Strong Antibacterial Activity Research Articles

Sodium alginate/gelatin hydrogel spheres loaded with Fructus Ligustri Lucidi essential oil: Preparation, characterization and biological activity

The application of plant essential oils in the food industry is often hindered by their poor water solubility and high volatilize. Encapsulation has emerged as an effective solution to this problem. This study focuses on the preparation of Fructus Ligustri Lucidi essential oil gel spheres (FEOH) based sodium alginate and gelatin. The optimum formulation for FEOH was established by Box-Behnken Design response surface testing, resulting in a composition of 10 % FEO, 5 % TW20 and 2 % CaCl2. This formulation achieved an encapsulation efficiency of 85.56 %. FTIR and SEM results indicated the successful encapsulation of FEO within the gel spheres. Furthermore, DSC and TGA results showed that encapsulation enhanced the thermal stability of the essential oil. At room temperature, the water content of FEOH exceeded 90 %, and it showed the highest swelling ratio of 62.5 % in an alkaline medium at different pH conditions. The in vitro release behavior showed that FEOH was released up to 85.28 % in oil-based food simulants within 2 h. FEOH showed strong antibacterial activity, with a Minimum Inhibitory Concentration (MIC) of 128 mg/mL against Staphylococcus aureus and 256 mg/mL against Escherichia coli. The gel spheres obtained in this research show significant potential as food preservatives in food matrices.

Біоінженерія наночастинок срібла з використанням Brassica oleracea sub sp. botrytis (L.) для посилення антибактеріальної активності

The green methodologies of nanoparticles with plant extracts have received an increase of interest. Silver nanoparticles (Ag NPs) have been utilized in a many of applications in the last few decades. The current study presents the synthesis of Ag NPs with aqueous extract of Brassica oleracea sub sp. botrytis (L.) as a stabilizing agent. UV-visible spectroscopy, FTIR, XRD, SEM, TEM, and EDAX analysis were performed to study the synthesized Ag NPs. The synthesized Ag NPs have been measured with dynamic light scattering (DLS), the average size and charge were discovered to be 81.62 ± 1.14 nm and -11.3 ± 2.51 mV, respectively. Furthermore, as-formed AgNPs shown strong antibacterial activity against the Gram-positive bacteria (Staphylococcus aureus). According to the results of this investigation, green synthesized Ag NPs with Brassica oleracea sub sp. botrytis (L.) may be used in biomedicine as a replacement agent for biological applications.

Green-synthesized zinc oxide nanoparticles by Enterobacter sp.: unveiling characterization, antimicrobial potency, and alleviation of copper stress in Vicia faba (L.) plants

BackgroundThe biosynthesis of zinc oxide nanoparticles (ZnO NPs) using Enterobacter sp. and the evaluation of their antimicrobial and copper stress (Cu+ 2)-reducing capabilities in Vicia faba (L.) plants. The green-synthesized ZnO NPs were validated using X-ray powder diffraction (XRD); Fourier transformed infrared (FTIR), Ultraviolet-Visible spectroscopy (UV-Vis), Transmission electron microscope (TEM) and scanning electron microscopy (SEM) techniques. ZnO NPs could serve as an improved bactericidal agent for various biological applications. as well as these nanoparticles used in alleviating the hazardous effects of copper stress on the morphological and physiological traits of 21-day-old Vicia faba (L.) plants.ResultsThe results revealed that different concentrations of ZnO NPs (250, 500, or 1000 mg L-1) significantly alleviated the toxic effects of copper stress (100 mM CuSO4) and increased the growth parameters, photosynthetic efficiency (Fv/Fm), and pigments (Chlorophyll a and b) contents in Cu-stressed Vicia faba (L.) seedlings. Furthermore, applying high concentration of ZnO NPs (1000 mg L-1) was the best dose in maintaining the levels of antioxidant enzymes (CAT, SOD, and POX), total soluble carbohydrates, total soluble proteins, phenolic and flavonoid in all Cu-stressed Vicia faba (L.) seedlings. Additionally, contents of Malondialdehyde (MDA) and hydrogen peroxide (H2O2) were significantly suppressed in response to high concentrations of ZnO NPs (1000 mg L-1) in all Cu-stressed Vicia faba (L.) seedlings. Also, it demonstrates strong antibacterial action (0.9 mg/ml) against various pathogenic microorganisms.ConclusionsThe ZnO NPs produced in this study demonstrated the potential to enhance plant detoxification and tolerance mechanisms, enabling plants to better cope with environmental stress. Furthermore, these nanoparticles could serve as an improved bactericidal agent for various biological applications.

