Biofouling最新文献

In this study, a comparison of biofilm formation, extracellular polymeric substances (EPS) production, protein and polysaccharides estimation, and protein profiling through SDS-PAGE, FTIR, GC-MS, ESI-MS, SEM, and AFM analysis were done for EPS from epilithic bacteria Brevundimonas faecalis BC1 obtained from monumental rock under normal room temperature and heat stressed condition. Heat stress (60 ± 2 °C) that simulates hot monumental rock surfaces during the summer season caused  bacteria BC1 to produce more EPS (8.56 g/L), biofilm, protein and polysaccharides, extra SDS-PAGE protein bands of different molecular weight than their control counterpart. FTIR and GC-MS analysis showed extra polysaccharide formation in the EPS under heat stress and ESI-MS analysis clearly showed differences in structural components of EPS from two different sources. Consistently, SEM and AFM showed more branching structural components with dentate spikes in the EPS obtained from a heat-stressed source than from its counterpart, suggesting their protective role toward heat stress and adhesive potential for biofilm.

The study evaluates the effectiveness of sodium hypochlorite (NaOCl) and a commercial quaternary ammonium compound (QAC) against planktonic and biofilm-associated yeast (Candida tropicalis, C. krusei, C. kefyr, and Rhodotorula mucilaginosa) isolated from ultrafiltration modules in a clarified apple juice production facility. The results demonstrated that the efficacy of disinfection against planktonic yeast cells did not directly correlate with the effectiveness against biofilm-embedded cells. QAC proved to be more effective than NaOCl in reducing yeast biofilms, achieving a higher than 3-log₁₀ reduction in cell counts. In contrast, NaOCl, even at its maximum permissible concentration for food-contact surfaces, exhibited limited efficacy against biofilms. Both disinfectants had limited success in preventing biofilm regrowth, indicating the potential for persistent contamination in food processing environments. Furthermore, both agents compromised biofilm structure, with QAC having a significantly more pronounced impact than NaOCl.

This study investigates the micro-topographic surfaces as a benign anti-fouling/fouling-release method. The bio-inspired engineered surfaces were manufactured by controlling the viscoelastic instabilities of carbon nanotubes (CNTs) and polydimethylsiloxane (PDMS) nanocomposites using a customized, scalable two-roll coating process. The effects of manufacturing conditions, i.e., roller speed and roller radius-to-gap ratio, on surface properties, such as Wenzel roughness factor, peak density, water contact angle, and the tensile testing of the nanocomposite, were studied. The results showed that decreasing roller gap distance would significantly increase the hydrophobicity of the samples. Moreover, a positive correlation was observed between surface peak density and roughness factor. A textured sample was manufactured that significantly outperformed the non-textured CNT-PDMS, indicating a correlation between surface roughness and diatom attachment density. The dynamic diatom attachment assay showed up to 35% reduction in surface coverage of textured samples by the Navicula perminuta diatom compared to the non-textured CNT-PDMS control samples.

Bacterial chemotaxis enhances bacterial adaptation to the environment and is important for biofilm formation. Biofilms play a key role in inducing larval settlement and metamorphosis in many marine invertebrates. However, the specific mechanisms by which bacterial chemotaxis influences larval settlement and metamorphosis in mussels remain unknown. The findings indicate that the absence of the chemotaxis gene cheW resulted in reduced motility of Pseudoalteromonas marina, accompanied by an increase in c-di-GMP content. The ΔcheW strain exhibited a higher capacity for biofilm formation compared to the wild-type strain. The extracellular protein content of the ΔcheW strain exhibited a significant 77% reduction, specifically in the flagellin content. The inducing activity of ΔcheW was reduced by 56% compared to the wild-type strain. This study highlights that the deficiency of the chemotaxis gene cheW inhibited larval settlement and metamorphosis in mussels through c-di-GMP regulation of extracellular protein production. It provides a novel ecological function of bacterial chemotaxis in regulating the larval settlement and metamorphosis of marine invertebrates.

The dried roots of an aquatic plant (Eichhornia crassipes commonly known as water hyacinth) were included in the biomass of an upflow anaerobic sludge bed (UASB) reactor to evaluate the improvement effect on treating antibiotic-containing synthetic pharmaceutical effluent. The removals of three different antibiotics, namely erythromycin (ERY), tetracycline (TET) and sulfamethoxazole (SMX), were investigated using the unacclimatized inoculum during the startup period. Then, about 2.5% E. crassipes (w/w of volatile solids) was added to biomass during the last month of operation. Almost complete removal of each antibiotic was achieved, with efficiencies up to 99% (with initial ERY, TET and SMX of 200, 75 and 230 mg L^-1, respectively) regardless of E. crassipes addition. The presence of transformation products (TPs) of selected antibiotics was also investigated and ERY showed a higher potential to transform into its metabolites than SMX and TET. With the studied amount of E. crassipes, no positive impact against TPs formation was observed.

This study aimed to investigate the effects of combined quercetin and antibiotics on the bacteriostatic activity and biofilm formation of Staphylococcus aureus. Optimal concentrations of quercetin and antibiotics (tetracycline and doxycycline) for inhibiting biofilm formation were determined using the Fractional Inhibitory Concentration Index and Minimum Biofilm Inhibitory Concentration assays. The impact of the drug combinations on biofilm clearance at various formation stages was determined using crystal violet staining, scanning electron microscopy and confocal laser microscopy. The results indicated that quercetin enhanced the bactericidal effect of tetracycline antibiotics against S. aureus. The combination significantly reduced both the metabolic activity within S. aureus biofilms and the production of biofilm matrix components. Scanning electron microscopy and confocal laser microscopy confirmed that the combination treatment significantly reduced bacterial cell counts within the biofilm. Quercetin treatment significantly increased the sensitivity of biofilms to antibiotics, supporting its potential application as a novel antibiotic synergist.

