Inhibit Biofilm Formation Research Articles

Antimicrobial, Antibiofilm and Anticancer Potentials of Glycine and Glycyl-Glycine; an in vitro study

Globally, there is a huge demand for novel agents capable of providing protection against both pathogen microorganisms and tumor cells. In this study, the antimicrobial, biofilm inhibitory, and anticancer effects of glycine and glycyl-glycine were investigated. The antimicrobial effects were determined using the broth dilution method, while the biofilm inhibitory effects were assessed through the crystal violet binding assay. Cytotoxic effects on HeLa cell viability were measured using the MTT assay. Our results indicate that, although 100 mg/mL of glycine only inhibited S. epidermidis W17 among the three tested isolates, 400 mg/mL of glycyl-glycine inhibited both S. epidermidis W17 and P. mirabilis U15 strains. Additionally, sub-MICs (concentrations below the Minimum Inhibition Concentration) of glycine inhibited biofilm formation by more than 70% in all tested clinical isolates and exhibited significantly more biofilm inhibition against P. mirabilis U15 and S. epidermidis W17 strains (p

The Antibacterial Efficacy and Mechanism of Tea Polyphenol Against Drug-Resistant Aeromonas veronii TH0426 In Vitro.

The emergence of Motile Aeromonas Septicemia (MAS) caused by Aeromonas veronii in sturgeon farming has become a significant concern due to its high mortality impact on the aquaculture industry. The threat posed by MAS highlights the urgent need for effective control measures to combat bacterial infections in sturgeon populations. Tea polyphenol (TP) has demonstrated promising antibacterial properties against livestock and poultry bacterial infections. However, its antibacterial efficacy and mechanism in bacterial diseases of aquatic animals remain largely unexplored. This study aimed to investigate the in vitro antibacterial effect and mechanism of TP on fish-borne drug-resistant A. veronii TH0426 by assessing the impact of TP on TH0426 cell growth, antibiofilm activity, morphology, as well as measuring electrical conductivity, DNA extravasation, lactate dehydrogenase (LDH) activity, protein, and DNA contents. Results demonstrated that the minimum inhibitory concentration and the minimum bactericidal concentration of TP on TH0426 were 1024 and 2048 μg/mL, respectively. After a 4 h treatment, the growth of TH0426 was completely inhibited at the concentration of 1024 and 2048 μg/mL of TP. Meanwhile, TP exhibited a significant antibiofilm activity. Both scanning electron microscope and transmission electron microscope analyses revealed disrupted cell membrane structure, irregular cell morphology, and loss of intracellular contents following TP treatment. Moreover, increased cell membrane permeability induced by TP led to intracellular ion and DNA leakage, resulting in elevated electrical conductivity and DNA extravasation. Furthermore, TP decreased LDH activity, protein concentration and content, DNA fluorescence intensity, and density in a time-dependent manner, indicating inhibition of protein metabolism and DNA synthesis. In conclusion, TP exhibits potent antibacterial properties by inhibiting biofilm formation, disrupting cell membrane integrity, and interfering with protein metabolism and DNA synthesis in drug-resistant A. veronii TH0426 in vitro.

A novel K57-specific Klebsiella pneumoniae phage disinfects milk and inhibits biofilm formation

Klebsiella pneumoniae (K. pneumoniae), especially serotype K57, is a major pathogen in dairy bovine mastitis, causing significant economic losses and posing a public health risk through contaminated dairy products. In addition, K57 is highly virulent among serotypes infecting humans, leading to serious conditions such as pyogenic liver abscess. In this study, we isolated and identified a bacteriophage called vB_Kp_Z57 that targets K57 serotype K. pneumoniae isolates from human and bovine sources. The phage has a latent period of 4 min and can produce approximately 233 phages per infected bacterial cell. vB_Kp_Z57 is stable over a temperature range of 4 °C to 60 °C and a pH range of 5–11. Sequencing and assembly of the phage genome revealed DNA molecules consisting of 40,316 base pairs. After genome annotation with bioinformatics software, it was discovered that the phage genome encodes 48 proteins, with no detected lysogeny genes, toxin genes, or tRNA-related genes. vB_Kp_Z57 was classified as a member of genus Przondovirus, family Autographiviridae. The results of bacteriostatic experiments show that vB_Kp_Z57 has a good effect on inhibiting bacterial growth. Notably, vB_Kp_Z57 significantly inhibited the growth of its host bacteria in milk at refrigerated temperatures of 4 °C and room temperature. Biofilm inhibition experiments revealed that phage vB_Kp_Z57 significantly reduced OD595 values in all phage-treated groups, indicating its potential as an effective biocontrol agent against K. pneumoniae. Our findings show the promise of vB_Kp_Z57 as a novel and environmentally friendly solution to address the challenges associated with K. pneumoniae in dairy production.

