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Lignin-carbohydrate complexes (LCCs) are important from the perspective of the anti-depolymerization barrier of lignocellulosic biomass, as it limits the high-value utilization of lignocellulosic biomass resources. In this study, the unit structure of lignin in the LCC has been investigated in depth. Oxidation of a selective lignin unit by chlorine dioxide revealed that the LCC structures are enriched with xylanase-macroporous resins, and the structure that was not oxidized in LCC was also identified. At a chlorine dioxide concentration of 90.93 mg/L, 1 g of LCC lignin is oxidized by 0.7 g chlorine dioxide. The purified residual hemicellulose lignin was mainly H-type. The β-O-4' signal was the strongest for the bond between lignin and carbohydrates. Therefore, it is speculated that most of the residual lignin in bamboo-alkali hemicellulose exists in the form of non-phenolic structural units. This study provides a reference for further studies on the specific structures of LCC.

The iron (Fe) metabolism plays important role in regulating systemic metabolism and obesity development. The Fe inside cells can form iron-sulfur (Fe-S) clusters, which are usually assembled into target proteins with the help of a conserved cluster assembly machinery. Family with sequence similarity 96A (FAM96A; also designated CIAO2A) is a cytosolic Fe-S assembly protein involved in the regulation of cellular Fe homeostasis. However, the biological function of FAM96A in vivo is still incompletely defined. Here, we tested the role of FAM96A in regulating organismal Fe metabolism, which is relevant to obesity and adipose tissue homeostasis. We found that in mice genetically lacking FAM96A globally, intracellular Fe homeostasis was interrupted in both white and brown adipocytes, but the systemic Fe level was normal. FAM96A deficiency led to adipocyte hypertrophy and organismal energy expenditure reduction even under nonobesogenic normal chow diet-fed conditions. Mechanistically, FAM96A deficiency promoted mechanistic target of rapamycin (mTOR) signaling in adipocytes, leading to an elevation of de novo lipogenesis and, therefore, fat mass accumulation. Furthermore, it also caused mitochondrial defects, including defects in mitochondrial number, ultrastructure, redox activity, and metabolic function in brown adipocytes, which are known to be critical for the control of energy balance. Moreover, adipocyte-selective FAM96A knockout partially phenocopied global FAM96A deficiency with adipocyte hypertrophy and organismal energy expenditure defects but the mice were resistant to high-fat diet-induced weight gain. Thus, FAM96A in adipocytes may autonomously act as a critical gatekeeper of organismal energy balance by coupling Fe metabolism to adipose tissue homeostasis.

Biofilm infection will cause chronic inflammation and hinder the normal healing process of wound. Here, based on the self-assembly of three designed amphiphilic pentapeptides named EK, GG, and DR, pH-switchable antibacterial hydrogels with amphiphilic fiber network are used for the eradication of biofilms and the rescue of delayed healing in infected wounds. These pentapeptides-based hydrogels exhibit an acidic pH-switchable antimicrobial effect and are biocompatible at neutral pH. Additionally, supramolecular nanofiber networks with physical cross-linking with thermosensitive polymers (PNIPAm) and loaded antibacterial oregano oil are further developed.

The tea beverages will be endowed with distinct aroma and taste, as well as various biologically active compounds including probiotic factors, when fermented with lactic acid bacteria (LAB). However, at present, few studies on the dynamics of flavors in tea soup at different fermentation stages were conducted. In this study, the composition of monosaccharides, aromatic components, free amino acids, and organic acids were measured, when the black tea beverages were fermented with

Background Since time immemorial, natural active compounds including essential oils (EOs) and their components have been used due to their flavor and fragrance. Out of 3000 known varieties, 300 are commercially utilized for the food and pharmaceutical industries. Scope and approach In recent years, studies on EOs have enormously increased owing to their remarkable biological activities and health benefits. As a result, their pharmacological attributes have played an immense role to identify natural and safe alternative therapeutics to extend their industrial applications. Key findings and conclusions: This review covers the sources and composition of EOs, recent progress in their extraction methods, factors affecting their quality and yield, their most important activities, such as antioxidant and antimicrobial activities as well as their mechanisms of action. Besides, the importance of EOs in food, biomedicine, and agricultural industries is also highlighted. For the food industrial applications, we mainly aimed at the incorporation of EOs as such or as nanoemulsions into active or smart packaging with a particular emphasis on the food preservation and shelf-life extension of food products.

