Inhibit Biofilm Formation Research Articles

Pseudomonas aeruginosa quorum sensing and biofilm attenuation by a di-hydroxy derivative of piperlongumine (PL-18)

Bacterial communication, Quorum Sensing (QS), is a target against virulence and prevention of antibiotic-resistant infections. 16 derivatives of Piperlongumine (PL), an amide alkaloid from Piper longum L., were screened for QS inhibition. PL-18 had the best QSI activity. PL-18 inhibited the lasR-lasI, rhlR-rhlI, and pqs QS systems of Pseudomonas aeruginosa. PL-18 inhibited pyocyanin and rhamnolipids that are QS-controlled virulence elements. Iron is an essential element for pathogenicity, biofilm formation and resilience in harsh environments, its uptake was inhibited by PL-18. Pl-18 significantly reduced the biofilm biovolume including in established biofilms. PL-18-coated silicon tubes significantly inhibited biofilm formation. The transcriptome study of treated P. aeruginosa showed that PL-18 indeed reduced the expression of QS and iron homeostasis related genes, and up regulated sulfur metabolism related genes. Altogether, PL-18 inhibits QS, virulence, iron uptake, and biofilm formation. Thus, PL-18 should be further developed against bacterial infection, antibiotic resistance, and biofilm formation.

Antibiofilm effect of biogenic silver nanoparticle alone and combined with polymyxin B against carbapenem-resistant Acinetobacter baumannii.

Acinetobacter baumannii is a bacteria associated with nosocomial infections and outbreaks, difficult to control due to its antibiotic resistance, ability to survive in adverse conditions, and biofilm formation adhering to biotic and abiotic surfaces. Therefore, this study aimed to evaluate the antibiofilm activity of biogenic silver nanoparticle (Bio-AgNP) and polymyxin B alone and combined in biofilms formed by isolates of carbapenem-resistant A. baumannii (CR-Ab). In the biofilm formation inhibition assay, CR-Ab strains were exposed to different concentrations of the treatments before inducing biofilm formation, to determine the ability to inhibit/prevent bacterial biofilm formation. While in the biofilm rupture assay, the bacterial biofilm formation step was previously carried out and the adhered cells were exposed to different concentrations of the treatments to evaluate their ability to destroy the bacterial biofilm formed. All CR-Ab isolates and ATCC® 19606™ used in this study are strong biofilm formers. The antibiofilm activity of Bio-AgNP and polymyxin B against CR-Ab and ATCC® 19606™ demonstrated inhibitory and biofilm-disrupting activity. When used in combination, Bio-AgNP and polymyxin B inhibited 4.9-100% of biofilm formation in the CR-Ab isolates and ATCC® 19606™. Meanwhile, when Bio-AgNP and polymyxin B were combined, disruption of 6.8-77.8% of biofilm formed was observed. Thus, antibiofilm activity against CR-Ab was demonstrated when Bio-AgNP was used alone or in combination with polymyxin B, emerging as an alternative in the control of CR-Ab strains.

Antifungal activity of synthetic xanthenone against fluconazole-resistant Candida auris and its mechanism of action

Candida auris, an emerging multidrug-resistant fungal pathogen discovered in Japan in 2009, poses a significant global health threat, with infections reported in about 25 countries. The escalation of drug-resistant strains underscores the urgent need for new treatment options. This study aimed to investigate the antifungal potential of 2,3,4,4a-tetrahydro-1H-xanthen-1-one (XA1) against C. auris, as well as its mechanism of action and toxic profile. The antifungal activity of XA1 was first evaluated by determining the minimum inhibitory concentration (MIC), time-kill kinetics and biofilm inhibition. In addition, structural changes, membrane permeability, reactive oxygen species (ROS) production, and in vitro and in vivo toxicity of C. auris after exposure to XA1 were investigated. The results indicated that XA1 exhibited an MIC of 50 μg/mL against C. auris, with time-kill kinetics highlighting its efficacy. Field emission scanning electron microscopy (FE-SEM) showed structural damage in XA1-treated cells, supported by increased membrane permeability leading to cell death. Furthermore, XA1 induced ROS production and significantly inhibited biofilm formation. Importantly, XA1 exhibited low cytotoxicity in human epidermal keratinocytes (HaCaT), with a cell viability of over 90 % at 6.25 μg/mL. In addition, an LD50 of 17.68 μg/mL was determined in zebrafish embryos 24 h post fertilization (hpf), with developmental delay observed at prolonged exposure at 6.25 μg/mL (48–96 hpf). These findings position XA1 as a promising candidate for further research and development of an effective antifungal agent.

