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Richard Piola, Andrew S M Ang, Matthew Leigh, Scott A Wade
Maritime hydraulic components are often exposed to harsh environmental conditions which can lead to accelerated deterioration, reduced function, equipment failure and costly repair. Two leading causes of maritime hydraulic failure are biofouling accumulation and corrosion. This study examined the antifouling performance of three candidate replacement high velocity oxygen fuel (HVOF) coatings relative to the performance of the current baseline air plasma spray (APS) ceramic coating for protection of hydraulic actuators...
May 18, 2018: Biofouling
J Fredrik Lindgren, Erik Ytreberg, Albin Holmqvist, Magnus Dahlström, Peter Dahl, Mattias Berglin, Anna-Lisa Wrange, Mia Dahlström
How zinc oxide influences copper release has been tested and the lowest release rate of copper from various combinations of copper and zinc in a paint matrix evaluated, whilst still deterring macrofouling, including barnacles and bryozoans. Copper (I) oxide was added to a generic AF paint in 0, 8.5, 11.7 or 16.3 wt% copper oxide in combination with 0, 10 or 20 wt% zinc oxide and applied on PMMA panels. The results show that zinc influences the release rate of copper. When 10 and 20 wt% zinc was added, the total amount of copper released significantly increased by on average 32 and 47% respectively...
May 15, 2018: Biofouling
A Perrin, P Herbelin, F P A Jorand, S Skali-Lami, L Mathieu
The present study was aimed at designing and optimizing a rotating disk reactor simulating high hydrodynamic shear rates (γ), which are representative of cooling circuits. The characteristics of the hydrodynamic conditions in the reactor and the complex approach used to engineer it are described. A 60 l tank was filled with freshwater containing free-living amoebae (FLA) and bacteria. Adhesion of the bacteria and formation of a biofilm on the stainless steel coupons were observed. FLA were able to establish in these biofilms under γ as high as 85,000 s-1 ...
May 10, 2018: Biofouling
Mark O Winfield, Adrian Downer, Jennifer Longyear, Marie Dale, Gary L A Barker
The bacterial and eukaryotic communities forming biofilms on six different antifouling coatings, three biocidal and three fouling-release, on boards statically submerged in a marine environment were studied using next-generation sequencing. Sequenced amplicons of bacterial 16S ribosomal DNA and eukaryotic ribosomal DNA internal transcribed spacer were assigned taxonomy by comparison to reference databases and relative abundances were calculated. Differences in species composition, bacterial and eukaryotic, and relative abundance were observed between the biofilms on the various coatings; the main difference was between coating type, biocidal compared to fouling-release...
May 10, 2018: Biofouling
Subhaswaraj Pattnaik, Tanveer Ahmed, Sampath Kumar Ranganathan, Dinakara Rao Ampasala, V Venkateswara Sarma, Siddharha Busi
Pseudomonas aeruginosa is an opportunistic nosocomial pathogen causing the majority of acute and persistent infections in human beings. The ability to form biofilm adds a new dimension to its resistance to conventional therapeutic agents. In the present study, down-regulation of quorum sensing regulated virulence and biofilm development resulting from exposure to Aspergillus ochraceopetaliformis SSP13 extract was investigated. The in vitro results inferred impairment in the production of LasA protease, LasB elastase, chitinase, pyocyanin, exopolysaccharides and rhamnolipids...
May 10, 2018: Biofouling
Kim A Nolte, Julian Koc, J M Barros, Kelli Hunsucker, Michael P Schultz, G E Swain, Axel Rosenhahn
Quick and reliable testing is crucial for the development of new fouling release (FR) coatings. Exposure of these coatings to natural multispecies communities is essential in evaluating their efficacy. To this end, we present a rotating disk setup for dynamic field exposure. To achieve a well-defined flow on the surface of the disk, an easy to use sample mounting system was developed that provides a smooth and even surface. We related the angular velocity of the disk to the wall shear stress on the surface with a hydrodynamic model...
May 8, 2018: Biofouling
C Cattò, G James, F Villa, S Villa, F Cappitelli
The active moieties of the anti-biofilm natural compounds zosteric (ZA) and salicylic (SA) acids have been covalently immobilized on a low density polyethylene (LDPE) surface. The grafting procedure provided new non-toxic eco-friendly materials (LDPE-CA and LDPE-SA) with anti-biofilm properties superior to the conventional biocide-based approaches and with features suitable for applications in challenging fields where the use of antimicrobial agents is limited. Microbiological investigation proved that LDPE-CA and LDPE-SA: (1) reduced Escherichia coli biofilm biomass by up to 61% with a mechanism that did not affect bacterial viability; (2) significantly affected biofilm morphology, decreasing biofilm thickness, roughness, substratum coverage, cell and matrix polysaccharide bio-volumes by >80% and increasing the surface to bio-volume ratio; (3) made the biofilm more susceptible to ampicillin and ethanol...