Whole-genome sequencing of Pseudoalteromonas piscicida 2515 revealed its antibacterial potency against Vibrio anguillarum: a preliminary invitro study.

Pseudoalteromonas piscicida 2515, isolated from Litopenaeus vannamei culture water, is a potential marine probiotic with broad anti-Vibrio properties. However, genomic information on P. piscicida 2515 is scarce. In this study, the general genomic characteristics and probiotic properties of the P. piscicida 2515 strain were analysed. In addition, we determined the antibacterial mechanism of this bacterial strain by scanning electron microscopy (SEM). The results indicated that the whole-genome sequence of P. piscicida 2515 contained one chromosome and one plasmid, including a total length of 5,541,406bp with a G + C content of 43.24%, and 4679 protein-coding genes were predicted. Various adhesion-related genes, amino acid and vitamin metabolism and biosynthesis genes, and stress-responsive genes were found with genome mining tools. The presence of genes encoding chitin, bromocyclic peptides, lantibiotics, and sactipeptides showed the strong antibacterial activity of the P. piscicida 2515 strain. Moreover, in coculture with Vibrio anguillarum, P. piscicida 2515 displayed vesicle/pilus-like structures located on its surface that possibly participated in its bactericidal activity, representing an antibacterial mechanism. Additionally, 16 haemolytic genes and 3 antibiotic resistance genes, including tetracycline, fluoroquinolone, and carbapenem were annotated, but virulence genes encoding enterotoxin FM (entFM), cereulide (ces), and cytotoxin K were not detected. Further tests should be conducted to confirm the safety characteristics of P. piscicida 2515, including long-term toxicology tests, ecotoxicological assessment, and antibiotic resistance transfer risk assessment. Our results here revealed a new understanding of the probiotic properties and antibacterial mechanism of P. piscicida 2515, in addition to theoretical information for its application in aquaculture.

Carboxymethyl cellulose/gelatin film incorporated with eggplant peel waste-derived carbon dots for active fruit packaging applications

Carbon dots (CDs) were derived using eggplant peel by a hydrothermal approach and incorporated into the carboxymethyl cellulose (CMC) and gelatin (Gel) blend to develop sustainable and functional packaging films for fruit preservation. The CD was uniformly dispersed within the CMC/Gel blend to form a dense and continuous film and fashioned a strong interaction with the polymer chain, increasing the tensile strength of the film by 5.0–16.0 %. Also, with the impregnation of CDs, the UV-blocking potential of the CMC/Gel film was greatly improved to the extent of blocking 94.3 % of UV-B and 72.5 % of UV-A, while the water vapor permeability slightly decreased (by 2.7–5.4 %), and the water contact angle of the film marginally expand (by 6.2–19.1 %). The CMC/Gel film with 3 wt% of CD added depicted strong antioxidant efficacy of 100 % against ABTS and 59.1 % against DPPH and displayed strong antibacterial action that inhibited the progress of Listeria monocytogenes and Escherichia coli by 99.8 %. In addition, when table grapes were packaged using a CMC/Gel composite film containing CD and stored at 4 °C for 24 days, the fruits packed with the composite film maintained excellent external quality and extended the shelf life.