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.

Cellulose Acetate and Polycaprolactone Fibre Coatings on Medical-Grade Metal Substrates for Controlled Drug Release.

This study explores a method that has the potential to be cost effective in inhibiting biofilm formation on metallic prostheses, thereby preventing rejection or the requirement for replacement. A cost-effective metal alloy used in biomedical implants was chosen as the substrate, and ibuprofen (Ibu), a well-known anti-inflammatory drug, was selected for drug release tests for its widespread availability and accessibility. Multilayer coatings consisting of cellulose acetate (CA), polycaprolactone (PCL), and chitosan (CHI), with or without ibuprofen (Ibu) content, were applied onto medical-grade stainless steel (SS-316 type) through electrospinning, electrospray, or blow spinning. The adhesion of the CA, PCL, and layered CA/PCL membranes, with thicknesses ranging from 20 to 100 μm, to SS substrates varied between 0.15 N and 0.22 N without CHI, which increased to 0.21 and 0.74 N, respectively, when a CHI interlayer was introduced by electrospraying between the SS and the coatings. Although drug release in a simulated body fluid (SBF) medium is predominantly governed by diffusion-driven mechanisms in all single- and multilayer coatings, a delayed release was noted in CA coatings containing Ibu when overlaid with a PCL coating produced by blow spinning. This suggests avenues for further investigations into combinations of multilayer coatings, both with and without drug-imbued layers.

Chemical composition, cytotoxicity, antimicrobial, antibiofilm, and anti-quorum sensing potential of Mentha Piperita essential oil against the oral pathogen Streptococcus mutans

ABSTRACT Dental caries is a highly prevalent oral disease affecting billions of individuals globally. The disease occurs chemically as a result of breakdown of the tooth surface attributed to metabolic activity in colonizing biofilm. Biofilms, composed of exopolysaccharides and proteins, protect bacteria like Streptococcus mutans, which is notable for its role in tooth decay due to its acid-producing abilities. While various antimicrobial agents may prevent biofilm formation, these drugs often produce side effects including enamel erosion and taste disturbances. This study aimed to examine utilization of the Mentha piperita essential oil as a potential antibiofilm activity agent against S. mutans. M. piperita oil significantly (1) reduced bacterial biofilm, (2) exhibited a synergistic effect when combined with chlorhexidine, and (3) did not induce cell toxicity. Chemical analysis identified the essential oil with 99.99% certainty, revealing menthol and menthone as the primary components, constituting approximately 42% and 26%, respectively. Further, M. piperita oil eradicated preformed biofilms and inhibited biofilm formation at sub-inhibitory concentrations. M. piperita oil also interfered with bacterial quorum sensing communication and did not produce any apparent cell toxicity in immortalized human keratinocytes (HaCaT). M. piperita represented an alternative substance for combating S. mutans and biofilm formation and a potential combination option with chlorhexidine to minimize side effects. An in-situ performance assessment requires further studies.

Limonium brasiliense rhizomes extract against virulence factors of Porphyromonas gingivalis: Inhibition of gingipains, bacterial adhesion, and biofilm formation

Periodontitis is clinically characterized by destruction of the tooth support system and tooth loss. Porphyromonas gingivalis (Pg) plays a dominant role in periodontitis. Fractions and isolated compounds from an acetone-water extract of the roots of Limonium brasiliense (Lb) were tested in vitro for their anti-adhesive capacity against Pg on human KB buccal cells, influence on gingipains, the main virulence factors of Pg, and biofilm formation. Fractions EAF and FLB7 (50 μg/mL) reduced the bacterial adhesion of Pg to KB cells significantly (63 resp. 70%). The proanthocyanidin samarangenin A inhibited the adhesion (72%, 30 μM), samarangenin B (71%, 20 μM), and the flavan-3-ol epigallocatechin-3-O-gallate (79%, 30 μM). Fraction AQF, representing hydrophilic compounds, reduced the proteolytic activity of Arginin-specific gingipain (IC50 12.78 μg/mL). Fractions EAF and FLB7, characterized by lipohilic constituents, inhibited Arg-gingipain (IC50 3 μg/mL). On Lysine-specific gingipain, AQF has an IC50 15.89, EAF 14.15, and FLB7 6 μg/mL. The reduced bacterial adhesion is due to a strong interaction of proanthocyanidins with gingipains. AQF, EAF, and FLB7 significantly inhibited biofilm formation: IC50 11.34 (AQF), 11.66 (EAF), and 12.09 μg/mL (FLB7). In silico analysis indicated, that the polyphenols act against specific targets of Pg, not affecting mammalian cells. Therefore, Lb might be effective for prevention of periodontal disease by influencing virulence factors of Pg.

