Effect of the structure of chitosan quaternary ammonium salts with different spacer groups on antibacterial and antibiofilm activities.

In this study, three types of dodecyl chitosan quaternary ammonium salts, each with different spacer groups were synthesized. These chitosan derivatives are N',N'-dimethyl-N'-dodecyl-ammonium chloride-N-amino-acetyl chitosan (DMDAC), N'-dodecyl-N-isonicotinyl chitosan chloride (DINCC) and N',N'-dimethyl-N'-dodecyl-ammonium chloride-N-benzoyl chitosan (DMDBC). The synthesized products were characterized using Fourier transform infrared spectrometers, nuclear magnetic resonance, thermogravimetric analysis, and elemental analysis. The antibacterial and antibiofilm activities against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) were investigated. The experimental results indicated that the introduction of hydrophobic groups of spacer groups could enhance the antibacterial and antibiofilm activities of the chitosan derivatives. The antibacterial rates of the chitosan derivatives were over 90 % for both E. coli and S. aureus at a concentration of 0.5 mg/mL. The chitosan derivatives removed >50 % of the mature biofilm of E. coli and over 90 % of the mature biofilm of S. aureus at a concentration of 2.5 mg/mL. Further, the synthesized chitosan derivatives were determined to be non-toxic to L929 cells. Among them, DMDBC exhibited the most promising overall performance and show potential for wide-ranging applications in food preservation, disinfectants, medical, and other fields.

Biogenic Synthesis and Characterisation of Novel Potassium Nanoparticles by Capparis spinosa Flower Extract and Evaluation of Their Potential Antibacterial, Anti-biofilm and Antibiotic Development.

Scientific researches on the synthesis, characterisation, and biological activity of potassium nanoparticles (K NPs) are extremely rare. In our study, we successfully synthesised a novel form of K NPs using Capparis spinosa (C. spinosa) flower extract as a reducing and capping agent. The formation of K NPs in new form (K2O NPs) was confirmed by UV-vis and XRD spectra. Furthermore, the FTIR results indicated the presence of specific active biomolecules in the C. spinosa extract which played a crucial role in reducing and stabilising K2O NPs. SEM imaging demonstrated that the K2O NPs exhibited irregular shapes with nanosizes ranging between 25 and 95 nm. Remarkably, the biosynthesised K2O NPs displayed considerable antibacterial activity against a wide range of multidrug-resistant (MDR) pathogenic bacteria. K2O NPs demonstrated considerable anti-biofilm activity against preformed biofilms produced by MDR bacteria. Combining K2O NPs with conventional antibiotics greatly improved their efficacy in compacting the MDR bacterial strains. Industrially, bulk form of potassium oxides was commonly used in the preparation of various antimicrobial compounds such as detergents, bleach, and oxidising solutions. The synthesis of potassium oxide in nanoform has shown remarkable biological efficacy, making it a promising therapeutic approach for pharmaceutical and medical applications.

Antibiofilm Metabolites from Marine-derived Streptomyces sp. ZS-A31.

A novel compound streptothiomycin F (1), and a new natural product, N-(5-nitropentyl)acetamide (2), were discovered alongside ten previously identified compounds (3-12) through solid fermentation of marine-derived Streptomyces sp. ZS-A31 based on rice. The chemical structures of compounds 1-2 were elucidated using 1D and 2D NMR, as well as HRESIMS data analysis. Evaluation of all isolated compounds for their antibiofilm and antibacterial activities against P. aeruginosa was carried out using microdilution and crystal violet staining methods. Results highlighted the weak potency of the known compounds lumichrome (3) and vanillic acid (7) in inhibiting biofilm formation.

Anti-biofilm effect of enzymatic hydrolysates of ovomucin in Listeria monocytogenes and Staphylococcus aureus.

