Search Results (1,312)

Propolis is a bee product with a complex chemical composition that exhibits remarkable antifungal activity against C. albicans and can inhibit resistant biofilms thanks to its content of compounds such as flavonoids and phenolic acids. Its efficacy varies depending on its geographic origin: European propolis inhibits the initial formation of biofilms, while Brazilian propolis is superior at inhibiting mature biofilms. This product also possesses fungicidal and fungistatic properties comparable in efficacy to conventional drugs, such as nystatin, fluconazole, and chlorhexidine. The use of nanotechnology, such as nanoparticles or nanorods, has overcome the low solubility of propolis compounds, improving their bioavailability and reducing cell adhesion and hyphal formation. Moreover, the integration of propolis into dental materials demonstrate its versatility for preventing recurrent infections. The study of isolated compounds such as pinocembrin, galangin, and chrysin has facilitated the identification of specific mechanisms of action, and the application of molecules such as guttiferone E in photodynamic therapies and the discovery of quorum-sensing inhibitors, such as kaempferol, using in silico models have opened new avenues for blocking yeast communication and virulence. These findings position propolis as a multifaceted and promising therapeutic alternative, although there is a need to optimize formulations to ensure clinical safety and biocompatibility. In this review, we analyze research published around the world over the last 15 years on the effects of propolis against C. albicans biofilms. Full article

This study assessed the impact of a topical phytocomplex on the acne skin microbiota, encompassing bacterial, fungal, and phage communities. Skin samples obtained from participants exhibiting a positive response to the treatment were analyzed using high-throughput sequencing and bioinformatic approaches including taxonomic profiling, metagenome assembly, functional annotation, and phage identification. Results showed that after treatment, microbial diversity increased, reflecting a more balanced microbial composition. Cutibacterium acnes levels were reduced, particularly virulent IA1/IA2 phylotypes, whereas non-pathogenic or unclassified strains increased. Opportunistic pathogens such as Klebsiella pneumoniae were no longer detected, and beneficial genera including Psychrobacter and Dermabacter were enriched. Functional analysis showed reduced virulence- and biofilm-related pathways, alongside enhanced tryptophan metabolism, SCFA production, lipid synthesis, and riboflavin and folate biosynthesis. Fungal populations, dominated by Malassezia, became more evenly distributed, with notable post-treatment reductions in M. arunalokei, Exophiala spinifera, and Wickerhamomyces anomalus. Phage populations mirrored bacterial changes, with enrichment of Cutibacterium-associated phages post-treatment. These findings demonstrate that the phytocomplex promotes functional rebalancing of the skin microbiota by reducing pathogenic features while maintaining ecosystem stability. The inhibition of quorum sensing, potentially mediated by N-acyl-homoserine lactone acetylation, emerged from metabolic pathway annotation as a hypothetic key mechanism impairing bacterial communication and virulence associated with acne vulgaris. Full article

Biofilms rapidly form on medical devices such as urinary catheters and surgical materials. These biofilms compromise patient safety and undermine infection prevention and control (IPC). Biofilms also reduce the effectiveness of antibiotics and disinfectants. As a result, they increase healthcare-associated infections and increase costs through device failure and the need for maintenance or replacement. Researchers are increasingly exploring biosurfactants (BSs) as surface coatings and cleaning additives to prevent microbial attachment and disrupt early biofilm formation on medical devices and healthcare-related surfaces. This review examines the translational potential of biosurfactants as preventive, disruptive, and adjunctive antibiofilm agents for medical devices and healthcare-related surfaces. Literature evidence on glycolipids (rhamnolipids, sophorolipids) and lipopeptides (surfactin) from static, flow-based, and microfluidic in vitro models that used clinically relevant materials, such as silicone and polydimethylsiloxane (PDMS), were examined. In our literature search, we focused on pathogens central to IPC, such as Staphylococcus aureus, Pseudomonas aeruginosa, Enterococcus spp., and Candida spp., and it was generally noted that BSs reduced microbial adhesion and delayed early biofilm formation on medical devices and healthcare-related surfaces. Significant evidence also suggests that they partially disrupt biofilms and improve antimicrobial penetration when co-applied, mainly through membrane disruption, destabilization of extracellular substances, interfering with quorum sensing, and synergistic and/or antagonistic interactions with other molecules. Their performance varied with class, formulation, hydrodynamic conditions, and microbial composition. BSs function better as preventive and adjunctive IPC tools than stand-alone antimicrobial agents and can help to reduce biofilm formation on devices and improve surface disinfection. However, translating this promise into practice demands more robust data on long-term safety, stability, and product quality. Full article