Chitosan microflower-embedded gelatin sponges for advanced wound management and hemostatic applications

The study explored the antimicrobial, antibiofilm, and hemostatic properties of chitosan microflowers (CMF) in sponge form. The main objective was to enhance the preparation of CMF by employing varying quantities of calcium chloride (CaCl2) and tripolyphosphate (TPP). CMF was then combined with gelatin (GE) in different proportions to produce three sponge samples: CMF0@GE, CMF1@GE, and CMF2@GE. The CMF had a morphology like that of a flower and produced surfaces with a porous sponge-like structure. The antibacterial activity, as determined by the zone of inhibition (ZOI), increased with greater doses of CMF. Among the tested samples, CMF2@GE had the greatest activity against Pseudomonas aeruginosa, Klebsiella pneumoniae, Staphylococcus aureus, and Enterococcus faecium. CMF2@GE successfully suppressed biofilm formation, decreased clotting time to an average of 212.67 s, and exhibited excellent biocompatibility by preserving over 90 % viability of human skin fibroblast cells at dosages below 100 μg/mL. The results indicated that gelatin sponges filled with CMF have considerable promise as flexible medical instruments for wound healing and infection control.

SYNERGISTIC EFFECTS OF NEEM OIL AND GENTAMICIN ON PSEUDOMONAS AERUGINOSA VIA PHZM GENE DOWNREGULATION: A COMPREHENSIVE REVIEW

Exploring the antibacterial potential of neem oil (Azadirachta indica) in combination with gentamicin (GEN) against pathogenic molds, especially Pseudomonas aeruginosa, has drawn concern due to the quest for natural treatment options against incurable diseases. Prospective research directions include looking for natural cures for many of the currently incurable diseases available now. microbial identification system, were used to identify the isolates. The research utilized a range of methods, such as the diffusion agar well (AWD) assays, TEM (transmission electron microscopy) analysis, minimum inhibitory concentration (MIC) assays, and real-time PCR (RT-qPCR) to analyze bacterial expression and the antibacterial action of neem oil (Azadirachta indica) combined with gentamicin (GEN) against the pathogenic bacteria Pseudomonas aeruginosa between others. The combined effects of neem oil and GEN on P. aeruginosa are extensively investigated in this study, with particular attention paid to the downregulation of the virulent factor gene phzM, inhibition of biofilm formation, morphological changes, and gene expression, in that proportion. Results show that neem oil has strong antibacterial activity against P. aeruginosa and S. aureus, preventing the formation of biofilms and causing morphological alterations. In addition, the synergistic effects of neem oil and GEN are demonstrated, together in order with the downregulation of the phzM gene in P. aeruginosa. These results highlight the increased effectiveness of neem oil when combined with GEN and point to the potential of the oil as a stand-alone antibacterial agent. They also highlight the need for more study to overcome antibiotic resistance in harmful bacteria. Overall, our results point to a possibility that neem oil extract, either alone or in combination with GEN, can suppress the development of pathogenic microbes. This synergistic impact is related to the downregulation of a virulence factor gene. To address the drug resistance linked to pathogenic microbes, greater study is required. Novelty of study addresses the important issue of antibiotic resistance by exploring the potential synergistic effects of neem oil and gentamicin on pathogenic bacteria, particularly Pseudomonas aeruginosa. This topic is highly relevant in the context of the global challenge of antimicrobial resistance.Novelty and relevanc the important issue of antibiotic resistance by exploring the potential synergistic effects of neem oil and gentamicin on pathogenic bacteria, particularly Pseudomonas aeruginosa. This topic is highly relevant in the context of the global challenge of antimicrobial resistance.