Despite modern advances in food hygiene, food poisoning due to microbial contamination remains a global problem, and poses a great threat to human health. Especially, Listeria monocytogenes and Staphylococcus aureus are gram-positive bacteria found on food-contact surfaces with biofilms. These foodborne pathogens cause a considerable number of food poisoning and infections annually. Ovomucin (OM) is a water-insoluble gel-type glycoprotein in egg whites. Enzymatic hydrolysis can be used to improve the bioactive properties of OM. This study aimed to investigate whether ovomucin hydrolysates (OMHs) produced using five commercial enzymes (Alcalase®, Bromelain, α-Chymotrypsin, Papain, and Pancreatin) can inhibit the biofilm formation of L. monocytogenes ATCC 15313, L. monocytogenes H7962, S. aureus KCCM 11593, and S. aureus 7. Particularly, OMH prepared with papain (OMPP; 500 µg/mL) significantly inhibited biofilm formation in L. monocytogenes ATCC 15313, L. monocytogenes H7962, S. aureus KCCM 11593, and S. aureus 7 by 85.56 %, 80.28 %, 91.70 %, and 79.00 %, respectively. In addition, OMPP reduced the metabolic activity, exopolysaccharide production (EPS), adhesion ability, and gene expression associated with the biofilm formation of these bacterial strains. These results suggest that OMH, especially OMPP, exerts anti-biofilm effects against L. monocytogenes and S. aureus. Therefore, OMPP can be used as a natural anti-biofilm agent to control food poisoning in the food industry.

Potential mechanism of gallic acid-coated iron oxide nanoparticles against associated genes of Klebsiella pneumoniae capsule, antibacterial and antibiofilm.

Antibiotic resistance has increased in recent years, especially for pathogens like Klebsiella pneumoniae. Discovering and developing new drugs is challenging due to the high resistance of pathogens. Metal nanoparticles have been widely used in recent years to overcome and treat infections. Gallic acid-coated iron oxide nanoparticles (IONPs-GA) were synthesized in a simple and cost-effective method. The morphology characteristics of synthesized IONPs-GA were analyzed using Fourier transform infrared spectroscopy (FTIR), x-ray diffraction analysis (XRD), and scanning electron microscope (SEM) analysis. IONPs were mostly spherical in shape with sizes ranging between 32 and 61 nm. All analyses used in this study confirmed the successful coating of gallic acid to iron oxide. Biological activities were studied phenotypically and on the molecular level, including antibacterial, antibiofilm, and mRNA levels of capsule-associated genes. The results showed high antimicrobial activity of the synthesized nanoparticles against different G+ve and G-ve bacteria. The highest activity was recorded against Staphylococcus aureus (43 mm) and K. pneumoniae (22 mm). The MIC of IONPs against K. pneumoniae was 3.12 mg/mL and SEM analysis showed adhering the IONPs-GA to the cell surface of K. pneumoniae resulted in disrupting the cell membrane. Different concentrations of sub-MIC inhibited K. pneumoniae biofilm formation with the highest inhibition percentage at ½ × MIC (66.86%). Also, the synthesized IONPs-GA differently affected the regulation and mRNA level of capsule-associated genes in K. pneumoniae. The results indicated that IONPs-GA could be useful in biological applications such as in drug delivery and treatment wide range of pathogens. RESEARCH HIGHLIGHTS: Gallic acid was successfully coated into iron oxide nanoparticles synthesized in a simple way. IONPs-GA was morphologically characterized using FTIR, XRD, and SEM. Evaluation the activity of IONPs-GA as antibacterial, antibiofilm, and study the potential level of mRNA affected by IONPs-GA.

Synthesis, characterization and evaluation of in vitro potential antimicrobial efficiency of new chitosan hydrogels and their CuO nanocomposites.

The phenomenon of microbial resistance and its resulting biofilms to traditional antibiotics is worsening over time. Therefore, the discovery of alternative substances that inhibit microbial activities through mechanisms different from those of known antibiotics requires attention. So, chitosan was crosslinked using different amounts of oxalyl dihydrazide yielding four novel hydrogels; ODHCs-I, ODHCs-II, ODHCs-III, and ODHCs-IV of crosslinking degree 12.17, 20.67, 31.67, and 43.17, respectively. Different amounts of CuO nanoparticles were impregnated into ODHCs-IV, obtaining ODHCs-IV/CuONPs-1 %, ODHCs-IV/CuONPs-3 % and ODHCs-IV/CuONPs-5 % composites. Their structure was emphasized using FTIR, SEM, XRD, TEM, EDX and elemental analysis. Their in vitro antimicrobial and anti-biofilm activities improved with increasing ODH and CuONPs content. ODHCs-IV exhibited minimal inhibition concentration (2 µg/mL) against S. pyogenes that was much lower than Vancomycin (3.9 µg/mL). ODHCs-IV/CuONPs-5 % displayed better inhibition performance than Vancomycin and Amphotericin B against Gram-positive-bacteria and fungi, respectively, and comparable one to that of Vancomycin against Gram-negative-bacteria. ODHCs-IV/CuONPs-5 % displayed much lower minimal biofilm inhibition concentrations (1.95 to 3.9 µg/mL) as compared with those of ODHCs-IV (7.81 and 15.63 µg/mL), against C. albicans, S. pyogenes, and K. pneumonia. ODHCs-IV/CuONPs-5 % composite is safe on normal human cells. Oxalyl dihydrazide and CuONPs amalgamated into chitosan in one formulation promoted its antimicrobial efficiency.