New LsrK Ligands as AI-2 Quorum Sensing Interfering Compounds against Biofilm Formation.

Antimicrobial resistance (AMR) represents a critical global health crisis. An innovative strategy to deal with AMR is to interfere with biofilm formation and bacterial quorum sensing (QS). In this study, newly designed autoinducer-2 (AI-2)-inspired compounds in targeting biofilm-associated infections were evaluated for their ability to inhibit biofilm formation in Staphylococcus aureus and Pseudomonas aeruginosa. The most effective compounds, 5d, 5e, and 7b, exhibited potent antibiofilm activity with minimal inhibitory concentrations in the low microgram per mL range. Detailed biological assays confirmed that the antibiofilm activity was primarily driven through AI-2 QS inhibition rather than direct antimicrobial effects. The combination of different spectroscopic techniques, such as differential scanning fluorimetry, intrinsic tryptophan fluorescence, circular dichroism, and nuclear magnetic resonance, elucidated the binding between the compounds and the LsrK enzyme, a key player in AI-2 mediated QS. Our findings highlight the potential of these novel QS inhibitors as promising therapeutic agents against biofilm-associated infections.

Inhibition of bacteria adhesion and biofilm formation using a precisely structured nitric oxide-releasing coating with repeatedly renewing antimicrobial and antifouling ability

Bacterial adhesion and colonization usually causes the formation of biofilm that cannot be easily eradicated by common antibiotics and disinfectants. Surface covalent immobilization of nitric oxide (NO)-releasing polymer is an effective surface modification strategy to combat the threat from bacteria. Although surface covalent strategy avoided the leaching of toxic NO donors, the existence of hydrophobic NO donors on topsurface could inevitably accelerate the microorganism adhesion and accumulation, and the NO-releasing period of time was still very limited. In this work, we prepared an antimicrobial and antibiofilm surface via tethering a precision-structured NO-releasing copolymer brush to an organic-inorganic hybrid hard coating (> 5H pencil hardness) on one end. The precision-structured diblock copolymer brush was composed of a surface antifouling block and a subsurface antimicrobial block of NO-releasing units. A typical effect of “kill two birds with one stone” was observed, the NO releasing subsurface segment within a polymeric matrix prolongs NO release while also preventing surface fouling caused by hydrophobic NO donors on top surface. The impacts of polymer architecture on bioactivity was detailed investigated, and the block copolymer brush exhibited the optimal inhibitory effects against bacteria colonization and biofilm formation. The developed bioactive diblock copolymer brush was grafted from a hard hybrid persistent coating that embeds considerable initiation sites for surface modification. Thanks to the presence of initiator throughout the hybrid network, the initiation layer could initiate polymerization repeatedly after the polymer brushes are worn off at high pressure. Thus, the coating exhibited repeatedly renewing antimicrobial and antifouling ability after multiple abrasion cycles. This work not only developed a novel strategy for regulating NO releasing via modulating the polymer architecture, but provided a feasible route for obtaining a robust initiator layer for synthesizing polymer brush for antimicrobial and antifouling applications.

Gum Arabic as a potential candidate in quorum quenching and treatment of periodontal diseases.

