beads immobilizing Bradyrhizobium sp. SEMIA6144 maintains bacterial vitality, efficacy in growth promotion, and ability to establish early interactions with Arachis hypogaea L. The recovery of viable SEMIA6144 cells decreased over time (10% at six months, 1% at one year, and 0.01% at four years), while cell vitality remained high at 94.1%, 90.2%, and 93.4%, respectively. The unsaturated/saturated fatty acid ratio declined during storage, reducing membrane fluidity and metabolic activity. Mobility and root adhesion of SEMIA6144 decreased after one and four years. However, growth promotion in peanuts inoculated with SEMIA6144 beads was observed through increased biomass, total chlorophyll, leaf number, leaf area, and decreased chlorophyll fluorescence compared to non-inoculated plants. Although nodulation was low in plants inoculated with four-year-old beads, leghemoglobin levels were maintained. These results demonstrate that Bradyrhizobium sp. SEMIA6144 can be stored for four years in alginate beads at 4 °C, maintaining its vitality and ability to establish a symbiosis that stimulates early peanut growth. Understanding these physiological changes could be valuable for the future improvement of long-lasting inoculants. [ABSTRACT FROM AUTHOR]

This study investigated the synergistic effects of lactic acid (0.5%, 1% and 2%) and ultrasound (400 W, 20 kHz) on the inactivation of Pseudomonas fluorescens. Combined ultrasound and 2% lactic acid for 5 min reduced the planktonic cell count below 1.40 log cfu/mL. Ultrasound promoted the inactivation of P. fluorescens biofilms by lactic acid and increased the release of ATP and nucleic acids from bacterial cells by 0.09–0.22 μmol/OD and 0.043–0.113 of OD260 values, respectively. Results indicated that combined ultrasound and lactic acid can serve as a potential technique to control P. fluorescens biofilms. [ABSTRACT FROM AUTHOR]

Currently, bacterial inoculant technology focuses on improving long-term storage conditions to ensure adequate rhizobia numbers and their effectiveness as plant growth promoters. This study aimed to investigate whether storage at 4 °C for four years of alginate beads immobilizing Bradyrhizobium sp. SEMIA6144 maintains bacterial vitality, efficacy in growth promotion, and ability to establish early interactions with Arachis hypogaea L. The recovery of viable SEMIA6144 cells decreased over time (10% at six months, 1% at one year, and 0.01% at four years), while cell vitality remained high at 94.1%, 90.2%, and 93.4%, respectively. The unsaturated/saturated fatty acid ratio declined during storage, reducing membrane fluidity and metabolic activity. Mobility and root adhesion of SEMIA6144 decreased after one and four years. However, growth promotion in peanuts inoculated with SEMIA6144 beads was observed through increased biomass, total chlorophyll, leaf number, leaf area, and decreased chlorophyll fluorescence compared to non-inoculated plants. Although nodulation was low in plants inoculated with four-year-old beads, leghemoglobin levels were maintained. These results demonstrate that Bradyrhizobium sp. SEMIA6144 can be stored for four years in alginate beads at 4 °C, maintaining its vitality and ability to establish a symbiosis that stimulates early peanut growth. Understanding these physiological changes could be valuable for the future improvement of long-lasting inoculants.

This research is aimed at the investigation the electrosurface and biochemical parameters of bacterial cells B. cereus B4368, L. plantarum, E. coli K-A, P. fluorescens B5040 under the influence of copper in ionic form and as nanoparticles in order to determine the nature and level of their toxic effect on bacteria. Copper nanoparticles synthesized in aqueous solution with NaBH4 and stabilized with dextran were used. Changes in membrane transport parameters were assessed by the value of ATPase activity; changes in transmembrane potential were assessed by the method of penetrating tetraphenylphosphonium cations (TPP+); and bacterial integrity was assessed by UV spectroscopy of cellular metabolites. A concentration-dependent inhibition of the membrane ATPase reaction and dissipation of the transmembrane potential under the action of both forms of copper was found, and the inhibitory effect in the case of the nanoparticles was on average 20 % higher than in the ionic form. As a result of heterocoagulation of dextran-stabilized copper nanoparticles and bacteria, a decrease in the negative ξ - potential of bacteria was observed, which was 40 % more effective under the action of copper nanoparticles compared to Cu2+ ions. The most significant changes in membrane parameters were observed in the range 10–60 μM of copper concentrations. With B. cereus B4368 cells taken as an example, we found a violation of the barrier function of their cell membrane under the influence of both copper preparations. In the case of copper nanoparticles, nucleic acid leakage from the bacterial cytoplasm was detected, which was confirmed by the absorption band at 260 nm. The results obtained indicate a high level of sensitivity of the studied electrosurface and biochemical parameters of bacterial cells to the effects of ionic and nanoparticle copper, which allows them to be used as indicators of the toxicity of metal nanoparticles in the development of metal-containing probiotic preparations. [ABSTRACT FROM AUTHOR]

Extensive application of reclaimed water alleviated water scarcity obviously. Bacterial proliferation in reclaimed water distribution systems (RWDSs) poses a threat to water safety. Disinfection is the most common method to control microbial growth. The present study investigated the efficiency and mechanisms of two widely used disinfectants: sodium hypochlorite (NaClO) and chlorine dioxide (ClO2) on the bacterial community and cell integrity in effluents of RWDSs through high-throughput sequencing (Hiseq) and flow cytometry, respectively. Results showed that a low disinfectant dose (1 mg/L) did not change the bacterial community basically, while an intermediate disinfectant dose (2 mg/L) reduced the biodiversity significantly. However, some tolerant species survived and multiplied in high disinfectant environments (4 mg/L). Additionally, the effect of disinfection on bacterial properties varied between effluents and biofilm, with changes in the abundance, bacterial community, and biodiversity. Results of flow cytometry showed that NaClO disturbed live bacterial cells rapidly, while ClO2 caused greater damage, stripping the bacterial membrane and exposing the cytoplasm. This research will provide valuable information for assessing the disinfection efficiency, biological stability control, and microbial risk management of reclaimed water supply systems. [ABSTRACT FROM AUTHOR]

