Biofouling最新文献

Traditional antifouling coating evaluations rely on manual sample retrieval, imaging and subjective visual assessments, which are labour-intensive and constrained by infrequent sampling intervals that may overlook critical fouling developments. This study presents a novel, automated biofouling assessment system at the CoaST Maritime Test Centre. A custom underwater camera captures daily images, while advanced image analysis techniques track fouling progression. To address imaging challenges, a median stacking technique removes transient artefacts such as overhanging algae and floating debris, enabling accurate assessment of attachment points, the primary metric for biofouling coverage. Multi-exposure fusion enhances image illumination. For image analysis, ilastik, a machine-learning tool using a random forest algorithm, performs pixel classification segmentation to differentiate biofouling classes and monitor their growth. This automated approach improves accuracy, repeatability and efficiency in biofouling assessment, reducing subjectivity and enhancing antifouling research.

Twenty-three phenolic acids (1-23), including three novel sulfur-containing derivatives, along with five alkaloids (24-28) were isolated from the marine-derived fungus Aspergillus iizukae GXIMD 00548. Their structures were elucidated through comprehensive spectroscopic analysis and comparison with literature. All isolated compounds were evaluated for antifouling activities against barnacle larval settlement. Compounds 1-6, 8-11, 13, 20, 22 and 24-26 exhibited potent antifouling effects with median effect concentration (EC₅₀) values ranging from 0.03 to 11.03 μg/mL. Additionally, compounds 9, 10 and 13 showed acetylcholinesterase (AChE) inhibitory effects with half maximal inhibitory concentration (IC₅₀) values of 49.67 ± 0.08, 77.69 ± 0.09, and 127.5 ± 0.09 μM, respectively.

Ocimum gratissimum L. (African basil) is widely used in ethnomedicine to treat infectious and inflammatory conditions, yet its antifungal mechanisms remain unclear. In this study, we evaluated the essential oil of O. gratissimum L. (OGEO) against Candida albicans biofilms, a clinically relevant driver of antifungal resistance in device-associated infections. Gas chromatography-mass spectrometry identified eugenol as the predominant constituent (59.5%), supported by terpenoid and sesquiterpene derivatives. Functional assays demonstrated potent antibiofilm activity, as exposure to 1% and 2% OGEO reduced viable biofilm cells by >2 log₁₀ CFU/biofilm at Day 1 and sustained ∼70% inhibition at Day 3, with corresponding biomass reductions of ∼65% and ∼80%, respectively. Confocal microscopy revealed marked thinning and fragmentation of hyphal networks, while scanning electron microscopy confirmed collapse of extracellular matrix architecture. Kinetic modeling showed that OGEO induced an intermediate suppression profile, delaying biofilm recovery compared to untreated controls and fluconazole (which permitted ∼90% regrowth by Day 7), but without the sustained fungicidal effect observed with caspofungin (>80% suppression). Transcriptomic profiling at Day 3 identified 463 differentially expressed genes, with strong repression of hyphal regulators (HWP1, ALS3, EFG1, BCR1) and extracellular matrix-associated genes (FKS1, ZAP1), alongside upregulation of oxidative and proteotoxic stress pathways (SOD5, HSP90, MAPK signaling). Together, these data suggest that OGEO functions as a biofilm modulator rather than a fungicidal agent, weakening structural resilience and redirecting C. albicans into a stress-adaptive state. Clinically, this modulatory activity-marked by early biomass suppression, matrix destabilization, and transcriptional remodeling-highlights OGEO's potential as a prophylactic or adjunctive strategy in device-associated candidiasis. Applications may include medical device coatings or topical formulations that prevent biofilm initiation and enhance susceptibility to existing antifungal drugs.

Polymicrobial biofilms are frequently associated with chronic infections and are highly tolerant to antibiotic treatment. Given that β-lactam antibiotics are the most prescribed antibiotics worldwide, we investigated β-lactam resistance in dual-species biofilms formed by Pseudomonas aeruginosa PAO1 and methicillin-sensitive Staphylococcus aureus (MSSA). Compared to monocultures, MSSA exhibited reduced susceptibility to cephalexin, ampicillin, and cefazolin, while P. aeruginosa showed reduced susceptibility to cefazolin and nafcillin within dual-species biofilms. Using a set of P. aeruginosa mutants, we demonstrate that the PAO1 AmpC β-lactamase, the exopolysaccharides Psl and Pel, and the quorum sensing regulators LasR and RhlR each play significant roles in protecting MSSA from β-lactam treatment. Interestingly, co-cultures of MSSA with the ΔpslA pelF mutant strain increased the survival of ΔpslA pelF under β-lactam exposure. Overall, these findings advance our understanding of how interdependent bacterial interactions compensate for the loss of matrix components and thereby contribute to antimicrobial tolerance in polymicrobial biofilms.