Effectively breaking down its anti-depolymerization barrier is key to the conversion and utilization of biomass resources. The anti-depolymerization barrier is mainly composed of a lignin-carbohydrate complex (LCC), which hinder the high-value utilization of biomass. In an alkaline environment, phenyl glycosidic bonds in LCC exist stably. Therefore, it is of great significance for the structural analysis of LCC in alkaline environment. In this study, LCC rich in carbohydrates was extracted from alkaline hemicellulose by using the xylanase-macroporous resin method, the effects of enzyme dosage and treatment time on LCC enrichment were discussed. The results showed that the LC bond of LCC samples was dominated by phenyl glucoside bond, the composition of lignin showed the rule of S H G. This method could fulfill the requirements of lignin enrichment and structural integrity. This provides a new method for solving the problems of LCC signal masking and low detection sensitivity.

The metabolic alterations of amino acid metabolism are closely associated with inflammatory response. However, relatively little is known about the roles of phenylalanine (Phe)/tyrosine (Tyr) catabolites during inflammation. Nitisinone (NTBC) is an orphan drug used to treat hereditary tyrosinemia type I potentially by changing Phe/Tyr metabolic flow. In this study, we used NTBC as a tool to investigate the potential role of the Phe/Tyr catabolic pathway in inflammatory responses. We found that NTBC was effective in tempering the bacterial endotoxin lipopolysaccharide (LPS)-induced septic shock in mice. Mechanistically, the protective effect was related to the accumulation of a Phe/Tyr catabolic intermediate, 4-hydroxyphenylpyruvate (4-HPP), induced by the NTBC treatment. 4-HPP could inhibit NLRP3 inflammasome priming and activation processes and therefore reduce IL-1β release and pyroptosis. Like NTBC, 4-HPP was also effective in attenuating endotoxic shock in mice. Our results suggest the Phe/Tyr catabolic pathway as a potential immunoregulatory hub that may be exploited therapeutically to alleviate inflammation.

Multidrug-resistant bacteria infections frequently occur in wound care due to the excessive use of antibiotics. It can cause scar formation, wound closure delay, multiple organ failure, and high mortality. Here, a double network hydrogel with injectability, hemostasis, and antibacterial activity was developed to prompt multidrug-resistant bacteria infected wound healing. The double network hydrogel is composed of gelatin methacryloyl (GelMA), oxidized dextran (ODex), ε-polylysine (EPL), and bacitracin, and formed through the Schiff-base and UV-initiated crosslinking reaction. The injectable hydrogel with an adhesion effect could adapt to the irregular shape of the wound and possesses good hemostatic ability. The hydrogel presents good flexibility and rapid resilience due to its double network structure, and it can prompt cell proliferation and migration. In particular, the hydrogel has broad-spectrum

The proliferation and global expansion of multidrug-resistant (MDR) bacteria have deepened the need to develop novel antimicrobials. Antimicrobial peptides (AMPs) are regarded as promising antibacterial agents because of their broad-spectrum antibacterial activity and multifaceted mechanisms of action with non-specific targets. However, if AMPs are to be applied sustainably, knowledge of how they induce resistance in pathogenic bacteria must be mastered to avoid repeating the traditional antibiotic resistance mistakes currently faced. Furthermore, the evolutionary constraints on the acquisition of AMP resistance by microorganisms in the natural environment, such as functional compatibility and fitness trade-offs, inform the translational application of AMPs. Consequently, the shortcut to achieve sustainable utilization of AMPs is to uncover the evolutionary constraints of bacteria on AMP resistance in nature and find the tricks to exploit these constraints, such as applying AMP cocktails to minimize the efficacy of selection for resistance or combining nanomaterials to maximize the costs of AMP resistance. Altogether, this review dissects the benefits, challenges, and opportunities of utilizing AMPs against disease-causing bacteria, and highlights the use of AMP cocktails or nanomaterials to proactively address potential AMP resistance crises in the future.