Synthesis and DFT-optimized structures of hydrazonal-based compound: Biological activity and molecular docking

Distinctive quinolinyl hydrazonal-based compound was synthesized by an azo-coupling reaction of an enaminonitrile (piperidinylacrylonitrile) with the diazonium salt of 8-aminoquinoline. The synthesized compound was characterized by different spectroscopic methods and displayed distinctive solvatochromism. The possible tautomeric transformation of the arylhydrazonal was studied using DFT quantum chemical calculations revealing that the E→Z tautomerization was a spontaneous exothermic process and its equilibrium constant (Keq) was high with positive power. Thus, the Z-tautomer is more favorable than E-tautomer. This study looks at arylhydrazonal's multiple biological actions, showing its substantial promise in antibacterial, antifungal, anticancer, and enzyme inhibition applications. The arylhydrazonal exhibited concentration-dependent strong antibacterial action against Gram-positive and negative bacteria. Moreover, it showed a comparable concentration-dependent antifungal efficiency against C. albicans and A. fumigatus, and close to fluconazole's potency against A. fumigatus. The arylhydrazonal exhibits significant anticancer action, targeting skin and breast cancer cells, suggesting lesser harm to normal cells. In comparison with acetazolamide (AZA), It inhibited carbonic anhydrase isozymes IX and XII with substantial potency against CA-XII. Molecular docking investigations demonstrated the compound's interactions with proteins such 1D2S, 1AS0, 4WW8, and 5Fl4, revealing different binding energies, RMSD values, and stable configurations via hydrogen bonding and π-H stacking interactions. These results highlight the compound's potential as a therapeutic agent in a variety of clinical applications, calling for more study into its development and clinical usage.

Self-assembled lyotropic liquid crystals from natural surfactant: A study on their structural, rheological and antimicrobial behaviour

Soft self-assembled systems with smart functions have been explored over the past decades for diverse applications. However, the toxicity of synthetic surfactant based self-assembled systems and their stability always remain a point of concern. There is always a great quest to find an alternative to overcome such shortcomings of self-assembled systems. Hence, in this context, we made an effort to engineer self-assembled lyotropic liquid crystals (LLCs) using different concentrations of the medicinal plant Glycyrrhiza glabra L. in the nonaqueous polar media of glycerol, ethylene glycol and formamide. These nonaqueous solvents with considerable polarity, high cohesive energy, dipole moment and hydrogen bonding ability, not only offer the perfect environment for self-assembly, but also provide longtime stability. Nematic lyotropic ordering is obtained for studied systems at different concentrations of Glycyrrhiza glabra L./ nonaqueous solvents as confirmed via polarising optical microscopy (POM) and X-ray diffraction (XRD) analysis. Electrostatic and hydrogen bonding interactions among polar solvents and amphiphilic Glycyrrhiza glabra L. molecules could be responsible for nematic ordering. FTIR spectroscopy is employed to confirm the hydrogen bonding in LLCs. The prepared LLCs are studied through static, dynamic rheology under the shear range 1–100 s-1 to explore their fluidic behaviour and establish correlation with structural parameters. The studied LLC systems from three solvents exhibit non-Newtonian shear thinning behaviour at all concentrations. The dynamic rheology tests indicate the elastic behaviour of all LLC systems. LLCs derived from glycerol exhibit soft-solid gel-like behaviour, while weak gel-type behaviour is observed for ethylene glycol and formamide-based LLCs. Considering the medicinal value of prepared LLCs, their antibacterial activity has been checked against the gram-positive bacteria Bacillus subtilis. LLC phases show strong antibacterial activity, about 2–3 times better than that of the standard drug streptomycin used for this study.