Periodontal diseases are chronic inflammatory conditions influenced by bacterial biofilm formation and host immune responses, affecting millions worldwide. Traditional treatments like mechanical debridement and systemic antibiotics often face limitations, including biofilm resilience and antibiotic resistance. Gum Arabic (GA), a natural exudate from Acacia trees, presents a promising alternative with its anti-biofilm and anti-inflammatory properties. This review highlights the role of GA in periodontal therapy, particularly its ability to interfere with quorum sensing (QS) pathways, specifically the AI-2 signaling system used by key periodontal pathogens such as Porphyromonas gingivalis, Aggregatibacter actinomycetemcomitans, and Fusobacterium nucleatum. By disrupting QS, GA inhibits biofilm formation, reduces bacterial virulence, and promotes a balanced oral microbiome. GA's prebiotic properties also encourage the growth of beneficial bacteria, enhancing the host's immune response while preserving the systemic microbiome. Clinical studies demonstrate GA's effectiveness as an adjunct in periodontal therapy, with significant reductions in plaque accumulation, gingival inflammation, and bleeding. This highlights GA's potential as a natural therapeutic agent, offering an effective, antibiotic-sparing option in managing periodontal disease. However, further research is warranted to fully establish GA's role in comprehensive periodontal care and its long-term benefits.

Zidovudine in synergistic combination with nitrofurantoin or omadacycline: in vitro and in murine urinary tract or lung infection evaluation against multidrug-resistant Klebsiella pneumoniae.

Limited treatment options and multidrug-resistant (MDR) Klebsiella pneumoniae present a significant therapeutic challenge, underscoring the need for novel approaches. Drug repurposing is a promising tool for augmenting the activity of many antibiotics. This study aimed to identify novel synergistic drug combinations against K. pneumoniae based on drug repurposing. We used the clinically isolated GN 172867 MDR strain of K. pneumoniae to determine the reversal resistance activity of zidovudine (AZT). The combined effects of AZT and various antibiotics, including nitrofurantoin (NIT) and omadacycline (OMC), were examined using the checkerboard method, growth curves, and crystal violet assays to assess biofilms. An in vitro combination activity testing was carried out in 12 isolates of K. pneumoniae. In vivo murine urinary tract and lung infection models were used to evaluate the therapeutic effects of AZT + NIT and AZT + OMC, respectively. The fractional inhibitory concentration index and growth curve demonstrated that AZT synergized with NIT or OMC against K. pneumoniae strains. In addition, AZT + NIT inhibited biofilm formation and cleared mature biofilms. In vivo, compared with untreated GN 172867-infected mice, AZT + NIT and AZT + OMC treatment decreased colony counts in multiple tissues (P < 0.05) and pathological scores in the bladder and kidneys (P < 0.05) and increased the survival rate by 60% (P < 0.05). This study evaluated the combination of AZT and antibiotics to treat drug-resistant K. pneumoniae infections and found novel drug combinations for the treatment of acute urinary tract infections. These findings suggest that AZT may exert significant anti-resistance activity.

Engineering the novel azobenzene-based molecular photoswitches for suppressing bacterial infection through dynamic regulation of biofilm formation.

Bacterial biofilm is a strong fortress for bacteria to resist harsh external environments, which can enhance their tolerance and exacerbate the drug/pesticide resistance risk. Currently, photopharmacology provides an advanced approach via precise spatiotemporal control for regulating biological activities by light-controlling the molecular configurations, thereby having enormous potential in the development of drug/pesticides. To further expand the photopharmacology application for discovering new antibiofilm agents, we prepared a series of light-controlled azo-active molecules and explored their photo isomerization, fatigue resistance, and anti-biofilm performance. Furthermore, their mechanisms of inhibiting biofilm formation were systematically investigated. Overall, designed azo-derivative A11 featured excellent anti-Xoo activity with an half-maximal effective concentration (EC50) value of 5.45 μg mL-1, and the EC50 value could be further elevated to 2.19 μg mL-1 after ultraviolet irradiation (converted as cis-configuration). The photo-switching behavior showed that A11 had outstanding anti-fatigue properties. An in-depth analysis of the action mechanism showed that A11 could effectively inhibit biofilm formation and the expression of relevant virulence factors. This performance could be dynamically regulated via loading with private light-switch property. In this work, designed light-controlled azo molecules provide a new model for resisting bacterial infection via dynamic regulation of bacterial biofilm formation. © 2024 Society of Chemical Industry.

