Pathogenic Gram-positive Bacteria Research Articles

In situ generation of antibacterial silver nanocomposite cotton fabrics by bio route

Antibacterial silver nanocomposite cotton fabrics were generated by in situ method using Senna auriculata (SA) leaf broth as reductant. Silver nanoparticles (AgNPs) synthesized on cotton fabrics (nanocomposite cellulose fabrics [NCCFs]) were analyzed by different spectral characteristics like FTIR, SEM correlated with EDX and XRD. The SEM analysis revealed that the generated AgNPs on NCCFs were spherical in shape with a mean size of 100 nm. The XRD studies showed that the biosynthesized NCCFs are exhibiting FCC crystalline lattice structure. The FTIR spectra indicated that the hydroxyl functional group in leaf extract is responsible for bioreduction of silver ions into metallic silver. The TG-DTG and DSC analysis showed higher thermal stability and the deterioration in stages. The biogenerated AgNPs in NCCFs exhibited good antibacterial activity against Gram-positive and Gram-negative pathogenic bacteria. The NCCFs also exhibited good mechanical strength. The NCCFs with bio generated AgNPs can be considered for medical and packing applications.

Novel composite films based on sodium alginate and gallnut extract with enhanced antioxidant, antimicrobial, barrier and mechanical properties

Composite films made of sodium alginate (NaAlg), glycerol, and gallnut extract (GE) at different NaAlg/GE weight ratios of 100/2.5, 100/25 and 100/50 were prepared and characterized in terms of antioxidant activity, water vapor permeability, mechanical, thermal and optical properties. Likewise, the antimicrobial activity of the produced films was evaluated against two common pathogenic bacteria including Staphylococcus aureus (ATCC 6538) and Escherichia coli (ATCC 11775) and two pathogenic fungi namely Aspergillus niger and Penicillium digitatum. Our results showed that increasing GE content from 0 to 25 wt% (based on NaAlg weight) increased tensile strength and elongation at break of NaAlg films respectively in the range of 48–103% and 135–185% without affecting their thermal stability. Moreover, increasing GE from 2.5 to 50 wt% reduced water vapor permeability of composite films in the range of 28.5–50.1% compared to the neat NaAlg films and increased their light barrier properties. As revealed by scanning electron microscopy and Fourier-transform infrared analysis, such improvements in functional and physical properties of NaAlg films can be attributed to the good compatibility between the polymeric matrix and the incorporated GE along with the increase in interactions between NaAlg molecules and GE polyphenolic compounds. Moreover, the incorporation of GE significantly improved the antioxidant capacity of NaAlg/GE composite films most likely due to the high total phenolic content of the incorporated GE. Furthermore, the resulting films showed good antibacterial activity against Gram-positive and Gram-negative pathogenic bacteria, suggesting their significant contribution, as antibacterial packaging materials, towards shelf life extension and food safety preservation.

PSXII-18 Treatment of composted poultry litter with natural hop extracts, effects on nitrogen accumulations, coliforms and select Gram-positive pathogenic and antimicrobial resistant bacteria

Abstract Poultry litter, produced by intensive poultry production systems, is a potentially valuable crude protein feedstuff for ruminants if effectively treated to kill pathogens before feeding. Composting effectively kills pathogens but risks losses of ammonia during uric acid degradation. To test if hop extracts may help preserve uric acid concentrations during composting, 11-g portions of used wood chip litter (WCL, 88% dry matter) were treated with 6 mL water containing Galena or Chinook hop extracts to achieve 0.06 g of either extract/g WCL. Control WCL was treated with buffer alone. The WCL was distributed to 50-mL tubes (3 tubes/treatment), capped and incubated in Gas Pac jars for 8 days at 30oC, followed by 3 days at 37oC and an additional 2 days at 42oC to simulate a 13-day compost period. A repeated measures analysis of variance revealed a treatment by day interaction on uric acid (P < 0.05), with concentrations being highest upon initiation of composting (41.9 ± 3.6 µmol/g), lowest on day 13 for the untreated compost (17.5 ± 9.2 µmol/g) and intermediate for Galena and Chinook hop-treated compost (28.0 ± 4.7 and 25.8 ± 0.8 µmol/g, respectively). Effects of treatment, day of composting or their interaction, however, were not observed (P > 0.05) on concentrations of ammonia and urea, which averaged 1.2 ± 1.0 and 2.9 ± 0.6 µmol/g, respectively. As expected, an effect of day-of composting on survivability (P < 0.05) of select bacterial populations was confirmed, with counts being decreased more than 3.0 log10 units after 13 days composting than on day 0 for enterococci, staphylococci, lactic acid bacteria, coliforms and total aerobes (6.7 ± 0.09, 9.0 ± 0.01, 5.8 ± 0.16, 5.9 ± 0.09 and 9,9 ± 0.06 log10 CFU/g, respectively). These results indicate that hops-treatment may help preserve crude protein within WCL during composting.

