Recent development in antibacterial activity and application of nanozymes in food preservation.

Nanozymes with excellent broad-spectrum antibacterial properties offers an alternative strategy for food preservation. This review comprehensively summarized the antibacterial mechanisms of nanozymes, including the generation of reactive oxygen species (ROS) and the destruction of biofilms. Besides, the primary factors (size, morphology, hybridization, light, etc.) regulating the antibacterial activity of different types of nanozymes were highlighted in detail, which provided effective guidance on how to design highly efficient antibacterial nanozymes. Moreover, this review presented elaborated viewpoints on the unique applications of nanozymes in food preservation, including the selection of nanozymes loading matrix, fabrication techniques of nanozymes-based antibacterial films/coatings, and the recent advances in the application of nanozymes-based antibacterial films/coatings in food preservation. In the end, the safety issues of nanozymes have also been mentioned. Overall, this review provided new avenues in the field of food preservation and displayed great prospects.

ATF4 promotes lung cancer cell proliferation and invasion partially through regulating Wnt/ß-catenin signaling.

Activating transcription factor 4 (ATF4) is a member of the cAMP response element binding (CREB) protein family and has been reported to participate in cancer progression; however, its molecular mechanism is not fully understood. In this study, we investigated the function of ATF4 in non-small cell lung cancer and its molecular regulation. We detected cytoplasmic and nuclear ATF4 expression in lung cancer A549, H1299, and LK2 cells, and the total expression of ATF4 was higher than that in HBE cells (p < 0.05). Higher nuclear ATF4 expression was detected in all these cells compared to cytoplasmic ATF4 expression (p < 0.05). Overexpression of ATF4 in A549 cells significantly promoted cancer cell growth and invasion (p < 0.05). Expression of Wnt signaling molecules, including ß-catenin, MMP7, and cyclin D1, and the activity of canonical Wnt signaling were also significantly promoted by ATF4 (p < 0.05). ICG001, a canonical Wnt signaling inhibitor that selectively inhibits ß-catenin/ cyclic adenosine monophosphate response element binding protein (CBP) interaction, significantly inhibited cancer cell invasion and Wnt signaling. The function of ATF4 was also significantly inhibited by ICG001 (p < 0.05). However, compared to treatment with ICG001, the invasion ability of cancer cells treated with both ICG001 and ATF4 cDNA significantly increased (p < 0.05), which indicates that the function of ATF4 was not dependent only on Wnt/ß-catenin signaling. The function of ATF4 in the regulation of ß-catenin expression was not significantly affected by ICG001 (p > 0.05). The function of ATF4 to promote the activity of Wnt/ß-catenin signaling in cancer cells was abolished by treatment with ICG001 (p > 0.05). These results indicate that ATF4 may contribute to lung cancer progression at least partly by regulating Wnt/ß-catenin signaling.

Nitrogen deficiency maintains the yield and improves the antioxidant activity of Coreopsis tinctoria Nutt.

Nitrogen (N) deficiency levels were investigated for their potential to maintain the yield and improve antioxidant activity of Coreopsis tinctoria. Inflorescences and leaves at 0, 10, 20, 30, 40, and 50 d after flowering were frozen at -80 °C and plant growth, antioxidant activity, bioactive substance, enzyme activity, and gene expression were evaluated. N deficiency maintained the total number of flowers, promoted phenol and flavonoid accumulation, and enhanced antioxidant activity. Moreover, N deficiency stimulated activities of phenylalanine ammonia-lyase (PAL), cinnamate-4-hydroxylase (C4H) and 4-coumarate:coenzyme A ligase (4CL), and induced CtPAL, CtC4H and Ct4CL gene expression. The data also suggest that N-deficiency-induced phenolic and flavonoid accumulation occurs due to the activation of biosynthetic pathways in C. tinctoria. We characterize the unique features of C. tinctoria under N-deficiency conditions and provide valuable information for the cultivation of high-N use efficiency varieties with low input and high output.

Ube2S regulates Wnt/ß-catenin signaling and promotes the progression of non-small cell lung cancer.