Baicalin, a natural plant-derived compound, holds promise in addressing clinical bacterial resistance when combined with antibiotics. This study evaluated the antibacterial activity of the combination of baicalin and cefotaxime and explored its mechanism of action on the cell wall and biofilm of multidrug-resistant Pseudomonas aeruginosa (MRPA). The results showed that the combination of baicalin and cefotaxime exerted a synergistic inhibitory effect on the growth of MRPA, with a fractional inhibitory concentration index (FICI) of 0.28. Mechanistically, compared with cefotaxime alone, the combination of baicalin and cefotaxime enhanced the permeability of the cell membrane and cell wall of MRPA, thereby increasing cell damage. It also exhibited stronger antibiofilm activity by inhibiting numerous virulence factors (pyocyanin, elastase, lectin), reducing cellular metabolic activity, and downregulating the expression of biofilm genes (pslA, pelA, algD) and quorum-sensing genes (lasl, lasR, rhll, rhlR, pqsA, pqsR). The molecular docking results revealed that baicalin could stably bind to wbpE, LasR, and RhlR. Therefore, this interaction may indirectly influence the processes related to antibiotic resistance and biofilm formation in bacterial cells. Metabolomic analysis revealed that the combination of baicalin and cefotaxime upregulated 863 metabolites and downregulated 587 metabolites. These metabolites mainly included amino acids, lipids, nucleotides, carbohydrates, and secondary metabolites. The combination primarily enriched key pathways such as amino acid metabolism, lipid metabolism (sphingolipid metabolism) and secondary metabolite biosynthesis. Through these pathways, it triggers significant metabolic reprogramming, thereby interfering with the supply of cell wall synthesis precursors, membrane structural stability, and the generation of biomembrane matrix. Ultimately, it synergistically enhances the effects of cell wall damage and biomembrane inhibition. In conclusion, this study confirms that the combination of baicalin and cefotaxime exerts significant synergistic antibacterial activity against MRPA. It also reveals the mechanism of action of the combination on the cell wall and biofilm of MRPA at the metabolic level, providing theoretical support for the development of novel strategies to combat MRPA. Full article

Periodontitis is a highly prevalent chronic inflammatory disease with significant oral and systemic consequences, including associations with cardiovascular disease, diabetes, and adverse pregnancy outcomes. Although mechanical debridement remains the cornerstone of therapy, adjunctive antibiotic use is increasingly limited by antimicrobial resistance, biofilm-associated tolerance, pharmacokinetic constraints, and disruption of the commensal microbiome, leading to inconsistent outcomes and disease recurrence. This review highlights the mechanistic limitations of conventional antibiotic therapies in periodontitis and critically examines emerging next-generation therapeutic strategies aimed at overcoming these challenges. Specifically, it explores antimicrobial peptides, quorum sensing inhibitors, nanotechnology-based drug delivery systems, host modulation approaches, and microbiome-targeted therapies, with emphasis on their molecular mechanisms, clinical relevance, and translational potential. By integrating microbial, host, and pharmacological perspectives, this review provides a comprehensive framework for advancing precision-guided periodontal therapy and supports the shift toward targeted, sustainable, and personalized treatment strategies. Full article

