Biofouling最新文献

Ship hull grooming, a form of proactive in-water cleaning, has been extensively researched in a warm, productive, subtropical Atlantic location using US Navy-approved commercial coatings. Less is known about how grooming performs on toughened fouling control coatings or the grooming frequencies required in locations with lower seawater temperatures and lower fouling intensities. The purpose of this study was to explore differences in proactive in-water cleaning schedules due to changes in location and coating types. This study compared the time-based frequency of in-water grooming of two commercial and two experimental fouling control coatings in Port Canaveral, Florida, and Monterey, California. The results demonstrated that a higher grooming frequency was required to maintain surfaces free of fouling at the warm-water Port Canaveral, FL site compared to the cooler-water site in Monterey, CA. They also showed that the type of fouling control coating will influence the grooming frequency.

Candidozyma auris has high rates of resistance to antifungals and hospital disinfectants. This yeast remains on surfaces for long periods, favoring the colonization of patients. Similarly Candida species, it produces persistent biofilms, which contribute to invasive infections, resulting in high mortality rates. In the search for new therapeutic alternatives of antifungal action, natural products have been widely studied due to their pharmacological potential and diverse biological activities. Eugenol and cinnamaldehyde are derived from the essential oils of cinnamon and clove, respectively, and have shown action against several microorganisms, including Candida species. The aims of the present study were to evaluate the antibiofilm activity of the natural products eugenol and cinnamaldehyde on clinical isolates of C. auris. Both products showed inhibitory action on planktonic form. Biofilm biomass was considerably reduced for most of the evaluated isolates. On the other hand, during the treatment period, the metabolic activity of most isolates increased, compared to control, possibly due to the heteroresistance phenomenon; however, further studies are still needed to support this hypothesis.

Biofilm-associated infections, particularly those caused by Staphylococcus aureus, pose a persistent challenge in clinical settings and in medical devices such as catheters, wound dressings, orthopaedic and dental implants, and contact lenses. The resilience of biofilms to conventional antimicrobial treatments underscores the need for innovative strategies. This study evaluated the efficacy of a synthetic analogue of the antimicrobial lipopeptide humimycin as a preventive measure against biofilm formation of S. aureus on catheters, contact lenses and contact lens cases, both as a coating agent and in combination with commercial multipurpose contact lens solutions. The results demonstrate a dose-dependent reduction in biofilm formation with the humimycin analogue coatings achieving up to 98% inhibition at 256 µg/mL. This significant reduction was accompanied by a marked decrease in bacterial metabolic activity, indicating that the humimycin analogue disrupts biofilm integrity and impairs bacterial function. When combined with commercial contact lens solutions such as Opti-Free^® Express^® and Solocare Aqua^®, the biofilm-disrupting activity of the lipopeptide was further enhanced, with lower minimum inhibitory concentration and minimum biofilm inhibitory concentration values. These findings suggest that the humimycin analogue holds significant promise as a novel antimicrobial strategy for preventing S. aureus biofilm-related infections acquired from medical devices.

Catheter-associated urinary tract infections (CA-UTI) are among the most prevalent infections, affecting over 150 million individuals worldwide annually. Candida is the most common fungal genus causing urinary infections, representing a significant medical challenge, particularly in patients undergoing prolonged catheterization-a risk factor that exacerbates clinical conditions by promoting the formation of resistant biofilms. In this context, the coating of catheters with antimicrobial substances combined with drug repositioning is an innovative alternative. In this study, we evaluated the activity of promethazine (PMT), a first-generation antihistamine, against the formation of Candida spp. biofilms on urinary catheter fragments. Broth microdilution, impregnation of urinary catheter fragments, and scanning electron microscopy (SEM) were the exploratory techniques employed. PMT proved to be an effective agent in inhibiting biofilm formation, achieving a 50% reduction in colony-forming units (CFU/mL). The results indicated that PMT exhibits high potential as an antifungal agent, with promising applications in coatings aimed at preventing Candida spp. infections associated with long-term urinary devices.