This study reports the isolation and identification of the endophytic fungus Exserohilum rostratum through molecular and morphological analysis using optical and transmission electron microscopy (TEM), as well as the procurement of its secondary metabolite monocerin, an isocoumarin derivative. Considering the previously observed biological activities of monocerin, this study was performed on human umbilical vein endothelial cells (HUVECs) that are widely used as an in vitro model for several different purposes. Important parameters, such as cell viability, senescence-associated β-galactosidase, cellular proliferation by using 5(6)-carboxyfluorescein diacetate N-succinimidyl ester (CFSE), apoptosis analysis with annexin, cellular morphology through scanning electron microscopy (SEM), and laser confocal analysis were evaluated after exposing the cells to monocerin. After 24 h of exposure to monocerin at 1.25 mM, there was more than 80% of cell viability and a low percentage of cells in the early and late apoptosis and necrosis. Monocerin increased cell proliferation and did not induce cell senescence. Morphological analysis showed cellular integrity. The study demonstrates aspects of the mechanism of action of monocerin on endothelial cell proliferation, suggesting the possibility of its pharmaceutical application, such as in regenerative medicine. [ABSTRACT FROM AUTHOR]

In this study, an iron–aluminum composite (IAC) coagulant was synthesized from bauxite residue, and its applicability was investigated by harvesting biomass of Chlorella vulgaris (C. vulgaris). Bauxite residue is not environmentally friendly due to its high alkalinity that could pose a risk for living organisms. In this study, the conversion of the bauxite residue into IAC coagulant was done, which delivered safe utilization of bauxite residue to reduce its deteriorating impact on the environment. The prepared IAC coagulant was characterized by scanning electron microscope, Fourier transform infrared spectroscopy, and ICP-MS (inductively coupled plasma mass spectrometer). Concurrently, the applicability of the IAC was examined by harvesting the biomass of a freshwater microalgae: C. vulgaris from culture media. Several parameters (dosage, settling time, pH, biomass concentration, and age of culture) were also optimized to achieve the maximum efficiency of IAC coagulant. It was found that the 0.92 g biomass of C. vulgaris can be effectively removed from a liter of culture media by using 0.2 g of IAC in 120 min of contact time, leaving no residual metals (aluminum and iron) in aqueous media. This study showed that IAC coagulant is an efficient coagulant due to simple steps of synthesis, its high efficacy, low dose requirements, relatively short settling time, its integrity with cells, and generating no secondary pollutions. [ABSTRACT FROM AUTHOR]

Endothelial cell integrity and cell junction disruption are involved in many biological processes such as vascular permeability, progression of ischemic injury and cancer metastasis. In this study, the protective effect of crocin in endothelial cells integrity induced by vascular endothelial growth factor (VEGF) was monitored by surface plasmon resonance (SPR), an optical-based method. In addition, the expression of vascular endothelial (VE)-cadherins, the basic endothelial adhesion molecule, which plays a crucial role in the integrity of endothelial cells and cellular junctions, was assessed using flow cytometry (FC). Also, actin filaments which have main roles in alignment and maintaining the integrity of intracellular integrity were investigated by the fluorescence staining method. For the SPR test, the human umbilical vein endothelial cells (HUVECs) were immobilized on cysteamine-coated gold chips, and the effect of VEGF injection on crocin-treated endothelial cells was studied. The increase of the angle shift (∆Ө) with cells deposition near 0.8° indicated that cells were successfully immobilized on the gold chip surface. A linear relation (R2 = 0.95) was obtained between the amount of VEGF absorbed on the cell surface and the change in the response unit (RU) values. Our SPR curve results along with FC and imaging data suggest that the crocin has a protective effect on cellular integrity. [ABSTRACT FROM AUTHOR]

The undesirable settlement and growth of microalgae on submerged installations is a universal problem in water environment. Soft hydrogels are promising fouling-resistant materials due to the inherent surface properties. Herein, a kind of chitosan hydrogels with increasing zinc oxide (ZnO) mineral phase content were prepared by in situ sol–gel and solvent casting method, to prevent growth of algae Microcystis. aeruginosa. Incorporation with ZnO mineral phase improved mechanical property, water absorption, and stability of the obtained chitosan-zinc oxide (CS@ZnO) hydrogel films in Zn dose-dependent manner. The highest strength and growth inhibition (63.45 ± 8.93%) were observed by CS@ZnO-1.5 hydrogel films with the concentrations of 1.5% precursor in comparison with other hydrogel films. During this process, algal cell membrane was slightly damaged (24.5 ± 1.57%) and accompanied by significantly synthesis inhibition such as chlorophyll a (55.22 ± 2.72%) and total soluble protein (42.97 ± 1.66%). To sum up, synthesis inhibition of algal cell is the main mechanism of CS@ZnO hydrogel films inhibiting algal growth, which has the potential in antibiofouling application. [ABSTRACT FROM AUTHOR]

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Abstract Background Exposure to air particulate matter (PM) is associated with various diseases in the human respiratory system. To date, most in vitro studies showing cellular responses to PM have been performed in cell culture using a single cell type. There are few studies considering how multicellular networks communicate in a tissue microenvironment when responding to the presence of PM. Here, an in vitro three-dimensional (3D) respiratory mucosa-on-a-chip, composed of human nasal epithelial cells, fibroblasts, and endothelial cells, is used to recapitulate and better understand the effects of urban particulate matter (UPM) on human respiratory mucosa. Results We hypothesized that the first cells to contact with UPM, the nasal epithelial cells, would respond similar to the tissue microenvironment, and the 3D respiratory mucosa model would be a suitable platform to capture these events. First, whole transcriptome analysis revealed that UPM induced gene expression alterations in inflammatory and adhesion-related genes in human nasal epithelial cells. Next, we developed an in vitro 3D respiratory mucosa model composed of human nasal epithelial cells, fibroblasts, and endothelial cells and demonstrated that the model is structurally and functionally compatible with the respiratory mucosa. Finally, we used our model to expose human nasal epithelial cells to UPM, which led to a disruption in the integrity of the respiratory mucosa by decreasing the expression of zonula occludens-1 in both the epithelium and endothelium, while also reducing vascular endothelial cadherin expression in the endothelium. Conclusions We demonstrate the potential of the 3D respiratory mucosa model as a valuable tool for the simultaneous evaluation of multicellular responses caused by external stimuli in the human respiratory mucosa. We believe that the evaluation strategy proposed in the study will move us toward a better understanding of the detailed molecular mechanisms associated with pathological changes in the human respiratory system.