Effect of Nitrogen Doping on the Photocatalytic Properties and Antibiofilm Efficacy of Reduced TiO2 Nanoparticles.

Nanomaterial-mediated antibacterial photodynamic therapy (aPDT) emerges as a promising treatment against antibiotic-resistant bacterial biofilms. Specifically, titanium dioxide nanoparticles (TiO2 NPs) are being investigated as photosensitizers in aPDT to address biofilm related diseases. To enhance their photocatalytic performance in the visible spectral range for biomedical applications, various strategies have been adopted, including reduction of TiO2 NPs. However, despite improvements in visible-light photoactivity, reduced TiO2 NPs have yet to reach their expected performance primarily due to the instability of oxygen vacancies and their tendency to reoxidize easily. To address this, we present a two-step approach to fabricate highly visible-light active and stable TiO2 NP photocatalysts, involving nitrogen doping followed by a magnesium-assisted reductive annealing process. X-ray photoelectron spectroscopy analysis of the synthesized reduced nitrogen-doped TiO2 NPs (H:Mg-N-TiO2 NPs) reveals that the presence of nitrogen stabilizes oxygen vacancies and reduced Ti species, leading to increased production of reactive oxygen species under visible-light excitation. The improved aPDT efficiency translates to a 3-fold enhancement in the antibiofilm activity of nitrogen-doped compared to undoped reduced TiO2 NPs against both Gram-positive (Streptococcus mutans) and Gram-negative (Porphyromonas gingivalis, Fusobacterium nucleatum) oral pathogens. These results underscore the potential of H:Mg-N-TiO2 NPs in aPDT for combating bacterial biofilms effectively.

Thiolated chitosan nanoparticles encapsulated nisin and selenium: antimicrobial/antibiofilm/anti-attachment/immunomodulatory multi-functional agent.

BACKGROUND: The increase in the resistance of bacterial strains to antibiotics has led to research into the bactericidal potential of non-antibiotic compounds. This study aimed to evaluate in vitro antibacterial/ antibiofilm properties of nisin and selenium encapsulated in thiolated chitosan nanoparticles (N/Se@TCsNPs) against prevalent enteric pathogens including standard isolates of Vibrio (V.) cholerae O1 El Tor ATCC 14,035, Campylobacter (C.) jejuni ATCC 29,428, Salmonella (S.) enterica subsp. enterica ATCC 19,430, Shigella (S.) dysenteriae PTCC 1188, Escherichia (E.) coli O157:H7 ATCC 25,922, Listeria (L.) monocytogenes ATCC 19,115, and Staphylococcus (S.) aureus ATCC 29,733. METHODS: The synthesis and comprehensive analysis of N/Se@TCsNPs have been completed. Antibacterial and antibiofilm capabilities of N/Se@TCsNPs were evaluated through broth microdilution and crystal violet assays. Furthermore, the study included examining the cytotoxic effects on Caco-2 cells and exploring the immunomodulatory effects of N/Se@TCsNPs. This included assessing the levels of both pro-inflammatory (IL-6 and TNFα) and anti-inflammatory (IL-10 and TGFß) cytokines and determining the gene expression of TLR2 and TLR4. RESULTS: The N/Se@TCsNPs showed an average diameter of 136.26 ± 43.17 nm and a zeta potential of 0.27 ± 0.07 mV. FTIR spectroscopy validated the structural features of N/Se@TCsNPs. Scanning electron microscopy (SEM) images confirmed their spherical shape and uniform distribution. Thermogravimetric Analysis (TGA)/Differential Scanning Calorimetry (DSC) tests demonstrated the thermal stability of N/Se@TCsNPs, showing minimal weight loss of 0.03%±0.06 up to 80 °C. The prepared N/Se@TCsNPs showed a thiol content of 512.66 ± 7.33 µmol/g (p < 0.05), an encapsulation efficiency (EE) of 69.83%±0.04 (p ≤ 0.001), and a drug release rate of 74.32%±3.45 at pH = 7.2 (p ≤ 0.004). The synthesized nanostructure demonstrated potent antibacterial activity against various isolates, with effective concentrations ranging from 1.5 ± 0.08 to 25 ± 4.04 mg/mL. The ability of N/Se@TCsNPs to reduce bacterial adhesion and internalization in Caco-2 cells underscored their antibiofilm properties (p ≤ 0.0001). Immunological studies indicated that treatment with N/Se@TCsNPs led to decreased levels of inflammatory cytokines IL-6 (14.33 ± 2.33 pg/mL) and TNFα (25 ± 0.5 pg/mL) (p ≤ 0.0001), alongside increased levels of anti-inflammatory cytokines IL-10 (46.00 ± 0.57 pg/mL) and TGFß (42.58 ± 2.10 pg/mL) in infected Caco-2 cells (p ≤ 0.0001). Moreover, N/Se@TCsNPs significantly reduced the expression of TLR2 (0.22 ± 0.09) and TLR4 (0.16 ± 0.05) (p < 0.0001). CONCLUSION: In conclusion, N/Se@TCsNPs exhibited significant antibacterial/antibiofilm/anti-attachment/immunomodulatory effectiveness against selected Gram-positive and Gram-negative enteric pathogens. However, additional ex-vivo and in-vivo investigations are needed to fully assess the performance of nanostructured N/Se@TCsNPs.