Concrete is a widely utilised material for infrastructure such as sea-crossing bridges, harbour terminals and sewage pipelines. However, concrete structures are susceptible to various forms of deterioration, including biological and chemical corrosion. Among these, bio-corrosion poses a significant threat to structural durability by promoting surface scaling and inducing complex physicochemical and biophysical damage. This study provides a comprehensive review of the current state of bio-corrosion research, with a focus on clarifying its mechanisms and established quantification techniques. Additionally, it examines advances in mathematical modelling and machine learning for analysing bio-corrosion in concrete structures. This review also addresses ongoing debates and insights within the field of bio-corrosion and bio-protection.

The essential oil of Hyssopus cuspidatus Boriss (HC B) exhibits diverse pharmacological properties, yet its antibacterial mechanisms remain underexplored. This study identified 59 compounds, predominantly ketones, via GC-MS analysis, and demonstrated potent anti-Staphylococcus aureus (S. aureus) activity with an MIC of 7.8125 mg/mL and an MBC of 62.5 mg/mL. The essential oil significantly suppressed acid production, lactate dehydrogenase (LDH) activity, and biofilm formation in S. aureus. Crystal violet staining confirmed the disruption of preformed biofilms at MIC concentrations. Through molecular docking and kinetic simulations, key bioactive components (e.g. α-gurjunene, cuminal, terpineol) were predicted to target inflammation and oxidative stress-related genes (PTGS2, MAOA/B, RELA, HSP90AA1), suggesting a multimodal antibacterial mechanism. These findings reveal the novel potential of HCB essential oil as a natural anti-biofilm and anti-virulence agent against S. aureus.

Escalating the efficacy of microalgal cultivation process is proposed in photobioreactor by using an innovative membrane-based bubble sparger for efficient dissolution of gas phase CO₂ using Scenedesmus sp. Surface functionalization was done on tubular ceramic substrates using Hexadecyltrimethylsiloxane (HDTMS) for enhancing mass transfer and antifouling property. The optimum membrane was found to be super-hydrophobic, contact angle >153°. The membrane sparger (HMS) based system resulted in higher biomass concentration (2.26 g/l) and higher CO₂ bio-fixation efficiency (0.57 g CO₂/l/day) after seven days compared to 0.69 g/l and 0.15 g CO₂/l/day for the conventional bubble sparger (CBS) system. Moreover, for HMS system biomass concentration and CO₂ bio-fixation efficiency increases up to 3.12 g/l and 0.80 g CO₂/l/day respectively using dairy wastewater (50%). The overall study demonstrates the applicability of proposed process for enhancing Scenedesmus sp. biomass productivity and CO₂ sequestration in membrane photobioreactor (C-MPBR) process using industrial waste resources along with minimizing microalgae induced biofouling of the spargers.

Bacteria play a vital role in the settlement and metamorphosis of marine invertebrates. However, the molecular mechanisms by which bacteria regulate the metamorphosis from larva to juvenile remain unknown. This study aims to investigate whether bacteria derived from Mytilus coruscus affect the larval settlement and metamorphosis of this species. Our results showed that all eight bacterial strains can induce settlement and metamorphosis in this mussel species. Polysaccharides and gamma-aminobutyric acid (GABA) produced by bacteria positively trigger this transformation in mussels, with GABA acting as the primary inducer. Marinomonas foliarum exhibited the highest GABA production and induction activity among the experimental strains. Compared with biofilms alone, the addition of a GABA synthesis inhibitor during Marinomonas foliarum biofilm formation reduced its induction activity by 56.02%. Our results reveal a novel role of bacterial GABA in triggering mussel larval settlement and metamorphosis.

The primary method for mitigating the growth of biofouling organisms on submerged surfaces is through the use of broad-spectrum biocides, such as irgarol, which can impact non-target species. We assessed the developmental and bioenergetic impacts of early-life-stage irgarol exposure on zebrafish (Danio rerio), including impacts on survival, hatching, developmental abnormalities, heart rate, mitochondrial function, and behaviour. We exposed zebrafish embryos 6-144 h post-fertilisation (hpf) to irgarol at concentrations currently detected in the environment and at pharmacological concentrations. At environmental concentrations, irgarol did not impact survival, hatching, morphological development or mitochondrial function. However, significant changes to heart rate and swimming behaviour occurred. Larvae were significantly hyperactive following exposure, then hypoactive after being grown in clean conditions for weeks. Our study showed that while irgarol is not acutely toxic at environmental levels, it has sublethal impacts on cardiac and neurological functions that could result in decreased fish fitness. The risks that irgarol presents to food security, environmental health, and human health warrant study.