The Clostridioides difficile Cysteine-Rich Exosporium Morphogenetic Protein, CdeC, Exhibits Self-Assembly Properties That Lead to Organized Inclusion Bodies in Escherichia coli.

Clostridioides difficile is an obligately anaerobic, spore-forming, Gram-positive pathogenic bacterium that is considered the leading cause of nosocomial diarrhea worldwide. Recent studies have attempted to understand the biology of the outermost layer of C. difficile spores, the exosporium, which is believed to contribute to early interactions with the host. The fundamental role of the cysteine-rich proteins CdeC and CdeM has been described. However, the molecular details behind the mechanism of exosporium assembly are missing. The underlying mechanisms that govern exosporium assembly in C. difficile remain poorly studied, in part due to difficulties in obtaining pure soluble recombinant proteins of the C. difficile exosporium. In this work, we observed that CdeC was able to form organized inclusion bodies (IBs) in Escherichia coli filled with lamella-like structures separated by an interspace of 5 to 15 nm; however, CdeC expression in an E. coli strain with a more oxidative environment led to the loss of the lamella-like organization of CdeC IBs. Additionally, dithiothreitol (DTT) treatment of CdeC inclusion bodies released monomeric soluble forms of CdeC. Deletions in different portions of CdeC did not affect CdeC's ability to aggregate and form oligomers stable under denaturation conditions but affected CdeC's self-assembly properties. Overall, these observations have important implications in further studies elucidating the role of CdeC in the exosporium assembly of C. difficile spores.IMPORTANCE The endospore of Clostridioides difficile is the vehicle for transmission and persistence of the pathogen, and, specifically, the exosporium is the first contact between the host and the spore. The underlying mechanisms that govern exosporium assembly in C. difficile remain understudied, in part due to difficulties in obtaining pure soluble recombinant proteins of the C. difficile exosporium. Understanding the exosporium assembly's molecular bases may be essential to developing new therapies against C. difficile infection.

Crotalaria verrucosa Leaf Extract Mediated Synthesis of Zinc Oxide Nanoparticles: Assessment of Antimicrobial and Anticancer Activity.

