Search Results (470)

The call for new approaches to prevent and treat metabolic syndrome-related diseases has led to research on the use of lacto-fermentative probiotics with beneficial metabolic properties like Lactobacilli. Here, we characterize the probiotic properties of a novel strain, Lactiplantibacillus plantarum CNTA 628, and investigate its potential anti-obesity and health-promoting activities in the Caenorhabditis elegans model, additionally elucidating the molecular mechanisms involved. Lactiplantibacillus plantarum CNTA 628 exhibited sensitivity to the entire spectrum of antibiotics analyzed, gastric and intestinal resistance in vitro, β-galactosidase and bile-salt hydrolysate activities, and the capacity to form biofilms and produce SCFAs. In addition, it reduced the binding of the pathogenic E. coli O157:H7 to intestinal epithelial cells (Caco-2) and exerted immune-modulating effects in cellular models. Supplementation with this probiotic significantly reduced C. elegans fat accumulation by more than 18% under control and high-glucose conditions, lowered senescence, improved oxidative stress, and significantly enhanced lifespan without affecting the development of the worms. Gene expression analyses evidenced that L. plantarum CNTA 628 plays a role in regulating daf-22 and maoc-1 gene expression, both linked to beta-oxidation pathways. Our results demonstrate the health-benefiting properties of this novel strain and suggest its potential as probiotic candidate for the prevention and treatment of metabolic syndrome-related conditions. Full article

Environmental conditions, including nutrient composition and temperature, influence biofilm formation and antibiotic resistance in Escherichia coli. Understanding how specific metabolites modulate these processes is critical for improving antimicrobial strategies. Here, we investigated the growth and composition of Escherichia coli in both planktonic and biofilm states in the presence of L-arabinose, with and without exposure to the fluoroquinolone antibiotic levofloxacin, at two temperatures: 28 and 37 °C. At both temperatures, L-arabinose increased the growth rate of planktonic E. coli but resulted in reduced total growth; concurrently, it enhanced biofilm growth at 37 °C. L-arabinose reduced the efficacy of levofloxacin and promoted growth in sub-minimum inhibitory concentrations (25 ng/mL). Transcriptomic analyses provided insight into the molecular basis of arabinose-mediated reduced susceptibility of E. coli to levofloxacin. We found that L-arabinose had a temperature- and state-dependent impact on the transcriptome. Using gene ontology overrepresentation analyses, we found that L-arabinose modulated the expression of many critical antibiotic resistance genes, including efflux pumps (ydeA, mdtH, mdtM), transporters (proVWX), and biofilm-related genes for external structures like pili (fimA) and curli (csgA, csgB). This study demonstrates a previously uncharacterized role for L-arabinose in modulating antibiotic resistance and biofilm-associated gene expression in E. coli and provides a foundation for additional exploration of sugar-mediated antibiotic sensitivity in bacterial biofilms. Full article

Acne is a highly prevalent skin condition with multifactorial pathophysiology, where Cutibacterium acnes (C. acnes) overgrowths generate inflammation. C. acnes can grow and adhere, through the formation of biofilms, to almost any surface, which enables chronic infections. Acne treatment with antibiotics can induce topical antimicrobial resistance, impair microbiome biodiversity and cause cutaneous dysbiosis. In this study, we assess the effect of a standardized propolis extract (PE) from Greece against C. acnes, whilst maintaining skin’s microbiome biodiversity, and we investigate its effect against genes related to the attachment and colonization of C. acnes, as well as against biofilm formation. The extract has been chemically characterized by GC-MS and was additionally tested for its antioxidant properties by the Folin–Ciocalteu method and the 2,2-Diphenyl-1-Picrylhydrazyl (DPPH) assay and its regulatory activity on the expression of antimicrobial and anti-inflammatory genes in normal human epidermal keratinocytes (NHEKs). The suggested efficacy of PE in targeting pathogenic C. acnes biofilm, via downregulation of virulence genes, represents an alternative strategy to modulate the behavior of skin microbiota in acne, paving the way for next-generation acne-targeting products. Full article