Exploring the Composition and Bioactivity of Hedychium flavum Leaf and Stem Essential Oil: In Vitro Assessment of Antibacterial, Antioxidant, Cytotoxicity, and Enzyme Inhibitory Activities

Hedychium flavum is an edible, medicinal, and aromatic plant widely cultivated for its essential oil. So far, little studies have been done on its phytoconstituents and bioactivities. Hence, the research aimed to determine the chemical constituents of leaf essential oil (L-EO) and stem essential oil (S-EO) of H. flavum and first estimate their antibacterial, antioxidant, cytotoxic, and enzyme inhibitory activities. According to gas chromatography-flame ionization detector/mass spectrometer (GC-FID/MS) assay, L-EO was mainly composed of β-pinene (33.4%), α-pinene (10.4%), humulene (6.8%), β-caryophyllene (6.0%), eucalyptol (6.0%), caryophyllene oxide (5.5%), endo-borneol (3.8%), humulene epoxide II (3.7%), and D-limonene (3.2%). The predominant components of S-EO were β-pinene (17.2%), eucalyptol (9.7%), nerolidol (7.8%), α-phellandrene (6.7%), α-pinene (5.8%), β-caryophyllene (5.4%), terpinen-4-ol (4.5%), D-limonene (4.4%), p-cymene (3.7%), endo-borneol (3.5%), and α-terpineol (3.5%). For the bioactivities, L-EO and S-EO showed strong antibacterial activity against Escherichia coli, Enterococcus faecalis, and Bacillus subtilis with the minimum inhibitory concentration (MIC) of 9.77–625.00 µg/mL and the minimum bactericidal concentration (MBC) of 9.77–1250.00 µg/mL. Both L-EO and S-EO exhibited moderate antioxidant activity in the DPPH (14.52 ± 0.93 mg/mL and 4.73 ± 0.15 mg/mL, respectively) and ABTS (4.05 ± 0.75 mg/mL and 2.38 ± 0.14 mg/mL, respectively) free radical scavenging capacity. S-EO showed selective cytotoxicity on human leukemic K562 cell line (IC50 = 93.94 ± 0.91 µg/mL), which was nearly three times that of noncancer L929 cell line (IC50 = 294.49 ± 9.40 µg/mL). In enzyme inhibitory properties, L-EO exerted a potent inhibition on α-glucosidase (IC50 = 1.03 ± 0.02 mg/mL), and both essential oils had weak inhibition against cholinesterase and tyrosinase. Thus, H. flavum L-EO and S-EO possess antibacterial, antioxidant, cytotoxic, and enzyme inhibitory activities with potential for exploitation in the food, cosmetic, and pharmaceutical industries.

Momordica charantia Leaf Extract Mediated Zinc Oxide Nanoparticles for Antibacterial Performance

We uncovered a simple and conservational process for the production of zinc oxide nanoparticles (ZnO NPs). This was accomplished by a biosynthetic method that included the leaf extract of Momordica charantia as a reducing agent. The UV-Vis absorption spectrum of them exhibits maxima at 352 nm. The presence of bands at 630cm-1 in the Fourier transform infrared spectrum verifies the production of zinc oxide nanoparticles. XRD determined that the particle size ranged between 20 and 58nm. Field emission scanning electron microscopy exposed that the ZnO NPs were irregular in nature and ranged in size from 20 to 60nm. The existence of oxygen and zinc in ZnO NPs is verified by energy-dispersive X-ray analysis. ZnO NPs exhibited strong antibacterial action against Klebsiella pneumoniae and Staphylococcus aureus. This biosynthetic technique could pave the way for simple, cost-effective, environmentally friendly products that avoid toxic chemicals and are helpful for applications in medication and the large-scale manufacture of nanoparticles.

The Effectiveness of LISTEXTM P100 in Reducing the Biofilm of Listeria spp. on Steel, Plastic, and Galvanised Surfaces.

