Cell Wall Of Bacteria Research Articles

A microbiological identification and recovery actions of critical symptoms of anammox image bacteria

Currently, the risks posed by bacteria are becoming increasingly important. It now appears that the cell wall of Anammox image bacteria is very different from what has been generally considered for many years. Not every textbook contains the peptidoglycan on the cell wall of Anammox image bacteria - the sugar-protein chain that strengthens the cells of most bacteria. Most researchers in this Anammox image bacteria diseased identification wanted to find out what gave the Anammox image cell its stability. It used powerful cryo-electron microscopes to examine the bacterial cell wall and find the exact structure of the peptidoglycan. A new algorithm is proposed to discover that Anammox image bacteria contain peptidoglycan, which completes a theory in microbiology. The identification of different diseases is listed, and the proposed model compares the exact results while comparing the parameters like accuracy, precision, recall, and F1-Score. Keywords: Anammox image bacteria, cell wall, cell stability, cryo-electron, microscope images, accuracy, precision, recall, F1-score.

Characterization of β-Glucans from Cereal and Microbial Sources and Their Roles in Feeds for Intestinal Health and Growth of Nursery Pigs.

The objectives of this review are to investigate the quantitative, compositional, and structural differences of β-glucans and the functional effects of β-glucans on the intestinal health and growth of nursery pigs. Banning antibiotic feed supplementation increased the research demand for antibiotic alternatives to maintain the intestinal health and growth of nursery pigs. It has been proposed that β-glucans improve the growth efficiency of nursery pigs through positive impacts on their intestinal health. However, based on their structure and source, their impacts can be extensively different. β-glucans are non-starch polysaccharides found in the cell walls of yeast (Saccharomyces cerevisiae), bacteria, fungi (Basidiomycota), and cereal grains (mainly barley and oats). The total β-glucan content from cereal grains is much greater than that of microbial β-glucans. Cereal β-glucans may interfere with the positive effects of microbial β-glucans on the intestinal health of nursery pigs. Due to their structural differences, cereal β-glucans also cause digesta viscosity, decreasing feed digestion, and decreasing nutrient absorption in the GIT of nursery pigs. Specifically, cereal β-glucans are based on linear glucose molecules linked by β-(1,3)- and β-(1,4)-glycosidic bonds with relatively high water-soluble properties, whereas microbial β-glucans are largely linked with β-(1,3)- and β-(1,6)-glycosidic bonds possessing insoluble properties. From the meta-analysis, the weight gain and feed intake of nursery pigs increased by 7.6% and 5.3%, respectively, through the use of yeast β-glucans (from Saccharomyces cerevisiae), and increased by 11.6% and 6.9%, respectively, through the use of bacterial β-glucans (from Agrobacterium sp.), whereas the use of cereal β-glucans did not show consistent responses. The optimal use of yeast β-glucans (Saccharomyces cerevisiae) was 50 mg/kg in nursery pig diets based on a meta-analysis. Collectively, use of microbial β-glucans can improve the intestinal health of nursery pigs, enhancing immune conditions, whereas the benefits of cereal β-glucans on intestinal health were not consistent.

Antipyretic Effect on LPS-Induced Pyrexia in Rats by Bupleurum Chinense

Bupleurum chinense is a medicinal plant commonly used in traditional Chinese medicine. It has been investigated for its potential therapeutic effects, including its antipyretic properties. Kang and colleagues focused on the antipyretic effect of Bupleurum chinense in rats with lipopolysaccharide (LPS)-induced pyrexia and found that it exerted a mild antipyretic effect. Pyrexia refers to an elevated body temperature or fever. LPS, a component of the cell wall of certain bacteria, is commonly used to induce an inflammatory response and fever in experimental animal models. The study investigated the potential antipyretic effect of Bupleurum chinense in LPS-induced pyrexia rats. TNF-α is a pro-inflammatory cytokine involved in the regulation of immune responses. In the study, Bupleurum chinense was found to inhibit the production of TNF-α in the peripheral tissues of LPS-induced pyrexia rats. The inhibition of peripheral TNF-α production by Bupleurum chinense resulted in a mild antipyretic effect, reducing the elevated body temperature in the LPS-induced pyrexia rats. The specific mechanisms by which Bupleurum chinense inhibits peripheral TNF-α production were not described in the study. However, the anti-inflammatory and immunomodulatory properties of Bupleurum chinense compounds may contribute to this effect. J Ethnopharmacol. 2023 Jun 28;310:116375. doi: 10.1016/j.jep.2023.116375.