Anti-Fungal (Aspergillus fumigatus) Activity of Pseudomonas aeruginosa in Cystic Fibrosis Synthetic Sputum.

Aspergillus fumigatus (Af) and Pseudomonas aeruginosa (Pa) are pathogens inhabiting the lungs of persons with cystic fibrosis (CF), or immune-compromised patients, causing or aggravating disease. We previously investigated their microbial interaction as well as susceptibility to anti-fungal drugs using RPMI medium (contains undetectable iron concentrations), as is standard for susceptibility testing. Here we investigated microbial interaction in synthetic sputum medium (SSPM), a complex mixture designed to mimic the milieu in CF lungs. SSPM contains Fe2+. Pa laboratory strain PA14 or PA14 siderophore mutant planktonic culture filtrate, prepared in RPMI or SSPM, were compared for inhibition of Af biofilm formation. SSPM enhanced bacterial and fungal growth and the production of the Pa molecules pyoverdine, phenazines, and rhamnolipids. Af was more susceptible to these molecules in SSPM (with the exception of pyoverdine). SSPM interfered with fungal susceptibility to pyoverdine. Studies with the mutant helped to reveal that the reduced anti-fungal activity of pyoverdine in SSPM appears to be compensated by higher production of other anti-fungal molecules, e.g., rhamnolipids, phenazines, and PQS, and higher Af sensitivity to these molecules. In summary, SSPM better defines Pa-Af intermicrobial competition in the milieu of CF lungs.

Preparation and evaluation the effects of retinoic acid loaded proliposomal nanofibers on microbial biofilm inhibition

The electrospinning method involves the production of different drug delivery systems using various polymers. The production of proliposomes with electrospinning provides the hybridization of two novel drug delivery systems. Retinoic acid, also known as all-trans retinoic acid (ATRA), is a common and effective drug for acne therapy. This study aimed to prepare ATRA-loaded proliposomal nanofibers and evaluate their effectiveness on microbial biofilm inhibition. Blank and ATRA-loaded proliposomal nanofiber formulations were fabricated in various polyvinylpyrrolidone, phosphatidylcholine and cholesterol ratios. TEM images verified the rapid formation of the liposomes after the hydration of nanofibers. The vesicle size, polydispersity index and zeta potential values of self-assembled liposomes were measured. The vesicle size values were found to be 321.9–363.8 nm with PDI values varying between 0.332 and 0.511 and zeta potential values of (−16.8) to (−20.5)mV. ATRA-loaded proliposomal nanofibers provided higher bioadhesion (0.25 mJ/cm2) than the commercial cream (0.07 mJ/cm2). The short-term stability results showed that the initial characteristics remained for three months at 4 °C. The proposed ATRA-loaded self-assembled proliposomal system provided antibacterial, fungistatic or fungicidal effects superior to retinoic acid itself and inhibited biofilm formation in lower concentrations. This approach can combine the stability advantage of nanofibers in the dry state with the high effectiveness of liposomes in acne treatment presenting antibacterial and anti-biofilm-forming activity against Candida albicans and Cutibacterium acnes.

BvgR is important for virulence-related phenotypes in Bordetella bronchiseptica.