Cytokinesis divides a mother cell into two daughter cells at the end of each cell cycle and proceeds via the assembly and constriction of a contractile actomyosin ring (CAR). Ring constriction promotes division furrow ingression, after sister chromatids are segregated to opposing sides of the cleavage plane. Cytokinesis contributes to genome integrity because the cells that fail to complete cytokinesis often reduplicate their chromosomes. While in animal cells, the last steps of cytokinesis involve extracellular matrix remodelling and mid-body abscission, in yeast, CAR constriction is coupled to the synthesis of a polysaccharide septum. To preserve cell integrity during cytokinesis, fungal cells remodel their cell wall through signalling pathways that connect receptors to downstream effectors, initiating a cascade of biological signals. One of the best-studied signalling pathways is the cell wall integrity pathway (CWI) of the budding yeast Saccharomyces cerevisiae and its counterpart in the fission yeast Schizosaccharomyces pombe, the cell integrity pathway (CIP). Both are signal transduction pathways relying upon a cascade of MAP kinases. However, despite strong similarities in the assembly of the septa in both yeasts, there are significant mechanistic differences, including the relationship of this process with the cell integrity signalling pathways. [ABSTRACT FROM AUTHOR]

Morphology plays an important role in fungal fermentation and secondary metabolites biosynthesis. One novel technique, microparticle‐enhanced cultivation was successfully utilized to control the morphology of Monascus purpureus precisely and enhance the yield of yellow pigments. The production of yellow pigments increased to 554.2 U/ml when 4 g/L 5000 mesh talc added at 24 h. Field emission scanning electron microscope observation indicated that the actual effect depends on the properties of microparticle. Sharp‐edged microparticles showed better stimulatory effects than smooth, round‐shaped ones. Particle size analysis, scanning electron microscope, and cell integrity evaluation proved obvious morphological changes were induced by talc addition, including smaller mycelial size, rougher hyphae, and decreased cell integrity. Furthermore, the expression levels of MrpigG, MrpigD, MrpigE, and MrpigH were significantly upregulated by the addition of talc. It indicated that the microparticle could not only affect the mycelial morphology, but also influence the expression levels of key genes in biosynthetic pathway of Monascus yellow pigments. [ABSTRACT FROM AUTHOR]

The objective of the present study is to analyze the changes in bioimpedance vector analysis (BIVA) and phase angle (PhA) in sarcopenic older people submitted to a 12-week resistance training (RT) program according to classic and specific analyses. To this end, 20 sarcopenic older adults of both sexes, invited through media, underwent bioimpedance analysis before and after the RT carried out three times a week, for 12 weeks. The mean impedance vectors of the groups established for the confidence ellipses (95% of the confidence ellipse) are compared using Hotelling's T 2 test. The distance D from Mahalanobis is also calculated. Classic and Specific BIVA are presented. The resistance values for the classical analyses (R/H) decreased across all groups (whole group, women and men, p < 0.05), with approximate decreases ranging from 9.4% to 10%, while the classic reactance (Xc/H) decreased (p < 0.05) only for the whole group (5.9%) and men (7.7%). For the specific BIVA, trends are verified for the whole sample, with a decrease in resistance (R.sp) and an increase in reactance (Xc.sp). In conclusion, the RT program in sarcopenic individuals promoted a reduction in resistance values in classical analyses, indicating a possible increase in hydration status and, consequently, musculoskeletal mass., (© 2024 Wiley‐VCH GmbH.)

UV/persulfate (UV/PS) could effectively degrade algal cells and micro-organic pollutants. This process was firstly applied to remove Microcystis aeruginosa (M. aeruginosa) and 2,4,6-trichlorophenol (TCP) simultaneously in bench scale. Algal cells can be efficiently removed after 120 min reaction accompanied with far quicker removal of the coexisted TCP, which could be totally removed within 5 min in the UV/PS process. Both SO4•- and HO• were responsible for algal cells and TCP degradation, while SO4•- and HO• separately dominated TCP degradation and algal cells removal. Apart from the role of radicals (SO4•- and HO•) for algal cells and TCP degradation, UV also played a role to some extent. Increased PS dose (0–4.5 mM) or UV intensity (2.71–7.82 mW/cm2) could enhance the performance of the UV/PS process in both TCP and algae removal. Although some intracellular organic matters can be released to the outside of algal cells due to the cell lysis, they can be further degraded by UV/PS process, which was inhibited by the presence of TCP. This study suggested the good potential of the UV/PS process in the simultaneous removal of algal cells and micro-organic pollutants.

Antimicrobial compounds produced by lactic acid bacteria emerged as a promising group of agents for managing the growth of pathogens in food. Previously, we have isolated a bacteriocinogenic strain, Weissella confusa Cys2-2, producing active substances with inhibitory potential, however, its antimicrobial mechanism is still undefined. This study was aimed to determine the Cys2-2 bacteriocins mechanism of action against food pathogens using: agar-well diffusion and broth assay to evaluate the spectrum of inhibition and the minimum inhibitory concentration, Tricine-SDS-PAGE analysis to estimate the molecular weight, determination of the target cell viability with the Cys2-2 compounds applied as cell-free supernatant (CFS) and precipitated peptides (PP) with or without an chelator agent (EDTA) and evaluate the effect on the membrane integrity by monitoring the release of DNA/RNA molecules. The results revealed that Cys2-2 bacteriocin exerted its bactericidal effect by weakening of membrane integrity of target cells leading to cell death.

Main conclusion: Silicon inhibits the growth ofAlternaria alternatainto sorghum root cells by maintaining their integrity through stimulating biochemical defense reactions rather than by silica-based physical barrier creation. Although the ameliorating effect of silicon (Si) on plant resistance against fungal pathogens has been proven, the mechanism of its action needs to be better understood on a cellular level. The present study explores the effect of Si application in sorghum roots infected with fungus Alternaria alternata under controlled in vitro conditions. Detailed anatomical and cytological observations by both fluorescent and electron microscopy revealed that Si supplementation results in the inhibition of fungal hyphae growth into the protoplast of root cells. An approach of environmental scanning electron microscopy equipped with energy-dispersive X-ray spectroscopy enabling spatial detection of Si even at low concentrations showed that there is no continual solid layer of silica in the root cell walls of the rhizodermis, mesodermis and exodermis physically blocking the fungal growth into the protoplasts. Additionally, biochemical evidence suggests that Si speeds up the onset of activities of phenylpropanoid pathway enzymes phenylalanine ammonia lyase, peroxidases and polyphenol oxidases involved in phenolic compounds production and deposition to plant cell walls. In conclusion, Si alleviates the negative impact of A. alternata infection by limiting hyphae penetration through sorghum root cell walls into protoplasts, thus maintaining their structural and functional integrity. This might occur by triggering plant biochemical defense responses rather than by creating compact Si layer deposits. [ABSTRACT FROM AUTHOR]