Role of microbiome in development of systemic inflammatory response syndrome and sepsis (review)

Sepsis is a life-threatening organ dysfunction caused by a disturbed response to infection. Its development is preceded by systemic inflammatory response syndrome, which is the overall inflammatory response of the body to severe lesions. The role of opportunistic pathogens in the development of systemic inflammatory response syndrome and sepsis may be known, but the value of the intestinal microbiome remains underestimated in this context.
 Experimental models are widely employed to study the role of the microbiome in the development of sepsis. Animal models of sepsis are created by disrupting the barrier function of the host intestine through cecal ligation/puncture, installation of an ascending bowel stent, and intraperitoneal feces injection. Toxemia is reproduced by the injection of lipopolysaccharides, peptidoglycans, lipoteichoic acid, CpG DNA, zymosan, and synthetic lipopeptides.
 The review systematized data on the role of the cell wall or membrane components of gram-positive and gram-negative bacteria, which are representatives of the intestinal microbiome in the pathogenesis of systemic inflammatory response syndrome and sepsis.

Near-infrared II fluorescent carbon dots for differential imaging of drug-resistant bacteria and dynamic monitoring of immune system defense against bacterial infection in vivo

In vivo fluorescence imaging allows the accurate acquisition of dynamic biological information, which plays a vital role in the early diagnosis and treatment of bacterial infectious diseases. Herein, a NIR-II-emitting CD-based nanoprobe (CyCDs) is synthesized using Cy7-CH3 as the carbon source and 3-hydroxytyramine hydrochloride as the surface passivator. Notably, the π-conjugated system and rigid planar structure of the carbon source can broaden the wavelength range of absorption and emission. The presence of amino groups enables CyCDs with a positive zeta potential (+0.32 mV), which can facilitate the interactions between CyCDs and bacteria. Interestingly, CyCDs can only stain the cell wall of drug-resistant bacteria, while normal bacteria have a bright fluorescent signal over all of the cell. This phenomenon enables the identification of drug-resistant bacteria in vitro. Furthermore, CyCDs can be used to monitor the interaction between the immune system and infected bacteria in vivo and guide the timely usage of antibiotics

Green Synthesis and Characterization of Novel Silver Nanoparticles Using Achillea maritima subsp. maritima Aqueous Extract: Antioxidant and Antidiabetic Potential and Effect on Virulence Mechanisms of Bacterial and Fungal Pathogens

Novel silver nanoparticles were synthesized based on a simple and non-toxic method by applying the green synthesis technique, using, for the first time, the aqueous extract of an extremophile plant belonging to the Achillea maritima subsp. maritima species. AgNP characterization was performed via UV-Visible, front-face fluorescence spectroscopy, and FTIR and XRD analyses. AgNP formation was immediately confirmed by a color change from yellow to brown and by a surface plasmon resonance peak using UV-Vis spectroscopy at 420 nm. The biosynthesized AgNPs were spherical in shape with a size ranging from approximatively 14.13 to 21.26 nm. The presented silver nanoparticles exhibited strong antioxidant activity following a DPPH assay compared to ascorbic acid, with IC50 values of about 0.089 µg/mL and 22.54 µg/mL, respectively. The AgNPs showed higher antidiabetic capacities than acarbose, by inhibiting both alpha amylase and alpha glucosidase. The silver nanoparticles could affect various bacterial mechanisms of virulence, such as EPS production, biofilm formation and DNA damage. The silver nanoparticles showed no lysozyme activity on the cell walls of Gram-positive bacteria. The AgNPs also had a strong inhibitory effect on the Candida albicans virulence factor (extracellular enzymes, biofilm formation). The microscopic observation showed abnormal morphogenesis and agglomeration of Candida albicans exposed to AgNPs. The AgNPs showed no cytotoxic effect on human cells in an MTT assay. The use of novel silver nanoparticles is encouraged in the formulation of natural antimicrobial and antidiabetic agents.