Ubiquitin conjugating enzyme E2S (Ube2S) plays important roles in cancer development in some malignant tumors. However, the functions and related molecular network of Ube2S in non-small cell lung cancer are not fully understood. In the current study, we examined the expression of Ube2S in non-small cell lung cancer and its clinicopathological significance. We also investigated the molecules and pathways regulated by Ube2S. An immunostaining study showed that the positive rate of Ube2s expression in lung cancer tissues was higher than that in normal lung tissues (p < 0.05). Upregulated Ube2S expression in cancer tissues significantly correlated with clinical progression (TNM III versus I + II), lymph node metastasis, and shorter survival time of the patients (p < 0.05). When Ube2S was overexpressed in A549 cells, the abilities of these cells to proliferate and migrate were increased (p < 0.05). Moreover, Ube2S significantly upregulated the expression of ß-catenin, cyclin D1, and MMP7 (novel molecules of the Wnt/ß-catenin pathway), and the activity of this pathway (p < 0.05). In addition, a Wnt/ß-catenin signaling inhibitor effectively abolished the function of Ube2S. These results indicate that Ube2S may be a novel marker contributing to lung cancer development, possibly through regulating canonical Wnt signaling.

Crystallinity of polyolefins with large side groups by low-field 1H NMR T2 relaxometry: Isotactic Polybutene-1 with form II and I crystals.

Phase composition and molecular mobility were studied using 1H NMR T2 relaxometry in isotactic polybutene-1 (iPB-1) with two polymorphs - form I and II crystals. Several types of NMR relaxation methods and data analysis were evaluated for determining the most reliable way for studying physical phases in iPB-1. Three-phase model provided the most appropriate description of the phase composition in iPB-1, i.e., a crystal-amorphous interface separates the crystalline and the amorphous phases. Due to complex molecular mobility in iPB-1, the amount of rigid fraction should be considered as NMR crystallinity number. Two types of chain segments are present in the amorphous phase: (1) chain segments with anisotropic mobility due to chain anchoring to crystals and chain entanglements; and (2) highly mobile chain end segments. The polymorphic phase II to I transition causes significant immobilization of polymer chains in the crystalline and the amorphous phases. Molecular weight of iPB-1 largely influences phase composition and molecular mobility in crystalline and amorphous phases.

Nucleopeptide Assemblies Selectively Sequester ATP in Cancer Cells to Increase the Efficacy of Doxorubicin.

Herein, we report that assemblies of nucleopeptides selectively sequester ATP in complex conditions (for example, serum and cytosol). We developed assemblies of nucleopeptides that selectively sequester ATP over ADP. Counteracting enzymes interconvert ATP and ADP to modulate the nanostructures formed by the nucleopeptides and the nucleotides. The nucleopeptides, sequestering ATP effectively in cells, slow down efflux pumps in multidrug-resistant cancer cells, thus boosting the efficacy of doxorubicin, an anticancer drug. Investigation of 11 nucleopeptides (including d- and l-enantiomers) yields five more nucleopeptides that differentiate ATP and ADP through either precipitation or gelation. As the first example of assemblies of nucleopeptides that interact with ATP and disrupt intracellular ATP dynamics, this work illustrates the use of supramolecular assemblies to interact with small and essential biological molecules for controlling cell behavior.

Pararhizobium antarcticum sp. nov., isolated from Antarctic water samples.

Two bacterial strains were isolated from sediments and microbial mats of Kingfisher Pond, Antarctica and characterized in a taxonomic study using a polyphasic approach. Cells were strictly aerobic, Gram-stain-negative, rod-shaped, motile (+50 flagellum-specific genes present in the genome sequence; motility observed under microscope) and formed creamy white, half-transparent colonies. Growth occurred at 4 to 28 °C with an optimum at 20 °C, with 0-5.0 % (w/v) NaCl (optimum at 0-1.0 %) and at pH 4.0-11.0 (optimum pH 7.0-9.0). The major fatty acid was C18 : 1ω7c. The respiratory quinone was ubiquinone 10 (Q-10). The DNA G+C content was 60.7 mol %. The polar lipids were phosphatidylglycerol, phosphatidylethanolamine and phosphatidylmethanolamine in addition to three unidentified lipids, one unknown glycolipid and five unidentified phospholipids. Comparative analysis of 16S rRNA gene sequences showed highest sequence similarity (98.1 %) to Pararhizobium giardinii H152T, Pararhizobium herbae CCBAU 83011T, and 'Pararhizobium polonicum' F5.1. In silico average nucleotide identity (ANI) and genome-to-genome distance calculator (GGDC) showed 81.1 % identity (ANI) and 22.6 % identity (GGDC) to the closest relative, 'P. polonicum' F5.1. On the basis of phenotypic, phylogenetic, genomic and chemotaxonomic data, the two strains represent a novel species of the genus Pararhizobium, for which the name Pararhizobium antarcticum sp. nov. is proposed. The type strain is NAQVI 59T(=DSM 103442T=LMG 29675T).