This study was performed to investigate the availability of forward osmosis (FO) for microalgae harvesting using sulfonated polyethersulfone (SPES)/PES porous membranes. In FO process, porous membranes (< 25.0 Lm−2 h−1) exhibited more superior water flux than TFC FO membranes (<2.6 L m−2 h−1). Furthermore, the incorporation of SPES has been demonstrated to enhance membrane performance. The effects of SPES content on pore structure and separation performance were investigated. Compared with pure PES porous membranes, porous membranes with 40% SPES yielded an improved hydrophilicity and greater porosity. It exhibited two times higher water fluxes than the pure PES porous membrane. For microalgae harvesting, AL-FS mode (active layer facing the feed solution) was more favourable than AL-DS mode (active layer facing the draw solution) because less deposited microalgae on the active layer mitigate the membrane biofouling. FO operation combined with SPES/PES porous membranes is conducive to preserving microalgae cell integrity under the mild condition. In addition, FO membrane can be cleaned by a simple water rinse. Potential implications were highlighted as a sustainable method for microalgae harvesting because of no pressure input and less chemical cleaning demand. [ABSTRACT FROM AUTHOR]

An in-situ dielectric measurement was implemented on garlic clove, onion, taro and Chinese yam cells undertaken slow cooling from 2.0 to -11.0°C. The double-membrane structure of vegetable cell corresponding to cell membrane and tonoplast was identified by splitting up one overlapping β-relaxation into two independent relaxations, and a double–shell model was applied to analyze the two dielectric relaxations based on interface polarization mechanism. The dielectric relaxation time (τ) of vegetable cells were found to respond sensitively to the freezing treatment. An abrupt shift of τ demonstrated the formation of extracellular ice, and the disappearance of the lower-frequency relaxation at the ice crystallization point was attributed to the frozen damage of cell integrity. [ABSTRACT FROM AUTHOR]

The present study explores the effect of chirality of the biological macromolecules, its functional aspects, and its interaction with other food components. Dihydromyricetin (DHM) is a natural novel flavonol isolated from the vine tea (Ampelopsis grossedentata) leaves. However, limited progress in enantiopure separation methods of such compounds hinder in the development of enantiopure functional studies. This study is an attempt to develop a simple, accurate, and sensitive extraction method for the separation of the enantiopure DHM from vine tea leaves. In addition, the identification and purity of the extracted enantiopure (−)‐DHM were further determined by the proton nuclear magnetic resonance (1H‐NMR) and the carbon nuclear magnetic resonance (13C‐NMR). The study further evaluates the antimicrobial activity of isolated (‐)‐DHM in comparison with racemate (+)‐DHM, against selected foodborne pathogens, whereas the action mode of enantiopure (−)‐DHM to increase the integrity and permeability of the bacterial cell membrane was visualized by confocal laser scanning microscopy using green fluorescence nucleic acid dye (SYTO‐9) and propidium iodide (PI). Moreover, the morphological changes in the bacterial cell structure were observed through field emission scanning electron microscope. During analyzing the cell morphology of B. cereus (AS11846), it was confirmed that enantiopure (−)‐DHM could increase the cell permeability that leads to the released of internal cell constituents and, thus, causes cell death. Therefore, the present study provides an insight into the advancement of enantiopure isolation along with its antimicrobial effect which could be served as an effective approach of biosafety. [ABSTRACT FROM AUTHOR]

Inorganic coagulants could effectively precipitate algae cells but might increase the potential risks of cell damage and coagulant residue. This study was conducted to critically investigate the suitability of polyaluminum (PAC), FeCl 3 and TiCl 4 for algae-laden water treatment in terms of the trade-off between algal substance removal, cell viability, and coagulant residue. The results showed that an appropriate increase in coagulant dosage contributed to better coagulation performance but severe cell damage and a higher risk of intracellular organic matter (IOM) release. TiCl 4 was the most destructive, resulting in 60.85% of the algal cells presenting membrane damage after coagulation. Intense hydrolysis reaction of Ti salts was favorable for the formation of larger and more elongated, dendritic structured flocs than Al and Fe coagulants. TiCl 4 exhibited the lowest residue level and remained in the effluents mainly in colloidal form. The study also identified charge neutralization, chemisorption, enmeshment, and complexation as the dominant mechanisms for algae water coagulation by metal coagulants. Overall, this study provides the trade-off analyses between maximizing algae substance removal and minimizing potential damage to cell integrity and is practically valuable to develop the most suitable and feasible technique for algae-laden water treatment. [Display omitted] • PAC and FeCl 3 were more effective than TiCl 4 in algae water treatment at low dosage. • TiCl 4 led to best DOC removal, least residue but severest cell damage and IOM release. • Appropriate coagulation dose contributed to large and compact flocs. • Algae-Ti aggregates were more long shaped and dendritic. • Colloidal coagulant formed by charge neutralization was the dominant residual component. [ABSTRACT FROM AUTHOR]

Banana anthracnose caused by Colletotrichum musae is a serious postharvest disease. Use of fungicides has potential adverse effects on the environment safety and human health. Application of biological control agents (BCA) is a promising strategy for managing postharvest fruit diseases. In this study, Streptomyces sp. XT34 was isolated from the banana rhizosphere soil and exhibited a strong antifungal activity against C. musae. Combining the phenotypic and whole-genomic alignment, strain XT34 was identified as Streptomyces diastatochromogenes. Strain XT34 extracts reduced the disease incidence of anthracnose and maintained the fruit quality of banana. Treatment of extracts reduced the colonization of C. musae on fruit surface. The activity inhibition of cell wall-degrading enzymes maintained the cell-wall strength of fruit. The activity increase of defense enzymes contributed to the low disease symptom. It was supported by the differentially expressed genes (DEGs) related to supramolecular fiber organization and flavonoid biosynthesis. In addition, spore germination of C. musae was effectively inhibited by extracts. The morphology of mycelia and spore become wrinkled and ruptured. The treatment of extracts increased the optical density of A 260 and soluble sugar and protein contents of C. musae. The integrity of cell membrane was also destroyed, reflecting on an increase in electrical conductivity and malondialdehyde. Several metabolites were found in the genome of strain XT34 using antiSMASH. Eleven volatile compounds were identified by gas chromatography-mass spectrometer (GC-MS). Notably, strain XT34 and extracts exhibited a broad-spectrum antifungal activity against eight phytopathogenic fungi. Hence, S. diastatochromogenes XT34 provides a potential BCA to control banana anthracnose. • Streptomyces XT34 exhibits strong antifungal activity against banana anthracnose. • Strain XT34 inhibits fruit decay and maintained quality in postharvest banana. • Strain XT34 extracts maintain cell-wall strength of fruit. • Extracts induce the biosynthesis of supramolecular fiber organization and flavonoid. • Strain XT34 extract inhibit pathogenic spore germination and caused cell rupture. [ABSTRACT FROM AUTHOR]