In this work, we present an ecofriendly, non-hazardous, green synthesis of zinc oxide nanoparticles (ZnO NPs) by leaf extract of Crotalaria verrucosa (C. verrucosa). Total phenolic content, total flavonoid and total protein contents of C. verrucosa were determined. Further, synthesized ZnO NPs was characterized by UV–visible spectroscopy (UV-vis), X-ray diffractometer (XRD), Fourier transform infra-red (FTIR) Spectra, transmission electron microscope (TEM), and Dynamic light scattering (DLS) analysis. UV-vis shows peak at 375 nm which is unique to ZnO NPs. XRD analysis demonstrates the hexagonal phase structures of ZnO NPs. FTIR spectra demonstrates the molecules and bondings associated with the synthesized ZnO NPs and assures the role of phytochemical compounds of C. verrucosa in reduction and capping of ZnO NPs. TEM image exhibits that the prepared ZnO NPs is hexagonal shaped and in size ranged between 16 to 38 nm which is confirmed by DLS. Thermo-gravimetric analysis (TGA) was performed to determine the thermal stability of biosynthesized nanoparticles during calcination. The prepared ZnO NPs showed significant antibacterial potentiality against Gram-positive (S. aureus) and Gram-negative (Proteus vulgaris, Klebsiella pneumoniae, and Escherichia coli) pathogenic bacteria and SEM image shows the generalized mechanism of action in bacterial cell after NPs internalization. In addition, NPs are also found to be effective against the studied cancer cell lines for which cytotoxicity was assessed using MTT assay and results demonstrate highest growth of inhibition at the concentration of 100 µg/mL with IC50 value at 7.07 µg/mL for HeLa and 6.30 µg/mL for DU145 cell lines, in contrast to positive control (C. verrucosa leaf extract) with IC50 of 22.30 µg/mL on HeLa cells and 15.72 µg/mL on DU145 cells. Also, DAPI staining was performed in order to determine the effect on nuclear material due to ZnO NPs treatment in the studied cell lines taking leaf extract as positive control and untreated negative control for comparison. Cell migration assay was evaluated to determine the direct influence of NPs on metastasis that is potential suppression capacity of NPs to tumor cell migration. Outcome of the synthesized ZnO NPs using C. verrucosa shows antimicrobial activity against studied microbes, also cytotoxicity, apoptotic mediated DNA damage and antiproliferative potentiality in the studied carcinoma cells and hence, can be further used in biomedical, pharmaceutical and food processing industries as an effective antimicrobial and anti-cancerous agent.

Bactericidal and In-Vitro Cytotoxic Efficacy of Silver Nanoparticles (Ag-NPs) Fabricated by Endophytic Actinomycetes and Their Use as Coating for the Textile Fabrics

An endophytic strain of Streptomyces antimycoticus L-1 was isolated from healthy medicinal plant leaves of Mentha longifolia L. and used for the green synthesis of silver nanoparticles (Ag-NPs), through the use of secreted enzymes and proteins. UV–vis spectroscopy, Fourier-transform infrared (FT-IR), transmission electron microscopy (TEM), X-ray diffraction (XRD), and dynamic light scattering (DLS) analyses of the Ag-NPs were carried out. The XRD, TEM, and FT-IR analysis results demonstrated the successful biosynthesis of crystalline, spherical Ag-NPs with a particle size of 13–40 nm. Further, the stability of the Ag-NPs was assessed by detecting the surface Plasmon resonance (SPR) at 415 nm for one month or by measuring the NPs surface charge (−19.2 mV) by zeta potential analysis (ζ). The green-synthesized Ag-NPs exhibited broad-spectrum antibacterial activity at different concentrations (6.25–100 ppm) against the pathogens Staphylococcus aureus, Bacillus subtilis Pseudomonas aeruginosa, Escherichia coli, and Salmonella typhimurium with a clear inhibition zone ranging from (9.5 ± 0.4) nm to (21.7 ± 1.0) mm. Furthermore, the green-synthesized Ag-NPs displayed high efficacy against the Caco-2 cancerous cell line (the half maximal inhibitory concentration (IC50) = 5.7 ± 0.2 ppm). With respect to antibacterial and in-vitro cytotoxicity analyses, the Ag-NPs concentration of 100 ppm was selected as a safe dose for loading onto cotton fabrics. The scanning electron microscopy connected with energy-dispersive X-ray spectroscopy (SEM-EDX) for the nano-finished fabrics showed the distribution of Ag-NPs as 2% of the total fabric elements. Moreover, the nano-finished fabrics exhibited more activity against pathogenic Gram-positive and Gram-negative bacteria, even after 10 washing cycles, indicating the stability of the treated fabrics.