Preliminary Identification and Quantification of Individual Polyphenols in Fallopia japonica Plants and Honey and Their Influence on Antimicrobial and Antibiofilm Activities.

Fallopia japonica (FJ), an invasive plant species known for its rich bioactive compounds, has been used for centuries in traditional Chinese medicine. Despite its significant beekeeping potential, this aspect of FJ remains underexplored. This research aims to investigate the antimicrobial and antibiofilm properties of FJ plants and honey. Notably, this study is the first to identify individual phenolic compounds in both FJ plant tissues and FJ honey, highlighting resveratrol as a marker of FJ honey. The study tested inhibitory activity against seven bacterial strains: Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, Pseudomonas aeruginosa, Bacillus cereus, Salmonella enteritidis, and the yeast Candida albicans. Disk diffusion and microdilution methods were used to assess antimicrobial activity, while the crystal violet staining test evaluated antibiofilm activity. Results showed that FJ plant tissues and honey exhibited strong inhibition, particularly against Gram-negative bacterial strains. The most significant inhibition of biofilm formation, by both FJ plant tissues and honey, was observed against Staphylococcus aureus and Escherichia coli. A significant positive correlation was found between antimicrobial activity and individual polyphenols, especially resveratrol. The antibacterial and antibiofilm potential of FJ plant tissues and honey suggests promising applications in sustainable beekeeping. Further research is necessary to evaluate the bioactive compounds found in FJ honey and their health effects.

Effect of post-harvest drying period on the chemical composition of Zingiber zerumbet Sm. Rhizomes essential oil and its biological activities.

Zingiber zerumbet Sm. (Family: Zingiberaceae) is an important perennial medicinal oil-bearing herb that is native to the Southeast Asia. This study examines the impact of different durations of post-harvest shade drying (ranging from 1 to 12 months) on essential oil yield and chemical composition of Z. zerumbet, in comparison to the freshly collected oil sample. This study explores how post-harvest shade drying impact the composition and longevity of Z. zerumbet rhizomes as well as its antimicrobial, antibiofilm activity. The oils were analyzed for their chemical composition analysis using a gas chromatography-flame ionization detector (GC-FID) and gas chromatography-mass spectrometry (GC-MS). The post-harvest periods of drying (1-12 months) were discovered to enhance the concentration of marker constituents in the oil. The primary constituent, Zerumbone, was detected in concentrations ranging from 69.38 ± 5.63% to a maximum of 80.19 ± 1.53% as the drying duration of the rhizome was extended. The output of the essential oil was not significantly affected by drying times; however, it did have a noticeable impact on the proportions of monoterpenes. Both disc diffusion and broth microdilution assay were used in freshly collected Z. zerumbet oil for its antimicrobial potential against S. aureus, L. monocytogens, S. hominis, Salmonella enterica serovar Typhimurium, P. aeruginosa, S. intermedius, E. coli, and C. albicans. For the first time, the oil reported to exhibit antibiofilm activity against S. aureus which was validated using fluorescence microscopy, and effectively disrupts the biofilm by 47.38% revealing that essential oil was able to disintegrate the clusters of the pathogen. Z. zerumbet rhizome oil is effective to reduce food-borne microorganisms. Therefore, its essential oil, a natural source of bioactive zerumbone, may improve flavor, aroma, and preservation.