Eliminating and managing L. monocytogenes, L. welshimeri, and L. ivanovii biofilms is a significant problem for food safety, as listeriosis is among the worst foodborne illnesses. The Listex P100 bacteriophage's bactericidal and inhibitory properties have been investigated in relation to varying strains of vegetative cells and biofilms of L. monocytogenes, L. welshimeri, and L. ivanovii. The phage concentrations of 109 and 1010 PFU/ml showed strong antibacterial activity against L. monocytogenes, L. welshimeri, and L. ivanovii at both 10°C and 30°C (P<0.05). In 96- well microplate experiments, bacteriophage treatment inhibited biofilm development and reduced biofilm by up to 57.6% (P ≤ 0.05). When compared to controls, Listex P100 bacteriophage significantly reduced the populations of L. monocytogenes, L. welshimeri, and L. ivanovii biofilms on the surfaces of galvanised, stainless steel, and plastic surfaces where holes were produced and the structure of Listeria spp. was disturbed. This study clearly demonstrated that L. monocytogenes, L. welshimeri, and L. ivanovii biofilms on galvanised, stainless steel, and plastic surfaces might be removed by using Listex P100 bacteriophage.

Isolation and identification of NEAU-CP5: A seed-endophytic strain of B. velezensis that controls tomato bacterial wilt

Bacterial wilt of tomato caused by Ralstonia solanacearum is a critical soilborne disease that drastically reduces yield. In the current study, an endophytic strain NEAU-CP5 with strong antagonistic activity against R. solanacearum was isolated from tomato seeds and characterized. The strain was identified as Bacillus velezensis based on 16S rRNA gene and whole genome sequence analysis. NEAU-CP5 can secrete amylase, protease, and cellulase, and also produce known antibacterial metabolites, including cyclo (leucylprolyl), cyclo (phenylalanyl-prolyl), cyclo (Pro-Gly), 3-benzyl-2,5-piperazinedione, pentadecanoic acid, eicosane, 2-methyoic acid, isovaleric acid, dibuty phthalate, and esters of fatty acids (HFDU), which may be responsible for its strong antibacterial activity. Fourteen gene clusters associated with antibacterial properties were also identified in the whole genome sequence of NEAU-CP5. Pot experiment demonstrated that the application of 108 CFU/mL NEAU-CP5 on tomato plants significantly reduced the incidence of tomato bacterial wilt by 68.36 ± 1.67 %. NEAU-CP5 also increased the activity of defense-related enzymes (CAT, POD, PPO, SOD, and PAL) in tomato plants. This is the first report of an effective control of bacterial wilt on tomato plants by B. velezensis and highlights the potential of NEAU-CP5 as a potential biocontrol agent for the management of tomato bacterial wilt.

Evaluation of functional properties of lactic acid bacteria isolated from traditional cheese

The objective of this research was to study a total of 10 strains of lactic acid bacteria previously isolated from traditional cheese, explore the effects of various in vitro tests, and evaluate their functional and potential probiotic properties. We tested the strains for cholesterol assimilation, antimicrobial activity, enzyme and exopolysaccharides (EPS) production, cell surface traits, antibiofilm, and tolerance to lysozyme and phenol. E. faecalis S135 and E. durans S1121 were characterized by strong antibacterial activities against C. albicans and S. aureus. The strains E. durans S092 and E. faecalis S135 were differentiated by phytase-producing and coagulation activity, respectively. Moreover, E. faecalis S135 had a greater cholesterol reduction percentage (66.6 ± 0.00 %) than the others. Separately, E. durans S104 and L. coryniformis subsp. torquens S232 were found to possess stronger cell surface properties, e.g., auto-aggregation (94.3 ± 0.30 %) and cell surface hydrophobicity (65.1 ± 0.11 %). All LAB 10 strains were able to handle 0.4 % phenol and 2 mg/mL lysozyme well. They also had some antibiofilm activity, but not much EPS production. Industrially important strains with antimicrobial activity, such as E. durans (S1121, S092, and S104) and E. faecalis S135, could serve as bio-protective agents. These four strains can therefore find application in various fields, including the production of fermented and/or functional foods and enzymes.

Addition of nisin to high-viscosity glass-ionomer cement: a comparative in vitro study on antibacterial and physical properties.