Pheromone cCF10 inhibits the antibiotic persistence of Enterococcus faecalis by modulating energy metabolism.

Bacterial resistance presents a major challenge to both the ecological environment and human well-being, with persistence playing a key role. Multiple studies were recently undertaken to examine the factors influencing the formation of persisters and the underlying process, with a primary focus on Gram-negative bacteria and Staphylococcus aureus (Gram-positive bacteria). Enterococcus faecalis (E. faecalis) is capable of causing a variety of infectious diseases, but there have been few studies of E. faecalis persisters. Previous studies have shown that the sex pheromone cCF10 secreted by E. faecalis induces conjugative plasmid transfer. However, whether the pheromone cCF10 regulates the persistence of E. faecalis has not been investigated. As a result, we investigated the effect and potential molecular mechanism of pheromone cCF10 in regulating the formation of persisters in E. faecalis OG1RF using a persistent bacteria model. The metabolically active E. faecalis OG1RF reached a persistence state and temporarily tolerated lethal antibiotic concentrations after 8 h of levofloxacin hydrochloride (20 mg/mL) exposure, exhibiting a persistence rate of 0.109 %. During the growth of E. faecalis OG1RF, biofilm formation was a critical factor contributing to antibiotic persistence, whereas 10 ng/mL cCF10 blocked persister cell formation. Notably, cCF10 mediated the antibiotic persistence of E. faecalis OG1RF via regulating metabolic activity rather than suppressing biofilm formation. The addition of cCF10 stimulated the Opp system and entered bacterial cells, inhibiting (p)ppGpp accumulation, thus maintaining the metabolically active state of bacteria and reducing persister cell generation. These findings offer valuable insights into the formation, as well as the control mechanism of E. faecalis persisters.

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.

Antibacterial and antibiofilm properties of cinnamon essential oil on Pseudomonas tolaasii and application of potato starch/CEO active pads in preservation of mushroom (Agaricus bisporus)

Pseudomonas tolaasii (P. tolaasii) is considered to be the main pathogen of brown spot disease in mushrooms. Cinnamon essential oil (CEO), a natural bacteriostatic agent, has potential application prospects in the field of food preservation. The purpose of this study was to explore the antibacterial mechanism of CEO on P. tolaasii, and to prepare an active pad to study the preservation effect of mushroom, so as to provide a basis for the development of natural antibacterial agents. P. tolaasii was isolated from browning mushroom and identified by 16S rRNA gene sequencing. The antibacterial and antibiofilm activities of cinnamon essential oil (CEO) on P. tolaasii and its application in mushrooms were investigated. The results indicated that CEO had a significant inhibitory effect on P. tolaasii. After the CEO treatment, the surface of P. tolaasii cells was damaged, and significant leakage of entocyte was observed. In addition, CEO could effectively induce oxidative stress and lipid peroxidation in P. tolaasii cells, and cause irreversible damage to cell membranes, leading to energy and respiratory metabolism disorders. The activity of ROS defense enzymes such as superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD) were significantly inhibited (P < 0.05), aggravating the oxidative damage to P. tolaasii. The crystal violet staining assay and scanning electron microscopy revealed that CEO treatment not only inhibited biofilm formation, but also effectively eradicated mature biofilm. The application effects displayed that the active pads packing containing CEO had excellent antibacterial effect and maintain the quality of mushroom (Agaricus bisporus). The results of this study will provide references for further research and application of natural food antibacterial agents.

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.

A bacteriocin-based coating strategy to prevent vancomycin-resistant Enterococcus faecium biofilm formation on materials of interest for indwelling medical devices