The shift toward plant-based feeds in aquaculture necessitates a search for probiotics to improve the digestibility of such feeds and fish growth. This study characterizes four Bacillus strains for their probiotic potential in carp (Cyprinus carpio). Strains isolated from river sediments underwent in vitro screening for proteolytic/amylolytic activity, antibiotic sensitivity, and biofilm formation. Whole-genome sequencing was performed and functional annotation identified probiotic-related genes. All strains were identified as Bacillus velezensis and harbored genes providing thermal, osmotic, and oxidative stress resistance, alongside enzymes and bioactive metabolite synthesis pathways. Two non-antagonistic strain pairs were solid-phase cultivated on soybeans and incorporated into carp feed (0.1% w/w) for a 76-day trial, and growth metrics and gene expression were analyzed in juvenile fish. Group 1 (strains MT14 + MT42) exhibited a 40.75% higher biomass increase than the control group while Group 2 (strains MT141 + MT142) exhibited a 56.62% higher biomass growth. No significant gene expression changes occurred in juveniles, though MT141 + MT142 transiently modulated fry expression profiles. Therefore, these Bacillus velezensis strains synergistically enhance growth in carp that are fed plant-rich diets, highlighting their viability as aquaculture probiotics. Full article

Oral diseases such as periodontitis and dental caries, as well as conditions related to oral health such as halitosis, are closely associated with dysbiosis of the oral microbiota and continue to pose significant public health challenges worldwide. With the increasing resistance to existing antibiotics and side effects of chemical disinfectants, probiotics have emerged as promising alternatives for oral healthcare. This study aimed to evaluate the oral health efficacy and probiotic properties of Limosilactobacillus fermentum (L. fermentum) MG4717 isolated from the human oral cavity. L. fermentum MG4717 showed notable antimicrobial activity against the key oral pathogens Streptococcus mutans (S. mutans), Aggregatibacter actinomycetemcomitans (A. actinomycetemcomitans), Porphyromonas gingivalis (P. gingivalis), and Fusobacterium nucleatum (F. nucleatum) and effectively inhibited biofilm formation. Additionally, L. fermentum MG4717 significantly downregulated methionine gamma-lyase (mgl) mRNA expression in P. gingivalis, which is implicated in halitosis and pathogenicity. L. fermentum MG4717 strongly adhered to the KB and HT-29 epithelial cells and exhibited good resilience under simulated gastrointestinal conditions. Whole-genome sequencing (WGS) and average nucleotide identity (ANI) analysis confirmed strain identity (98.73% average nucleotide identity with L. fermentum DSM20052) and the absence of transferable antibiotic resistance genes. Safety assessments revealed no cytotoxicity, hemolytic activity, or bile salt hydrolase activity. These findings suggest that L. fermentum MG4717 has the potential to be used as a safe and effective oral probiotic beneficial for oral health. Full article

Plant-beneficial microbes are a perennial ally in an agroecosystems, providing multiple benefits to crop plants. The present study explored the potential of two microbial biocontrol agents (MBCAs), viz., Trichoderma asperellum and Pseudomonas fluorescens, against the bacterial blight pathogen of rice, Xanthomonas oryzae pv. oryzae. In vitro, MBCAs resulted in significant inhibition of X. oryzae pv. oryzae, as evidenced through the distortion of pathogen cell morphology and formation of a pathogen biofilm. Pot studies on the effect of MBCAs in rice showed increased germination, increased vigor index of seedlings, increased tiller numbers, a 10.29% reduction in percentage disease incidence (PDI), and low disease severity following individual inoculation. Activity of plant defense enzymes also increased with MBCA treatment (phenylalanine ammonia-lyase, 2.7-fold increase; peroxidase and polyphenol oxidase, 5-fold increase), establishing the priming effect of MBCAs on host defense. The quantitative polymerase chain reaction data revealed that pathogenesis-related genes (OsPR1a, OsPR1b, and OsPR10a) and X. oryzae pv. oryzae resistance genes (Xa1 and Xa26) were upregulated 4- to 14-fold in MBCA-treated rice plants over control plants. These results provide insights into the phenological, physiological, and molecular responses of rice crops treated with MBCAs in the presence of X. oryzae pv. oryzae and could be used to develop an effective field management strategy. Full article