Long-term antibacterial activity of guanidinium carbon dots without detectable resistance for the effective treatment of pneumonia caused by Gram-negative bacteria

The development of nanomedicine for the treatment of infection caused by resistant bacteria, especially Gram-negative bacteria, is still in the bottleneck. The long-term antibacterial activity and the low induced resistance risk need improvement. Herein, guanidinium-based carbon dots (G-CDs) were prepared from citric acid, dimethyldiallylammonium chloride, and polyhexamethyleneguanidine through melting strategy. The antibacterial properties of G-CDs against Gram-negative and resistant bacteria were investigated. G-CDs exhibit strong and long-term antibacterial activity, as well as antibiofilm activity, with less potential for inducing bacterial resistance. The antibacterial mechanism of G-CDs of the adsorption action and killing effect was elucidated, which was different from the mechanism of antibiotics. Moreover, derived from the interacting mode of nanomaterials and ssDNA, the enhanced ability of G-CDs against Gram-negative bacteria was studied based on the found interaction of G-CDs and lipopolysaccharide (LPS) for the understanding of the mode for the absorption of G-CDs on the cell wall of Gram-negative bacteria. The multimode interactions of van der Waals force, electrostatic adsorption and hydrogen bonding were clarified. Furthermore, G-CDs had excellent in vivo safety and in vivo therapeutic effects in E. coli-infected pneumonia through an intravenous approach. This study provides a hopeful strategy for developing antibacterial drugs from understanding the interacting mode of the drug and the cell wall of bacteria.

Development of an antimicrobial fungal egg tray containing orange oil and smoke for eggs preservation at room temperature

The prevention and controlled growth of pathogenic bacteria on eggs during storage and distribution at room temperature is important to ensure commercial eggs and egg products are safe for consumer. This study investigated the combined effects of orange oil (0.001%-0.004% v/w) and smoke for 10 min in paper egg tray packaging produce from the fungal pulp of Trametes versicolor. Eggs were kept in the developed paper egg tray at room temperature (30 ± 2°C). The mechanism of the combined antibacterial effects againstEscherichia coli, Salmonella Typhimurium, and Staphylococcus aureus and egg quality were investigated. The combination of orange oil (0.004%) and smoke delayed all bacteria and suppressed changes in weight loss and the quality factor of eggs (Haugh unit, yolk index, albumen index) for at least 14 d. It was found that the volatile orange oil smoke in the egg tray could be passed through the structure of the cell wall and membrane of bacteria, giving rise to loss of cell viability by irreversibly damaging the cell membranes ofall the bacteria in this test. Moreover, higher antioxidant activity was found on the eggs than on the eggshells, which is linked to greater shelf-life of treated eggs. The study demonstrates an improved paper egg tray packaging system and the possibility of combining released essential oils and smoke, which can be extended to egg products. Smoke can also be modified on the surface ofpaper egg trayseasily, which shows potential in functionalizing implanted materials with antibacterial properties.