Nisin is a lantibiotic effective against Gram-positive microorganisms such as Streptococcus mutans. The study aimed to determine the effect of the addition of nisin to high-viscosity glass-ionomer cement (HVGIC) on its antibacterial activity, setting time, surface microhardness, and compressive strength. 1 and 3% w/w nisin were added to HVGIC before mixing. Unmodified HVGIC was the control. Agar disc diffusion, direct contact test, and scanning electron microscopy (SEM) analysis were used to evaluate antibacterial activity against S. mutans. Setting time, surface microhardness, and compressive strength were measured using Gilmore needle apparatus, digital microhardness tester, and universal testing machine, respectively. Statistical analysis included Student's t test, one-way ANOVA with Tamhane's post hoc test, and repeated-measures ANOVA. As evidenced by the agar disc diffusion (p < 0.001), direct contact tests (p = 0.025), and SEM analysis of the S. mutans cell count and cell surface area (p = 0.049 and 0.003), 3% nisin had the strongest antibacterial activity. There was a dose-dependent increase in setting time (p = 0.005) and surface microhardness (p = 0.006), with no significant difference in compressive strength compared to control. The addition of 3% nisin to HVGIC enhances the antibacterial action against S. mutans and surface microhardness without adversely affecting setting time and compressive strength.

Hydrothermal preparation, crystal structure, Hirshfeld surface analysis, photophysical properties and antifungal activity of a series of complexes assembled by 5-bromo-2-(carboxymethoxy)benzoic acid ligands

Five complexes [Co(BCBA)(H2O)3]n (1), [Co(BCBA)(4,4′-Bipy)2·(H2O)]n (2), [Cu(BCBA)(H2O)]n (3), [Zn(BCBA)(H2O)]n (4) and [Cd(BCBA)(2,2′-Bipy)(H2O)·(H2O)]n (5) (H2BCBA= 5‑bromo-2-(carboxymethoxy)benzoic acid, 4,4′-Bipy = 4,4′-bipyridine and 2,2′-Bipy = 2,2′-bipyridine) have been synthesized with H2BCBA ligand by solvothermal condition. All the complexes have been structurally characterized by infrared spectra (IR), elemental analyses and single-crystal X-ray diffraction analyses. Complex 1 is a zero-dimensional structure, and complexes 2–5 are one-dimensional chain structure. Furthermore, thermogravimetric analyses (TGA), Hirshfeld surface analysis, photo-luminescence properties, Solid-state UV–Vis diffuse reflectance spectroscopy and antifungal activity for complexes 1–5 were investigated. The reciprocal H···O/H/Br/C contacts dominate over 86 % of total Hirshfeld surface. Complexes 1–5 have certain inhibitory effects on 8 pathogenic fungi. Among them, complex 5 has the strongest antibacterial activity against Rhizoctonia solani AG1, Sphaeropsis sapinea and Colletotrichum fructicola, and the inhibitory rate reached 100 %.

Tannic acid-crosslinked gelatin composite microspheres adsorbed with CQAS or Ca2+ for rapid hemostasis

In the case of massive blood loss due to natural disasters and wars, timely and rapid hemostasis is of great significance to improve the survival rate of injured people. Nevertheless, uncontrolled, noncompressible, and irregular bleeding wounds remain a giant challenge for rapid hemostasis. In this study, the tannic acid-crosslinked gelatin was first obtained by Michael addition reaction, and then the tannic acid-crosslinked gelatin composite microspheres (TGMs) were prepared by the emulsion cross-linking method. TGMs could significantly improve the water absorption and hemostatic performance compared with single component gelatin microspheres (GMs). Increasing the water absorption ratio and introducing blood coagulation factors into composite materials are simple and effective strategies to enhance the hemostatic properties. Therefore, chitosan quaternary ammonium salt (CQAS) and Ca2+ were electrostatic adsorbed to obtain two kinds of functional TGMs, which were respectively CQAS-absorbed TGMs (T2GMs-CQAS) and calcium ion-absorbed TGMs (T2GMs-Ca2+). Notably, T2GMs-CQAS, and T2GMs-Ca2+ could absorb water rapidly within 3 seconds, in addition, especially the water absorption ratio of T2GMs-CQAS could reach 2.95 times compared with GMs. Benefited from rapid water absorption, coagulation pathway activation, and red blood cells aggregation of T2GMs-CQAS and T2GMs-Ca2+, resulting in rapid blood coagulation in vitro. In addition, CQAS and Ca2+ provided strong and intrinsic antibacterial activity due to positive charge. Moreover, in the tail amputation and liver hemostatic models, T2GMs-CQAS and T2GMs-Ca2+ demonstrated superior hemostatic effects compared to commercial Yunnan Baiyao®. In conclusion, T2GMs-CQAS and T2GMs-Ca2+ have potential applications as hemostatic dressings in uncontrolled, noncompressible, and irregular bleeding wounds.