Bacterial biofilms are structured microbial communities enclosed within a self-produced extracellular polymeric substance matrix composed of polysaccharides, proteins, extracellular DNA, and lipids. This matrix promotes adhesion, structural stability, and the development of heterogeneous microenvironments that restrict antimicrobial penetration and shield bacteria from host immune responses. As a result, biofilms are major contributors to chronic, recurrent, device-related, and difficult-to-treat infections, posing a major challenge for clinical management and antimicrobial stewardship. This review summarizes current understandings of biofilm biology, its clinical relevance, including the stages of biofilm development, the composition and protective roles of the matrix, and the physiological heterogeneity that arises during maturation. It also examines key mechanisms underlying biofilm tolerance and resistance, such as limited antibiotic diffusion, and sequestration, enzymatic inactivation, efflux pump upregulation, persister cell formation, and horizontal gene transfer. In addition, it highlights important clinical settings in which biofilms are implicated, including cystic fibrosis, chronic wounds, osteomyelitis, implant- or device-associated infections, and breast implant illness, in which persistent implant-associated biofilms and the resulting chronic inflammatory milieu have been hypothesized to contribute to local and systemic manifestations in a subset of patients. The review further discusses conventional and emerging approaches for biofilm detection alongwith real-time monitoring. Biofilm-associated infections remain difficult to eradicate because persistence is driven by multiple interconnected protective mechanisms. Effective management therefore requires integrated strategies that combine accurate detection with multifaceted therapies, including antibiotics alongside matrix-disrupting enzymes, quorum-sensing inhibitors, bacteriophages, metabolic reactivators, and nanotechnology-based delivery systems. Advances in multi-omics and system-level modeling will be essential for developing next-generation strategies to prevent, monitor, and treat biofilm-associated disease. Full article

Streptococcus parauberis is a major pathogen responsible for streptococcosis in both marine and freshwater fish species, causing substantial economic losses in aquaculture. The increasing prevalence of multidrug resistance has highlighted the urgent need for alternative disease control strategies. Interference with bacterial quorum sensing (QS) systems represents a promising approach. This study aimed to identify and biochemically characterize an Rgg-family transcriptional regulator and evaluate its potential as a target for quorum sensing-related regulatory interference in vitro. We hypothesized that this Rgg regulator may function as a quorum sensing-associated transcription factor capable of promoter binding and modulation by small molecules. Bioinformatic analyses were used to identify the rgg gene encoding an Rgg-family transcriptional regulator and predict its structural features. The gene was cloned, heterologously expressed, and purified. Promoter binding activity was examined using electrophoretic mobility shift assay (EMSA), and key amino acid residues were identified through site-directed mutagenesis. The inhibitory effect of the cyclic peptide cyclosporin A (CsA) on Rgg-promoter binding was further assessed. The rgg gene (864 bp) encoding a 287-amino-acid protein (34.1 kDa) was successfully identified and expressed. Purified Rgg specifically bound to its own promoter region in a concentration-dependent manner. Mutations at conserved arginine residues R12 and R15 within the helix-turn-helix DNA-binding domain abolished promoter binding activity. Furthermore, CsA disturbed Rgg-promoter binding in a dose-dependent manner. This study provides the first in vitro characterization of an Rgg-family transcriptional regulator in fish-derived S. parauberis. The findings expand current understanding of Rgg-family regulators potentially associated with quorum sensing in aquatic streptococci and provide a preliminary basis for further investigation of quorum sensing-related regulatory interference strategies for controlling streptococcal diseases in aquaculture. Full article