Antimicrobial peptide A20L: in vitro and in vivo antibacterial and antibiofilm activity against carbapenem-resistant Klebsiella pneumoniae.

Antimicrobial resistance has become a growing public health threat in recent years. Klebsiella pneumoniae is one of the priority pathogens listed by the World Health Organization. Antimicrobial peptides are considered promising alternatives to antibiotics due to their broad-spectrum antibacterial activity and low resistance. In this study, we investigated the antibacterial activity of antimicrobial peptide A20L against K. pneumoniae. In vitro antibacterial activity of A20L against K. pneumoniae was demonstrated by broth microdilution method. We confirmed the in vivo efficacy of A20L by Galleria mellonella infection model. In addition, we found that A20L also had certain antibiofilm activity by crystal violet staining. We also evaluated the safety and stability of A20L, and the results revealed that at a concentration of ≤128 µg/mL, A20L exhibited negligible toxicity to RAW264.7 cells and no substantial toxicity to G. mellonella. A20L was stable at different temperatures and with low concentration of serum [5% fetal bovine serum (FBS)]; however, Ca2+, Mg2+, and high serum concentrations reduced the antibacterial activity of A20L. Scanning electron microscope (SEM) and membrane permeability tests revealed that A20L may exhibit antibacterial action by damaging bacterial cell membranes and increasing the permeability of outer membrane. Taken together, our results suggest that A20L has significant development potential as a therapeutic antibiotic alternative, which provides ideas for the treatment of K. pneumoniae infection. IMPORTANCE: A20L showed antibacterial and anti-infective efficacy in vitro and in vivo against Klebsiella pneumoniae. It can have an antibacterial effect by disrupting the integrity of cell membranes. A20L displayed anti-biofilm and anti-inflammatory activity against carbapenem-resistant K. pneumoniae and certain application potential in vivo, which provides a new idea for the clinical treatment of biofilm-associated infections.

Long-Term Prevention of Biofilm Formation by Polycatechol-Based Supramolecular Assemblies with Low Molecular Weight Polymers on Surfaces.

Achievement of a stable surface coating with long-term resistance to biofilm formation remains a challenge. Catechol-based polymerization chemistry and surface deposition are used as tools for surface modification of diverse materials. However, the control of surface deposition of the coating, surface coverage, coating properties, and long-term protection against biofilm formation remain to be solved. We report a new approach based on supramolecular assembly to generate long-acting antibiofilm coating. Here, we utilized catechol chemistry in combination with low molecular weight amphiphilic polymers for the generation of such coatings. Screening studies with diverse low molecular weight (LMW) polymers and different catechols are utilized to identify lead compositions, which resulted in a thick coating with high surface coverage, smoothness, and antibiofilm activity. We have identified that small supramolecular assemblies (∼10 nm) formed from a combination of polydopamine and LMW poly(N-vinyl caprolactam) (PVCL) resulted in relatively thick coating (∼300 nm) with excellent surface coverage in comparison to other polymers and catechol combinations. The coating properties, such as thickness (10-300 nm) and surface hydrophilicity (with water contact angle: 20-60°), are readily controlled. The optimal coating composition showed excellent antibiofilm properties with long-term (>28 days) antibiofilm activity against both Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) strains. We further utilized the combination of optimal binary coating with silver to generate a coating with sustained release of silver ions, resulting in killing both adhered and planktonic bacteria and preventing long-term surface bacterial colonization. The new coating method utilizing LMW polymers opens a new avenue for the development of a novel class of thick, long-acting antibiofilm coatings.

Biological potential, chemical profiling, and molecular docking study of Morus alba L. extracts.