Recent progress indicates that the gut microbiota plays important role in regulating the host's glucose homeostasis. However, the mechanisms remain unclear. Here, we reported that one integral member of the murine gut microbiota, the protozoan

The herpes virus entry mediator (HVEM) is an immune checkpoint molecule regulating immune response, but its role in tissue repair remains unclear. Here, we reported that HVEM deficiency aggravated hepatobiliary damage and compromised liver repair after 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC)-induced injury. A similar phenotype was observed in B and T lymphocyte attenuator (BTLA)-deficient mice. These were correlated with impairment of neutrophil accumulation in the liver after injury. The hepatic neutrophil accumulation was regulated by microbial-derived secondary bile acids. HVEM-deficient mice had reduced ability to deconjugate bile acids during DDC-feeding, suggesting a gut microbiota defect. Consistently, both HVEM and BTLA deficiency had dysregulated intestinal IgA responses targeting the gut microbes. These results suggest that the HVEM-BTLA signaling may restrain liver injury by regulating the gut microbiota.

Asparanin A (AA), a natural compound present in vegetables and medicinal herbs like Asparagus officinalis L., has been investigated extensively for its pharmacological attributes. So far, the effect of AA on endometrial cancer (EC) cell migration and invasion has not been explored. Herein, we elucidated the anti-metastasis mechanism of AA on Ishikawa cells based on miRNA-seq and mRNA-seq integrated analyses. AA treatment led to altered miRNAs expression in Ishikawa cells and inhibited the cell wound healing, cell migration and invasion. Gene Ontology and KEGG enrichment analyses showed that the target genes of different expression miRNAs were significantly enriched in Ras, Rap1 and MAPK signaling pathways. Further verification of these changes via qRT-PCR and Western blot assays in vitro and in vivo demonstrated that AA could suppress human EC cell migration and invasion through Ras/ERK/MAPK pathway. Furthermore, top two miRNAs (miR-6236-p5 and miR-12136_R+8) and top three target genes (KITLG, PDGFD, and NRAS) were identified as functional hub miRNAs and genes through miRNA-target gene network analysis. Our data presented a holistic approach to comprehend the anti-metastatic role of AA in EC after in vitro and in vivo analyses.

Synergistic antibacterial effect is a promising way to overcome the challenge of microbial contamination in food. In this study, we detected the synergistic interactions of nisin and carvacrol. The MIC of nisin and carvacrol against S. aureus were 60 and 125 μg/mL, respectively. The FICI and FBCI were 0.28125 and 0.09375, which suggested that the nisin/carvacrol combination presented synergistic antibacterial effect against S. aureus. The antibacterial activity of nisin/carvacrol combination was much higher than their individuals and the dose of antibacterials was obviously reduced. The combination could completely kill S. aureus within 8 h, accelerate the destruction of cell membrane, and inhibit formation of biofilm. Under the intervention of nisin, more CAR could enter cell to hunt intracellular targets, leading to an increase in intracellular antibacterial level. Besides, in the storage of pasteurized milk, the combinational treatment successfully inhibited microbial reproduction at 25 °C and 4 °C. Thus, the combination of nisin and carvacrol was a potential synergistic strategy for food preservation.

Endometrial cancer (EC) is a malignancy that severely threatens women's health and there is an urgent need to find novel natural compounds as effective treatment drugs. At the same time, multi-omics analysis of cells has been widely used in basic research to find new pathogenesis and mechanisms. Due to the lack of data on the functional importance of mRNAs and miRNAs in plant-derived asparanin A (AA) induced cancer cells, the underlying mechanisms of AA on endometrial cancer (EC) Ishikawa cells were investigated using mRNA-seq and miRNA-seq, qRT-PCR, western blot, and immunohistochemistry. The combined analysis of 37 differentially expressed miRNAs (DEMs) and 489 differentially expressed genes (DEGs) with negative regulatory relationships revealed that AA not only induced apoptosis, but also triggered autophagy through endoplasmic reticulum (ER) stress and DNA damage-related pathways. 23 DEMs and 39 DEGs participated in protein processing in the endoplasmic reticulum (PPER) and p53 signaling pathways, as shown by miRNA-target gene network analyses. Among them, we concluded that miR-6236-p5, miR-1246-p5, miR-11987_L-1, PC-5p-21544, and miR-5100-p3_1ss17TC function as hub miRNAs, and their regulation may be essential for the anti-cancer activity of AA. This study may provide a comprehensive understanding of the potential anticancer regulation of AA on EC, suggesting AA as a potential candidate for dietary supplementation in cancer medication and prevention.