To reveal the responsible microorganisms of microbiologically-influenced-corrosion (MIC), using 16S rRNA and ITS sequencing techniques, we investigated the bacterial and fungal communities in rust layer and seawater. Results show that the corrosion-related genera of Erythrobacter, norank_f__Rhodothermaceae, and Acinetobacter bacteria, as well as Aspergillus fungi, were overrepresented in the rust layer, along with the Pseudoalteromonas and Marinobacterium bacteria in seawater, and Ramlibacter, Aquimarina, and Williamsia bacteria were first detected in the rust layer. SourceTracker analysis revealed that approximately 23.08% of bacteria and 21.48% of fungi originated from seawater. Stochastic processes governed the rust layer and seawater microbial communities, and network analysis showed coexistence and interaction among bacterial and fungal communities. These results indicate that the composition of microbial communities in the rust layer was influenced by the marine environmental microbial communities, which can provide basic data support for the control of MIC in marine-related projects.

The traditional medicinal value of Curcuma longa (turmeric) and its potential relevance in modern healthcare suggests that traditional remedies and natural products can provide valuable solutions to contemporary challenges, such as combating biofilms and antibiotic-resistant pathogens, potentially offering new strategies for addressing health and safety issues in the fields of food and medicine. This study assessed the antibiofilm and antibacterial characterization of Curcuma longa rhizome extract against antibiotic-resistant foodborne pathogens. Gas Chromatography-Mass Spectrometry (GC-MS) and Fourier-transform infrared (FTIR) analysis were determined to check for the compounds, functional groups, and constituents of the plant extract. In-vitro antibiofilm and antibacterial bioassay of the extract were determined using standard bacteriological procedures. Potential mechanisms of the plant extract were also studied using standard biological methods. The important chemical constituents from the GC-MS extract of C. longa are arturmerone, cinnamyl angelate, tumerone, γ-atlantone, atlantone, α-atlantone, γ-atlantone and curlone. The FTIR analysis of the extract comprises alkyl halides, bromoalkanes, alkanes, ethylene molecules, arenes, amines, alcohols, sulfones, carboxylic acids and their derivatives, aromatic compounds, and phenols. The MIC of C. longa crude extract ranges from ethanol extract (0.03125 - 0.5 mg/mL) and acetone extract (0.0625 - 0.5 mg/mL). The MBC range is as follows: ethanol extract (0.125 - 1 mg/mL), acetone extract (0.125 - 1 mg/mL). The time-kill kinetics showed significant cell reduction with time. The bacterial isolates' nucleic acids and protein leakage were consistent with increased extract concentration and time. There was a reduction in the biofilm cell on the shrimp surface and EPS with increased concentration and time. C. longa exerted significant anti-biofilm activity by removing existing biofilms, disrupting cell connections, and decreasing cells in biofilms. These findings can aid food protection from microbial contamination and prevent biofilms-related infections.

Both Candida albicans and Issatchenkia orientalis have been isolated from different types of infections over the years. They have the ability to form communities of microorganisms known as biofilms. It has been demonstrated that the medium employed in studies may affect the biofilm development. The aim of this study was to investigate the arrangement of dual-species biofilms of C. albicans and I. orientalis cultivated on either RPMI-1640 or Sabouraud Dextrose Broth (SDB), as well as the inhibitory effect of Voriconazole (VRC). For the experiments performed, ATCC strains were used, and yeast-mixed suspensions were inoculated in 96-well plates with either RPMI-1640 or SDB, in the presence or absence of VRC. The results were observed by counting the number of CFU obtained from scraping off the biofilms produced and plating the content on CHROMagar Candida medium. It was observed that for all conditions tested the medium chosen affected the arrangement of dual-species biofilms: when RPMI-1640 was used, there was a prevalence of C. albicans, while the opposite was noted when SDB was used. It could be suggested that the medium and environment could regulate interactions between both yeast species, including the response to different antifungal drugs.

Reactive chlorine species (RCS) like sodium hypochlorite (NaOCl) are potent oxidizing agents and widely used biocides in surface disinfection, water treatment, and biofilm elimination. Moreover, RCS are also produced by the human immune system to kill invading pathogens. However, bacteria have developed mechanisms to survive the damage caused by RCS. Using the comprehensive Pseudomonas aeruginosa PA14 transposon mutant library in a genetic screen, we identified a total of 28 P. aeruginosa PA14 mutants whose biofilms showed increased susceptibility to NaOCl in comparison to PA14 WT biofilms. Of these, ten PA14 mutants with a disrupted apaH, PA0793, acsA, PA1506, PA1547, PA3728, yajC, queA, PA3869, or PA14_32840 gene presented a 4-fold increase in NaOCl susceptibility compared to wild-type biofilms. While none of these mutants showed a defect in biofilm formation or attenuated susceptibility of biofilms toward the oxidant hydrogen peroxide (H₂O₂), all but PA14_32840 also exhibited a 2-4-fold increase in susceptibility toward the antibiotic ciprofloxacin. Further analyses revealed attenuated levels of intracellular ROS and catalase activity only for the apaH and PA1547 mutant, providing insights into the oxidative stress response in P. aeruginosa biofilms. The findings of this paper highlight the complexity of biofilm resistance and the intricate interplay between different mechanisms to survive oxidative stress. Understanding resistance strategies adopted by biofilms is crucial for developing more effective ways to fight resistant bacteria, ultimately contributing to better management of bacterial growth and resistance in clinical and environmental settings.