The ever-increasing use of exogenous materials as indwelling medical devices in modern medicine offers to pathogens new ways to gain access to human body and begin, in some cases, life threatening infections. Biofouling of such materials with bacteria or fungi is a major concern during surgeries, since this is often associated with biofilm formation and difficult to treat, recalcitrant infections. Intense research efforts have therefore developed several strategies to shield the medical devices' surface from colonization by pathogenic microorganisms. Here, we used dopamine as a coupling agent to coat four different materials of medical interest (plastic polyetheretherketone (PEEK), stainless steel, titanium and silicone catheter) with the bacteriocins, enterocin EJ97-short and the thiopeptide micrococcin P1. Water contact angle measurements and x-ray photoelectron spectroscopy were used to verify the effective coating of the materials. The effect of bacteriocins coated on these materials on the biofilm formation by a vancomycin resistant Enterococcus faecium (VRE) strain was studied by biofilm-oriented antimicrobial test (BOAT) and electron scanning microscopy. The in vitro biocompatibility of bacteriocin-modified biomaterials was tested on cultured human cells. The results demonstrated that the binding of the bacteriocins to the implant surfaces is achieved, and the two bacteriocins in combination could inhibit biofilm formation by E. faecium on all four materials. The modified implant showed no cytotoxicity to the human cells tested. Therefore, surface modification with the two bacteriocins may offer a novel and effective way to prevent biofilm formation on a wide range of implant materials.

Inhibitory effect of Lonicera japonica flos on Streptococcus mutans biofilm and mechanism exploration through metabolomic and transcriptomic analyses.

Streptococcus mutans was the primary pathogenic organism responsible for dental caries. Lonicera japonica flos (LJF) is a traditional herb in Asia and Europe and consumed as a tea beverage for thousands of years. The inhibitory effect and mechanism of LJF on biofilm formation by S. mutans was investigated. The active extracts of LJF were validated for their inhibitory activity by examining changes in surface properties such as adherence, hydrophobicity, auto-aggregation abilities, and exopolysaccharides (EPS) production, including water-soluble glucan and water-insoluble glucan. LJF primarily inhibited biofilm formation through the reduction of EPS production, resulting in alterations in cell surface characteristics and growth retardation in biofilm formation cycles. Integrated transcriptomic and untargeted metabolomics analyses revealed that EPS production was modulated through two-component systems (TCS), quorum sensing (QS), and phosphotransferase system (PTS) pathways under LJF stress conditions. The sensing histidine kinase VicK was identified as an important target protein, as LJF caused its dysregulated expression and blocked the sensing of autoinducer II (AI-2). This led to the inhibition of response regulator transcriptional factors, down-regulated glycosyltransferase (Gtf) activity, and decreased production of water-insoluble glucans (WIG) and water-soluble glucans (WSG). This is the first exploration of the inhibitory effect and mechanism of LJF on S. mutans, providing a theoretical basis for the application of LJF in functional food, oral health care, and related areas.

UM FILME DE POLIURETANO DE BASE AQUOSA CONTENDO ÓLEO DE MAMONA E NANOPARTÍCULAS DE PRATA INDUZIU A INIBIÇÃO DE BIOFILME BACTERIANO IN VITRO

Healthcare-related infections (HAIs) are a huge global issue. In 2020, about 11,124 patients (12.7%) with an ICU (intensive care unit) stay of over two days developed at least one ICU-acquired healthcare-associated infection (European Centre for Disease Prevention and Control, 2024). Hospital-acquired infections are mainly caused by contamination of these facilities, which often involves the transmission of microorganisms through contact with contaminated surfaces. In this context, the advancement of novel strategies to mitigate the contamination of medical devices, biomaterials, and hospital equipment is crucial and drives the demand for advancements in materials sciences. The application of antimicrobial polymers to coat medical devices and other hospital equipment has emerged as a promising approach, reducing the risk of healthcare-related contamination. The main goal of this research was to incorporate silver nanoparticles (Ag-NPs) into a waterborne castor oil-based polyurethane (PU) suspension to produce a film coating and evaluate its effectiveness in preventing bacterial adhesion. The films of pristine polyurethane (WBPU) and polyurethane containing Ag-NPs were subjected to physicochemical characterization and antimicrobial assays. Thermogravimetric analysis showed that no decomposition occurs below 200 oC, and the PU can be used in materials at the body temperature range. The WBPU film with 0.4% (w/w) Ag-NPs exhibited 36.4% inhibition of Staphylococcus aureus adhesion and 20.5% inhibition of biofilm formation. This castor oil-based polyurethane antimicrobial film is a promising alternative for coating the surfaces of equipment and devices used in the healthcare sector.

1H-Pyrrole-2,5-dicarboxylic acid, a quorum sensing inhibitor from one endophytic fungus in Areca catechu L., acts as antibiotic accelerant against Pseudomonas aeruginosa.