Allium longistylum is a relatively understudied species whose phytochemical composition and biological activities remain largely unexplored. In this study, the first true leaf (FTL) and the second true leaf (STL) of A. longistylum were compared with respect to phenolic composition, antioxidant capacity, antimicrobial activity, and quorum-sensing (QS) inhibition. Total phenolic content (TPC) and total flavonoid content (TFC) were determined spectrophotometrically, while antioxidant activity was evaluated using ABTS and DPPH radical scavenging assays. Antimicrobial and anti-QS activities were assessed against Staphylococcus aureus, Acinetobacter baumannii, and Chromobacterium violaceum. STL exhibited significantly higher TPC and TFC than FTL, consistent with its stronger radical scavenging activity. Both extracts showed moderate antimicrobial activity and reduced violacein production in C. violaceum, indicating interference with QS. UPLC-Q-Orbitrap-ESI-MS/MS profiling tentatively identified several phenolic acids and flavonoid derivatives. HPLC analysis confirmed the presence of selected phenolic compounds, although several prominent peaks in the chromatograms remained unidentified. Many of the compounds detected by UPLC-Q-Orbitrap-ESI-MS/MS and HPLC have previously been reported to exhibit antioxidant, antimicrobial, and anti-QS activities; their presence may therefore contribute to the bioactivities observed in both extracts. However, their contribution to the observed effects remains speculative and requires further validation through targeted isolation and bioactivity testing. The results suggest that A. longistylum is a promising source of phenolic compounds with antioxidant and antimicrobial properties. Full article

Cross-kingdom pathogenesis—human and animal pathogens colonizing and persisting in plants—is transforming our understanding of microbial ecology, food safety, and public health. This review translates incoming research that demonstrates plants as more than mute carriers to dynamic ecological interfaces where human and zoonotic pathogens, such as Salmonella enterica, Escherichia coli O157:H7, and Listeria monocytogenes, will adhere, internalize, and, in some cases, potentially evade host defenses. Such pathogens exploit evolutionarily conserved molecular processes like Type III secretion system 1 (TTSS), biofilm formation, quorum sensing, and small RNA-mediated immune sabotage that have allowed them to cross biological kingdom boundaries. To provide an entry point for pathogens, environmental conditions (e.g., contaminated irrigation water, manure application, wildlife access, and mechanical wounding) promote pathogen transfer to and penetration into plant tissues through stomata hydathodes above ground or roots below ground. Once inside, pathogens confront a range of plant immune responses, indigenous microbiota, and abiotic stresses such as UV radiation exposure, nutrient starvation, and osmotic fluctuations. Nonetheless, biofilm production, metabolic versatility, and virulence gene expression contribute to their persistence. Interactions with plant pathogens and microbiomes additionally shape colonization dynamics, for example, through co-survival and niche manipulation. With the acceleration of these processes due to climate change, urbanization, and intensified agriculture, cross-kingdom pathogenesis becomes a rising concern for One Health. Critical knowledge gaps, including seedborne transmission, microbiome engineering, and predictive modeling, are pointed out in the review along with emerging mitigation strategies, including point-of-care diagnostics and microbial biocontrol. In conclusion, this review advocates for interdisciplinary collaboration from microbiology, plant science, and One Health perspectives to predict and mitigate cross-kingdom threats to global food production. Full article

Chrome tanning of fish skins generates hazardous effluents and carcinogenic Cr(VI) residues; chromium-free routes to valorize collagen-rich by-products from aquaculture and coastal fisheries are therefore needed. We report a 12-stage ecological protocol employing acetic acid/NaCl pickling, Acacia mearnsii tannin, A. podalyriifolia retanning, mashed-papaya enzymatic bating, and cinnamon as antimicrobial/odor adjunct, scaled from bench to pilot using exclusively locally sourced inputs, for Nile tilapia (Oreochromis niloticus) and Patagonian flounder (Paralichthys patagonicus). Three trained operators evaluated macroscopic quality against five predefined criteria adapted from SATRA and ISO 3376 grading conventions, providing a structured feasibility baseline that does not substitute for the standardized instrumental testing designated as priority future work. Both species achieved satisfactory grain stability, complete tannin penetration, pliable handle, and cinnamon-dominant odor without residual amines; dark-brown coloration is a recognized practical limitation for fashion applications. In silico molecular docking (GNINA v1.0) was used to explore the mechanistic plausibility of each ecological substitution, generating testable hypotheses rather than definitive mechanistic conclusions: the multidentate polyphenol proxy (PGG) exhibited consistently superior collagen engagement over the flavanol monomer across both collagen constructs and all three scoring metrics (1CAG: Vina affinity −5.51 ± 0.13 vs. −3.54 ± 0.35 kcal/mol; CNNscore 0.874 ± 0.009 vs. 0.771 ± 0.010; 7CWK: Vina affinity −6.98 ± 1.43 vs. −4.37 ± 0.16 kcal/mol; CNNscore 0.858 ± 0.024 vs. 0.635 ± 0.094). Dipeptide probes were reproducibly accommodated in the papain catalytic cleft, with the closest configuration reaching 3.997 Å from the catalytic nucleophile (OCS25-SG). Trans-cinnamaldehyde occupied the quorum-sensing pocket with reproducible placement (CNNscore 0.718 ± 0.034) but without score-based selectivity over structural decoys, a result interpreted as hypothesis-generating for future microbiological validation. The protocol is reproducible from bench to pilot and generalizable across two species with distinct dermal architectures. Quantitative physical-mechanical testing (shrinkage temperature, tensile strength, elongation, tear load), CIELab colorimetric analysis, and effluent characterization (COD, BOD₅, total phenolics) are designated as priorities for future validation. Full article