Though essential oils exhibit antibacterial activity against food pathogens, their underlying mechanism is understudied. We extracted ginger essential oil (GEO) using supercritical CO2 and steam distillation. A chemical composition comparison by GC-MS showed that the main components of the extracted GEOs were zingiberene and &alpha, curcumene. Their antibacterial activity and associated mechanism against Staphylococcus aureus and Escherichia coli were investigated. The diameter of inhibition zone (DIZ) of GEO against S. aureus was 17.1 mm, with a minimum inhibition concentration (MIC) of 1.0 mg/mL, and minimum bactericide concentration (MBC) of 2.0 mg/mL. For E. coli, the DIZ was 12.3 mm with MIC and MBC values of 2.0 mg/mL and 4.0 mg/mL, respectively. The SDS-PAGE analysis revealed that some of the electrophoretic bacterial cell proteins bands disappeared with the increase in GEO concentration. Consequently, the nucleic acids content of bacterial suspension was raised significantly and the metabolic activity of bacteria was markedly decreased. GEO could thus inhibit the expression of some genes linked to bacterial energy metabolism, tricarboxylic acid cycle, cell membrane-related proteins, and DNA metabolism. Our findings speculate the bactericidal effects of GEO primarily through disruption of the bacterial cell membrane indicating its suitability in food perseveration.

Owing to the existence of lignin-carbohydrate complex (LCC) linkages, the extracted hemicellulose contains lignin, which is difficult to remove. Chlorine dioxide selectively oxidizes lignin without reacting with carbohydrates. In this study, chlorine dioxide was used to remove lignin from the hemicellulose sample. Ion chromatography and 2D-HSQC NMR were used to observe the changes in the LCC. After chlorine dioxide treatment, acid-insoluble lignin was largely degraded, with a removal rate reaching 68%. Furthermore, the 2D-HSQC NMR spectrum showed that guaiacyl (G) lignin underwent dramatic degradation and degradation of syringyl (S) lignin was also obvious. Phenyl glycoside-type LC linkages were also largely degraded. Moreover, the sugar composition and structure of the hemicellulose did not change significantly. This suggests that it is feasible to remove lignin from LCCs through oxidation of hemicellulose using chlorine dioxide. Meanwhile, hemicellulose with high molecular weight and high purity can be obtained by this method.

LI-F type peptides are a family of cyclic lipodepsipeptide antibiotics isolated from Paenibacillus polymyxa and display potent activities against positive bacteria including methicillin-resistant S. aureus (MRSA). In this study, we investigated the mechanism of action of LI-F type peptide AMP-jsa9 against a MRSA (S. aureus CICC10790), which is resistant to ciprofloxacin, gentamicin, kanamycin, chloramphenicol, methicillin, and tetracycline. It was found that AMP-jsa9 mainly targets the cell membrane of MRSA and is able to inhibit biofilm formation through killing planktonic bacteria cells. Moreover, AMP-jsa9 can bind to DNA in vitro, which represents another pathway for the action on MRSA. Furthermore, in vivo treatment of scalded mice with AMP-jsa9 resulted in inhibiting MRSA infections and healing of the scalded wound. In addition, it was demonstrated that AMP-jsa9 can effectively inhibit MRSA infections in scalded murine epidermis and that inflammatory cytokines including IL-8, IL-6, tumor necrosis factor alpha (TNF-α), and monocyte chemotactic factor-1 (MCP-1) were reduced; moreover, both protein and gene expression levels of vascular endothelial growth factor (VEGF) and endothelial nitric oxide synthase (e-NOS) were enhanced, which promote neovascularization and proliferation of new granulation tissue.