Background: The global rise of multidrug-resistant Gram-negative bacteria, particularly non-fermenting species and carbapenemase-producing Enterobacteriaceae, poses a significant challenge to hospital infection control. Methods: In this study, a total of 89 Acinetobacter spp. isolates, 14 Pseudomonas aeruginosa, and 14 carbapenem-resistant Enterobacteriaceae isolates were collected from patients in a tertiary hospital. Whole-genome sequencing and antimicrobial susceptibility testing were conducted. Resistance mechanisms and evolutionary relationships were analyzed using phylogenetic analysis and genetic context mapping. Results: Among the non-fermenting isolates, A. baumannii exhibited high resistance to carbapenems, clustering into distinct clonal groups enriched with genes associated with biofilm formation and virulence genes. P. aeruginosa isolates harbored fewer resistance genes but carried notable mutations in the efflux pump systems and the oprD gene. In Enterobacteriaceae, four bla_NDM alleles were identified within a conservative structural sequence, while bla_KPC-2 was located in a non-Tn4401 structure flanked by IS481- and IS1182-like insertion sequences. Phylogenetic analysis revealed that bla_NDM-positive E. coli strains were closely related to susceptible lineages, indicating horizontal gene transfer. Conversely, K. pneumoniae isolates harboring bla_KPC-2 formed a tight clonal cluster, suggesting clonal expansion. Conclusions: The study reveals distinct transmission patterns between resistance genes: horizontal dissemination of bla_NDM and clonal expansion of bla_KPC-2 in K. pneumoniae. These findings emphasize the need for resistance-gene-specific genomic surveillance and infection control strategies to prevent further nosocomial dissemination. Full article

Spore-forming Bacilli have been explored due to their potential biotechnological features and applications in human health and functional food research. This study focuses on the genetic and phenotypical characterization of the functional probiotic properties of Bacillus velezensis P45, a strain isolated from fish intestines. B. velezensis P45 exhibited antimicrobial activity against Gram-positive and Gram-negative pathogens and demonstrated strong autoaggregation and biofilm formation properties in vitro. The strain also showed tolerance to gastrointestinal conditions and ability to metabolize and adhere to mucin. In silico analysis confirmed the absence of virulence factors and antibiotic resistance genes, reinforcing its safety as a probiotic candidate. Genome mining revealed the presence of genes related to adhesion, such as fibronectin-binding protein and enolases, and for the synthesis of secondary metabolites, including the antimicrobial lipopeptides fengycin, surfactin, and bacillibactin. In addition, phylogenetic comparison using the yloA (rqcH) gene associated with gut adhesion clustered strain P45 with other probiotic Bacillus and B. velezensis strains, while separating it from pathogenic bacteria. Thus, the strain B. velezensis P45 could be a valuable candidate as a probiotic due to its functional properties and safety. Full article

With 80% of bacterial infections occurring as biofilms, biofilm-related infections have evolved into a critical public health concern. Probiotics such as Bacillus licheniformis have emerged as promising alternatives, offering new avenues for effective treatment. This study aimed to evaluate the activity of licheniformis against the growth, biofilm formation, motility, and quorum sensing (QS) of Salmonella typhimurium. Several experiments were conducted: The minimum inhibitory concentration (MIC) of Bacillus licheniformis against Salmonella typhimurium was determined to be 0.5 mg/mL using the broth microdilution method. The inhibition zone of 100 mg/mL of B. licheniformis against Salmonella typhimurium was 19.98 ± 1.38 mm; the time-growth curve showed that B. licheniformis can effectively inhibit the growth of Salmonella typhimurium. In biofilm experiments, at the MIC of B. licheniformis, the inhibition rate of immature biofilm of Salmonella typhimurium was 86.9%, and it significantly reduced the production of biofilm components (EPS, e-DNA, and extracellular proteases) (p < 0.05). The disruption rate of mature biofilm by B. licheniformis at the MIC was 66.89%, and it significantly decreased the levels of biofilm components (EPS and e-DNA) (p < 0.5). Microscopic observation showed that both the MIC and 1/2 MIC of B. licheniformis could reduce the number of bacteria in the Salmonella typhimurium biofilm, which was not conducive to the formation and maintenance of the biofilm structure. Swimming/Swarming assays and QS experiments confirmed that B. licheniformis inhibits the motility of Salmonella typhimurium and the secretion of AI-1-type quorum sensing molecules and downregulates the AI-2 quorum sensing system by upregulating lsr gene expression. These findings suggest that B. licheniformis could be a potential antimicrobial agent and biofilm inhibitor. Full article