May 4, 2018: Biofouling
Gopal Bhojani, Sweta Binod Kumar, Nirmal Kumar Saha, Soumya Haldar
In this study, bacteria isolated from a lake were characterised for their chlorine resistivity and the effects of chlorination on growth, mortality, protein expression and attachment propensity towards membranes. Biofouling and membrane performance were analysed. All isolated chlorine resistant strains, characterised by 16s rRNA gene sequencing, belonged to the genus Bacillus. Chlorination caused limited effects on bacterial growth and mortality. B. safensis and B. lechinoformis suffered the maximum effects due to chlorination...
May 4, 2018: Biofouling
Fernanda Alves, Ana Cláudia Pavarina, Ewerton Garcia de Oliveira Mima, Anthony P McHale, John Francis Callan
Candida albicans biofilms exhibit unique characteristics and are highly resistant to antifungal agents. Antimicrobial photodynamic therapy (aPDT) is an alternative treatment limited to treating superficial infections due to the poor light penetration. In this manuscript, the antifungal properties of sonodynamic therapy (SDT) were assessed. SDT uses ultrasound instead of light, enabling the treatment of deeper infections. Planktonic cells and biofilms of C. albicans were treated with aPDT or SDT, in addition to combined aPDT/SDT, with cell survival determined using colony forming units...
April 19, 2018: Biofouling
Carina Hüwe, Jennifer Schmeichel, Florian Brodkorb, Sophia Dohlen, Katrin Kalbfleisch, Martin Kreyenschmidt, Reinhard Lorenz, Judith Kreyenschmidt
Antimicrobial surfaces are one approach to prevent biofilms in the food industry. The aim of this study was to investigate the effect of poly((tert-butyl-amino)-methyl-styrene) (poly(TBAMS)) incorporated into linear low-density polyethylene (LLDPE) on the formation of mono- and mixed-species biofilms. The biofilm on untreated and treated LLDPE was determined after 48 and 168 h. The comparison of the results indicated that the ability of Listeria monocytogenes to form biofilms was completely suppressed by poly(TBAMS) (Δ168 h 3...
April 17, 2018: Biofouling
Matthew N George, Emily Carrington
Marine mussels (Mytilus trossulus) attach to a wide variety of surfaces underwater using a protein adhesive that is cured by the surrounding seawater environment. In this study, the influence of environmental post-processing on adhesion strength was investigated by aging adhesive plaques in a range of seawater pH conditions. Plaques took 8-12 days to achieve full strength at pH 8, nearly doubling in adhesion strength (+94%) and increasing the work required to dislodge (+59%). Holding plaques in low pH conditions prevented strengthening, causing the material to tear more frequently under tension...
April 11, 2018: Biofouling
Jin-Hyung Lee, Yong-Guy Kim, Jintae Lee
Pseudomonas aeruginosa biofilms are problematic and play a critical role in the persistence of chronic infections because of their ability to tolerate antimicrobial agents. In this study, various cell-wall degrading enzymes were investigated for their ability to inhibit biofilm formation of two P. aeruginosa strains, PAO1 and PA14. Xylanase markedly inhibited and detached P. aeruginosa biofilms without affecting planktonic growth. Xylanase treatment broke down extracellular polymeric substances and decreased the viscosity of P...
April 4, 2018: Biofouling
Rossana de Aguiar Cordeiro, Ewerton Weslley Caracas Cedro, Ana Raquel Colares Andrade, Rosana Serpa, Antonio José de Jesus Evangelista, Jonathas Sales de Oliveira, Vandbergue Santos Pereira, Lucas Pereira Alencar, Patrícia Bruna Leite Mendes, Bárbara Cibelle Soares Farias, Vânia Maria Maciel Melo, Zoilo Pires de Camargo, Débora de Souza Collares Maia Castelo-Branco, Raimunda Sâmia Nogueira Brilhante, José Júlio Costa Sidrim, Marcos Fábio Gadelha Rocha
The present study aimed to investigate the inhibitory effect of a bacterial biosurfactant (TIM96) on clinical strains of Trichosporon. Additionally, the effect of TIM96 on the ergosterol content, cell membrane integrity, and the hydrophobicity of planktonic cells was assessed. The inhibitory activity of TIM96 against Trichosporon biofilms was evaluated by analyzing metabolic activity, biomass and morphology. MIC values ranged from 78.125 to 312.5 μg ml-1 for TIM96; time-kill curves revealed that the decline in the number of fungal cells started after incubation for 6 h with TIM96 at both MIC and 2×MIC...