Pseudomonas aeruginosa has already been stipulated as a "critical" pathogen, emphasizing the urgent need for researching and developing novel antibacterial agents due to multidrug resistance. Bacterial biofilm formation facilitates cystic fibrosis development and restricts the antibacterial potential of many current antibiotics. The capacity of P. aeruginosa to form biofilms and resist antibiotics is closely correlated with quorum sensing (QS). Bacterial QS is being contemplated as a promising target for developing novel antibacterial agents. QS inhibitors are a promising strategy for treating chronic infections. This study reported that the active compound PT22 (1H-pyrrole-2,5-dicarboxylic acid) isolated from Perenniporia tephropora FF2, one endophytic fungus from Areca catechu L., presents QS inhibitory activity against P. aeruginosa. Combined with gentamycin or piperacillin, PT22 functions as a novel antibiotic accelerant against P. aeruginosa. PT22 (0.50 mg/mL, 0.75 mg/mL, and 1.00 mg/mL) reduces the production of QS-related virulence factors, such as pyocyanin and rhamnolipid, and inhibits biofilm formation of P. aeruginosa PAO1 instead of affecting its growth. The architectural disruption of the biofilms was confirmed by visualization through scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). Real-time quantitative PCR (RT-qPCR) indicated that PT22 significantly attenuated the expression of QS-related genes followed by docking analysis of molecules against QS activator proteins. PT22 dramatically increased the survival rate of Galleria mellonella. PT22 combined with gentamycin or piperacillin presents significant inhibition of biofilm formation and eradication of mature biofilm compared to monotherapy, which was also confirmed by visualization through SEM and CLSM. After being treated with PT22 combined with gentamycin or piperacillin, the survival rates of G. mellonella were significantly increased compared to those of monotherapy. PT22 significantly enhanced the susceptibility of gentamycin and piperacillin against P. aeruginosa PAO1. Our results suggest that PT22 from P. tephropora FF2 as a potent QS inhibitor is a candidate antibiotic accelerant to combat the antibiotic resistance of P. aeruginosa.

Antimycobacterial and Anticancer Properties of Myrtus communis Leaf Extract.

Plant-derived products or extracts are widely used in folk/traditional medicine to treat several infections, ailments, or disorders. A well-known medicinal herb, Myrtus communis is an evergreen fragrant plant native to the Mediterranean region that has been used for ages in traditional medicine around the world. The microplate alamarBlue assay and the well diffusion method were used to evaluate the zone of inhibition and MIC, respectively. The double-disc diffusion method was used to investigate the synergy between antibiotics and the extract. The crystal violet method was used to investigate biofilm development. The SulphoRhodamine-B assay and DNA flow cytometry were used to investigate the proliferation and subsequent distribution of cells among different phases of the cell cycle. The apoptotic and necrotic phases of the cancer cells were examined using flow cytometry in conjunction with Annexin V-FITC/PI labeling. Using the IBM SPSS statistical program, a one-way ANOVA with Tukey's post hoc test was employed for statistical analysis. The ethanolic leaf extract of M. communis showed a strong growth inhibition effect (zone of inhibition: 20.3 ± 1.1-26.3 ± 2.5 mm, MIC: 4.88-312.5 µg/mL, and MBC: 39.07-1250 μg/mL) against several rapidly growing and slow-growing mycobacterial strains in a dose-dependent manner. Damage to the cell wall of bacterial cells was determined to be the cause of the antimycobacterial action. The extract inhibited biofilm formation (MBIC of 9.7 µg/mL) and eradicated already-formed mature and ultra-mature biofilms of M. smegmatis, with MBEC values of 78 µg/mL and 156 µg/mL, respectively. Additionally, the extract exhibited potent anticancer effects against diverse cancer cell lines of the breast (MCF-7), liver (HepG2), cervix (HeLa), and colon (HCT116) (IC50 for HCT116: 83 ± 2.5, HepG2: 53.3 ± 0.6, MCF-7: 41.5 ± 0.6, and HeLa: 33.3 ± 3.6) by apoptosis after arresting the cells in the G1 phase of the cell cycle. These results suggest that M. communis leaf extract is a potential source of secondary metabolites that could be further developed as potential anticancer and antimycobacterial agents to treat diverse types of cancers and mycobacterial infections.