Exploration of synthesis, structural aspects, DFT studies and bio-efficacy of some new DHA-benzohydrazide based copper(II) complexes

A copper (II) complex with ligand obtained by the dehydrative condensation of 3-acetyl-6-methyl-2H-pyran-2,4(3H)‑dione (DHA) and benzohydrazide has been synthesized (4). This species was additionally coordinated by various solvent molecules, namely ethanolamine, methanol, DMF, dimethyl amine, isopropyl amine, diisobutylamine, and ethylenediamine to synthesize complexes 5a-5g. All the complexes were characterized by single crystal X-ray diffraction analysis and other analytical techniques. In each case, the copper atom is tetra-coordinated by chelating carbohydrazide ligand through O, N, O donor atoms and the N/O heteroatom from the coordinated solvent (except for ethylenediamine, where Cu is pentacoordinated). The intermolecular interactions present in each complex have been quantified using Hirshfeld surface analysis, and the electrostatic properties associated with these complexes were calculated using DFT studies. Considering the expected bioactivity of carbohydrazide derivatives, the antibacterial activity of ligand and copper complexes was tested against pathogenic Gram-positive and Gram-negative bacteria using ciprofloxacin as positive control. Compounds 4 and 5f show potent antibacterial activity against B. subtilis with MIC and MBC value of 32 μM.

Pharmacological Evaluation of Novel Organoiron Dendrimers as Antimicrobial and Anti-Inflammatory Agents.

The synthesis of a novel and attractive class of nonsteroidal anti-inflammatory and antimicrobial organoiron dendrimers attached to the well-known drug ibuprofen is achieved. The structures of these dendrimers are established by spectroscopic and analytical techniques. The antimicrobial activity of these dendrimers is investigated and tested against five human pathogenic Gram-positive and Gram-negative bacteria, and minimum inhibitory concentrations are reported. Some of these synthesized dendrimers exhibit higher inhibitory activity against methicillin-resistant Staphylococcus aureus, vancomycin-resistant Enterococcus faecium, andStaphylococcus warnericompare to the reference drugs. As well, the in vitro and in vivo anti-inflammatory activities of these dendrimers are evaluated. The results of in vivo anti-inflammatory activity and histopathology of inflamed paws show that all dendrimers display considerable anti-inflammatory activity; however, second-generation dendrimer(G2-D6)shows the best anti-inflammatory activity, which is more potent than the commercial drug ibuprofen at the same tested dose. Results of the toxicity study reveal that G2-D6is the safest drug on biological tissues.

Antimicrobial activity of Lavandula stoechas phenolic extracts against pathogenic bacteria isolated from a hospital in Morocco

The objective of this study was to determine the chemical families and the total phenolic content in a hydro-ethanolic extract of Lavandula stoechas, as well as to evaluate the antibacterial effect of the different phenolic fractions of this plant against pathogenic bacterial strains isolated from a hospital in the city of Fez, Morocco. The hydro-ethanolic extract was obtained and phytochemical screening of the different chemical families of the plant was conducted using colorimetric methods. The quantification of the total concentration of polyphenols in the L. stoechas extract was conducted according to the Folin–Ciocalteu method. The antimicrobial effects of the hydro-ethanolic, flavonoid and tannin extracts against Gram-positive and Gram-negative pathogenic bacteria isolated from a hospital in Fez were determined using the disc diffusion method. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined for all pathogenic and reference strains. The total phenolic content of L. stoechas was 130.15 ± 3.72 mg gallic acid equivalent/g plant extract. The total phenolic content of L. stoechas was 130.15 ± 3.72 mg gallic acid equivalent/g plant extract. The flavonoid extract had the highest effect against bacteria, with MIC and MBC values varying from 10 to 40 mg/ml and 20–80 mg/ml, respectively. The results also revealed that the hydro-ethanolic extract showed a MIC value of 80 mg/ml against all bacteria except Acinetobacter baumanii and Pseudomonas aeruginosa (ATCC27853). The results obtained in our study showed an important antibacterial effect of flavonoid extracts from L. stoechas compared to other extracts. These results can aid in the discovery of new antimicrobial molecules of natural origin. Further research on phenolic compounds in L. stoechas is required.

Synthesis and evaluation of protein-based biopolymer in production of silver nanoparticles as bioactive compound versus carbohydrates-based biopolymers.