LI-F type peptides (AMP-jsa9) produced by Paenibacillus polymyxa JSa-9 are a group of cyclic lipodepsipeptide antibiotics that exhibit a broad antimicrobial spectrum against Gram-positive bacteria and filamentous fungi, especially Bacillus cereus and Fusarium moniliforme . In this study, to better understand the antibacterial mechanism of AMP-jsa9 against B. cereus , the ultrastructure of AMP-jsa9-treated B. cereus cells was observed by both atomic force microscopy and transmission electron microscopy, and quantitative proteomic analysis was performed on proteins extracted from treated and untreated bacterial cells by using isobaric tag for relative and absolute quantitation (iTRAQ) labeling and LC-MS/MS analysis to access differentially expressed proteins. Furthermore, multiple experiments were conducted to validate the results of the proteomic analysis, including determinations of ATP, NAD (+) H, NADP (+) H, reactive oxygen species (ROS), the activities of catalase (CAT) and superoxide dismutase (SOD), and the relative expression of target genes by quantitative real-time PCR. Bacterial cells exposed to AMP-jsa9 showed irregular surfaces with bleb projections and concaves; we hypothesize that AMP-jsa9 penetrated the cell wall and was anchored on the cytoplasmic membrane and that ROS accumulated in the cell membrane after treatment with AMP-jsa9, modulating the bacterial membrane properties and increasing membrane permeability. Consequently, the blebs were formed on the cell wall by the impulsive force of the leakage of intercellular contents. iTRAQ-based proteomic analysis detected a total of 1317 proteins, including 176 differentially expressed proteins (75 upregulated (fold > 2) and 101 downregulated (fold B. cereus can be summarized as: (i) inhibition of bacterial sporulation, thiamine biosynthesis, energy metabolism, DNA transcription and translation, and cell wall biosynthesis, through direct regulation of protein levels; and (ii) indirect effects on the same pathways through the accumulation of ROS and the consequent impairment of cellular functions, resulting from downregulation of antioxidant proteins, especially CAT and SOD. Biological significance The mode of action of LI-F type antimicrobial peptides (AMP-jsa9) against B. cereus was elucidated at the proteomic level. Two pathways of AMP-jsa9 action upon B. cereus cells were identified and the mechanism of bleb formation on the surfaces of bacterial cells was predicted based on the results of ultrastructural observation and proteomic analysis. These results are helpful in understanding the mechanism of LI-F type peptides and in providing the theoretical base for applying AMP-jsa9 or its analogs to combat Gram-positive pathogenic bacteria in the food and feed industries.

Artemisia selengensis Turcz possesses various health-promoting functions. However, the available information regarding the structure and biological activity of polysaccharides from A. selengensis Turcz (APS) is still limited. In the present study, the preliminary structure, antioxidant and immunostimulatory activities of a polysaccharide fraction from APS (APS1) were investigated. Results of Fourier transform-infrared spectroscopy (FT-IR), gas chromatography-mass spectrometry (GC-MS) and nuclear magnetic resonance (NMR) analyses showed that the main chain of APS1 was made up of T-α-D-Glcp-(1→, →4)-α-D-Glcp-(1 → and → 4)-α-D-Galp-(1 → residues). In addition, the moderate superoxide and ABTS radical scavenging activities and noticeable Fe2+ chelating activity of APS1 were observed. Furthermore, the administration of APS1 could significantly restore spleen and thymus indexes, increase the levels of serum hemolysin and lysozyme, and improve the liver function by remarkably preventing the elevation of MDA level and increasing the levels of catalase (CAT), total antioxidant capacity (T-AOC), superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) in cyclophosphamide-treated mice. These results suggested that APS1 exhibits antioxidant and immunostimulatory activities with potential application in functional foods.

Bacteriocins are ribosomally synthesized peptides with antimicrobial activity produced by numerous bacteria. A novel bacteriocin-producing strain, Lactobacillus plantarum JLA-9, isolated from Suan-Tsai, a traditional Chinese fermented cabbage, was screened and identified by its physiobiochemical characteristics and 16S rDNA sequence analysis. A new bacteriocin, designated plantaricin JLA-9, was purified using butanol extraction, gel filtration, and reverse-phase high-performance liquid chromatography. The molecular mass of plantaricin JLA-9 was shown to be 1044 Da by MALDI-TOF-MS analyses. The amino acid sequence of plantaricin JLA-9 was predicted to be FWQKMSFA by MALDI-TOF-MS/MS, which was confirmed by Edman degradation. This bacteriocin exhibited broad-spectrum antibacterial activity against Gram-positive and Gram-negative bacteria, especially Bacillus spp., high thermal stability (20 min, 121 °C), and narrow pH stability (pH 2.0-7.0). It was sensitive to α-chymotrypsin, pepsin, alkaline protease, and papain. The mode of action of this bacteriocin responsible for outgrowth inhibition of Bacillus cereus spores was studied. Plantaricin JLA-9 had no detectable effects on germination initiation over 1 h on monitoring the hydration, heat resistance, and 2,6-pyridinedicarboxylic acid (DPA) release of spores. Rather, germination initiation is a prerequisite for the action of plantaricin JLA-9. Plantaricin JLA-9 inhibited growth by preventing the establishment of oxidative metabolism and disrupting membrane integrity in germinating spores within 2 h. The results suggest that plantaricin JLA-9 has potential applications in the control of Bacillus spp. in the food industry.