Background/Objectives: The present study was aimed at documenting S. maltophilia occurrence in dogs with skin ailments, investigating its virulence, biofilm-forming ability, antimicrobial susceptibility, and zoonotic potential to inform preventive and therapeutic strategies against multidrug resistant S. maltophilia infections. Methods: Skin swabs (n = 300) were collected from dogs with dermatological ailments. Isolation was performed using selective media and confirmed with molecular methods, validated by MALDI Biotyper. Antimicrobial susceptibility testing and efflux activity assessment were conducted. Resistance genes related to sulfonamides, quinolones, and β-lactams were screened. Virulence was assessed by biofilm formation, motility, and virulence gene profiling. Results: In total, 15 S. maltophilia (5%) isolates were identified. All 15 isolates were susceptible to trimethoprim-sulfamethoxazole, enrofloxacin, gatifloxacin, levofloxacin, minocycline, and tigecycline, but resistant to cefpodoxime and aztreonam. The following resistance genes qnr (93.3%), bla_OXA-48 (46.7%), bla_KPC (33.3%), bla_NDM (33.3%), bla_CTX-M (20%), bla_SHV (20%), and bla_TEM (6.7%) were detected. All 15 isolates displayed high efflux activity. Overall, 9 isolates (60%) were strong biofilm producers, and 6 (40%) were moderate. Virulence genes such as virB, motA, rmlA, and fliC were present in all 15 isolates, with others varying in frequency. All isolates exhibited swimming motility. Heat map clustering showed diverse profiles, with no identical isolate patterns. Correlation analysis indicated positive associations between several antimicrobial resistance and virulence genes. Conclusions: This study underscores the zoonotic potential of S. maltophilia from dogs, advocating for a One Health approach to mitigate infection risks and limit the spread of virulent multidrug resistant pathogens. Full article

Bats serve as key ecological reservoirs of diverse microbial communities, including emerging viruses and antibiotic resistance genes. This study investigates the intestinal microbiota of two insectivorous bat species, Nyctalus noctula and Vespertilio murinus, at the Rostov Bat Rehabilitation Center in Southern Russia using whole metagenome shotgun sequencing. We analyzed taxonomic composition, functional pathways, antibiotic resistance genes, and virulence factors. Densoviruses, especially those closely related to Parus major densovirus, were the most dominant viral sequences identified. Metagenome-assembled densovirus genomes showed high sequence similarity with structural variations and clustered phylogenomically with viruses from mealworms and birds, reflecting both dietary origins and the potential for vertebrate infection. Functional profiling revealed microbial pathways associated with cell wall biosynthesis, energy metabolism, and biofilm formation. A total of 510 antibiotic resistance genes, representing 142 unique types, mainly efflux pumps and β-lactamases, were identified. Additionally, 870 virulence factor genes were detected, with a conserved set of iron acquisition systems and stress response regulators across all samples. These findings highlight the ecological complexity of bat-associated microbiota and viromes and suggest that synanthropic bats may contribute to the circulation of insect-associated viruses and antimicrobial resistance in urban settings. Full article

Background: The opportunistic pathogen Staphylococcus aureus causes skin and soft tissue infections that are associated with biofilm formation, and in immunocompromised patients can progress to surgical site infections, pneumonia, bacteremia, sepsis, and even death. Most antibiotics actively damage living, dividing cells on the surface of the biofilm, where there is a high concentration of nutrients and oxygen, while in the depths, where these factors are scarce, slowly growing cells remain. Objectives: The aim of our study was to evaluate the antibiofilm potential of ethyl acetate roots (EtOAcR) and aerial parts (EtOAcAP) extracts from the perennial Bulgarian plant Geum urbanum L. against methicillin-resistant S. aureus (MRSA) NBIMCC 8327. Methods: The effects of both extracts on the expression of biofilm-related genes, icaA and icaD, were investigated. The cytotoxicity of EtOAcR and EtOAcAP on A-375 (human melanoma), A-431 (epidermoid skin cancer) and HaCaT (normal keratinocytes) cell lines, and the induction of apoptosis were determined. Finally, the in vivo skin irritation potential of the most active extract was studied. Results: Both tested extracts inhibited biofilm formation at concentrations that did not affect bacterial growth. Interestingly, the expression of icaA and icaD was upregulated, although the biofilm development was inhibited 72.4–90.5% by EtOAcAP and 18.9–20.4% by EtOAcR at sub-MICs. EtOAcAP extract showed a more favorable cytotoxic profile on non-tumorigenic cells and stronger antineoplastic activity (IC₅₀ = 6.7–14.68 µg/mL) as compared to EtOAcR extract (IC₅₀ = 8.73–23.67 µg/mL). Therefore, a skin irritation test was performed with the EtOAcAP extract at ten-times higher concentrations than the minimum inhibitory one, and, resultantly, the primary irritation index was equal to zero (no skin irritation observed). Conclusions: The EtOAcAP extract was proven to be an effective antistaphylococcal agent with favorable skin tolerance. The extract showed strong antineoplastic activity and antibiofilm effect at sub-MICs, which outlines new prospects for its development as a natural product for specific skin applications in medical practice. Full article