Survival in amoeba--a major selection pressure on the presence of bacterial copper and zinc resistance determinants? Identification of a "copper pathogenicity island".

The presence of metal resistance determinants in bacteria usually is attributed to geological or anthropogenic metal contamination in different environments or associated with the use of antimicrobial metals in human healthcare or in agriculture. While this is certainly true, we hypothesize that protozoan predation and macrophage killing are also responsible for selection of copper/zinc resistance genes in bacteria. In this review, we outline evidence supporting this hypothesis, as well as highlight the correlation between metal resistance and pathogenicity in bacteria. In addition, we introduce and characterize the "copper pathogenicity island" identified in Escherichia coli and Salmonella strains isolated from copper- and zinc-fed Danish pigs.

Adaptive recursive sliding mode based trajectory tracking control for cable-driven continuum robots.

To improve the transient response, accuracy and robustness of trajectory tracking control for cable-driven continuum robots (CDCRs), a recursive integral terminal sliding mode control combined with an adaptive disturbance observer (ADO-RITSMC) is proposed. The recursive integral terminal sliding mode control (RITSMC) guarantees fast transient response and high tracking accuracy with a fast zero convergence of the tracking error without chattering. To attenuate the effect of uncertain dynamics, an adaptive disturbance observer (ADO) is constructed to derive uncertain dynamics. Particularly, an improved grey wolf optimizer (IGWO) is merged into the ADO to enhance the estimating accuracy of uncertain dynamic factors. Simulation and experiment results demonstrate the superiority of the ADO-RITSMC in enabling fast transient response, high accuracy and strong robustness of trajectory tracking control.

Colorimetric sensor array for the rapid distinction and detection of various antibiotic-resistant psychrophilic bacteria in raw milk based-on machine learning.

In this study, a rapid, inexpensive, and accurate colorimetric sensor for detecting psychrophilic bacteria was designed, comprising gold (Au) nanoparticles (NPs) modified by d-amino acid (D-AA) as color-metric probes. Based on the aggregation of Au NPs induced by psychrophilic bacteria, a noticeable color shift occurred within 6 h. Depending on the various metabolic behaviors of bacteria to different D-AA, four primary psychrophilic bacteria in raw milk were successfully distinguished by learning the response patterns. Furthermore, the quantification of single bacteria and the practical application in milk samples could be realized. Notably, a rapid colorimetric method was constructed by combining Au/D-AA with antibiotics for the minimum inhibitory concentration of psychrophilic bacteria, which relied on differences in bacteria metabolic activity in response to diverse antibiotic treatments. Therefore, the method enables the rapid detection and susceptibility evaluation of psychrophilic bacteria, promoting clinical practicability and antibiotic management.

Succession of microbiota and its influence on the dynamics of volatile compounds in the semi-artificial inoculation fermentation of mulberry wine.

To improve the delightful flavor of mulberry wine through semi-artificial inoculation fermentation with Saccharomyces cerevisiae, we studied the dynamics change of microbiota, along with the physicochemical properties and metabolite profiles and their interaction relationship during the fermentation process. The abundance of lactic acid bacteria (Weissella, Lactobacillus, Fructobacillus, and Pediococcus) increased significantly during fermentation, while yeasts gradually established dominance. The inter-kingdom network of the dominant genera analysis further identified the following as core microbiota: Alternaria, Botrytis, Kazachstania, Acremonium, Mycosphaerella, Pediococcus, Gardnerella, and Schizothecium. Additionally, pH, alcohol, and total acid were significantly affected by microbiota variation. Fourteen of all identified volatile compounds with key different aromas were screened using PCA, OPLS-DA, and rOAV. The network of interconnected core microbiota with key different aromas revealed that Kazachstania and Pediococcus had stronger correlations with 1-butanol, 3-methyl-, propanoic acid, and 2-methyl-ethyl ester.

Optimization of Fermentation Conditions and Metabolite Profiling of Grape Juice Fermented with Lactic Acid Bacteria for Improved Flavor and Bioactivity.