Background/Objectives: Cyanobacteria represent a diverse group of microorganisms capable of synthesizing a broad array of biologically active metabolites. Some of these compounds, believed to contribute to the ecological and evolutionary success of cyanobacteria, are increasingly being investigated for potential biomedical and biotechnological applications. They also hold promise in combating the growing threat of antimicrobial resistance (AMR). This screening study aimed to identify Baltic cyanobacterial strains with the potential to produce antibacterial compounds active against streptococci and mycobacteria, as well as quorum sensing inhibitors. Methods/Results: Extracts from forty-four cyanobacterial strains were tested using a broth microdilution assay. The most pronounced activity was observed for extracts derived from two Pseudanabaenaceae strains (KUCC C3 and C4), two Anabaena spp. strains (CCNP 1405 and CCNP 1406), and Aphanizomenon sp. KUCC C1. Inhibition of quorum sensing was the most frequently detected activity, with 30% of the tested extracts inhibiting violacein production in Chromobacterium violaceum ATCC 12472. Growth inhibition of Gram-positive bacteria was less common: 16% of cyanobacterial strains inhibited Streptococcus pyogenes ATCC 12344, and 11% inhibited Mycobacterium smegmatis ATCC 14468. Bioassay-guided fractionation of Aphanizomenon sp. KUCC C1, followed by LC–MS/MS analysis, revealed the presence of glycerolipids and glycolipids, including diacylglycerols (DAGs) and galactosyldiacylglycerols (MGDGs and DGDGs), as major constituents of fractions exhibiting quorum quenching activity. Conclusions: These findings highlight the potential of Baltic cyanobacteria as a source of natural compounds capable of disrupting bacterial communication and growth, offering prospects for the development of novel antimicrobial and anti-virulence agents. Full article

Biofouling remains a critical challenge in membrane bioreactors (MBR), which is primarily caused by the production of extracellular polymeric substances (EPS) as an initial step in biofilm formation. This still limits their widespread application in wastewater treatment. In the past decades, much research has been carried out to understand and consequently reduce biofouling in MBR. More recent studies have focused primarily on inhibiting the release of EPS by applying quorum quenching (QQ) to control biofouling in MBR. This study presents the first investigation of the QQ potential of Rubellimicrobium mesophilum and its effects on biofilm inhibition by EPS reduction, which is demonstrated for MBR operated with submerged flat sheet (PTFE, PS) and hollow fibre polyvinylidene fluoride (PVDF) membranes operated in parallel for 114 days. The QQ effect has a significant impact on the reduction in biofilm thickness on PTFE membranes by 45% and on PS membranes by about 47%, respectively. Additionally, the performance of PVDF was improved by 287.5%. Similarly, the total protein concentration on the PTFE membranes was reduced by 57%, while on the PS membranes, the reduction was 78%. In mixed liquor, protein reduction was 55%, indicating its effectiveness in controlling biofouling over extended operation. The biofilm formation was monitored by measuring the biofilm thickness via fluorescence microscopy and by analyzing the protein and sugar content of the developing biofilm and of the mixed liquor. All parameters indicated decreasing biofilm formation with increasing amounts of entrapped QQ bacteria, while the removal efficiency of organic compounds and ammonia remained similar between all MBRs. Full article