تثبيط تكوين الاغشية الحيوية في بكتيريا Agrobacterium tumefaciens بالمادة الطافية الخالية من خلايا Pseudomonas aeruginosa والمحللة بجهاز GC-MS

تعد Agrobacterium tumefaciens من أنواع البكتيريا المسببة للأمراض النباتية المهمة اقتصاديا، وتحصل الاصابة نتيجة استخدام اغشيتها الحيوية لالصاق نفسها بالجروح المتكونة على سطح العائل النباتي، ونظرًا لمحدودية العلاجات الحالية وفعاليتها، أصبح البحث عن عوامل جديدة مضادة لهذه البكتيريا أمرا ضروريا، لذلك تم تسليط الضوء في هذه الدراسة على معرفة التأثير التثبيطي للمادة الطافية الخالية من خلايا Pseudomonas aeruginosa على تكوين الاغشية الحيوية من قبل A. tumefaciens، فضلا عن تحديد المركبات الكيمياوية المكونة لها بجهاز GC-MS. بناءا على ذلك عزلت P. aeruginosa من التربة وتم تشخيصها باستخدام العدةAPI 20 E وتفاعل البلمرة المتسلسل باستخدام الجين 16S rRNA واظهرت تطابقا بنسبة 93% مع البكتيريا القياسية Pseudomonas sp.SeaQual P_B_845W, MT626817.1 في بنك الجينات. وعند الكشف عن قدرة المادة الطافية المجفدة وبتسعة تراكيز10، 15، 20 ،25 ، 30، 35، 40، 45، 17، 17، 15 ،على التوالي. وحسب عدد القمم التي تم إنتاجها بعد حقنها بجهاز GC، تبين انها مكونة من 30 مادة كيميائية، وبعد إدخال هذه المعلومات في جهاز MS، تم تشخيصها بأسمائها ومنها(Pyrrolo[1,2-a]pyrazine-1,4-dione, hexahydro-، Hexadecanoic acid, methyl ester، Pyrrolo[1,2-a]pyrazine-1,4-dione, hexahydro-3-(2-methylpropyl)-،9-Octadecenoic acid (Z)-,methyl ester،cis-13-Octadecenoic acid,methyl ester،Octadecanoic acid, methyl ester)، البالغ وزنها الجزيئي(154، 270، 210، 296، 296، 298) دالتون ومقدار المساحة التي تشغلها (9.38، 19.12، 6.8، 4.45، 8.33، 5.90)%، على التوالي. أهم النتائج التي شخصتها هذه الدراسة هو تحديد المركبات الكيميائية لأول مرة للمادة الطافية الخالية من خلايا الزائفة الزنجارية وتأثيرها المثبط على إنتاج الأغشية الحيوية من قبل A. tumefaciens.

Targeting ThyA: Investigating the mechanisms of 5-FU-induced inhibition of biofilm formation and virulence in Streptococcus suis through LuxS/AI-2 quorum sensing1

Streptococcus suis is a significant zoonotic agent affecting both human and pig health and poses a substantial public health concern. The pathogenicity of S. suis is intricately linked to its ability to form biofilms and express virulence factors, which are regulated by the LuxS/AI-2 quorum sensing (QS) system. Herein, we uncover a novel therapeutic avenue by demonstrating that 5-fluorouracil (5-FU), an FDA-approved anti-cancer agent, effectively mitigates biofilm formation and attenuates the virulence of S. suis. Mechanistically, we observe a significant reduction in capsular polysaccharide and extracellular polysaccharide production upon 5-FU treatment, elucidating a potential mechanism for biofilm weakening. Additionally, 5-FU down-regulates virulence traits, diminishing S. suis‘s ability to adhere to host cells and evade phagocytosis. Crucially, our study identifies the thymidylate synthase regulatory gene thyA as a key mediator of 5-FU’s effects on the LuxS/AI-2 QS system. Virtual molecular docking and gene knockout experiments provide compelling evidence that 5-FU modulates the LuxS/AI-2 QS system by targeting thyA. In vivo experiments further validate the therapeutic potential of 5-FU, showcasing a significant reduction in bacterial load and mitigation of tissue damage in a mouse model. In conclusion, our investigation unveils 5-FU as a potent disruptor of S. suis‘s biofilm formation and virulence, offering a promising avenue for the control of this devastating pathogen.