Salmonella spp. are health-threatening foodborne pathogens. The increasingly common spread of antibiotic-resistant Salmonella spp. is a major public healthcare issue worldwide. In this study, we wished to explore (1) antibiotic or polypeptide combinations to inhibit multidrug-resistant Salmonella bredeney and (2) the regulation of cross-resistance and collateral sensitivity of antibiotics and polypeptides. We undertook a study to select antibiotic combinations. Then, we promoted drug-resistant strains of S. bredeney after 15 types of antibiotic treatment. From each evolving population, the S. bredeney strain was exposed to a particular single drug. Then, we analyzed how the evolved S. bredeney strains acquired resistance or susceptibility to other drugs. A total of 105 combinations were tested against S. bredeney following the protocols of CLSI-2016 and EUCAST-2017. The synergistic interactions between drug pairings were diverse. Notably, polypeptides were more likely to be linked to synergistic combinations: 56% (19/34) of the synergistic pairings were relevant to polypeptides. Simultaneously, macrolides demonstrated antagonism toward polypeptides. The latter were more frequently related to collateral sensitivity than the other drugs because the other 13 drugs sensitized S. bredeney to polypeptides. In an experimental evolution involving 15 drugs, single drug-evolved strains were examined against the other 14 drugs, and the results were compared with the minimal inhibitory concentration of the ancestral strain. Single drug-evolved S. bredeney strains could alter the sensitivity to other drugs, and S. bredeney evolution against antibiotics could sensitize it to polypeptides.

This work provides an optimized extraction approach intended to maximize the recovery of dihydromyricetin (DHM) from Chinese vine tea (Ampelopsis grossedentata) leaves. The presented work adopts a Box-Behnken design as a response surface methodology to understand the role and influence of specific extraction parameters including: time, temperature, and solvent composition/ethanol (%) on DHM final yields. Initially, single factor experiments were used to delineate the role of above factors (temperature, time, and solvent composition) before proceeding with three factors-three levels Box-Behnken design with 17 separate runs to assess the effect of multifactorial treatments on DHM recovery rates. The collected data shows that independent variables (solvent composition, time, and temperature) can significantly affect DHM recovery rates with maximum yields resulting from a combined 60 °C, 60% aqueous ethanol, and 180 min treatment. From the empirical point of view, the above optimized extraction protocol can substantially enhance processing and profitability margins with a minimum need of interventions or associated costs.

Methicillin-resistant Staphylococcus aureus (MRSA) has become increasingly prevalent in hospitals, clinics, and the community. MRSA can cause significant and even lethal infections, especially in skin burn wounds. The currently available topical agents have largely failed to eliminate MRSA infections due to resistance. Therefore, there is an urgent need for new and effective approaches for treating MRSA. Here, we show that a novel engineered amphipathic peptide, WRL3 (WLRAFRRLVRRLARGLRR-NH2), exhibits potent antimicrobial activity against MRSA, even in the presence of various salts or serum. The cell selectivity of WRL3 was demonstrated by its ability to specifically eliminate MRSA cells over host cells in a coculture model. Additionally, WRL3 showed a synergistic effect against MRSA when combined with ceftriaxone and effectively inhibited sessile biofilm bacteria growth leading to a reduction in biomass. Fluorescent measurements and microscopic observations of live bacterial cells and artificial membranes revealed that WRL3 exerted its bactericidal activity possibly by destroying the bacterial membrane. In vivo studies indicate that WRL3 is able to control proliferation of MRSA in wound tissue and reduce bioburden and provides a more favorable environment for wound healing. Collectively, our data suggest that WRL3 has enormous potential as a novel antimicrobial agent for the treatment of clinical MRSA infections of skin burn wounds.