This overall process deals with evaluating the performance of silver nanoparticles, synthesized from sodium caseinate (SC) as green biological active agent, in comparison with widely produced from carboxymethyl cellulose, other carbohydrates (oxidized nanocellulose fibres (OC) and starch (St)). The TGA, FTIR and TEM, as well as its antimicrobial activities toward pathogenic Gram-positive and Gram-negative bacteria in addition to the yeast strain Candida albicans NRRL Y-477 were examined. In addition, with regard to their anti-tumour activity, the evaluation was studied via many cancer cell lines against RPE1 (normal retina cell line). The results revealed that the SC–Ag(I) and CMC–Ag(I) complexes were formed in six- and five-membered chelate rings, respectively, as nanoparticles, while linear chelation structure was formed in case of OC–Ag(I) and St–Ag(I) complexes. The complexation of SC with Ag(I) ions was recommended as promising stable and antimicrobial agent, with lower free Ag(I) ions and particle size than other Ag-complexes. Moreover, it provided anti-tumour activity of most tested cell lines (in vitro), with the following sequence HCT116 > PC3 > HePG 2 > MCF-7 > A549 with IC50 and IC90 values of 25.8 and 54.73 µg ml−1, 45.1 and 66.7 µg ml−1, 64.3 and 110.7 µgml−1, 71.4 and 114.8 µgml−1 and 80.1 and 127.7 µgml−1, respectively. The promising effect of SC–Ag complex was also clear from its selective index versus RPE1 (normal retina cell line).

Synthesis and Pharmacological Evaluation of 2-(4-(3 (Substituted Phenyl) Acryloyl) Phenoxy)-N, N Diphenylacetamides

Recently a series of Schiff bases of diphenylamine derivatives have been synthesized and evaluated in vitro for their antibacterial activity against pathogenic both Gram-positive bacteria B. subtitles and Gram-negative bacteria E. coli using ciprofloxacin as standard drug at conc. of 50 μg/ml and 100 μg/ml. Literature review revels that chalcones possesses various biological activities like antimicrobial, antiviral, anti-inflammatory, anticancer and sedative etc. Therefore the present study was designed on synthesis and pharmacological evaluation of 2-(4-(3 (Substituted Phenyl) Acryloyl) Phenoxy)-N, N Diphenylacetamides. Target compound was synthesized by reaction of chloroacetylchloride with diphenylamine to afford 2-chloro-N, N-diphenylacetamide which further by reaction with substituted Chalcones and characterized following recrystallization and evaluated for anti-microbial potential through cup-diffusion method. In results, the target compounds were tested for activity against B. Subtilis, E.Coli and C. albicans. The chalcones having the lipophilic 4-chloro group (RKCT2) showed the greatest antimicrobial activity (zone of inhibition 20 & 22 mm against. B. subtilis, E. Coli, C. Albicans respectively. It suggests further researchers to go through anti-microbial evaluations against a more varieties of bacteria and fungi.
 Keywords: Schiff bases of diphenylamine derivatives, antibacterial activity, Gram-positive bacteria, 2-(4-(3 (Substituted Phenyl) Acryloyl) Phenoxy)-N, N Diphenylacetamides

A Novel Peptide Antibiotic Produced by Streptomyces roseoflavus Strain INA-Ac-5812 With Directed Activity Against Gram-Positive Bacteria.