Natural approach of using nisin and its nanoform as food bio-preservatives against methicillin resistant Staphylococcus aureus and E.coli O157:H7 in yoghurt

BackgroundNatural antimicrobial agents such as nisin were used to control the growth of foodborne pathogens in dairy products. The current study aimed to examine the inhibitory effect of pure nisin and nisin nanoparticles (nisin NPs) against methicillin resistant Staphylococcus aureus (MRSA) and E.coli O157:H7 during the manufacturing and storage of yoghurt. Nisin NPs were prepared using new, natural, and safe nano-precipitation method by acetic acid. The prepared NPs were characterized using zeta-sizer and transmission electron microscopy (TEM). In addition, the cytotoxicity of nisin NPs on vero cells was assessed using the 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The minimum inhibitory concentrations (MICs) of nisin and its nanoparticles were determined using agar well-diffusion method. Further, fresh buffalo’s milk was inoculated with MRSA or E.coli O157:H7 (1 × 106 CFU/ml) with the addition of either nisin or nisin NPs, and then the inoculated milk was used for yoghurt making. The organoleptic properties, pH and bacterial load of the obtained yoghurt were evaluated during storage in comparison to control group.ResultsThe obtained results showed a strong antibacterial activity of nisin NPs (0.125 mg/mL) against MRSA and E.coli O157:H7 in comparison with control and pure nisin groups. Notably, complete eradication of MRSA and E.coli O157:H7 was observed in yoghurt formulated with nisin NPs after 24 h and 5th day of storage, respectively. The shelf life of yoghurt inoculated with nisin nanoparticles was extended than those manufactured without addition of such nanoparticles.ConclusionsOverall, the present study indicated that the addition of nisin NPs during processing of yoghurt could be a useful tool for food preservation against MRSA and E.coli O157:H7 in dairy industry.

Graphene Quantum Dots Nanoantibiotic-Sensitized TiO2- x Heterojunctions for Sonodynamic-Nanocatalytic Therapy of Multidrug-Resistant Bacterial Infections.

The exploration of sonodynamic therapy (SDT) as a possible replacement for antibiotics by creating reactive oxygen species (ROS) is suggested as a non-drug-resistant theranostic method. However, the low-efficiency ROS generation and complex tumor microenvironment which can deplete ROS and promote tumor growth will cause the compromised antibacterial efficacy of SDT. Herein, through an oxygen vacancy engineering strategy, TiO2- x microspheres with an abundance of Ti3+ are synthesized using a straightforward reductant co-assembly approach. The narrow bandgaps and Ti3+/Ti4+-mediated multiple-enzyme catalytic activities of the obtained TiO2- x microspheres make them suitable for use as sonosensitizers and nanozymes. When graphene quantum dot (GQD) nanoantibiotics are deposited on TiO2- x microspheres, the resulting GQD/TiO2- x shows an increased production of ROS, which can be ascribed to the accelerated separation of electron-hole pairs, as well as the peroxidase-like catalytic activity mediated by Ti3+, and the depletion of glutathione mediated by Ti4+. Moreover, the catalytic activities of TiO2- x microspheres are amplified by the heterojunctions-accelerated carrier transfer. In addition, GQDs can inhibit Topo I, displaying strong antibacterial activity and further enhancing the antibacterial activity. Collectively, the combination of GQD/TiO2- x-mediated SDT/NCT with nanoantibiotics can result in a synergistic effect, allowing for multimodal antibacterial treatment that effectively promotes wound healing.