March 21, 2018: Biofouling
Gael Pérez-Rodríguez, Sónia Dias, Martín Pérez-Pérez, Florentino Fdez-Riverola, Nuno F Azevedo, Anália Lourenço
Experimental incapacity to track microbe-microbe interactions in structures like biofilms, and the complexity inherent to the mathematical modelling of those interactions, raises the need for feasible, alternative modelling approaches. This work proposes an agent-based representation of the diffusion of N-acyl homoserine lactones (AHL) in a multicellular environment formed by Pseudomonas aeruginosa and Candida albicans. Depending on the spatial location, C. albicans cells were variably exposed to AHLs, an observation that might help explain why phenotypic switching of individual cells in biofilms occurred at different time points...
March 8, 2018: Biofouling
Carla Corrêa Mendes-Gouvêa, Jackeline Gallo do Amaral, Renan Aparecido Fernandes, Gabriela Lopes Fernandes, Luiz Fernando Gorup, Emerson Rodrigues Camargo, Carlos Alberto Botazzo Delbem, Debora Barros Barbosa
This study aimed to synthesize and characterize materials containing silver nanoparticles (AgNP) with polyphosphates (sodium trimetaphosphate (TMP) or sodium hexametaphosphate (HMP), and evaluate their effect against Candida albicans and Streptococcus mutans. The minimum inhibitory concentration (MIC) was determined, which was followed by the quantification of the biofilm by counting colony-forming units (CFUs), the amount of metabolic activity, and the total biomass. The MICs revealed greater effectiveness of composites containing 10% Ag (TMP + Ag10% (T10) and HMP + Ag10% (H10)) against both microorganisms...
February 27, 2018: Biofouling
Debaprasad Parai, Malabika Banerjee, Pia Dey, Arindam Chakraborty, Ekramul Islam, Samir Kumar Mukherjee
This study aimed to evaluate the effect of reserpine, a plant-derived indole-alkaloid, against Pseudomonas aeruginosa PAO1 biofilms. The anti-biofilm activity of reserpine was evaluated by crystal violet staining, MTT assay, confocal laser scanning microscopy and scanning electron microscopy. Reserpine effects were also assessed by qRT-PCR of quorum sensing (QS)-regulated genes and biochemical quantification of the QS-mediated virulence factors pyocyanin, rhamnolipids, proteases and elastases. Reserpine reduced biofilm formation, cell motility, virulence factor production, and QS-controlled gene expression...
February 27, 2018: Biofouling
Dinis Oliveira, Ann I Larsson, Lena Granhag
Hull biofouling is a well-known problem for the shipping industry, leading to increased resistance and fuel consumption. Considering that the effects of hull form on resistance are known to be higher for a less slender hull, it is hypothesised in this paper that the effect of biofouling roughness on resistance is also dependent on the hull form. To test this hypothesis, previously reported full-scale numerical results on a containership are re-analysed. Form effects on roughness penalties, corresponding to KΔCT  = 0...
February 19, 2018: Biofouling
Guillermo E Juarez, Estela M Galván
Klebsiella pneumoniae and Escherichia coli form mixed species biofilms in catheter-associated urinary tract infections. Recently, a detrimental effect of K. pneumoniae over E. coli was observed in mixed species biofilms grown in an artificial urine medium. The mechanism behind this competitive interaction was studied. K. pneumoniae partially outcompeted E. coli in early-stage batch-fed biofilms, whereas both microorganisms co-exist at longer times (K. pneumoniae:E. coli ratio, 55:1), as shown by cell counts and confocal microscopy...
February 19, 2018: Biofouling
Lisendra Marbelia, Marie-Aline Hernalsteens, Shazia Ilyas, Basak Öztürk, Anthony Szymczyk, Dirk Springael, Ivo Vankelecom
The influence of membrane surface charge on biofouling community composition during activated sludge filtration in a membrane bioreactor was investigated in this study using polyacrylonitrile-based membranes. Membranes with different surface properties were synthesized by phase inversion followed by a layer-by-layer modification. Various characterization results showed that the membranes differed only in their surface chemical composition and charge, ie two of them were negative, one neutral and one positive...
February 15, 2018: Biofouling
Ashwin Ambi, Nisharg Parikh, Carolina Vera, Krystal Burns, Naidel Montano, Leonard Sciorra, Jessica Epstein, Debing Zeng, Christian Traba
Many research groups have attained slow, persistent, continuous release of silver ions through careful experimental design using existing methods. Such methods effectively kill planktonic bacteria and therefore prevent surface adhesion of pathogens. However, the resultant modified coatings cannot provide long-term antibacterial efficacy due to sustained anti-microbial release. In this study, the anti-infection activity of AgNP immobilized biomaterials was evaluated, facilitated by argon plasma grafting technology and activated by bacterial colonization...
February 15, 2018: Biofouling
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