To enrich the flavor compounds and retain the content of polyphenolics in grape juice (GJ) under long-term storage, Lactiplantibacillus plantarum, Lactobacillus acidophilus, Lacticaseibacillus casei, and Lacticaseibacillus paracasei, were screened and the optimal fermentation conditions were determined as fermentation temperature of 41.2 °C for 24 h with an initial LAB density of 8.5 × 106 CFU/mL. Surprisingly, the retention rates of TPC still remained at 50% after storage for 45 days at 4 °C. Moreover, 251 different metabolites were identified, include 23 polyphenolics, 11 saccharides, and 9 organic acids. Most importantly, the total content of polyphenolics reserved was 92.65% at the end of fermentation. Among them, ephedrannin A content significantly decreased; however, 2',6'-Di-O-acetylononin gradually increased with the fermentation time, which resulted in FGJ maintaining excellent bioactivity. Meanwhile, organic acid content (palmitoylethanolamide, tetraacetylethylenediamine) increased with saccharides (linamarin) decreasing, which leads to FGJ having a unique taste. Furthermore, a total of 85 Volatile organic compounds (VOCs) were identified, mainly including esters, aldehydes, and alcohols. Interestingly, key VOCs could be formed by carboxylic acids and derivatives, and fatty acyls via complex metabolic pathways.

Recent advances in nanomaterial-mediated bacterial molecular action and their applications in wound therapy.

Because of the multi-pathway antibacterial mechanisms of nanomaterials, they have received widespread attention in wound therapy. However, owing to the complexities of bacterial responses toward nanomaterials, antibacterial molecular mechanisms remain unclear, making it difficult to rationally design highly efficient antibacterial nanomaterials. Fortunately, molecular dynamics simulations and omics techniques have been used as effective methods to further investigate the action targets of nanomaterials. Therefore, the review comprehensively analyzes the antibacterial mechanisms of nanomaterials from the morphology-dependent antibacterial activity and physicochemical/optical properties-dependent antibacterial activity, which provided guidance for constructing excellently efficient and broad-spectrum antibacterial nanomaterials for wound therapy. More importantly, the main molecular action targets of nanomaterials from the membranes, DNA, energy metabolism pathways, oxidative stress defense systems, ribosomes, and biofilms are elaborated in detail. Furthermore, nanomaterials used in wound therapy are reviewed and discussed. Finally, future directions of nanomaterials from mechanisms to nanomedicine are further proposed.

Specifically functionalized MTT-Ag NP/SA film sensor for the ultrasensitive detection of Hg2+ in lettuce samples.

In the present study, highly efficient 5-Methyl-1,3,4-thiadiazole-2-thiol-modified silver nanoparticles (MTT-Ag NPs) were successfully synthesized and could be used for convenient and sensitive detection of Hg2+. MTT acts as a protective agent by forming Ag-S bonds with Ag NPs, meantime, MTT can also be captured Hg2+ through NN bonds. Furthermore, to improve the sustainability and stability of MTT-Ag NPs, sodium alginate (SA) was used as a substrate material for the formation of SA-MTT-Ag NPs films. As expected, SA-MTT-Ag NPs could be stored for more than 180 days at room temperature. When used SA-MTT-Ag NPs thin films as colourimetric sensors for detection of Hg2+ in lettuce, the low detection limit could be down to 0.22 µM (44 ppb) with wide linear range (0-1 µM and 1-150 µM) and good recovery (96.25 % - 98.75 %). Therefore, the method enables highly selective and efficient monitoring of Hg2+ in food samples.

Transcriptomic and metabolomic investigation of molecular inactivation mechanisms in Escherichia coli triggered by graphene quantum dots.

Graphene quantum dots (GQDs), a novel broad-spectrum antibacterial agent, are considered potential candidates in the field of biomedical and food safety due to their outstanding antimicrobial properties and excellent biocompatibility. To uncover the molecular regulatory mechanisms underlying the phenotypes, the overall regulation of genes and metabolites in Escherichia coli (E. coli) after GQDs stimulation was investigated by RNA-sequencing and LC-MS. Gene transcription and metabolite expression related to a series of crucial biomolecular processes were influenced by the GQDs stimulation, including biofilm formation, bacterial secretion system, sulfur metabolism and nitrogen metabolism, etc. This study could provide profound insights into the GQDs stress response in E. coli, which would be useful for the development and application of GQDs in food safety.

Based on multi-omics technology study the antibacterial mechanisms of pH-dependent N-GQDs beyond ROS.