Aims LI–Fs are a family of highly potent cyclic lipodepsipeptide antibiotics with a broad antimicrobial spectrum (Gram–positive bacteria and fungi). In this study, LI–F type antimicrobial peptides (AMP–jsa9) composing of LI–F03a, LI–F03b, LI–F04a, LI–F04b, and LI–F05b were isolated from Paenibacillus polymyxa JSA–9. To better understand the antimicrobial mechanism of AMP–jsa9, the potency and action(s) of AMP–jsa9 against B. cereus were examined. Methods and Results Flow cytometry, confocal laser microscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and atomic force microscopy (AFM) observation, as well as determination of peptidoglycan and cell wall associated protein, and other methods were used. The results indicate that AMP–jsa9 exhibits strong, broad spectrum antimicrobial activity. Moreover, AMP–jsa9 targets the cell wall and membrane of B. cereus to impair membrane integrity, increase membrane permeability, and enhance cytoplasm leakage (e.g., K+, protein, nucleic acid). This leads to bacterial cells with irregular, withered, and coarse surfaces. In addition, AMP–jsa9 is also able to bind to DNA and break down B. cereus biofilms. Conclusions In this study, the action mechanism of LI–Fs against B. cereus were clarified in details. Significance and Impact of Study The results of this study provides a theoretical basis for utilizing AMP–jsa9 or similar analogs as natural and effective preservatives in the food and feed industries. These efforts could also stimulate research activities interested in understanding the specific effects of other antimicrobial agents. This article is protected by copyright. All rights reserved.

To convert the lipopeptide non-producer strain Bacillus subtilis pB2 into a plipastatin and surfactin coproducer, a gene expression cassette composed of a constitutive promoter (P43), functional gene sfp, and pleiotropic regulatory gene degQ was integrated into the chromosomal amyE locus of strain B. subtilis pB2 by homologous recombination, which generated a plipastatin and surfactin co-producer. Thirteen plipastatins and fifteen surfactins were identified in lipopeptide extracts using analytical techniques, and their effects on microorganisms were described by microscopic, cytoskeleton analysis and flow-cytometry, respectively. Plipastatins isolated from the engineered strain pB2-L exhibited strong antifungal activity (MIC 16 μg ml−1) by disrupting the cell walls, membranes and cytoskeleton of Fusarium oxysporum f. sp. cucumerinum hyphae. Surfactins affected the cell membrane of Staphylococcus aureus (MIC 20 μg ml−1), resulting in nucleic acid leakage and ultimately, cell death. Based on the convenience of genetic manipulation in the engineering strain, this work could be useful for the rational design of lipopeptide synthetases via the recombination of gene fragments to generate arrays of peptide derivatives and thus expand the diversity of microbial-produced lipopeptides.

Non-ribosomal peptide synthetases (NRPSs) are large enzymatic complexes that catalyse the synthesis of biologically active peptides in microorganisms. Genetic engineering has recently been applied to reprogram NRPSs to produce lipopeptides with a new sequence. The carboxyl-terminal thioesterase (TE) domains from NRPSs catalyse cleavage products by hydrolysis or complex macrocyclization. In this study, we modified plipastatin synthetase by moving the intrinsic TE region to the end of the internal thiolation (T) domains, thus generating Bacillus subtilis strains that could produce new truncated cyclic or linear peptides of the predicted sequence, which further provided an important insight into the regioselectivity of plipastatin TE. The TE was capable of recognizing and catalysing the lactone formation between L-Try3 with the last few residues L-Pro7 and L-Gln8 at the C-terminus. Additionally, the unmatched linkers connecting the TE region and T domain resulted in nonproduction strains, suggesting that the native T–TE linker is necessary and sufficient for the TE domain to release the products from the hybrid enzymes. This is the first report to demonstrate truncated cyclic lipopeptides production and module skipping by simply moving the TE domain forward in an NRPS system.

LI-F type peptides (AMP-jsa9) are a group of cyclic lipodepsipeptides that exhibit broad antimicrobial spectrum against Gram-positive bacteria and filamentous fungi. We sought to assess the toxicity of AMP-jsa9 and the mechanism of AMP-jsa9 action against Fusarium moniliforme. AMP-jsa9 exhibited weak hemolytic activity and weak cytotoxicity at antimicrobial concentrations (32μg/ml). Confocal laser microscopy, SEM, and TEM indicated that AMP-jsa9 primarily targets the cell wall, plasma membrane, and cytoskeleton, increases membranepermeability, and enhances cytoplasm leakage (e.g., K+, protein). Quantitative proteomic analysis using isobaric tags for relative and absolute quantitation (iTRAQ) detected a total of 162 differentially expressed proteins (59 up-regulated and 103 down-regulated) following treatment of F. moniliforme with AMP-jsa9. AMP-jsa9 treatment also led to reductions in chitin, ergosterol, NADH, NADPH, and ATP levels. Moreover, fumonisin B1 expression and biosynthesis was suppressed in AMP-jsa9-treated F. moniliforme. Our results provide a theoretical basis for the application of AMP-jsa9 as a natural and effective antifungal agent in the agricultural, food, and animal feed industries.

