Biofouling最新文献

This study investigated the multifunctional oral cavity simulator (MOCS) in terms of microbial composition, functional profile, and dentin root demineralization. Microcosm biofilms were grown on dentin using human saliva for 4, 7, and 14 days, with exposure to sucrose and a mucin-enriched medium. Biofilms were analyzed for microbial viability and composition through CFU count and 16S-rRNA gene sequencing. Demineralization was quantified by percentage surface hardness change (%SHC), mineral loss (ML), and lesion depth (LD). The results showed microbial viability at all time points. After 7 days, aciduric/acidogenic and proteolytic organisms increased in abundance. The functional profile reflected the oscillations in microbial composition. No significant differences in %SHC, ML, or LD were observed across the time points. Carious lesions exhibited 60-70% SHC and 125-200 µm depth. MOCS was able to induce root carious lesions as result of microcosm biofilm metabolic activity, indicating its potential use in preclinical studies on root dentin caries.

This study aimed to determine the optimum conditions for biofilm formation by Salmonella isolates and evaluate the effect of cinnamon essential oil nanoemulsion (CEON) against Salmonella biofilms formed under these conditions. The optimum conditions for biofilm formation by Salmonella serotype Enteritidis and Salmonella serotype Typhimurium were temperatures of 27.3 and 29.7 °C, pH levels of 6.3 and 6.8, and NaCl concentrations of 0.66 and 0.65%, respectively. CEON exhibited a significant inhibitory effect even at low concentrations, with a greater impact on the biofilm of S. Enteritidis compared to S. Typhimurium. The effectiveness of CEON in removing biofilms was increased with higher concentrations and longer contact times, with better results observed at 8 °C compared to 25 °C. In conclusion, CEON demonstrated excellent anti-biofilm activity against S. Enteritidis and S. Typhimurium biofilms, suggesting its potential use as a natural and effective disinfectant in the food industry.

This study examined the corrosion inhibition mechanisms of extracellular polymeric substances (EPS) from Lactobacillus reuteri, Pseudomonas fluorescens, and Escherichia coli on carbon steel. Using UV spectrophotometry, LC-MS, infrared spectroscopy, and atomic force microscopy (AFM), it was apparent that all three EPS effectively inhibited corrosion, with optimal concentrations of 300 mg/L for Lactobacillus reuteri and 400 mg/L for the other species, yielding inhibition efficiencies of 28.25%, 23.87%, and 21.72%, respectively. The carboxyl group content was critical, with Lactobacillus reuteri EPS having the highest proportion. Functional group analysis showed it contained 12.39% and 12.93% more carboxyl groups than those from Pseudomonas fluorescens and Escherichia coli. Iron ion adsorption was primarily physical and occurred in a monolayer, with a greater capacity for Fe³⁺ than Fe²⁺, peaking at 600 mg/L.

Marine biofouling is a substantial economic and environmental issue. Hard fouling-release coatings present a promising solution, combining fouling-release characteristics with durability. This study tested proprietary hard fouling-release prototype coatings from GIT Coatings, Inc. alongside uncoated controls, colour controls, and commercial performance standards. Three successive experiments were completed, incorporating static and dynamic flow conditions at sites in Nova Scotia, Canada. Initially, biofouling percent cover and cleanability for prototype coatings were comparable to untreated controls. By the final experiment, prototype coatings had significantly lower percent covers than both uncoated controls and the durability performance comparison, Ecospeed. Furthermore, several prototype hard fouling-release coatings had comparable percent cover (and possibly cleanability) to the fouling-release performance comparison, Intersleek. The results indicate that hard fouling-release coatings with potentially greater durability and longevity can achieve similar fouling-release performance as commercial fouling-release coatings. Further tests are needed to determine if unintended toxicity contributes to the antifouling effects.

Vulvovaginal candidiasis (VVC) is especially prevalent among intrauterine device (IUD) and intravaginal ring (IVR) users. Candida albicans is the leading causative agent of VVC followed by Candida glabrata. Ascribed to the increased drug resistance by Candida spp. to the currently available drugs, this study has focused on the novel quinazoline-derived copper(I) complexes as anti-candida agents. As a novel approach, a vaginal ring was coated with the best quinazoline-derived copper(I) complex, and biofilm disruption ability was evaluated. The coated vaginal ring eradicated 70% of preformed biofilms and also inhibited the hyphal transition of Candida albicans in a simulated vaginal fluid (SVF). The overall study validates the anti-biofilm and anti-virulent properties of the metal complex-coated vaginal ring using various microscopic studies.