Synergistic antibacterial study of nano-Cu2O/CuO@Ag-tetracycline composites

The rapid increase in drug resistance has not reduced the antibacterial activity of most antibacterial drugs but also brought great challenges to society. Therefore, there is an urgent need to develop new antibacterial agents. In this study, copper nitrate trihydrate [Cu(NO3)2·3H2O] was used as a raw material and hydrazine hydrate as a reducing agent to prepare cuprous oxide (Cu2O/CuO). Next, silver nitrate (AgNO3) was added and monomeric silver was loaded on the surface of Cu2O by in situ reduction to obtain Cu2O/CuO@Ag composites. Lastly, nano-Cu2O/CuO@Ag-tetracycline composites were obtained by combining them with tetracycline. Systematic characterization of inhibitors was conducted using transmission electron microscopy (TEM), energy dispersive spectrometry (EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier-transform infrared spectroscopy (FT-IR), and ultraviolet–visible spectroscopy (UV–vis). The inhibitory properties and mechanism of Cu2O/CuO@Ag-tetracycline on the Gram-positive bacterium Staphylococcus aureus (S. aureus), Gram-negative bacterium Escherichia coli (E. coli), and drug-resistant bacterium Salmonella (T-Salmonella) were studied. The inhibition performance study showed that the inhibition rate of Cu2O@CuO@Ag-tetracycline was almost 99.99% against the three tested bacteria at 40 min when used at a concentration of 150 μg/mL. Compared with tetracycline and Cu2O/CuO alone, Cu2O/CuO-tetracycline composites have several times higher antibacterial efficiency against E. coli, S. aureus and T-Salmonella. Moreover, the nano-Cu2O/CuO@Ag-tetracycline composites were most sensitive to E. coli. The inhibition mechanism revealed that the nanocomposites could effectively destroy the cell wall of Gram-negative bacteria, enter the cell interior, inhibit cell respiration, and eventually lead to bacterial rupture and death. The nano-Cu2O/CuO@Ag-tetracycline composites exhibited excellent antibacterial properties, indicating their wide application prospects in the fields of medical devices and medical materials.

The usnic acid derivative peziculone targets cell walls of Gram-positive bacteria revealed by high-throughput CRISPRi-seq analysis

Usnic acid, a representative dibenzofuran metabolite, is known to have antimicrobial properties. However, despite considerable interest as an antimicrobial agent, the mechanism by which usnic acid and its derivatives exert their action is not fully characterized. This article describes the synthesis of peziculone, a 5:1 equilibrium mixture of two inseparable usnic acid derivatives: peziculone A and peziculone B. The antibacterial activity of peziculone against several Gram-positive bacterial pathogens was found to be significantly better compared with usnic acid. Clustered regularly interspaced short palindromic repeats interference sequencing analysis and membrane fluorescent staining were used to demonstrate that peziculone destabilizes the cell walls of Gram-positive bacteria. Additionally, peziculone 2.5 and 3.5 µg/mL impaired cell surface appendages and biofilm formation by Staphylococcus aureus. Taken together, these data demonstrate that peziculone, a derivative compound of usnic acid, has significant antimicrobial activity against Gram-positive bacteria by targeting the cell walls; this provides a platform for development of novel antibacterial drugs.

Advances and Prospects in Antimicrobial Research using Nanomedicines

Background: Nanotechnology is moving toward future goals in the field of medicines, cosmetics and hospitality due to the size reduction of material in the range of 1-100nm, enhancing the stability and bioavailability of the material. Objective: This review includes the progress in the field of nanotechnology, its advantages, understanding and applications in antimicrobial therapy. Methods: The manuscripts were collected in the field of antimicrobial research with the help of nanotechnology platforms from different sources like PubMed, ScienceDirect and Google. A total of 236 manuscripts were collected and analyzed, out of which 93 were relevant and considered for the present manuscript. Results: There are diverse forms of metallic nanomaterials that show antimicrobial properties, such as gold, silver, copper, zinc, titanium and many such metal oxides. Various carriers are used to deliver the drug at targeted sites via encapsulating the nanomaterial in polymers, liposomes or in the lipoidal structure. The inhibition of microorganism growth may be attributed to different mechanisms like destroying the synthesis of a cell wall, nucleic acid, injury to the bacteria cell wall and inhibiting the metabolic pathways in bacteria. This enhanced the antimicrobial activity and reduced the toxicity that could be significant due to a reduction in the dose proportionality. Conclusion: The recent advances in drug delivery with the help of liposomes, solid lipid nanoparticles, dendrimers, and various nanoparticles led to effective prevention, treatment and diagnosis of various microbial infections and this could dramatically change the way antimicrobial therapy explored for reducing drug resistance.