Multidrug-resistant bacteria in biofilms are a growing public health threat, due to their resistance to conventional antibiotics. Phytochemicals are attractive candidates because of their structural diversity and ability to potentiate antimicrobial activity. This study investigated the antibiofilm and resistance-modifying effects of two monoterpenes, menthol and linalool, alone and in combination with ten antibiotics, against Escherichia coli and Staphylococcus epidermidis. Menthol exhibited MIC and MBC of 800 µg/mL against E. coli and the same MIC against S. epidermidis, while linalool showed MICs of 800 µg/mL and 400 µg/mL, respectively. Combination assays revealed enhanced activity of erythromycin with both monoterpenes against E. coli and of amoxicillin with menthol against S. epidermidis, although sessile cells were largely unaffected. When applied individually, both monoterpenes caused a 3-log reduction in culturable E. coli biofilm cells. The overall findings highlight the antibiofilm activity of linalool and, particularly, menthol, supporting their role as antibiotic adjuvants against biofilm-associated infections.

Methicillin-resistant Staphylococcus aureus (MRSA) poses a major global health threat and is recognized by the World Health Organization as a high-priority pathogen for new drug development. MRSA's ability to form biofilms further complicates treatment and enhances antibiotic resistance. Antimicrobial peptides (AMPs) present a promising alternative to conventional antibiotics, however, their discovery remains labor-intensive. This study utilized computational and experimental approaches to evaluate the physicochemical properties, anti-MRSA activity against 10 clinical isolates, bacterial selectivity, cytotoxicity, and antibiofilm effects of AMPs. Temporin-PF (TPF) peptide was identified as a leading candidate and modified to generate TPF-M1, achieving an improved anti-MRSA score of 600.0. TPF-M1 exhibited enhanced killing activity and selectivity against MRSA with low toxicity toward human cells. At 20 µM, TPF-M1 effectively reduced MRSA biofilm viability using the transferable solid-phase pin lid method and disrupted the biofilm structure. These findings underscore the potential of AI-guided AMP development for anti-MRSA therapy.

Antibiotics incorporated into spacers do not guarantee complete eradication of infection. This study aimed to compare, in vitro, the antimicrobial activity of antibiotic-loaded cement with and without additional alternative antimicrobial molecules for the eradication of polymicrobial biofilms. Methicillin-resistant Staphylococcus aureus (MRSA), Pseudomonas aeruginosa (PA), and Candida albicans (CA) were selected to form mono- and polymicrobial biofilms on polyurethane sponges. Bone cement was supplemented with vancomycin, imipenem, silver nitrate (SN), and xylitol in different combinations. In monomicrobial biofilms, the combination of vancomycin + SN + xylitol showed superior activity against MRSA compared with other formulations. In polymicrobial biofilms, the combinations imipenem + vancomycin + xylitol, imipenem + vancomycin + SN, and imipenem + vancomycin + SN + xylitol were most effective in eradicating PA. For MRSA, all combinations achieved complete eradication, whereas CA eradication remained incomplete. Overall, the inclusion of SN and xylitol in cement improved antimicrobial performance compared with antibiotic-only formulations.

Resin materials enriched with bioglass (45S5) could potentially improve the physicochemical properties of dental materials. Specimens were categorized into five groups: (GIC)- conventional glass ionomer cement; (RMGIC.1)- resin-modified GIC with non-lyophilised polyacrylic acid, (RMGIC.1_45S5)- RMGIC.1 with 45S5 (10 w/w%); (RMGIC.2)- resin-modified GIC with freeze-dried polyacrylic acid; and (RMGIC.2_45S5)- RMGIC.2 with 45S5 (10 w/w%). The specimens were tested at acid/neutral pH, and the antibacterial activity colony-forming units (CFU/mg), sorption, solubility, calcium ion release, and bioactivity were measured in a Streptococcus mutans biofilm model. Analysis of variance and Scheffe/Tukey statistical tests were used. The 45S5 in the RMGICs resulted in higher alkalinization and the formation of calcium/phosphorus precipitates. RMGIC.1_45S5 improved pH stability and increased the sorption and solubility. In the S.mutans biofilm, none of the materials significantly increased the pH. The enrichment of RMGIC.1 (45S5) increased the sorption, solubility, calcium release, and showed bioactivity, but had no antimicrobial effect on the S.mutans biofilm model.