This study evaluated the effect of two inactivation methods on probiotic, and aimed to determine a suitable inactivation method and condition for obtaining beneficial paraprobiotics from Lactobacillus plantarum (LP) and Lactobacillus gasseri (LG). The effect of inactivation condition on culturability, physiological properties, and morphological characteristics was evaluated by a plating method, flow cytometry, and field emission-scanning electron microscopy, respectively. The result revealed that each strain conferred different resistance to inactivation methods. The heat-treated (75 and 90 °C for 15 and 30 min) LG lost its growth ability, but it's all sonicated samples (50 and 100 W for 5 and 10 min) were stable and maintained their growth ability. However, the ability to grow on culture media of sonicated (50 and 100 W for 5 and 10 min) LP was less than its heat-treated (75 and 90 °C for 15 min) specimens. According to flow cytometry data, the membrane integrity of each probiotic cell was affected by both inactivation methods; however, the severe heat process (90 for 30 min) causes the most serious membrane damage to LG cells (PI = 97.7%). Morphological properties of both strains were significantly affected by inactivation methods. After inactivation treatment, damaged cell, cell roughness, lysed cell, cell adhesions, cell disruption, and cell bending were increased, significantly. Results indicate that for obtaining a functional paraprobiotic the inactivation process should be optimized. Also, it should be noticed that a particular optimized inactivation method is not suitable for obtaining paraprobiotic from all probiotic strains. • Sonication and thermal process impose different effects on viable cells. • The flow cytometry method is a promising method for observing the viability of cells. • Selection of a proper inactivation method is very important for obtaining a health-benefit paraprobiotic. [ABSTRACT FROM AUTHOR]

The incorporation of microalgae into processed food products is considered a sustainable strategy to enrich food products in omega-3 long chain polyunsaturated fatty acids (ω3-LC-PUFA). However, the microstructural properties of the microalgae might influence the nutrient digestibility and bioaccessibility during consumption. The current study proved the importance of cell disruption of Nannochloropsis sp. for the in vitro lipid digestibility and bioaccessibility of ω3-LC-PUFA and carotenoids. While an incomplete lipid digestion and low bioaccessibility values (1–6% for carotenoids and 13% for ω3-LC-PUFA) were observed for untreated biomass, cell disruption by high pressure homogenization resulted in a complete lipid digestibility and a threefold increase in bioaccessibility. It was shown that the Nannochloropsis sp. cell wall and/or cell membrane act as a natural barrier for (lipophilic) nutrients during in vitro digestion. Hence, microalgal cell disruption is a crucial step in the design of healthy food products enriched with microalgae.

Citrulline is a precursor of arginine and is believed to have the same beneficial effects as arginine. Lactobacillus helveticus ASCC 511 (LH511) utilizes arginine to produce extra energy for cell growth via arginine deiminase (ADI) pathway. Supplementation of both citrulline and LH511 is considered to be beneficial to intestinal tract. LH511 + Cit-2 mM was tested with IPEC-J2 cells to determine (i) the anti-adhesion effect against pathogenic infection (ii) effect on cell integrity by measuring transepithelial electrical resistance (TEER) and (iii) effect on tight junction (TJ)-proteins expression by qPCR and western-blot analyses. LH511 + Cit-2 mM exhibited a protective effect against adhesion of enterohemorrhagic (EHEC) and enteroinvasive (EIEC) Escherichia coli; it stimulated nitric oxide (NO) production, improved TEER and stimulated TJ-proteins expression. LH511 + Cit-2 mM showed better effects than that with arginine and citrulline alone. This study suggests supplementation of citrulline with LH511 has a synergistic effect and it might be a potential supplement for enhancing the health of the intestine.

GH72 family of β-(1,3)-glucanosyltransferases is unique to fungi and is required for cell wall biogenesis, morphogenesis, virulence, and in some species is essential for life. Candida albicans PHR1 and PHR2 are pH-regulated genes that encode GH72 enzymes highly similar to Gas1p of Saccharomyces cerevisiae. PHR1 is expressed at pH ≥ 5.5 while PHR2 is transcribed at pH ≤ 5.5. Both are essential for C. albicans morphogenesis and virulence. During growth at neutral-alkaline pH, Phr1p-GFP preferentially localizes to sites of active cell wall formation as the incipient bud, the mother-daughter neck, the bud periphery, and concentrates in the septum at cytokinesis. We further investigated this latter localization. In chs3Δ cells, lacking the chitin of the chitin ring and lateral cell wall, Phr1p-GFP still concentrated along the thin line of the primary septum formed by chitin deposited by chitin synthase I (whose catalytic subunit is Chs1p) suggesting that it plays a role during formation of the secondary septa. RO-09-3143, a highly specific inhibitor of Chs1p activity, inhibits septum formation and blocks cell division. However, alternative septa are produced and are crucial for cell survival. Phr1p-GFP is excluded from such aberrant septa. Finally, we determined the effects of RO-09-3143 in cells lacking Phr1p. PHR1 null mutant was more susceptible to the drug than the wild type. The phr1Δ cells were larger, devoid of septa, and underwent endomitosis and cell death. Phr1p and Chs1p cooperate in maintaining cell integrity and in coupling morphogenesis with nuclear division in C. albicans.

Adaptation to higher temperatures would increase the environmental competitiveness of psychrophiles, organisms that thrive in low‐temperature environments. Methanolobus psychrophilus, a cold wetland methanogen, 'evolved' as a mesophile, growing optimally at 30 °C after subculturings, and cells grown with ample substrates exhibited higher integrity. Here, we investigated N‐glycosylation of S‐layer proteins, the major archaeal envelope component, with respect to mesophilic adaptation. Lectin affinity enriched a glycoprotein in cells grown at 30 °C under ample substrate availability, which was identified as the S‐layer protein Mpsy_1486. Four N‐glycosylation sites were identified on Mpsy_1486, which exhibited different glycosylation profiles, with N94 only found in cells cultured at 30 °C. An N‐linked glycosylation inhibitor, tunicamycin, reduced glycosylation levels of Mpsy_1486 and growth at 30 °C, thus establishing a link between S‐layer protein glycosylation and higher temperature adaptation of the psychrophilic archaeon M. psychrophilus. [ABSTRACT FROM AUTHOR]