Antibacterial Activity Test of Mahkota Dewa Fruit (Phaleria macrocarpa) Extract against Escherichia Coli Bacteria

Exposure to Escherichia coli during pregnancy may cause serious problems such as anemia, premature birth and an increased risk of inflammation of the lining of the brain in the fetus. Mahkota Dewa (Phaleria macrocarpa) is a medicinal plant that is widely known and used to treat allergies and chronic diseases. One of the compounds contained in Mahkota Dewa is flavonoids. There is certain mechanism of action of flavonoids in inhibiting bacteria namely by damaging the cytoplasmic cell wall in bacteria. This study aims to analyze the antibacterial properties of various flavonoid concentrations of Mahkota Dewa fruit (Phaleria macrocarpa) extract against Escherichia coli bacteria through a laboratory experimental study design by testing the antimicrobial potency of the well method, namely 10percent, 20percent, 40percent, 60percent, 80percent and 100percent. Statistical analysis using One-Way Anova Test showed a significant difference between changes in the concentration of flavonoids in Mahkota Dewa fruit extract and the inhibition zones towards the growth of Escherichia coli bacteria (p less than 0.05). Pearson correlation test showed a very strong relationship with a positive direction (r equals 0.874) which indicated that the higher the concentration of flavonoids in Mahkota dewa fruit extract, the stronger the antimicrobial effect. Based on the study findings, it can be concluded that the flavonoid extract in Mahkota Dewa fruit extract had an antimicrobial potential against Escherichia Coli in vitro.

Dielectrophoresis microbial characterization and isolation of Staphylococcus aureus based on optimum crossover frequency.

Characterization of antibiotic-resistant bacteria is a significant concern that persists for the rapid classification and analysis of the bacteria. A technology that utilizes the manipulation of antibiotic-resistant bacteria is key to solving the significant threat of these pathogenic bacteria by rapid characterization profile. Dielectrophoresis (DEP) can differentiate between antibiotic-resistant and susceptible bacteria based on their physical structure and polarization properties. In this work, the DEP response of two Gram-positive bacteria, namely, Methicillin-resistant Staphylococcus aureus (MRSA) and Methicillin-susceptible S. aureus (MSSA), was investigated and simulated. The DEP characterization was experimentally observed on the bacteria influenced by oxacillin and vancomycin antibiotics. MSSA control without antibiotics has crossover frequencies ( ) from 6 to 8MHz, whereas MRSA control is from 2 to 3MHz. The changed when bacteria were exposed to the antibiotic. As for MSSA, the decreased to 3.35MHz compared to MSSA control without antibiotics, MRSA, increased to 7MHz when compared to MRSA control. The changes in the DEP response of MSSA and MRSA with and without antibiotics were theoretically proven using MyDEP and COMSOL simulation and experimentally based on the modification to the bacteria cell walls. Thus, the DEP response can be employed as a label-free detectable method to sense and differentiate between resistant and susceptible strains with different antibiotic profiles. The developed method can be implemented on a single platform to analyze and identify bacteria for rapid, scalable, and accurate characterization.

Comprehensive In Silico Characterization of the Coding and Non-Coding SNPs in Human Dectin-1 Gene with the Potential of High-Risk Pathogenicity Associated with Fungal Infections.