In this work, we report the isolation and detailed functional characterization for the new non-ribosomally synthesized antibiotic 5812-A/C, which was derived from metabolites of Streptomyces roseoflavus INA-Ac-5812. According to its chemical structure, the studied 5812-A/C preliminary is composed of a cyclic peptide part covalently bounded with an arabinose residue. N-terminal amino acid sequencing of the native peptide has identified its partial structure of Leu-Asp-Gly-Ser-Gly and consisting of a Tyr residue that is supposed to have a two-component peptide nature for the molecule studied. However, the structural analysis of the antibiotic complex derived from S. roseoflavus INA-Ac-5812 is still ongoing. The mechanism of action of 5812-A/C was assessed in comparison with its most related analog, the lipopeptide antibiotic daptomycin, given the presence in both antimicrobials of an L-kynurenine amino acid residue. The inhibitory activity of 5812-A/C against Gram-positive bacteria including methicillin-resistant strain of Staphylococcus aureus was similar to daptomycin. The mechanism of action of 5812-A/C was associated with the disruption of membrane integrity, which differs in comparison with daptomycin and is most similar to the antimicrobial membrane-disturbing peptides. However, 5812-A/C demonstrated a calcium-dependent mode of action. In addition, unlike daptomycin, 5812-A/C was able to penetrate mature biofilms and inhibit the metabolic activity of embedded S. aureus cells. At the same time, 5812-A/C has no hemolytic activity toward erythrocyte, but possessed weak cytotoxic activity represented by heterochromatin condensation in human buccal epithelium cells. The biological properties of the peptide 5812-A/C suggest its classification as a calcium-dependent antibiotic effective against a wide spectrum of Gram-positive pathogenic bacteria.

Synergistically-acting Enterocin LD3 and Plantaricin LD4 Against Gram-Positive and Gram-Negative Pathogenic Bacteria.

The efficacy of antimicrobials is an important aspect during their applications in food and therapeutics. In this study, combination of two bacteriocins, enterocin LD3 and plantaricin LD4, was studied against two pathogenic bacteria, Staphylococcus aureus subsp. aureus ATCC25923 and Salmonella enterica subsp. enterica serovar Typhimurium ATCC13311 for increasing their potency and bactericidal activity. The minimal inhibitory concentrations (MICs) of enterocin LD3 and plantaricin LD4 against Staph. aureus subsp. aureus ATCC25923 were 180 and 220 μg/mL, whereas in combination, reduced to 115 μg/mL, respectively. The MICs of enterocin LD3 and plantaricin LD4 against Salm. enterica subsp. enterica serovar Typhimurium ATCC13311 were 240 and 320 μg/mL, respectively, whereas in combination, these were found to be 130 μg/mL, respectively. The fractional inhibitory concentration (FIC) indices calculated as 0.50 against Staph. aureus subsp. aureus ATCC25923 and 0.43 against Salm. enterica subsp. enterica serovar Typhimurium ATCC13311 were found to be ≤ 0.5 indicating the synergy. The isobologram showed MIC of combined bacteriocins falls below the plotted straight line further signifies synergy. The growth response of Staph. aureus subsp. aureus ATCC25923 and Salm. enterica subsp. enterica serovar Typhimurium ATCC13311 was significantly reduced in the presence of combined bacteriocins in comparison with their individual effects. The number of dead cells was higher as a result of combined effect as compared with their independent effect evidenced by fluorescent microscopy. Transmission electron microscopy (TEM) revealed the higher disruption of cell membrane in the combined bacteriocin-treated cells as compared with alone effects. The FTIR spectra of enterocin LD3-treated cells showed alteration at ~ 1,451.82 and ~ 1,094.30/cm corresponding to nucleic acids and phospholipids suggesting its interaction with cell membrane and nucleic acids. In contrast, plantaricin LD4-treated cells did not show such alterations suggesting plantaricin LD4 may kill target cells using other mechanism. Our data suggest that different mode of action of both bacteriocins results in division of labour and may be responsible for their synergistic activity against target cells. Similarly, the synergistic effect of bacteriocins was also observed against other pathogenic bacteria such as Proteus mirabilis ATCC43071, Pseudomonas aeruginosa ATCC27853 and Escherichia coli ATCC25922. These bacteriocins, therefore, act synergistically against target pathogens and may be applied in appropriate combinations for food safety and medical applications.