Identifying and characterization of novel broad-spectrum bacteriocins from the Shanxi aged vinegar microbiome: Machine learning, molecular simulation, and activity validation

Shanxi aged vinegar microbiome encodes a wide variety of bacteriocins. The aim of this study was to mine, screen and characterize novel broad-spectrum bacteriocins from the large-scale microbiome data of Shanxi aged vinegar through machine learning, molecular simulation and activity validation. A total of 158 potential bacteriocins were innovatively mined from 117,552 representative genes based on metatranscriptomic information from the Shanxi aged vinegar microbiome using machine learning techniques and 12 microorganisms were identified to secrete bacteriocins at the genus level. Subsequently, employing AlphaFold2 structure prediction and molecular dynamics simulations, eight bacteriocins with high stability were further screened, and all of them were confirmed to have bacteriostatic activity by the Escherichia coli BL21 expression system. Then, gene_386319 (named LAB-3) and gene_403047 (named LAB-4) with the strongest antibacterial activities were purified by two-step methods and analyzed by mass spectrometry. The two bacteriocins have broad-spectrum antimicrobial activity with minimum inhibitory concentration values of 6.79 μg/mL-15.31 μg/mL against Staphylococcus aureus and Escherichia coli. Furthermore, molecular docking analysis indicated that LAB-3 and LAB-4 could interact with dihydrofolate reductase through hydrogen bonds, salt-bridge forces and hydrophobic forces. These findings suggested that the two bacteriocins could be considered as promising broad-spectrum antimicrobial agents.

Highly stable, antibacterial and antiviral composites films via improved non-solvent induced phase separation for textile application

Textile composites are ubiquitous in daily life and are one of the main ways in which bacteria and viruses spread. Highly effective antibacterial and antiviral flexible composites are effective for reducing microbe transmission. Herein, we reported an improved nonsolvent-induced phase separation method for the fabrication of flexible textile composites. Cu2O/polyurethane (Cu2OPU) composite films containing antibacterial and antiviral coatings were constructed using a Cu2O-polyvinyl butyral coagulation bath and binary solvent mixtures, yielding a composite that had excellent mechanical properties and stability and the components did not leach out. The as-prepared Cu2OPU composite films exhibited strong antibacterial and antiviral activity against Staphylococcus aureus and the H1N1 virus (above 99.99 % inactivation ratio). What’s more, Cu2OPU has excellent mechanical and environmental stability owing to the strong interfacial adhesion of Cu2O with the polymer matrix. Furthermore, it can withstand multiple washes and be suitable for daily use. Cu2OPU may be sustainably produced with great scalability, which may meet public, home, and textile applications.

Cultivable epiphytic bacteria of the Chlorophyta Ulva sp.: diversity, antibacterial, and biofilm-modulating activities.

Macroalgae harbor a rich epiphytic microbiota that plays a crucial role in algal morphogenesis and defense mechanisms. This study aims to isolate epiphytic cultivable microbiota from Ulva sp. surfaces. Various culture media were employed to evaluate a wide range of cultivable microbiota. Our objective was to assess the antibacterial and biofilm-modulating activities of supernatants from isolated bacteria. Sixty-nine bacterial isolates from Ulva sp. were identified based on 16S rRNA gene sequencing. Their antibacterial activity and biofilm modulation potential were screened against three target marine bacteria: 45%, mostly affiliated with Gammaproteobacteria and mainly grown on diluted R2A medium (R2Ad), showed strong antibacterial activity, while 18% had a significant impact on biofilm modulation. Molecular network analysis was carried out on four bioactive bacterial supernatants, revealing new molecules potentially responsible for their activities. R2Ad offered the greatest diversity and proportion of active isolates. The molecular network approach holds promise for both identifying bacterial isolates based on their molecular production and characterizing antibacterial and biofilm-modulating activities.