The human C-type lectin domain family 7 member A (CLEC7A) gene encodes a Dectin-1 protein that recognizes beta-1,3-linked and beta-1,6-linked glucans, which form the cell walls of pathogenic bacteria and fungi. It plays a role in immunity against fungal infections through pathogen recognition and immune signaling. This study aimed to explore the impact of nsSNPs in the human CLEC7A gene through computational tools (MAPP, PhD-SNP, PolyPhen-1, PolyPhen-2, SIFT, SNAP, and PredictSNP) to identify the most deleterious and damaging nsSNPs. Further, their effect on protein stability was checked along with conservation and solvent accessibility analysis by I-Mutant 2.0, ConSurf, and Project HOPE and post-translational modification analysis using MusiteDEEP. Out of the 28 nsSNPs that were found to be deleterious, 25 nsSNPs affected protein stability. Some SNPs were finalized for structural analysis with Missense 3D. Seven nsSNPs affected protein stability. Results from this study predicted that C54R, L64P, C120G, C120S, S135C, W141R, W141S, C148G, L155P, L155V, I158M, I158T, D159G, D159R, I167T, W180R, L183F, W192R, G197E, G197V, C220S, C233Y, I240T, E242G, and Y3D were the most structurally and functionally significant nsSNPs in the human CLEC7A gene. No nsSNPs were found in the predicted sites for post-translational modifications. In the 5' untranslated region, two SNPs, rs536465890 and rs527258220, showed possible miRNA target sites and DNA binding sites. The present study identified structurally and functionally significant nsSNPs in the CLEC7A gene. These nsSNPs may potentially be used for further evaluation as diagnostic and prognostic biomarkers.

The Unique N-Terminal Domain of Chlamydial Bactofilin Mediates Its Membrane Localization and Ring-Forming Properties.

Chlamydia trachomatis is an obligate intracellular bacterial pathogen. In evolving to the intracellular niche, Chlamydia has reduced its genome size compared to other bacteria and, as a consequence, has a number of unique features. For example, Chlamydia engages the actin-like protein MreB, rather than the tubulin-like protein FtsZ, to direct peptidoglycan (PG) synthesis exclusively at the septum of cells undergoing polarized cell division. Interestingly, Chlamydia possesses another cytoskeletal element-a bactofilin ortholog, BacA. Recently, we reported BacA is a cell size-determining protein that forms dynamic membrane-associated ring structures in Chlamydia that have not been observed in other bacteria with bactofilins. Chlamydial BacA possesses a unique N-terminal domain, and we hypothesized this domain imparts the membrane-binding and ring-forming properties of BacA. We show that different truncations of the N terminus result in distinct phenotypes: removal of the first 50 amino acids (ΔN50) results in large ring structures at the membrane whereas removal of the first 81 amino acids (ΔN81) results in an inability to form filaments and rings and a loss of membrane association. Overexpression of the ΔN50 isoform altered cell size, similar to loss of BacA, suggesting that the dynamic properties of BacA are essential for the regulation of cell size. We further show that the region from amino acid 51 to 81 imparts membrane association as appending it to green fluorescent protein (GFP) resulted in the relocalization of GFP from the cytosol to the membrane. Overall, our findings suggest two important functions for the unique N-terminal domain of BacA and help explain its role as a cell size determinant. IMPORTANCE Bacteria use a variety of filament-forming cytoskeletal proteins to regulate and control various aspects of their physiology. For example, the tubulin-like FtsZ recruits division proteins to the septum whereas the actin-like MreB recruits peptidoglycan (PG) synthases to generate the cell wall in rod-shaped bacteria. Recently, a third class of cytoskeletal protein has been identified in bacteria-bactofilins. These proteins have been primarily linked to spatially localized PG synthesis. Interestingly, Chlamydia, an obligate intracellular bacterium, does not have PG in its cell wall and yet possesses a bactofilin ortholog. In this study, we characterize a unique N-terminal domain of chlamydial bactofilin and show that this domain controls two important functions that affect cell size: its ring-forming and membrane-associating properties.

False Positives in Brucellosis Serology: Wrong Bait and Wrong Pond?

This review summarizes the status of resolving the problem of false positive serologic results (FPSR) in Brucella serology, compiles our knowledge on the molecular background of the problem, and highlights some prospects for its resolution. The molecular basis of the FPSRs is reviewed through analyzing the components of the cell wall of Gram-negative bacteria, especially the surface lipopolysaccharide (LPS) with details related to brucellae. After evaluating the efforts that have been made to solve target specificity problems of serologic tests, the following conclusions can be drawn: (i) resolving the FPSR problem requires a deeper understanding than we currently possess, both of Brucella immunology and of the current serology tests; (ii) the practical solutions will be as expensive as the related research; and (iii) the root cause of FPSRs is the application of the same type of antigen (S-type LPS) in the currently approved tests. Thus, new approaches are necessary to resolve the problems stemming from FPSR. Such approaches suggested by this paper are: (i) the application of antigens from R-type bacteria; or (ii) the further development of specific brucellin-based skin tests; or (iii) the application of microbial cell-free DNA as analyte, whose approach is detailed in this paper.