Urinary infections caused by Staphylococcus aureus are commonly associated with urinary catheterization and often result in severe complications. Given this problem, the objective of the study was to investigate the preventive action of promethazine (PMT) against the formation of methicillin-resistant Staphylococcus aureus (MRSA) biofilms when impregnated in urinary catheters. For this purpose, techniques such as broth microdilution, checkerboard, impregnation on urinary catheter fragments, flow cytometry assays and scanning electron microscopy were employed. PMT exhibited antimicrobial activity with Minimum Inhibitory Concentration (MIC) values ranging from 171 to 256 µg/mL, predominantly additive interaction in combination with oxacillin (OXA) and vancomycin (VAN), and a reduction in cell viability of biofilms formed and forming by methicillin-sensitive and -resistant S. aureus. Morphological alterations, damage to the membrane, and genetic material of cells treated with promethazine were also observed. The results demonstrated that PMT can be classified as a promising antimicrobial agent for use in the antibacterial coating of long-term urinary devices.

Biofilms are subjected to various forces in the fluid field, as a result, the biofilm forms a head-tail structure known as a streamer to reduce pressure differential resistance. To characterize biofilm growth in fluid, we establish a head-tail biofilm streamer growth model based on the immersed boundary method using MATLAB software, and simulate streamer growth in various environmental conditions to explore the factors affecting its growth. Firstly, we found that a higher flow velocity makes the streamer grow faster and thereby produce more biomass. Secondly, we explored the effect of the position of nutrient source on the streamer growth, found that when the nutrient source overlaps with the streamer, its length is longer than when the nutrient source and the streamer are mismatched. Further we found that the Young's modulus of the streamer also influences its growth length. Streamers with small Young's modulus were more likely to deform, making them grow longer than the streamers with large Young's modulus. Finally, we determined the relationship between the tail length and the head diameter of the streamer through mechanical analysis, and found that there is an optimal ratio of the tail length to the head diameter which exposes the streamer to the minimum drag in the fluid field.

Microbial infections are causing numerous deaths and can be found on various surfaces such as fabrics used in healthcare facilities as wound dressings or protective clothing in operating or sterile rooms. The study aimed to determine the difference in antibacterial activity of sheet, sphere, and rod-like ZnO NPs embedded in poly(allylamine hydrochloride) (PAH) multilayers on cotton, nylon, and polyester with Staphylococcus aureus. Additionally, the adhesion of recombinant human SARS-CoV-2 RBD S-protein on the coated materials and the water droplet absorption after placement on the fabric surface were tested. Results demonstrated that PAH/ZnO coating with rod-like NPs achieved the highest antibacterial activity on the cotton fabric, with the Staphylococcus aureus cell viability reduced by more than 99%. ZnO NPs significantly reduced bacterial surface coverage on textiles, particularly on cotton and polyester. The adhesion of SARS-CoV-2 RBD protein was reduced considerably on the coated nylon fabrics due to the change in the material's hydrophobicity and wettability. Due to its better ZnO NP adherence, cotton demonstrated slightly higher antibacterial performance than polyester and nylon, showing potential for wound dressings, especially with the addition of rod-like ZnO NPs. PAH/ZnO coated nylon showed potential for usage in protective clothing in operating and sterile rooms against bacteria, viral adhesion, and aerosol absorption through the fabrics to the skin.

Among the opportunistic species related to Invasive Fungal Infections (IFIs), Trichosporon spp. are particularly noteworthy, being responsible for infections with high mortality rates in patients with hematological cancers. Trichosporon spp. are intrinsically resistant to echinocandins and their biofilms are tolerant to polyenes and triazoles. This study investigated the effect of calcineurin inhibition on the development and antifungal tolerance of Trichosporon biofilms. Mature biofilms of T. inkin and T. asahii were treated with Ciclosporin A (CsA) and analyzed for biomass reduction and viability, ultrastructure, and tolerance tolerance to antifungals. Molecular docking studies were performed to understand the attachment of CsA to the calcineurin of T. asahii. CsA was able to significantly reduce both the biomass and metabolic activity of biofilms. Mature biofilms formed in the presence of CsA showed greater susceptibility to antifungals, compared to biofilm growth control. CsA caused structural changes in biofilms. Molecular modeling suggested that CsA can block the active site of the calcineurin A subunit of T. asahii. Calcineurin inhibition seems to be a promising strategy for controlling antifungal-resistant fungal biofilms.

As biofilms are a crucial factor in the proliferation of Legionella pneumophila in evaporative cooling systems (ECS), the impact of biocides on L. pneumophila containing biofilms in ECS needs to be evaluated by cultivation-independent methods. Therefore, a trickling biofilm chamber that simulates the spraying of process water was developed. Through this setup, the cultivation of Legionella-containing biofilms was possible. To demonstrate a potential application of the biofilm chamber, experiments using oxidizing and non-oxidizing biocides were conducted. Differences in cell survival were observed, alongside variations in the efficacy of culture and flow cytometry as analytical methodologies for assessing both intact and total cell populations. These findings also highlight the benefits of flow cytometry as a culture-independent analytical approach. This proof-of-principle study illustrates the need of the biofilm chamber for conducting experiments related to biofilm growth and biocide impact.