Morus alba L. is a plant with a long history of dietary and medicinal uses. We hypothesized that M. alba possesses a significant biological potential. In that sense, we aimed to generate the chemical, antimicrobial, toxicological, and molecular profile of M. alba leaf and fruit extracts. Our results showed that extracts were rich in vitamin C, phenols, and flavonoids, with quercetin and pterostilbene concentrated in the leaf, while fisetin, hesperidin, resveratrol, and luteolin were detected in fruit. Extracts exhibited antimicrobial activity against all tested bacteria, including multidrug-resistant strains. The widest inhibition zones were in Staphylococcus aureus ATCC 33591. The values of the minimum inhibitory concentration ranged from 15.62 µg/ml in Enterococcus faecalis to 500 µg/ml in several bacteria. Minimum bactericidal concentration ranged from 31.25 µg/ml to 1000 µg/ml. Extracts impacted the biofilm formation in a concentration-dependent and species-specific manner. A significant difference in the frequency of nucleoplasmic bridges between the methanolic extract of fruit (0.5 µg/ml, 1 µg/ml, 2 µg/ml), as well as for the frequency of micronuclei between ethanolic extract of leaf (2 µg/ml) and the control group was observed. Molecular docking suggested that hesperidin possesses the highest binding affinity for multidrug efflux transporter AcrB and acyl-PBP2a from MRSA, as well as for the SARS-CoV-2 Mpro. This study, by complementing previous research in this field, gives new insights that could be of great value in obtaining a more comprehensive picture of the Morus alba L. bioactive potential, chemical composition, antimicrobial and toxicological features, as well as molecular profile.

Isolation and characterization of bacteriophages against E.coli urinary tract infection and evaluating their anti-biofilm activity and antibiotic synergy.

Urinary tract infections (UTIs) by Uropathogenic Escherichia coli (UPEC) are a significant health concern, especially due to the increasing prevalence of antibiotic resistance. This study focuses on isolating and characterizing bacteriophages specific to UPEC strains isolated from UTI samples. The isolated phages were assessed for their ability to target and lyse UPEC in vitro, focusing on their efficacy in disrupting biofilms, a key virulence factor contributing to UTI recurrence and antibiotic resistance. The morphological structure observed by TEM belongs to Myoviridae, the phage exhibited icosahedral symmetry with a long non-constricting tail, the approximate measurement of the phage head was 39 nm in diameter, and the phage tail was 105.317 nm in length. One-step growth experiments showed that the latent period was approximately 20 min, followed by a rise period of 40 min, and a growth plateau was reached within 20 min and the burst size observed was 26 phages/infected bacterial cells. These phages were capable of killing cells within the biofilms, leading to a reduction in living cell counts after a single treatment. This study highlights the potential of phages to play a significant role in disrupting, inactivating, and destroying Uropathogenic Escherichia coli (UPEC) biofilms. Such findings could be instrumental in developing treatment strategies that complement antibiotics and disinfectants. The phage-antibiotic synergistic activity was compared to have the possibility to facilitate the advancement of focused and enduring alternatives to traditional antibiotic therapies for UTIs.

The application of pH-responsive hyaluronic acid-based essential oils hydrogels with enhanced anti-biofilm and wound healing.

pH could play vital role in the wound healing process due to the bacterial metabolites, which is one essential aspect of desirable wound dressings lies in being pH-responsive. This work has prepared a degradable hyaluronic acid hydrogel dressing with wound pH response-ability. The aldehyde-modified hyaluronic acid (AHA) was obtained, followed by complex mixture formation of eugenol and oregano antibacterial essential oil in the AHA-CMCS hydrogel through the Schiff base reaction with carboxymethyl chitosan (CMCS). This hydrogel composite presents pH-responsiveness, its disintegration mass in acidic environment (pH = 5.5) is 4 times that of neutral (pH = 7.2), in which the eugenol release rate increases from 37.6 % to 82.1 %. In vitro antibacterial and in vivo wound healing investigations verified that hydrogels loaded with essential oils have additional 5 times biofilm removal efficiency, and significantly accelerate wound healing. Given its excellent anti-biofilm and target-release properties, the broad application of this hydrogel in bacteria-associated wound management is anticipated.

Bimetallic nanoparticles with sulfated galactan eliminate Vibrio parahaemolyticus in shrimp Penaeus vannamei.