Currently, graphene quantum dots (GQDs) are widely used as antibacterial agents, and their effects are dependent on the reactive oxygen species (ROS) generated by photodynamic and peroxidase activities. Nevertheless, the supply of substrates or light greatly limits GQDs application. Besides, due to compensatory mechanisms in bacteria, comprehensive analysis of the molecular mechanism underlying the effects of GQDs based on cellular-level experiments is insufficient. Therefore, N-GQDs with inherent excellent, broad-spectrum antibacterial efficacy under acidic conditions were successfully synthesized. Then, via multi-omics analyses, the antibacterial mechanisms of the N-GQDs were found to not only involve generation ROS but also be associated with changes in osmotic pressure, interference with nucleic acid synthesis and inhibition of energy metabolism. More surprisingly, the N-GQDs could destroy intracellular acid-base homeostasis, causing bacterial cell death. In conclusion, this study provides important insights into the antibacterial mechanism of GQDs, offering a basis for the engineering design of antibacterial nanomaterials.

Metabolomics-Based Analyses of Dynamic Changes in Flavonoid Profiles in the Black Mulberry Winemaking Process.

To overcome the fruit's perishability, mulberry wine has been developed as a method of preservation. However, dynamic changes in metabolites during mulberry wine fermentation have not been reported yet. In the present investigation, UHPLC-QE-MS/MS coupled with multivariate statistical analyses was employed to scrutinize the metabolic profiles, particularly the flavonoid profiles, throughout the process of vinification. In general, the major differential metabolites encompassed organic heterocyclic compounds, amino acids, phenylpropanoids, aromatic compounds, and carbohydrates. The contents of total sugar and alcohol play a primary role that drove the composition of amino acids, polyphenol, aromatic compound, and organic acid metabolites based on the Mantel test. Importantly, among the flavonoids, abundant in mulberry fruit, luteolin, luteolin-7-O-glucoside, (-)-epiafzelechin, eriodictyol, kaempferol, and quercetin were identified as the differential metabolic markers during blackberry wine fermentation and ripening. Flavonoid, flavone and flavonol biosynthesis were also identified to be the major metabolic pathways of flavonoids in 96 metabolic pathways. These results will provide new information on the dynamic changes in flavonoid profiles during black mulberry winemaking.

Correction: Liu et al. Functionalized MoS2 Nanoflowers with Excellent Near-Infrared Photothermal Activities for Scavenging of Antibiotic Resistant Bacteria. Nanomaterials 2021, 11, 2829.

In the original publication [...].

The Antibiotic Resistome and Its Association with Bacterial Communities in Raw Camel Milk from Altay Xinjiang.

Raw camel milk is generally contaminated with varied microbiota, including antibiotic-resistant bacteria (ARB), that can act as a potential pathway for the spread of antibiotic resistance genes (ARGs). In this study, high-throughput quantitative PCR and 16S rRNA gene-based Illumine sequencing data were used to establish a comprehensive understanding of the antibiotic resistome and its relationship with the bacterial community in Bactrian camel milk from Xinjiang. A total of 136 ARGs and up to 1.33 × 108 total ARG copies per gram were identified, which predominantly encode resistance to ß-lactamas and multidrugs. The ARGs' profiles were mainly explained by interactions between the bacteria community and physicochemical indicators (77.9%). Network analysis suggested that most ARGs exhibited co-occurrence with Corynebacterium, Leuconostoc and MGEs. Overall, raw camel milk serves as a reservoir for ARGs, which may aggravate the spread of ARGs through vertical and horizontal gene transfer in the food chain.

Amino-functionalized Fe(III)-Based MOF for the high-efficiency extraction and ultrasensitive colorimetric detection of tetracycline.

In order to achieve the simultaneous extraction and detection of tetracycline (TC) in milk, the amino-functionalized Fe-based metal-organic frameworks (NH2-MIL-88B) was synthesized via a solvothermal method with Fe3+ and 2-aminoterephthalic acid (NH2-BDC) as precursor. Thanks to the unique structure of NH2-MIL-88B, it could be used to highly effective extract of TC in milk. More interestedly, the introduced -NH2 could react with -OH from TC by a hydrogen-bonding interaction to cause the electronic interactions that enhances the peroxidase-like activity of NH2-MIL-88B, which result in the enhancement of Fenton reaction by the transfer of the electron between TC and NH2-MIL-88B. Under the optimal testing conditions, the linear absorbance response is well correlated with the TC concentration range of 50-1000 nM, which can reach a low LOD of 46.75 nM. Besides, the sensor exhibits excellent selectivity to TC, and the proposed strategy can also be applied to milk with good recovery (83.33-107.00%). Finally, the NH2-MIL-88B and cellulose acetate (CA) are combined to form nanozyme hybrid membranes through the non-solvent induced phase separation method, which can be used to prepare point-of-care testing (POCT) for rapid and in-situ detection of TC.