MNQ derivative D21 protects against LPS-induced inflammatory damage in bovine ovarian follicular GCs in vitro via the steroid biosynthesis signaling pathway

Bacterial infections of the reproductive system of dairy cows lead to inflammation, and lipopolysaccharide (LPS) of the cell wall of Gram-negative bacteria is the main pathogenic component of inflammation. LPS inhibits follicular growth and development and alters the expression of follicular granulosa cells (GCs) genes in the ovary, leading to their functional disorders. Naphthoquinones have anti-inflammatory effects. In this experiment, 2-methoxy-1,4-naphthoquinone (MNQ), an extract of Impatiens balsamina L, and its derivative D21 were used to eliminate the inflammatory response of GCs exposed to LPS in vitro and to restore functional disorders in GCs. The anti-inflammatory effects of the two compounds were compared and their mechanism of action was investigated. The cytotoxicity of MNQ and its derivative D21 on follicular GCs was determined by MTT method. The relative expression of inflammatory factors and steroid synthesis-related genes were determined by qRT-PCR. The protective effects of MNQ and D21 on cellular inflammatory damage were observed by TEM. ELISA were performed to detect the levels of estradiol (E2) and progesterone (P4) in the culture supernatant. The expression of differential genes was analyzed by RNA-seq, and GO and KEGG enrichment analysis of differential genes were performed to investigate the mechanism of anti-inflammatory effect of D21. The results showed that the maximum no-cytotoxic concentrations of MNQ and D21 acting on GCs for 12 h were 4 μM and 64 μM, respectively. LPS concentration of 10 μg/mL had little effect on the survival of follicular GCs, but the relative expressions of IL-6, IL-1β and TNF-α were significantly higher (P < 0.05). The results of qRT-PCR, ELISA and TEM observations showed that the anti-inflammatory effect of D21 was stronger than that of MNQ. RNA-seq analysis revealed a total of 341 differential genes between the LPS vs CK group (Control group) and the D21+L vs LPS group, which were mainly enriched in signaling pathways such as steroid biosynthesis. Nine genes in this signaling pathway were analyzed, and the RNA-seq and qRT-PCR results were found to be basically consistent. In this study, we confirmed that derivative D21 has stronger in vitro anti-inflammatory effects and better efficacy in protecting bovine follicular GCs from inflammatory damage than MNQ and acts through the steroid biosynthesis signaling pathway.

Antibacterial activity of vB_AbaM_PhT2 phage hydrophobic amino acid fusion endolysin, combined with colistin against Acinetobacter baumannii

Phage lytic enzymes are promising antimicrobial agents. In this study, an endolysin derived from vB_AbaM_PhT2 (vPhT2), was identified. This endolysin represented the conserved lysozyme domain. Recombinant endolysin (lysAB- vT2) and hydrophobic fusion endolysin (lysAB-vT2-fusion) were expressed and purified. Both endolysins showed lytic activity against bacterial crude cell wall of Gram-negative bacteria. The MIC of lysAB-vT2-fusion was 2 mg/ml corresponding to 100 µM, while the MIC of lysAB-vT2 was more than 10 mg/ml (400 µM). Combination of lysAB-vT2-fusion with colistin, polymyxin B or copper was synergistic against A. baumannii (FICI value as 0.25). Antibacterial activity of lysAB-vT2-fusion plus colistin at the fractional inhibitory concentrations (FICs) revealed that it can inhibit Escherichia coli, Klebsiella pneumoniae and various strains of extremely drug-resistant A. baumannii (XDRAB) and phage resistant A. baumannii. The lysAB- vT2-fusion still retained its antibacterial activity after incubating the enzyme at 4, 20, 40 and 60 °C for 30 min. The lysAB-vT2-fusion could inhibit the mature biofilm, and incubation of lysAB-vT2-fusion with T24 human cells infected with A. baumannii led to a partial reduction of LDH release from T24 cells. In summary, our study highlights the antimicrobial ability of engineered lysAB-vT2-fusion endolysin, which can be applied for the control of A. baumannii infection.