Environmental and biomedical applications of AgNPs synthesized using the aqueous extract of Solanum surattense leaf

A novel eco-friendly and biocompatible method has been used with the help of Solanum surattense aqueous leaves extract to synthesis silver nanoparticles (AgNPs). The cost-effective green synthesis route has been given much care to ensure an environmentally friendly and straightforward approach, as it is most demanded in the biomedical industry. The proposed novel synthesis method offers additional compensations over other synthesizing approaches. Different analytical systems such as UV–vis, IR, XRD, DLS, SEM, EDAX, XPS, and TEM characterization techniques were used to understand the quality of the green synthesized nanoparticles for biomedical applications. The surface plasmon resonance peak of green synthesized silver nanoparticles at 446 nm was observed by UV absorbance spectral analysis. The XRD, SEM, and TEM analysis using to study the crystal structure, particle size, and surface morphology of the AgNPs. The results confirmed the synthesized spherical shape silver nanoparticles were crystallized in a face-centered cubic structure. The zeta potential measurement was used to authorize the excellent stability of AgNPs employing the dynamic light scattering method. FTIR spectral study confirmed that phytocompound participate in the bioreduction as well as stabilization of biosynthesized AgNPs by Solanum surattense. Also, the phytochemical content acts as the capping agent on surface AgNPs. The synthesized silver nanoparticles are subjected to antibacterial activity against both gram-positive and negative pathogenic bacteria for finding suitability in biocompatible applications. Also, the cytotoxicity of AgNPs was studied against the human breast cancer cell line and compared with one of the commercially available cancer drugs. Also, we have shown that the prepared AgNPs could serve as an excellent photocatalyst for degrading the Rhodamine B (RhB) dye and Acid Violet 7 (AV 7) dye under direct sunlight radiation.

An In Vitro Evaluation of the Ability of Ozone Nano-bubble Water to Kill Pathogenic Gram-Negative and Gram-Positive Bacteria

An In Vitro Evaluation of the Ability of Ozone Nano-bubble Water to Kill Pathogenic Gram-Negative and Gram-Positive Bacteria

Preparation of poly(butylene adipate-co-terephthalate)/ZnSnO3 composites with enhanced antimicrobial activity

Poly(butylene adipate-co-terephthalate) (PBAT) composites with ZnSnO3 nanosheets as inorganic dispersed constituent have been prepared by a convenient solution mixing method, where ZnSnO3 is obtained by hydrothermal synthesis. The structure and morphology of ZnSnO3 and PBAT/ZnSnO3 composite are characterized. The obtained composite films, made by drop casting, display significantly-improved antimicrobial activity against Gram-negative (E. coli) and Gram-positive (S. aureus) food-borne pathogenic bacteria. The results suggest that the PBAT/ZnSnO3 composites may serve as promising candidate for antimicrobial food packaging materials.

MMPphg from the thermophilic Meiothermus bacteriophage MMP17 as a potential antimicrobial agent against both Gram-negative and Gram-positive bacteria

BackgroundNew strategies are urgently needed to deal with the growing problem of multidrug-resistant bacterial pathogens. As the natural viruses against bacteria, recently, bacteriophages have received particular attention. Here, we identified and characterized a novel peptidoglycan hydrolase named MMPphg by decoding the complete genome sequence of Meiothermus bacteriophage MMP17, which was isolated in Tengchong hot spring in China and contains a circular genome of 33,172 bp in size and a GC content of 63.4%.FindingsWe cloned the MMPphg gene, overproduced and purified the phage lytic protein, which contains a highly conserved M23 metallopeptidase domain and can be activated by Mg2+ and Zn2+. MMPphg is capable of withstanding temperatures up to 70 °C, and preserved more than 80% of its activity after a 30 min treatment between 35 and 65 °C. More interestingly, by disrupting bacterial cells, MMPphg exhibits surprising antimicrobial activity against both Gram-negative and Gram-positive pathogenic bacteria, especially antibiotic-resistant strains such as Escherichia coli O157, Staphylococcus aureus and Klebsiella pneumonia.ConclusionsIn the current age of mounting antibiotic resistance, these results suggest the great potential of MMPphg, the gene product of bacteriophage MMP17, in combating bacterial infections and shed light on bacteriophage-based strategies to develop alternatives to conventional antibiotics for human or veterinary applications.

