Biofouling最新文献

Bedrock lithological properties shape the structure and dynamics of benthic communities across spatial and time scales. This study investigates how mineral composition, grain size, and colour influence early colonization of benthic communities in Genoa harbour during summer 2024. Panels of marbles, travertines, quartzite, siltite and granitoids (10 × 10 cm) were used to monitor settlement of fouling species like the barnacle Amphibalanus amphitrite, the serpulid Hydroides elegans, and the bryozoan Schizoporella errata. Results showed the highest settlement on dark siltite and the lowest on light marbles and travertines. No significant effect of mineral composition or grain size was detected, including the expected inhibitory effect of quartz. Larval preference for darker substrata, confirmed by comparisons between marble and granitoids with varying grey levels, suggests colour as a key driver of settlement. Post-settlement survival was mainly influenced by substratum stability. These findings highlight the complex interactions between physical properties and colonization patterns.

The aim of this study was to evaluate effects of neovestitol-vestitol fraction (NVF) on an in vitro subgingival multispecies biofilm. The 33-species biofilm was formed for seven days using a Calgary device. Starting on day 3, treatments for applied twice daily for 1 min each: NV (400-1,600 µg ml^-1), chlorhexidine 0.12% (CHX; positive control) or vehicle (negative control). After seven days, metabolic activity and microbial composition were accessed through colorimetric reaction and DNA-DNA hybridization, respectively. ANOVA/Tukey's and Kruskal-Wallis/Dunn's were performed (p < 0.05). NV1,600 and NV800 and CHX significantly reduced biofilm metabolic activity by 67%, 48% and 64% respectively, compared to vehicle-treatment. NV1,600, NV800 and CHX reduced red complex proportions versus vehicle-treatment. NV1,600 also reduced orange complex and increased healthy-associated purple complex compared to negative control (p < 0.05). NV1,600, NV800 and CHX reduced nine species, including Fusobacterium periodonticum and Porphyromonas gingivalis. NV1,600 also reduced Fusobacterium nucleatum polymorphum. NV seems to be a good candidate to control biofilm formation and pathogenicity in dental practice.

Mitigating marine biofouling using marine resources has become a research hotspot as it is considered an environmentally friendly approach. Hence, this study investigated the biofilm mitigating property and antifouling activity of bio-oil extracted from the pyrolysis of seaweed biomass. The bio-oil inhibited up to 73-80% of biofilm and extracellular polymeric substance (EPS) formation of the predominant marine microfoulers Nitratireductor kimnyeongensis, Nitratireductor aquibiodomus and Stutzerimonas stutzeri. Gas chromatography-mass spectrometry (GC-MS) analysis of the bio-oil identified that 13-Docosenamide (Z) is a prominent compound that accounts for about 27.42% of the total bio-oil composition which might be responsible for its antibiofilm property. The bio-oil was further formulated into antifouling paint equivalent to the consistency of traditional antifouling paints and coated on titanium plates. The water contact angle results showed that bio-oil and antifouling paint exhibit hydrophilic surfaces, effectively reducing bacterial attachment. Scanning electron microscopic analysis revealed that the anti-fouling paint coated on titanium plates against mixed species of microfoulers significantly reduced biofilms. Molecular docking of 13-Docosenamide (Z) against the mussel adhesive foot protein of Perna viridis (Pvfp-5b) exhibited favorable binding scores, indicating that it may reduce the bio-adhesion of macrofoulers to the substrate.

Antifouling coating development requires extensive performance testing. Coatings that prevent aquatic larval settlement are of interest because many forms of macrofouling begin at the larval stage. However, field testing can be time consuming and poorly controlled. Herein is reported a screening tool, Settlement of Larvae Assay using Mussels (SLAM), for down-selecting materials prior to field testing. The method entails using a dense concentration of mussel larvae that are allowed to settle on submerged test surfaces. Settled larvae are then quantified to provide a measure of antifouling performance. The SLAM test differentiated coatings with only slight differences in formulation. To enable efficient quantification of dense larvae settlement, an automated counting method was developed that combines two analyses: a color thresholding identifies larvae clumps, and a machine learning algorithm identifies non-clumped larvae. This automated 'hybrid' approach rapidly quantifies settled larvae as effectively as manual counting but in a fraction of the time.

The aim was to evaluate the antibacterial activity of diazepam against methicillin-susceptible (MSSA) and methicillin-resistant (MRSA) strains of Staphylococcus aureus and its possible mechanism of action. The broth microdilution assay was used to determine the minimum inhibitory concentration (MIC) of diazepam. A checkerboard assay was used to evaluate the interaction of diazepam with different antibiotics. Colorimetric assays with MTT were used to evaluate the effect of diazepam against the biofilms by MSSA and MRSA. Flow cytometry and fluorescence microscopy were used to evaluate the possible mechanism of action of diazepam against MRSA. Diazepam had a MIC of 256 µg/mL. It only had indifferent interactions with the analyzed antibiotics. Diazepam significantly reduced the viability of MSSA and MRSA biofilms. Diazepam caused fragmentation of bacterial DNA and carbonylation of proteins, resulting in reduced cell viability. Therefore, diazepam has in vitro antimicrobial activity against planktonic and biofilm strains of MRSA and MSSA.