GH72 family of β-(1,3)-glucanosyltransferases is unique to fungi and is required for cell wall biogenesis, morphogenesis, virulence, and in some species is essential for life. Candida albicans PHR1 and PHR2 are pH-regulated genes that encode GH72 enzymes highly similar to Gas1p of Saccharomyces cerevisiae. PHR1 is expressed at pH ≥ 5.5 while PHR2 is transcribed at pH ≤ 5.5. Both are essential for C. albicans morphogenesis and virulence. During growth at neutral-alkaline pH, Phr1p-GFP preferentially localizes to sites of active cell wall formation as the incipient bud, the mother-daughter neck, the bud periphery, and concentrates in the septum at cytokinesis. We further investigated this latter localization. In chs3 Δ cells, lacking the chitin of the chitin ring and lateral cell wall, Phr1p-GFP still concentrated along the thin line of the primary septum formed by chitin deposited by chitin synthase I (whose catalytic subunit is Chs1p) suggesting that it plays a role during formation of the secondary septa. RO-09-3143, a highly specific inhibitor of Chs1p activity, inhibits septum formation and blocks cell division. However, alternative septa are produced and are crucial for cell survival. Phr1p-GFP is excluded from such aberrant septa. Finally, we determined the effects of RO-09-3143 in cells lacking Phr1p. PHR1 null mutant was more susceptible to the drug than the wild type. The phr1 Δ cells were larger, devoid of septa, and underwent endomitosis and cell death. Phr1p and Chs1p cooperate in maintaining cell integrity and in coupling morphogenesis with nuclear division in C. albicans. [ABSTRACT FROM AUTHOR]

This study aims at investigating different forms of calcium ion absorption in asparagus during thermal processing, and its correlation with the texture and tissue microstructure. Calcium ion (bound and free) absorption in asparagus and texture changes were evaluated by immersion in 1 g/100 g calcium lactate solution (with or without 0.4 g/100 g pectin methylesterase) under temperatures ranging from 50 to 90 °C. Results showed the infused calcium in the tissue existed mainly in the form of free calcium at the tested temperatures. PME addition could fasten the formation of bound calcium in asparagus tissue at the tested temperatures, but has little influence on free calcium absorption. Significantly positive correlation was only observed between the texture and bound calcium in asparagus when its cell integrity maintained (50–80 °C). The results of this study allow for a better appreciation of the role of different forms of calcium ion and tissue microstructure in improving asparagus texture. • Bound calcium in asparagus with cell integrity strongly correlated with texture. • PME addition enhanced calcium firming effects of asparagus texture during heating. • Calcium infused in asparagus at 50-80 °C mainly existed in the form of free calcium. • Adding PME to calcium solution increased the bound calcium level in asparagus. [ABSTRACT FROM AUTHOR]

Sperm morphology varies enormously across the animal kingdom. Whilst knowledge of the factors that drive the evolution of interspecific variation in sperm morphology is accumulating, we currently have little understanding of factors that may constrain evolutionary change in sperm traits. We investigated whether susceptibility to sperm abnormalities could represent such a constraint in songbirds, a group characterized by a distinctive helical sperm head shape. Specifically, using 36 songbird species and data from light and scanning electron microscopy, we examined among‐species correlations between the occurrence of sperm head abnormalities and sperm morphology, as well as the correlation between sperm head abnormalities and two indicators of sperm competition. We found that species with more helically shaped sperm heads (i.e., a wider helical membrane and more pronounced cell waveform) had a higher percentage of abnormal sperm heads than species with less helical sperm (i.e., relatively straight sperm) and that sperm head traits were better predictors of head abnormalities than total sperm length. In contrast, there was no correlation between sperm abnormalities and the level of sperm competition. Given that songbird species with more pronounced helical sperm have higher average sperm swimming speed, our results suggest an evolutionary trade‐off between sperm performance and the structural integrity of the sperm head. As such, susceptibility to morphological abnormalities may constrain the evolution of helical sperm morphology in songbirds. [ABSTRACT FROM AUTHOR]

The frequent occurrence of algal blooms in surface water has attracted more and more attention, which caused many water quality problems, including disinfection byproducts (DBPs). Algal organic matter (AOM) including intracellular organic matter (IOM) and extracellular organic matter (EOM), was a well-known precursor to DBPs formation in drinking water. This study evaluated the effect of ultraviolet (UV) irradiation on the cell integrity, IOM release and DBPs formation during subsequent chlorination of Chlorella sp. Results showed the damage rates of algal cells increased to 40.1% after the high UV irradiation of 528 mJ/cm2, which contributed to the release of IOM. In addition, UV irradiation was effective in reducing the formation of haloacetic acids (HAAs) both in AOM and IOM, but promoted the formation of nitrogenous DBPs (N-DBPs) from AOM in subsequent chlorination. Furthermore, neutral pH exerted a positive effect on the formation of DBPs. UV irradiation decreased the bromine substitution factor (BSF) value of AOM at a high bromide level. The BSF values increased with increasing of the concentration of bromide. Moreover, more amino acids and low molecular weight precursors were produced after UV irradiation in filtered supernatant, which contributed to the formation of N-DBPs with algal chlorination. Overall, this information demonstrated pre-oxidation of UV irradiation could be used to treat the algal-rich drinking water. Unlabelled Image • Loss of cell integrity and IOM release was caused by UV irradiation. • UV decreased THMs and HAAs formation from Chlorella sp. in chlorination. • UV had less effect on BSF-THMs and BSF-DHAAs at a high bromide level. • The main amino acids contributed to the formation of N-DBPs with chlorination. [ABSTRACT FROM AUTHOR]

Frequent off-flavor events caused by geosmin and 2-methylisoborneol have caused concern among consumers about the quality of potable water. Pseudanabaena galeata , a filamentous cyanobacterium, is a known producer of 2-methylisoborneol in lakes and reservoirs. The use of algicides to control cyanobacteria must consider the potential release of contaminants into the water. This is the first study to systematically investigate the effectiveness of copper sulphate (CuSO 4), potassium permanganate (KMnO 4), and hydrogen peroxide (H 2 O 2) on the cell viability and integrity of Pseudanabaena galeata. Following algicide or oxidant treatment, the release and degradation of 2-methylisoborneol was also examined. It is evident that all of these chemicals can decrease Pseudanabaena galeata viability and damage cell membranes and the filamentous Pseudanabaena galeata was more susceptible to treatment by these three algicides than unicellular colonial Microcystis aeruginosa. Of the three compounds used, KMnO 4 showed the stronger ability to compromise cell integrity and 5.0 mg/L KMnO 4 could induce 91 ± 1.5% lysis of Pseudanabaena galeata within 2 h. It was found that H 2 O 2 had the potential to degrade 2-methylisoborneol with 16.0 ± 0.4% degraded by 20.0 mg/L H 2 O 2 within 8 h. In contrast, 2-methylisoborneol could not be degraded by CuSO 4 (dosage: ≤ 1.5 mg/L; reaction time: ≤ 8 h) and KMnO 4 (dosage: ≤ 5.0 mg/L; reaction time: ≤ 3 h) basically. Results showed that the oxidation capacity of H 2 O 2 against Pseudanabaena galeata was enhanced under sunlight. The results will help drinking water utilities to better understand the risk of Pseudanabaena galeata lysis and 2-methylisoborneol release during raw water treatment. Image 1 • KMnO 4 can lyse Pseudanabaena galeata faster than CuSO 4 or H 2 O 2 under visible light. • Pseudanabaena galeata was more susceptible to treatment than Microcystis aeruginosa. • Among CuSO 4 , H 2 O 2 and KMnO 4 , only H 2 O 2 can partially degrade 2-MIB. • The Delayed Chick Watson Model well describes the kinetics of cell rupture. [ABSTRACT FROM AUTHOR]