Bordetella bronchiseptica is a pathogenic bacterium that causes respiratory infections in mammals. Adhesins, toxins, and secretion systems necessary for infection are regulated by the two-component system BvgAS. When the BvgAS system is inactive, there is no transcription of virulence-activated genes, and virulence-repressed genes (vrg) are expressed. The regulation of some vrgs in B. bronchiseptica is dependent upon the virulence-activated gene bvgR. Although having a regulatory role, no DNA-binding domain is described for BvgR. Instead, it contains an EAL domain, usually found in cyclic-di-GMP (c-di-GMP)-specific phosphodiesterases. c-di-GMP is a bacterial second messenger that regulates multiple phenotypes in bacteria, including B. bronchiseptica. The current study aimed to deepen our knowledge about BvgR. We employed RNA-seq analysis to define the BvgR regulon, and then we investigated the phenotypes in which BvgR regulation might be involved such as biofilm formation, cytotoxicity, and virulence. Our result revealed that BvgR inhibits biofilm formation and flagellin expression in virulent phase. Although BvgR has long been considered a repressor protein, our results show that it also upregulates almost 100 genes. This regulation is likely indirect, as BvgR lacks a DNA-binding domain. Notably, among the upregulated genes, we identified 15 associated with the type three secretion system. Consistent with these findings, a B. bronchiseptica strain deficient in bvgR was less cytotoxic than the wild-type strain, elicited a milder immune response, and was less able to persist in the lower respiratory tract of mice.IMPORTANCEBordetella bronchiseptica is a harmful bacterium responsible for respiratory infections in mammals. Its ability to cause disease is tightly regulated by a system called BvgAS. In this study, we focused on understanding the role of a specific gene called bvgR in regulating B. bronchiseptica's virulence factors. Our findings revealed that BvgR, previously thought to primarily repress gene expression, actually plays a complex role in both activating and inhibiting various genes involved in bacterial virulence. This newfound understanding sheds light on the intricate mechanisms underlying B. bronchiseptica's ability to cause infections, providing valuable insights for developing strategies to combat these infections in humans and animals.

Antiquorum Sensing Effect, Theoretical, and X‐Ray Studies of a Schiff Base Molecule Containing Pyrimidine Nucleus

AbstractCompound 4, a Schiff base‐containing pyrimidine moiety, was synthesized from the reaction of N‐amino pyrimidine derivative with 4‐fluorobenzaldehyde. The molecular and crystallographic structure of 4 was determined by the SC‐XRD method. According to these results, compound 4 crystallized in the triclinic P‐1 space group, and the stability of its crystal structure was ensured through intermolecular C−H⋅⋅⋅π and π⋅⋅⋅π interactions. In addition to the antibacterial effects of the molecule on some Gram‐positive and Gram‐negative bacteria, the inhibition of biofilm formation in P. aeruginosa PAO1 and the production of violacein pigment in Chromobacterium violaceum (C. violaceum) 12472 were studied. The results demonstrated that compound 4 had strong effectiveness in preventing the formation of biofilms produced by PAO1 with an inhibition rate of 69 %. Extensive theoretical calculation studies of molecule have been conducted and the molecular structure of 4 has been optimized in the ground state using density functional theory (DFT). The investigated compound's frontier molecular orbitals, chemical parameters, and molecular electrostatic potential surfaces were examined. Molecular docking studies were performed to explain the binding interaction 4 with the high inhibitory effect against C. violaceum phenylalanine hydroxylase D139A (PDB ID: 4Q3Y), D139E (PDB ID: 4Q3W), D139K (PDB ID: 4Q3Z), and D139N (PDB ID: 4Q3X) mutations.

Synergistic effect of the combination of phenolic compounds and tobramycin on the inhibition of Pseudomonas aeruginosa biofilm

Bacteria coordinate gene expression in a cell density-dependent manner using a communication process called quorum sensing (QS). The expression of virulence factors, biofilm formation and enzyme production are examples of QS-regulated phenotypes that can interfere with food quality and safety. Due to the importance of these phenotypes, the inhibition of bacterial communication as an anti-virulence strategy is of great interest. This work aimed to evaluate the effect of phenolic compounds on the inhibition of biofilm formation by Pseudomonas aeruginosa PAO1, using concentrations that do not interfere in bacterial growth. The synergistic effect of rosmarinic acid, baicalein, curcumin and resveratrol with tobramycin and between the phenolics themselves was evaluated. The tested combinations proved to be a good strategy for reducing the dose of antibiotics used in treatments and obtaining satisfactory results against P. aeruginosa biofilms. The combination of the four compounds at the highest concentration (500 μM) completely inhibited biofilm formation. The obtained results contribute to understanding the effect of phenolic compounds on QS inhibition, which may help to define the mechanism of inhibition, in addition to expanding the biotechnological potential of these compounds for future applications in the food, pharmaceutical and medical fields.