Bimetallic (Au/Ag) nanoparticles (BNPs) have shown enhanced antibacterial activity compared to their monometallic counterparts. Sulfated galactans (SG) are a naturally occurring polymer commonly found in red seaweed Gracilaria fisheri. They are biocompatible and biodegradable and environmentally friendly. In this study, we utilized SG in combination with BNPs to develop composite materials that potentially enhance antibacterial activity against shrimp pathogens Vibrio parahaemolyticus and Vibrio harveyi, compared to BNPs or SG alone. BNPs were coated with sulfated galactan (SGBNPs) and characterized using UV-vis spectroscopy, Fourier transform infrared (FTIR) spectroscopy, zeta potential, and transmission electron microscopy (TEM). UV-vis spectroscopy analysis revealed that the surface plasmon peaks of BNPs and SGBNPs appeared at 530 nm and 532 nm, respectively. Zeta potential measurements showed that SGBNPs had a negative charge of -32.4 mV, while the BNPs solution had a positive charge of 38.7 mV. TEM images demonstrated the spherical morphology of both BNPs and SGBNPs with narrow size distributions (3-10 nm). Analysis of the FTIR spectra indicated that SG maintained its backbone structure in SGBNPs, but some functional groups were altered. Notably, SGBNPs showed superior antimicrobial and antibiofilm activities against V. parahaemolyticus and V. harveyi compared to SG and BNPs. Furthermore, treatment with SGBNPs significantly down-regulated the expression of virulence-related genes (toxR, cpsQ, and mfpA) for V. parahaemolyticus 3HP compared to the respective control, bacteria treated with BNPs or SG. Diets supplemented with SGBNPs, BNPs, or SG showed no detrimental impact on the growth of shrimp Penaeus vannamei. Shrimp fed with SGBNPs-supplemented feed showed significantly higher survival rates than those fed with BNPs-supplemented feed when infected with 3HP after being on the supplemented feed for seven days and a subsequent number of fifteen days. These findings collectively demonstrate the benefit of using SG capped Au-Ag BNPs as an antibacterial agent for the prevention and control of Vibrio sp. Infection in shrimp while reducing the risk of environmental contamination.

Boosting the Anti-Helicobacter Efficacy of Azithromycin through Natural Compounds: Insights From In Vitro, In Vivo, Histopathological, and Molecular Docking Investigations.

BACKGROUND: Antimicrobial-resistant Helicobacter pylori (H. pylori) poses a significant public health concern, especially given the limited therapeutic options for azithromycin-resistant strains. Hence, there is a necessity for new studies to reconsider the use of azithromycin, which has diminished in effectiveness against numerous strains. Thus, we aimed to augment azithromycin's anti-Helicobacter properties by combining it with curcumin in different formulations, including curcumin in clove oil, curcumin nano-gold emulsion, and curcumin nanoemulsion. METHODS: The antimicrobial activities of the investigated compounds, both individually and in combination with other anti-Helicobacter drugs, were evaluated. Their antibiofilm and anti-virulence properties were assessed using both phenotypic and genotypic methods, alongside molecular docking studies. Our findings were further validated through mouse protection assays and histopathological analysis. RESULTS: We observed high anti-Helicobacter activities of curcumin, especially curcumin nanoemulsion. A synergistic effect was detected between curcumin nanoemulsion and azithromycin with fraction inhibitory concentration index (FICI) values <0.5. The curcumin nanoemulsion was the most active anti-biofilm and anti-virulence compound among the examined substances. The biofilm-correlated virulence genes (babA and hopQ) and ureA genes were downregulated (fold change <1) post-treatment with curcumin nanoemulsion. On the protein level, the anti-virulence activities of curcumin nanoemulsion were documented based on molecular docking studies. These findings aligned with histopathological scoring of challenge mice, affirming the superior efficacy of curcumin nanoemulsion/azithromycin combination. CONCLUSION: The anti-Helicobacter activities of all curcumin physical forms pose significant challenges due to their higher  minimum inhibitory concentration (MIC) values exceeding the maximum permissible level. However, using curcumin nanoemulsion at sub-MIC levels could enhance the anti-Helicobacter activity of azithromycin and exhibit anti-virulence properties, thereby improving patient outcomes and addressing resistant pathogens. Therefore, more extensive studies are necessary to assess the safety of incorporating curcumin nanoemulsion into H. pylori treatment.

Screening of Antimicrobial, Antibiofilm, and Cytotoxic Activities of Some Medicinal Plants from Balikesir Province, Türkiye: Potential Effects of Allium paniculatum Flower.