Cyanobacterial blooms continue to serve as one of the most serious global issues threatening water supply and human health. During cyanobacterial bloom season, a large •OH-yield equipment was developed and installed after coagulation settling in a 12000 ton/day drinking water treatment system in Xiamen, China. An •OH concentration of 7.76∼57.8 μmol/L was formed by using the oxygen activated species generated by strong ionisation discharge combining with the effect of water jet cavitation. •OH pre-treatment at a dose of 1.0 mg/L inactivated cyanobacterial blooms in the process of conveying bloom water within only 20s, which were then removed by sand filtration. Under SEM observation, dominant Microcystis sp. colonies connected by mucilage were dispersed into individuals that still retained the cell integrity, indicating no release of intracellular organic matter (IOM). According to a flow cytometry analysis, the main cause of •OH inactivation was the breakage of DNA strands. Meanwhile, the •OH-mineralized microcystin-LR was by breaking the C=C conjugated diene bond and crucial opening the persistent benzene ring to carboxylic acid m/z 158.0. During •OH pre-treatment of 1.0 mg/L and NaClO disinfection of 0.5 mg/L, all water quality indexes and disinfection by-product (DBP) contents complied with the Chinese Sanitary Standards for Drinking Water. Therefore, the •OH based on the strong ionisation discharge showed great prospect for large-scale drinking water treatment in the removal of cyanobacterial blooms while retaining cell integrity as well as the degradation of toxins. Image 1 • A novel •OH equipment was developed for the full scale treatment of algae blooms. • •OH inactivated algae and degraded microcystin-LR during conveying the bloom water. • •OH-inactivated algae still retained cell integrity, indicating no release of IOM. • The main cause of •OH inactivation was the breakage of DNA strands. • All water quality indexes and DBP contents complied with the Chinese Standards. [ABSTRACT FROM AUTHOR]

Abstract A wide range of cyanobacterial species and their harmful metabolites are increasingly detected in water bodies worldwide, exacerbated by climate change and human activities. The resulting bloom conditions represent significant challenges to production of safe drinking water and cost effective water reuse, therefore their removal is a priority to ensure public safety. While current microscopic taxonomy identification methods provide valuable information about cell numbers during treatment, these methods are incapable of providing information about the fate of cells during treatment. The objectives of this study were to (1) identify the critical control points for breakthrough and accumulation of cells by investigating the fate of cells during treatment processes using a combination of taxonomy, cell integrity and next-generation sequencing (NGS), and (2) assess the impact of pre-treatment processes on breakthrough prevention at critical control points, and the benefits of cell integrity and NGS analysis for improved management purposes. This paper presents the results of an unprecedented cyanobacterial monitoring program conducted in four full scale water treatment plants located in three different climate zones. Cyanobacterial cell integrity and accumulation during operation process were assessed for the first time using next generation of gene sequencing methods. NGS analysis led to detection of cyanobacterial and melainabacteria orders in water samples that were not identified by microscopy. 80 ± 5% of cells were completely lysed post pre-oxidation (for both ozone and potassium permanganate). However unlike pre-ozonation, the remaining cells were undamaged cells with the potential to accumulate and grow within the plants post-KMnO 4 treatment, particularly in clarifier sludge. To effectively monitor water quality, this study presents a synergistic approach coupling new and traditional analytical methods and demonstrates the importance of identifying critical points for managing accumulation of cyanobacteria within plants. Graphical abstract Image 1 Highlights • Studied performance of treatment barriers for removal of cyanobacterial cells. • Applied combination of taxonomy, cell integrity & next-generation sequencing (NGS). • NGS detected new cyanobacterial & melainabacteria orders in water samples. • 80 ± 5% of cells were completely lysed after pre-oxidation (O 3 & KMnO 4). • Viable cells with potential to accumulate & grow within plants remained post-KMnO 4. [ABSTRACT FROM AUTHOR]

Algal fouling has become one of the most critical factors hindering the large-scale development of membrane processes in algae-laden water treatment. Herein, novel calcium hypochlorite (Ca(ClO) 2)/ferrous iron (Fe(II)) process was proposed as an ultrafiltration (UF) membrane pretreatment technology, and its effects on membrane fouling and water properties were systematically studied. Results showed that the terminal specific fluxes were significantly elevated to 0.925 and 0.933, with the maximum removal ratios of reversible resistance reaching 99.65% and 96.99% for algae-laden water and extracellular organic matter (EOM), respectively. The formation of cake filtration was dramatically delayed, accompanied by a significant reduction of the adhesion free energy, and the contaminants attached to the membrane surface were effectively decomposed. With respect to water quality, the removal ratios of OD 685 and turbidity achieved 81.25–95.31% and 90.16–97.72%, individually. The maximum removal rates of DOC, UV 254 and fluorescent organics in influent water reached 46.14%, 55.17% and 75.77%, respectively. Furthermore, the generated reactive species (e.g., •OH, Cl•, Cl 2 •- and ClO•) could efficiently degrade EOM, which appreciably reduced the electrostatic repulsion between the algal foulants while ensuring the integrity of algal cells. At the Ca(ClO) 2 /Fe(II) dosage of 0.04/0.24 mM, the zeta potential changed from −32.9 mV to −10.8 mV, and a large range of aggregates was formed. The macromolecules in the algal solution were significantly removed, and the proportion of micromolecular organics was increased to some extent. Coagulation of in-situ formed Fe(III) dominated the membrane fouling mitigation, and the reactive species also contributed to the improvement of filtration performance. Overall, Ca(ClO) 2 /Fe(II) pretreatment has an exceptional prospect for efficient degradation of algal pollutants and enhancement of UF capability. [Display omitted] • Calcium hypochlorite/ferrous iron was used as a membrane pretreatment technology. • The terminal specific flux of algae-laden water was improved from 0.099 to 0.925. • Several active species (e.g.,.•OH, Cl•, Cl 2 •- and ClO•) were produced and involved. • The integrity of algal cells was well preserved in the synergistic pretreatment. • The deposited porous flocs minimized the contact between foulants and membrane. [ABSTRACT FROM AUTHOR]