Both donors and acceptors of communication-mediating (COM) domains are essential for coordinating intermolecular communication within nonribosomal peptides synthetases (NRPSs) complexes. Different sets of COM domains provide selectivity, allowing NRPSs to utilize different natural biosynthetic templates. In this study, novel lipopeptides were synthesized by reprogramming the plipastatin biosynthetic machinery. A Thr-to-Asp point mutation was sufficient to shift the selectivity of the donor COM domain of ppsB toward that of ppsD. Deletion and/or interchangeability established donor and acceptor function. Variations in acceptor COM domain did not result in novel product formation in the presence of its partner donor, whereas plipastatin formation was completely abrogated by altering donor modules. Five novel lipopeptides (cyclic pentapeptide, linear hexapeptide, nonapeptide, heptapeptide, and cyclic octapeptide) were identified and verified by high-resolution LC-ESI-MS/MS. In addition, we demonstrated the potential to generate novel strains with the antimicrobial activity by selecting compatible COM domains, and the novel lipopeptides exhibited antimicrobial activity against five of the fungal species at a contention of 31.25-125 μg/ml.

Aims To explore the influence of carbohydrates on the production of fengycin by Bacillus amyloliquefaciens fmb-60. Methods and Results Fermentation and gene expression levels were examined following culture supplementation with fructose, arabinose and sorbitol. Compared with other carbohydrates, fructose most efficiently increased the concentration of the essential component amino acids for fengycin synthesis in the cell. The maximum production of fengycin was found to be 392.87 mg l-1, increased by 76% in fed-batch fermentation. Furthermore, fructose enhanced the biosynthesis of fengycin by increasing the expression of fengycin synthetase genes (fenA, fenB, fenC, fenD, fenE and fenTE) and regulatory genes (comA, degU, degQ and sigma H). Conclusion Fructose is important for fengycin production in B. amyloliquefaciens fmb-60, and it could enhance fengycin biosynthesis by raising the expression of the fengycin synthetase genes and upregulating signal factors. Significance and Impact of the Study The results identify regulatory mechanisms involved in fengycin biosynthesis and provide an effective method to enhance production of fengycin. This article is protected by copyright. All rights reserved.

Auxotrophic strains of N1-37 (Phe-) and N2-27 (His-), screened from mutations of Paenibacillus polymyxa JSa-9 previously, were used as the parent strains to screen high-producing LI-F antibacterial lipopeptide fusion strain through protoplast fusion with polyethylene glycol as a promote agent. Fusion strain F5-15 was obtained. Then the product of LI-F antibacterial lipopeptide was quantified by HPLC, and the difference of expression of the key genes of lipopeptide synthase between wild strain JSa-9 and the fusion strain was analyzed by real-time PCR. LI-F antibacterial lipopeptide yield of the fusion strain F5-15 was 3.1-fold of the original strain JSa9's, and the expression levels of the target genes were 10.48, 2.48, 2.1 and 11.8 fold of the initial strain JSa-9, respectively.

Localization is emerging as a fundamental component in wireless sensor network and is widely used in the fields of environmental monitoring, national defense and military, transportation, and so on. Current positioning system, however, can only locate an object's position in isotropy wireless sensor network with high accuracy but cannot locate it accurately in anisotropy wireless sensor network. Besides, past proposals only mentioned anisotropy to show that connectivity of network is different in each direction. However, how to quantify the degree of anisotropy is not clearly pointed out. This paper introduces NDSL (node density-based subregional localization), a positioning system that is used in anisotropy wireless sensor network. The network is divided into many subregions where the nodes density is relatively uniform and then corrects the single-hop distance for each beacon node to locate unknown nodes. We also use nodes distribution and signals distribution to build a model to evaluate the degree of anisotropy for anisotropy network. Through the analysis of the degree of anisotropy for different topologies, the results show that the model is consistent with the facts. Results from actual deployments and simulation experiments show that the accuracy of NDSL algorithm obviously improves compared with DV-Hop algorithm.

Earthen site is an important part of our cultural heritage, so monitoring and protecting its living condition is vital. Like other country, in china many sites also face collapse even destruction danger. In this paper, we present a novel framework and a site survival model to monitor Danfeng Gate of Daming Palace, analyze the data collected by wireless sensor networks (WSNs) for early warning. In order to forecast the health trend, we also adopt the Neural networks and Bayesian model processing internal and external environment data to predict the health status.