Ag quantum dots-doped poly (vinyl alcohol)/chitosan hydrogel coatings to prevent catheter-associated urinary tract infections

The prevention of catheter-associated urinary tract infections (CAUTIs) significantly impacts the reduction of morbidity and mortality associated with the use of indwelling urinary catheters. This study focused on developing an antibacterial double network hydrogel coating for latex urinary catheters, which incorporated Ag quantum dots (Ag QDs) in a polyvinyl alcohol (PVA)-chitosan (CS) double network hydrogel matrix. The PVA-CS-Ag QDs, referred to as the PCA hydrogel coating exhibited excellent mechanical and physiochemical properties with controlled release of Ag QDs. The antibacterial properties of the PCA hydrogel-coated urinary catheters were studied against both gram-negative Escherichia coli (E. coli, ATCC25922) and gram-positive Staphylococcus aureus (S. aureus, ATCC29213). The continuous release of CS oligomers and Ag QDs from the hydrogel coating contributed to the synergistic antibacterial and antiadhesion effects. Measurements of the Ag release rate revealed that even after 30 days, the concentration of Ag QDs from the PCA hydrogel-coated urinary catheters remained significantly higher than the effective antibacterial concentration of the total Ag (0.1 μg·L−1). These results indicated that the PCA hydrogel coating not only efficiently prevented bacteria attachment, but also exhibited long-term antibacterial activity, thereby inhibiting biofilm formation. Furthermore, the PCA hydrogel-coated urinary catheter demonstrated excellent biocompatibility and hemocompatibility. Overall, this novel PCA hydrogel-coated urinary catheter, with its exceptional antibacterial properties, holds great potential in reducing the incidence of CAUTIs.

Allyl isothiocyanate suppressed periodontal tissue destruction in mice via bacteriostatic and anti-inflammatory activities against Porphyromonas gingivalis

ObjectivesAllyl isothiocyanate (AITC) is a phytochemical that is abundantly present in cruciferous vegetables, such as wasabi and mustard. Among its pharmacological properties, it demonstrates anticancer, antifungal, and anti-inflammatory activities. This study aimed to investigate the functions of AITC against periodontopathic bacteria and its effects on a mouse model of periodontitis. DesignThe antimicrobial and antibiofilm functions of AITC were assessed against Porphyromonas gingivalis, Fusobacterium nucleatum, and Streptococcus mitis. To clarify its anti-inflammatory effects, macrophage-like cells from THP-1 were stimulated with P. gingivalis lipopolysaccharide (LPS), and the release of inflammatory cytokines was analyzed by ELISA. Experimental periodontitis was induced in 9-week-old mice by ligation and oral infection of P. gingivalis, and AITC was injected into the gingiva once daily for 8 days. Alveolar bone resorption was evaluated by measuring the exposed root area. Gene expressions in the periodontal tissue were analyzed via qPCR. ResultsAITC exerted weak bacteriostatic effects against P. gingivalis, inhibiting biofilm formation. AITC also impeded the production of interleukin-6 and tumor necrosis factor-α induced by P. gingivalis LPS. Additionally, transient receptor potential ankyrin 1(TRPA1) channel agonist inhibited the anti-inflammatory effects of AITC. In vivo, AITC inhibited alveolar bone destruction and decreased the gene transcription of Il6 in the periodontal tissue. ConclusionAITC exerted weak bacteriostatic and anti-inflammatory effects against P. gingivalis, reducing alveolar bone destruction and suppressing the inflammatory response in experimental periodontitis. Therefore, AITC may serve as a valuable adjunct in controlling periodontal disease.