The activity of iron tetracarboxyphthalocyanine (FeTcPc) was investigated in the formation of subgingival biofilm by bacterial species associated with periodontal disease. A multispecies biofilm model was developed using the Calgary biofilm device and incubated at 37 °C under anaerobic conditions for 7 days. Starting from day 3, the biofilm was treated with FeTcPc twice daily for one minute over four days, at concentrations ranging from 1,000 to 10,000 μM. Chlorhexidine at 0.12% and the vehicle used to dissolve the test agent, phosphate-buffered saline (PBS), served as positive and negative controls, respectively. After 7 days, the biofilm metabolic activity was measured using 2,3,5-triphenyl tetrazolium chloride (TTC) to differentiate metabolically active cells from inactive ones. Finally, the microbial profile of the treated biofilm was assessed using the DNA-DNA hybridisation method. FeTcPc at 10,000 μM and chlorhexidine treatments reduced the total bacterial counts, without a significant difference from each other. Additionally, FeTcPc at 10,000 μM inhibited the growth of 7 microorganisms when compared with the negative control, highlighting effects on Porphyromonas gingivalis, Tannerella forsythia and Fusobacterium nucleatum vincentii. The study demonstrated that FeTcPc, at a concentration of 10,000 μM, was as effective as chlorhexidine (0.12%) in reducing the total bacterial counts and well-recognised periodontal pathogens levels in the subgingival biofilm, highlighting the potential of FeTcPc as an alternative to conventional periodontal treatments. These findings indicate that FeTcPc has a promising impact on the inhibition of key bacteria involved in periodontal disease, which may open new perspectives for targeted and less aggressive therapies.

This investigation scrutinizes the manner in which sodium acetate (SA) and calcium cations (Ca²⁺) independently and collaboratively affect biofilm development. Confocal microscopy revealed that SA (1 mM) increased biofilm biovolume (5.5-fold) and thickness by enhancing microbial growth, while Ca²⁺ (1.5 mM) stabilized the matrix via EPS crosslinking. Combined, SA and Ca²⁺ synergistically boosted biovolume (1.5-fold) and thickness (21.3 µm) compared to SA alone. 16S rRNA sequencing showed SA-enriched Actinobacteriota (11%) and exopolysaccharide-producing Brevifollis, whereas Ca²⁺ improved surface coverage (22.3%). Functional predictions linked SA to purine degradation and Ca²⁺ to fatty acid oxidation, aligning with EPS modifications. These findings highlight how carbon sources and divalent cations collaboratively shape biofilm resilience, offering insights for biofilm management in environmental, industrial, and medical settings where SA and Ca²⁺ gradients exist.

Marine biofouling presents a major challenge for the maritime industry and marine ecosystems, traditionally managed through biocide-based antifouling (AF) coatings. However, the environmental toxicity of these biocides has intensified the search for sustainable, environmentally friendly alternatives. In this study, a novel approach using flavonoid-based compounds as environmentally safe AF agents is presented. Building on the previous identification of the prenylated dihydrochalcone (DH345P), the first reported dihydrochalcone with AF activity, here a series of dihydrochalcone analogues was synthesized and evaluated to further explore the structure-activity relationship studies (SAR). Among the compounds studied, dihydrochalcone (10) emerged as the most effective, exhibiting the best performance regarding anti-settlement activity (EC₅₀ 2.34 µM), while remaining non-toxic to A. salina. To assess real-world applicability, compound 10 was incorporated into marine polyurethane (PU)-based coatings, which resulted in significantly reduced mussel larvae adherence compared to blank control coatings. These findings highlight dihydrochalcone-based compounds as a promising scaffold for sustainable AF agents. Considering their AF potential, non-toxic profile and feasible synthesis, flavonoids such as compound 10 might be explored as an alternative for conventional AF biocides, paving the way for greener marine coatings.

This study evaluated the effects of a bioadhesive liquid crystal system containing citral on cariogenic biofilm and enamel demineralisation. Citral (C) at 10× and 15× the minimum inhibitory concentration (MIC) was incorporated into the formulation (F) (30% oleic acid, 50% alkoxylated cetyl alcohol, and 20% aqueous dispersion of poloxamer 1%), FC1 and FC2, respectively. Both formulations underwent physicochemical characterisation, including polarised light microscopy, rheology, adhesive strength, and citral release. For biofilm and enamel demineralisation analyses, polymicrobial biofilms were cultivated for 4 days on bovine enamel blocks and treated with the formulations (n = 14/group). Analyses included pH measurement, total bacteria, aciduric bacteria, and mutans streptococci quantification. Enamel demineralisation was assessed via surface hardness loss (SH%) and integrated hardness loss (KHN × µm). Data were analyzed using appropriate statistical tests, with significance set at 5%. FC1 and FC2 exhibited Newtonian fluid characteristics, releasing 22.9% and 40.7% of citral, respectively, over 24 h. FC2 released citral near the MIC between 1-3 h. FC2 treatment showed antimicrobial activity in biofilms, maintained pH levels closer to neutrality for longer periods, and reduced SH% and KHN × µm values. Thus, FC2 demonstrated adequate physicochemical properties, antimicrobial efficacy, and the ability to reduce enamel mineral loss under cariogenic conditions.

Stalactite-like rust formations, known as 'rusticles' have been observed on some ocean shipwrecks usually after extended exposures and sometimes associated with microbiological influences. Herein that possibility is examined using field observations for some 40 different shipwrecks in seawaters and open freshwaters. Comparison is made to somewhat similar rust formations, known for more than 100 years as 'tubercles', that are mounds of highly non-uniform corrosion product found both in freshwaters and in seawaters. The data show that tubercles are widespread in occurrence but that rusticles form only in seawaters and that their typical stalactite-like formation is possible only in quiescent exposure conditions, caused by the extended build-up of rusts resulting from the oxidation of downward migration of ferrous chloride, itself generated by pitting corrosion under localized anaerobic seawater conditions. The processes in the formation of rusticles and tubercles are otherwise similar. Microbiological processes may be involved but are not essential.