Objectives: Plant extracts are important natural resources that may have antimicrobial and antibiofilm effects against pathogens. This study was conducted to investigate the in vitro antimicrobial activities of methanol extracts of some medicinal plants (Achillea nobilis subspecies neilreichii (A. Kern.) Velen., Aetheorhiza bulbosa (L.) Cass, Allium paniculatum L, Asphodelus aestivus Brot., Ballota nigra L., Cistus laurifolius L., Cistus salviifolius L., Dioscorea communis (L.) Caddick and Wilkin, Galium verum L., Hypericum triquetrifolium Turra, Paliurus spina-christi Mill., Primula vulgaris Huds. subspecies rubra (Sm.) Arcang., Ranunculus arvensis L. and Teucrium polium L.) from Balikesir province in Türkiye. Materials and Methods: Preliminary antimicrobial activity screening was conducted for all extracts. Antibiofilm activity studies were conducted on mature Candida albicans biofilms. Moreover, the cytotoxicities of A. paniculatum flower extract on A549 and Vero cell lines were determined using a colorimetric tetrazolium-based assay. Results: A. paniculatum flower, P. vulgaris root, C. laurifolius, C. salviifolius, and A. nobilis displayed good activity [minimum inhibitory concentrations (MIC): 9.75, 156, 312, 312 and 312 µg/mL, respectively] against C. albicans American Type Culture Collection 10231. Biofilm studies were conducted on these plant extracts. The methanol extract of A. paniculatum flower decreased the number of C. albicans [colony-forming unit (CFU)/mL] in mature biofilm statistically at 32 x MIC and higher concentrations (p < 0.01). A. paniculatum flower extract had a cytotoxic effect (killing more than 50% of cells) at high concentrations, and its effect on Vero cells was similar to that on A549 cells. Conclusion: This study demonstrated the importance of the methanol extract of A. paniculatum flower as a natural alternative against C. albicans infections, including biofilms.

Intestinal biofilms: pathophysiological relevance, host defense, and therapeutic opportunities.

SUMMARYThe human intestinal tract harbors a profound variety of microorganisms that live in symbiosis with the host and each other. It is a complex and highly dynamic environment whose homeostasis directly relates to human health. Dysbiosis of the gut microbiota and polymicrobial biofilms have been associated with gastrointestinal diseases, including irritable bowel syndrome, inflammatory bowel diseases, and colorectal cancers. This review covers the molecular composition and organization of intestinal biofilms, mechanistic aspects of biofilm signaling networks for bacterial communication and behavior, and synergistic effects in polymicrobial biofilms. It further describes the clinical relevance and diseases associated with gut biofilms, the role of biofilms in antimicrobial resistance, and the intestinal host defense system and therapeutic strategies counteracting biofilms. Taken together, this review summarizes the latest knowledge and research on intestinal biofilms and their role in gut disorders and provides directions toward the development of biofilm-specific treatments.

Myrtus communis leaf compounds as novel inhibitors of quorum sensing-regulated virulence factors and biofilm formation: In vitro and in silico investigations.

Antibiotic resistance of the Gram-negative bacterium Pseudomonas aeruginosa and its ability to form biofilm through the Quorum Sensing (QS) mechanism are important challenges in the control of infections caused by this pathogen. The extract of Myrtus communis (myrtle) showed strong anti-QS effect on C hromobacterium . violaceum 6267 by inhibiting 80 % of the production of violacein pigment at a sub-MIC concentration of 1/8 (31.25 µg/mL). In addition, the extract exhibited an inhibitory effect on virulence factors of P. aeruginosa PAO1 at half MIC (125 µg/mL), significantly reducing the formation of biofilms (72.02 %), the swarming activity (75 %), and the production of protease (61.83 %) and pyocyanin (97 %). The active fraction also downregulated the expression of selected regulatory genes involved in the biofilm formation and QS in the P. aeruginosa PAO1 strain. These genes included the autoinducer synthase genes (lasI and rhlI), the genes involved in the expression of their corresponding receptors (lasR and rhlR), and the pqsA genes. The analysis of the active fraction by HPLC/UV/MS and NMR allowed the identification of three phenolic compounds, 3,5-di-O-galloylquinic acid, myricetin 3-O-α-l-rhamnopyranoside (myricitrin), and myricetin 3-O-(2″-O-galloyl)-ß-d-galactopyranoside. In silico studies showed that 3,5-di-O-galloylquinic acid, with an affinity score of -9.20 kcal/mol, had the highest affinity to the active site of the CviR protein (3QP8), a QS receptor from C. violaceum. Additionally, myricetin 3-O-α-l-rhamnopyranoside (myricitrin) and myricetin 3-O-(2″-O-galloyl)-ß-d-galactopyranoside interact to a lesser extent with 3QP8. In conclusion, this study contributed significantly to the discovery of new QS inhibitors from M. communis leaves against resistant Gram-negative pathogens.