Co-selective effect of dissolved organic matter and chlorine on the bacterial community and their antibiotic resistance in biofilm of drinking water distribution pipes

The proliferation of pathogenic bacteria and antibiotic resistance genes (ARGs) in the biofilm of drinking water distribution pipes poses a serious threat to human health. This work adopted 15 polyethylene (PE) pipes to study the co-selective effect of dissolved organic matter (DOM) and chlorine on the bacterial community and their antibiotic resistance in biofilm. The results indicated that ozone and granular activated carbon (O3-GAC) filtration effectively removed lignins and proteins from DOM, and chlorine disinfection eliminated carbohydrate and unsaturated hydrocarbons, which both contributed to the inhibition of bacterial growth and biofilm formation. After O3-GAC and disinfection treatment, Porphyrobacter, unclassified_d_bacteria, and Sphingopyxis dominated in the biofilm bacterial community. Correspondingly, the bacterial metabolism pathways, including the phosphotransferase system, phenylalanine, tyrosine and tryptophan biosynthesis, ABC transporters, and starch and sucrose metabolism, were downregulated significantly (p < 0.05), compared to the sand filtration treatment. Under such a situation, extracellular polymeric substances (EPS) secretion was inhibited in biofilm after O3-GAC and disinfection treatment, postponing the interaction between EPS protein and pipe surface, preventing bacteria, especially pathogens, from adhering to the pipe surface to form biofilm, and restraining the spread of ARGs. This study revealed the effects of various water filtration and disinfection processes on bacterial growth, metabolism, and biofilm formation on a molecular level, and validated that the O3-GAC filtration followed by chlorine disinfection is an effective and promising pathway to control the microbial risk of drinking water.

Antibacterial and Antibiofilm potential of Thuja orientalis L. extract targeting cariogenic Enterococcus faecalis ATCC 29212: A combined in-vitro, in-silico study, and cytotoxicity screening

ObjectivesIn this study, we explored the efficacy of methanolic extract of Thuja orientalis (TOME) as a novel antibacterial and antibiofilm agent against a cariogenic bacterium, Enterococcus faecalis ATCC 29212. DesignAntibacterial susceptibility studies were conducted and surface morphology analysis was performed using field emission scanning electron microscopy (FESEM). Antibiofilm activity was evaluated through both qualitative and quantitative biofilm inhibition assays and validated by microscopic analysis. In-silico molecular docking studies were conducted using the EDock server. The effectiveness of TOME was substantiated by biofilm model on dentin discs and cytotoxicity towards the HaCaT cell line was assessed using the MTT assay. ResultsTOME exhibited significant bactericidal activity with minimum inhibitory concentration of 12.5mg/mL and additionally, it effectively compromised bacterial cell wall integrity. Qualitative, quantitative and microscopic studies depicted the inhibition of biofilm formation. TOME significantly impacted the production of extracellular polymeric substance and extracellular DNA. Molecular docking studies identified beta-caryophyllene as a potent inhibitor of the Enterococcal surface protein (Esp). Biofilm model depicted the reduction of bacterial load on dentin discs. Additionally, TOME showed reduced cytotoxicity on HaCaT cells, indicating its potential as a safe therapeutic agent. ConclusionThese findings highlight TOME's promise for developing novel treatments for dental infections and biofilm-associated diseases. Further research should focus on isolating and characterizing the active compounds within TOME, particularly beta-caryophyllene, to elucidate their precise mechanisms of action.

Biofilm formation dynamics in long-distance water conveyance pipelines: Impacts of nutrient levels and metal stress

Biofilm formation in long-distance water conveyance pipelines poses significant risks to water quality, particularly under varying nutrient levels and heavy metal stress. However, the impacts of pipeline material on biofilm formation dynamics under different raw water conditions remain elusive. This study investigated the effects of nutrient availability and Fe-Mn stress on biofilm development, structural stability, bacterial community composition, and the occurrence of viable but non-culturable (VBNC) bacteria. Using reactors with different nutrient conditions, we observed that increased nutrient levels promote biofilm growth but lead to greater instability, heightening the risk of secondary contamination. Notably, nutrient escalation beyond a critical threshold had a diminishing impact on biofilm community composition. Additionally, Fe-Mn stress, while initially enhancing microbial adhesion and metabolic activity, ultimately inhibited biofilm formation over time and increases the prevalence of VBNC bacteria, particularly on stainless steel (SS) surfaces. Our findings also highlighted the importance of material selection for pipelines, with polyvinyl chloride (PVC) showing reduced biofilm formation compared to SS, making it a more suitable option for transporting raw water in environments with high metal content. Dispersal limitation determined the bacterial community assembly during the biofilm formation, accounting for 64.53–90.67 % of the variability in different scenarios. These insights offer valuable guidance for managing biofilm-related issues in water distribution systems, emphasizing the need for careful control of nutrient levels and material choice to ensure water safety over long distances.