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Rhodococcus species have been successfully used as cell catalysts for valuable chemicals production due to their well-characterized resistance to harmful factors. An understanding of how they respond to stress is of great interest, which will enable the identification of engineering strategies for further improving their resistance and maintaining cell integrity and viability. Here, we assessed the transcriptome response of R. ruber TH3 to heat shock. Approximately, 376 genes were up-regulated in heat-shocked TH3. Among all the up-regulated functional genes, the small heat-shock-protein (Hsp16) with maximal enhanced transcript (463-fold) was identified, and its function was investigated. Results showed that overexpressed Hsp16 has no significant promotive effect on stress tolerance of in-cell enzyme. Interestingly, compared to the control TH3, a little fewer pores and folds on the surface of TH3(Hsp16) and more intact TH3(Hsp-GFP) cells under AM treatment were observed by SEM and LCSM, respectively. Moreover, survival test showed that more (about 501-700) TH3(Hsp16) colonies were observed while only 1-100 TH3 colonies after 50% AM treatment, and this trend is also found in high-temperature cultivation experiments. These results indicate that Hsp16 does great contributions to preventing cell leakage, maintaining cell integrity and viability of R. ruber under stress conditions. [ABSTRACT FROM AUTHOR]

Inactivation of Microcystis aeruginosa by UV/chlorine process was investigated in this study. Chlorine decay with or without the presence of algal cells was modeled based on a kinetic model, and the second-order rate constant between chlorine and algal cells was determined to be 3.3 × 10 −4 (mgC/L) −1  s −1 . Flow cytometry as well as confocal laser scanning microscopy were used to characterize the cell integrity of M. aeruginosa . Results demonstrated that UV/chlorine pre-oxidation was responsible for the inactivation of M. aeruginosa , and the inactivation efficiency increased with the increasing dosage of chlorine. UV/chlorine process can significantly change the surface characteristics of M. aeruginosa and enhance the coagulation efficiency. Moreover, due to the destruction of algal cells, microcystin-LR would be released and then degraded during pre-oxidation, and the releasing endotoxin could be removed during subsequent coagulation-sedimentation process. This study suggests that UV/chlorine process might be a potential alternative for the pretreatment of cyanobacterial cells in treating cyanobacteria-laden water. [ABSTRACT FROM AUTHOR]

The water eutrophication caused by cyanobacteria seasonally proliferates, which is a hot potato to be resolved for water treatment plants. This study firstly investigated coagulation performance of titanium tetrachloride (TiCl4) for Microcystis aeruginosa synthetic water treatment. Results show complete algal cell removal by TiCl4 coagulation without damage to cell membrane integrity even under harsh conditions; 60 mg/L TiCl4 was effective in removing the microcystins up to 85%. Furthermore, besides having stronger UV254 removal capability and the higher removal of fluorescent substances over Al- and Fe-based coagulants, TiCl4 coagulant required more compact coagulation and sedimentation tanks due to its significantly improved floc growth and sedimentation speed. Meanwhile, its’ short hydraulic retention time avoided algal cell breakage and subsequent algal organic matter release. Microcystin concentrations were kept at a low level during sludge storage period, indicating that the TiCl4 flocs could prevent algal cells from natural lysis. To facilitate water recycling without secondary contamination, the algae-containing sludge after TiCl4 coagulation ought to be disposed within 12 days at 20 °C and 8 days at 35 °C. [ABSTRACT FROM AUTHOR]

Alternaria alternata is a critical phytopathogen that causes foodborne spoilage and produces a polyketide mycotoxin, alternariol (AOH), and its derivative, alternariol monomethyl ether (AME). In this study, the inhibitory effects of the essential oil citral on the fungal growth and mycotoxin production of A. alternata were evaluated. Our findings indicated that 0.25 μL/mL (222.5 μg/mL) of citral completely suppressed mycelial growth as the minimum inhibitory concentration (MIC). Moreover, the 1/2MIC of citral could inhibit more than 97% of the mycotoxin amount. Transcriptomic profiling was performed by comparative RNA-Seq analysis of A. alternata with or without citral treatment. Out of a total of 1334 differentially expressed genes (DEGs), 621 up-regulated and 713 down-regulated genes were identified under citral stress conditions. Numerous DEGs for cell survival, involved in ribosome and nucleolus biogenesis, RNA processing and metabolic processes, and protein processing, were highly expressed in response to citral. However, a number of DEGs responsible for the metabolism of several carbohydrates and amino acids, sulfate and glutathione metabolism, the metabolism of xenobiotics and transporter activity were significantly more likely to be down-regulated. Citral induced the disturbance of cell integrity through the disorder of gene expression, which was further confirmed by the fact that exposure to citral caused irreversibly deleterious disruption of fungal spores and the inhibition of ergosterol biosynthesis. Citral perturbed the balance of oxidative stress, which was likewise verified by a reduction of total antioxidative capacity. In addition, citral was able to modulate the down-regulation of mycotoxin biosynthetic genes, including pksI and omtI. The results provide new insights for exploring inhibitory mechanisms and indicate citral as a potential antifungal and antimytoxigenic alternative for cereal storage.

Potassium ferrate (K 2 FeO 4 ) is an effective oxidant that may be used as a pre- or post-oxidant in the purification of source water with cyanobacterial issues. To provide a better basis for the application of this oxidant during water treatment processes, the impacts of K 2 FeO 4 on the cell viability of Microcystis aeruginosa and the fate of associated microcystins (MCs) were investigated in various water matrices. The results showed that a water matrix can significantly affect the effectiveness of K 2 FeO 4 on cyanobacteria inactivation. 10 mg L −1 K 2 FeO 4 induced significant cell lysis of M. aeruginosa in Ran Yi Tan Reservoir (RYTR) water while the membrane integrity was relatively unaffected in ASM-1 media and Cheng Kung Lake (CKL) water. The reduced efficiency of K 2 FeO 4 oxidation may be attributed to the manganese (Mn 2+ ) and organic matter (Ethylenediaminetetraacetic acid, EDTA) in the ASM-1 media and high concentrations of natural organic matters (NOMs) in the CKL water. A delayed Chick-Watson model was applied to simulate the experimental data for cyanobacterial cell rupture, and the cell lysis rates of the M. aeruginosa samples were determined to be 128-242 M −1 s −1 (mol L −1 s −1 ). Generally, no significant increases in extracellular MCs were observed in the three different waters, even in the RYTR water where the membrane integrity of the cyanobacterial cells was severely disrupted. Therefore, K 2 FeO 4 could be a potential pre-oxidant to enhance subsequent treatments for cyanobacteria removal without affecting the cell integrity, or could serve as a post-oxidant to inactivate cyanobacterial cells and degrade MCs effectively, depending on the specific water matrix. [ABSTRACT FROM AUTHOR]