Composite films of sodium alginate and konjac glucomannan incorporated with tea polyphenols for food preservation

At present, food waste has become a serious issue and the use of petroleum-based food packaging films has resulted in a series of potential hazards. Therefore, more attention has been focused on the development of new food packaging materials. The polysaccharide-based composite film loaded with active substances considered to be an excellent preservative material. A novel packaging film based on sodium alginate and konjac glucomannan (SA-KGM) blended with tea polyphenols (TP) was prepared in the present study. The excellent microstructure of films was shown by atomic force microscopy (AFM). It was indicated by FTIR spectra that the components could interact with each other through hydrogen bonds, which was also confirmed by molecular docking simulation. Meanwhile, the mechanical properties, barrier property, oxidation property, antibacterial activity, and stability of the structure of the TP-SA-KGM film were significantly improved. The AFM images and results of molecular docking simulation indicated that TP could affect the cell wall of bacteria by acting with peptidoglycan. Finally, the film showed excellent preservation effects in both beef and apples, which suggested that TP-SA-KGM film could be a novel bioactive packaging material with wide application potential in food preservation.

Morphostructural damage to bacterial cells exposed to chlorine-containing derivatives of 5-,6-,7-aminoindoles assessed by scanning electron microscope

The cell wall and membranes of Gram-positive and Gram-negative bacteria provide a physical, osmotic, and metabolic barrier between the internal contents of the bacterial cell and the external environment. Observation of changes in the integrity of the bacterial structure using a scanning electron microscope (SEM) can help elucidate the detailed mechanisms of cell death. The aim of the study was to analyze the morphological changes in microbial cells exposed to new compounds with antimicrobial activity chlorine-containing derivatives of 5-,6-,7-aminoindoles using SEM. Methods. The present study was carried out using strains of Pseudomonas aeruginosa, Staphylococcus aureus, and Escherichia coli obtained from patients with nonspecific diseases of the respiratory, urinary tract, and intestines with different sensitivities to traditionally used antimicrobial drugs. Results. As a result, the studied chloromethyl-containing compounds of the indole series showed own biological activity, namely antimicrobial. Control cells were morphologically correct and typical. Statistical analysis of cell surface morphometry in control and experimental samples did not reveal significant changes in size after exposure to compounds with laboratory codes T1, T4, T7 and T12. At the same time, compared with control untreated cells of P. aeruginosa, S. aureus and E. coli, treatment with chlorine-substituted derivatives of 5-,6-,7-aminoindoles caused obvious morphological changes, which indicates a deteriorated state of the cell wall. Filamentous cells were observed in P. aeruginosa exposure to T7 and T12. The appearance of long filaments may be associated with the stress experienced by the cell after exposure to the compounds under study. It is believed that the formation of such filaments in bacteria under stress conditions results from defects in cell division, especially in the separation of daughter cells. There are data according to which, when DNA synthesis is suppressed, a bacterium changes its morphology, becomes longer, without reaching cell division. Treatment with T1, T7 and T12 resulted in degradation of the P. aeruginosa cell wall, while treatment with T4 caused the formation of pores on the cell surface. In this study, microscopy showed marked morphological changes in the cell walls of S. aureus, which led to deformation of the cell wall under the influence of T1, T4, T7 and T12. Treatment of E. coli T1, T4, T7 and T12 cells at a concentration of 500 g/ml caused cell lysis, although normal cells were also found. The appearance of cellular debris around whole E. coli cells indicates membrane damage, which probably leads to a change in osmotic pressure. Conclusion. The results using SEM confirmed the data on the antimicrobial activity of chlorine-substituted derivatives of 5-,6-,7-aminoindoles.