Antibiofilm activity of Morganella morganii JB8F and Pseudomonas fluorescens JB3B compound to control single and multi-species of aquaculture pathogens

BackgroundIndonesia is a country that uses half or more aquatic foods as protein intake. The increased production in aquaculture industries might cause several problems, such as bacterial disease resulting in mass mortality and economic losses. Antibiotics are no longer effective because aquaculture pathogens can form biofilm. Biofilm is a microbial community that aggregates and firmly attaches to living or non-living surfaces. Biofilm formation can be caused by environmental stress, the presence of antibiotics, and limited nutrients. Therefore, it is important to explore antibiofilm to inhibit biofilm formation and/or eradicate mature biofilm. Phyllosphere bacteria can produce bioactive compounds for antimicrobial, antibiofilm, and anti-quorum sensing. Three aquaculture pathogens were used in this study, such as Aeromonas hydrophila, Streptococcus agalactiae, and Vibrio harveyi.ResultsPseudomonas fluorescens JB3B and Morganella morganii JB8F extracts could disrupt single and multi-species biofilms. Both extracts could inhibit single biofilm formation from one to seven days of incubation time. We confirmed the destruction activity on multi-species biofilm using light microscope and scanning electron microscope. Using GC-MS analysis, indole was the most active fraction of the P. fluorescens JB3B extracts and octacosane from the M. morganii JB8F extract. We also conducted a toxicity test using brine shrimp lethality assay on P. fluorescens JB3B and M. morganii JB8F extracts. P. fluorescens JB3B, M. morganii JB8F, and a mixture of both extracts were confirmed non-toxic according to the LC50 value of the brine shrimp lethality test.ConclusionsP. fluorescens JB3B and M. morganii JB8F phyllosphere extracts had antibiofilm activity to inhibit single biofilm and disrupt single and multi-species biofilm of aquaculture pathogens. Both extracts could inhibit single species biofilm until seven days of incubation. Bioactive compounds that might contribute to antibiofilm properties were found in both extracts, such as indole and phenol. P. fluorescens JB3B, M. morganii JB8F extracts, and mixture of both extracts were non-toxic against Artemia salina.

Preparation and characterization of moringin-loaded chitosan-coated liposomes and their antibacterial activity against Staphylococcus aureus

This study aimed to improve the stability of moringin and clarify the inhibitory mechanisms of moringin-loaded chitosan-coated liposomes (MR-CS-LPs) against Staphylococcus aureus. Optimisation of MR-CS-LPs was conducted using the response surface methodology, and extensive characterization was performed. The anti-bacterial activity of MR-CS-LPs was assessed by determining the minimum inhibitory concentration (MIC) and conducting growth curve analyses. The effects of MR-CS-LPs on S. aureus cell wall and membrane integrity were investigated using techniques such as scanning electron microscopy and physical and chemical analyses. Apoptotic effects were evaluated by examining oxidative stress parameters, and the impact on S. aureus biofilm formation was explored. An LC–MS/MS analysis provided insights into the inhibitory mechanism of MR-CS-LPs against S. aureus. The results indicated that MR-CS-LPs achieved an encapsulation rate of 69.02 %. Furthermore, they demonstrated potent anti-bacterial activity against S. aureus, with an MIC of 0.125 mg/mL. MR-CS-LPs disrupted cell wall and membrane integrity, resulting in macromolecule leakage, induced oxidative stress–mediated apoptosis and effectively suppressed biofilm formation, ultimately leading to bacterial death. Metabolomics analysis revealed that MR-CS-LPs inhibit S. aureus by regulating pyruvate pathways. These findings affirm that MR-CS-LPs possess significant anti-microbial properties, underscoring their potential as effective anti-microbial agents against S. aureus.