Dermatophytosis is a fungal infection that affects the skin, hair, and nails, impacting approximately 25% of the global population. Nannizzia gypsea is a geophilic fungus that can cause infections in humans and animals. Several studies have been conducted regarding its virulence, or ability to cause disease. This species may produce keratinolytic enzymes and form biofilms, which can increase resistance to treatment. Thus, this study focuses on investigating the biofilm formation of N. gypsea isolated from canine dermatophytosis using an ex vivo hair model, its biofilm extracellular matrix macromolecular contents, and the expression of genes involved in the colonization of keratinized surfaces. The biofilm was analyzed for metabolic activity using the XTT reduction assay, crystal violet staining to measure biofilm biomass, scanning electron microscopy (SEM), and the presence of polysaccharides, proteins, and extracellular DNA in the biofilm extracellular matrix. The virulence genes subtilisin 7, fungalysin (extracellular metalloproteinase), and efflux pump (Multidrug and Toxin Extrusion Protein 2) were evaluated by qPCR, comparing the planktonic and biofilm phenotypes. N. gypsea formed a robust biofilm, which matured after 5 days. Scanning electron microscopy (SEM) revealed the presence of an extensive extracellular matrix. In the hair model, the characteristic ectothrix parasitism of the species is observable. The gene expression analysis revealed a higher expression of all evaluated genes in the biofilm form compared to the planktonic form. Thus, N. gypsea exhibits a biofilm characterized by a robust extracellular matrix and high gene expression of factors related to pathogenesis and resistance. Full article

A backyard cat with symptoms of otitis was transferred to a veterinary clinic in Central Greece. A sample was obtained and P. aeruginosa was isolated. The strain exhibited an extensively drug-resistant (XDR) profile, as it was non-susceptible to all tested agents except colistin. DNA extraction and whole-genome sequencing (WGS) were performed using a robotic extractor and Ion Torrent technology, respectively. The genome was assembled and screened for resistance and virulence determinants. The isolate belonged to the high-risk clone ST308 with a total of 67 antibiotic resistance genes (ARGs) and 221 virulence factor-related genes being identified. No plasmids were detected. The metallo-beta-lactamase (MBL) bla_NDM-1 gene and 46 efflux pumps were included in the strain’s resistome. Both ARGs conferring tolerance to disinfecting agents and biofilm-related genes were identified, associated with the ability of this clone to adapt and persist in healthcare facilities. This case highlights the risk of relevant bacterial clones spreading in the community and even being transmitted to companion animals, causing challenging opportunistic infections to susceptible individuals, while others may become carriers, further spreading the clones to their owners, other animals and the environment. Full article

The emergence of methicillin-resistant Staphylococcus aureus (MRSA) and its biofilm-forming ability underscore the limitations of current antibiotics. In this study, a new compound named tripterhyponoid A was found to effectively combat MRSA, with an MIC of 2.0 μg/mL. It inhibited biofilm formation by downregulating genes related to the quorum sensing (QS) pathway (sarA, agrA, agrB, agrC, agrD, and hld) and eradicated mature biofilms. Furthermore, it induced DNA damage by binding to bacterial DNA, enhancing its efficiency against MRSA. Therefore, its anti-MRSA properties with multiple mechanisms of action make it less prone to developing resistance over 20 days. In addition, it reduced the bacterial load and regulated the levels of inflammatory cytokines IL-6 and IL-10 at the wound site in a mouse skin infection model. This paper provides the first in-depth investigation of the mechanisms of triterpenoids against MRSA by inhibiting the expression of QS system genes and binding to DNA. Full article