Antimicrobial Effect of Natural Berry Juices on Common Oral Pathogenic Bacteria.

(1) Background: Antimicrobial agents such as chlorhexidine (CHX) are commonly used in oral plaque control. However, sometimes those agents lack antimicrobial efficiency or cause undesired side effects. To identify alternative anti-infective agents, the present study investigated the antibacterial activity of all-fruit juices derived from blackcurrant, redcurrant, cranberry and raspberry on common oral pathogenic gram-positive and gram-negative bacteria (Streptococcus mutans, Streptococcus gordonii, Streptococcus sobrinus, Actinomyces naeslundii, Fusobacterium nucleatum, Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Enterococcus faecalis). (2) Methods: Antibacterial efficiency was evaluated by agar diffusion assay and in direct contact with bacteria in planktonic culture. Furthermore, cytotoxicity on human gingival fibroblasts was determined. (3) Results: Blackcurrant juice was most efficient at suppressing bacteria; followed by the activity of redcurrant and cranberry juice. Raspberry juice only suppressed P. gingivalis significantly. Only high-concentrated blackcurrant juice showed minimal cytotoxic effects which were significantly less compared to the action of CHX. (4) Conclusion: Extracts from natural berry juices might be used for safe and efficient suppression of oral pathogenic bacterial species.

Biovolume and spatial distribution of foodborne Gram-negative and Gram-positive pathogenic bacteria in mono- and dual-species biofilms

The objective of this study was to characterize the biofilms formed by Salmonella enterica serotype Agona, Listeria monocytogenes, methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus faecium (VRE) after 12, 48, 72, 120 and 240 h of incubation at 10 °C. Biofilms containing a single species, together with dual-species biofilms in which S. enterica and a Gram-positive bacterium existed in combination, were formed on polystyrene and evaluated by using confocal laser scanning microscopy (CLSM). All strains were able to form biofilm. The greatest biovolume in the observation field of 14,161 μm2 was observed for mono-species biofilms after 72 h, where biovolumes of 94,409.0 μm3 ± 2131.0 μm3 (S. enterica), 58,418.3 μm3 ± 5944.9 μm3 (L. monocytogenes), 68,020.8 μm3 ± 5812.3 μm3 (MRSA) and 59,280.0 μm3 ± 4032.9 μm3 (VRE) were obtained. In comparison with single-species biofilms, the biovolume of S. enterica was higher in the presence of MRSA or VRE after 48, 72 and 120 h. In dual-species biofilms, the bacteria showed a double-layer distribution pattern, with S. enterica in the top layer and Gram-positive bacteria in the bottom layer. This spatial disposition should be taken into account when effective strategies to eliminate biofilms are being developed.

Structural characterization, antioxidant and antibacterial activities of a novel water soluble polysaccharide from Cordia myxa fruits

In this study, water-soluble polysaccharide and fatty acids of Cordia myxa fruit harvested from the southwest of Iran were isolated and investigated. The extraction yield of water-soluble polysaccharide of C. myxa fruit (WSPCM) was 24.12%, and its experimental purity was 79.43%. The High Performance Liquid Chromatography results indicated that the WSPCM consisted of glucose, fructose, sucrose, maltose, ribose, maltitol, and maltoheptaose. The atomic absorption spectrometer analysis indicated that WSPCM was a rich source of Ca and Na. The dynamic light scattering results illustrated that the average particle size and zeta potential were 1510.7 nm and − 64.96, respectively. Fourier transform infrared spectroscopy revealed the presence of α and β-configurations in WSPCM. The total unsaturated and saturated fatty acids were 60.62% and 39.38%, respectively and oleic, palmitic, and linoleic were the main fatty acids. The WSPCM represented good antibacterial activities against both Gram-positive and Gram-negative pathogenic bacteria. Moreover, it showed a relatively good antioxidant activity. In conclusion, WSPCM could be introduced as a novel natural antioxidant and antibacterial substance in functional food.