Streptococcus mutans (S. mutans), one of the main etiological pathogens of dental caries, forms dental plaque biofilms that drive tooth decay. Although bacterial membrane vesicles (MVs) are increasingly recognized as modulators of biofilm biology, little is known about MVs generated by S. mutans. The objective of this study is to investigate the role of S. mutans-derived MVs in the development of S. mutans biofilms formed under static conditions in plates or confocal dishes. Transmission electron microscopy and nanoparticle tracking analysis revealed that the MVs were cup-shaped with bilayered membranes and averaged 80.49 $\pm$ 32.24 nm in diameter. The addition of ≥5 µg/mL MVs enhanced biofilm formation during the initial adhesion stage (0 to 6 h), as demonstrated by crystal violet staining and XTT assays. Confocal laser scanning microscopy and scanning electron microscopy confirmed the incorporation of PKH26-labeled MVs into S. mutans biofilms and showed that supplemental MVs increased bacterial viability and extracellular polysaccharide biomass. Furthermore, RT-qPCR analysis revealed upregulated expression of genes related to adhesion and quorum-sensing systems in MV-treated biofilms. In conclusion, these findings indicate that S. muants MVs are integral biofilm components that promote biofilm establishment at the early stage of biofilm formation. Full article

Phenyllactic acid (PLA), a natural antimicrobial metabolite produced by lactic acid bacteria (LAB), has emerged as a key compound for biopreservation in food systems. The aims of this review are to summarize the main findings on LAB-producing strains, the effects of primary PLA precursors, the impacts of culture conditions on PLA production, antimicrobial activity, mechanisms of action, quantification and analysis methods, food applications, regulatory status, and the challenges in PLA production and applications. In this review, the quorum sensing role in PLA production and multi-omics strain improvement was revised. Applications in dairy, bakery, fruits, vegetables, meat, and fish products as well as active packaging are analyzed, demonstrating their effectiveness in controlling microbial spoilage and pathogens while preserving sensory quality. Its broad-spectrum antifungal and antibacterial activities make it particularly attractive as a clean-label alternative to synthetic preservatives, contributing to both food safety and extended shelf life. Finally, current limitations and future research needs are outlined, particularly in optimizing PLA production and establishing its role as a sustainable and effective tool for food safety management. Full article

Due to increasing antimicrobial resistance and oxidative stress, the exploration of new therapeutic agents from medicinal plants such as Galium aparine L., has become essential. This study aimed to provide a scientific basis for the ethnomedicinal applications of G. aparine by evaluating its biological activities and biochemical composition. Plant samples were extracted using different solvents and their biological activities were assessed through antimicrobial, antibiofilm, and anti-quorum sensing (AQS) assays against different microorganisms. Antioxidant capacity was determined using four complementary assays representing distinct mechanisms, while the biochemical composition was analyzed via GC–MS. The results revealed that although the extracts exhibited limited antimicrobial activity overall, significant inhibition was observed against Staphylococcus aureus, and Enterococcus strains, with MIC values as low as 30 µg/mL. The ethanol extract demonstrated the highest antibiofilm inhibition (60.38%) against Streptococcus mutans, surpassing the positive control Halamid, and showed the strongest AQS inhibition (46.16%). Moreover, a strong antioxidant potential comparable to ascorbic acid was detected in the ABTS assay, with 88.10% inhibition. Overall, these findings indicate that G. aparine extracts possess notable antibiofilm, AQS, and antioxidant properties that support their traditional medicinal uses and suggest their potential as promising sources for the development of new natural therapeutic agents. Full article