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Ji-Soo Park, Jeung-Hoon Lee
An ultrasonic antifouling treatment was applied to a 96,000 m3 class drill-ship to verify its feasibility through a sea-trial. Soon after the hull cleaning had been performed, six ultrasonic projectors were evenly deployed around the starboard shell plate. Driven by a 23 kHz sinusoidal ultrasound in an intermittent manner, the projectors emitted a high-intensity sound reaching 214 dB at the source level causing cavitation around the adjacent water and eventually deterring the settlement of marine fouling organisms...
December 12, 2017: Biofouling
María C Tarifa, Diego Genovese, Jorge E Lozano, Lorena I Brugnoni
The factors affecting the mechanical properties of biofilms formed by yeast species (Rhodotorula mucilaginosa, Candida krusei, C. kefyr and C. tropicalis) isolated from the juice processing industries have been investigated. Variables studied were: the food matrix (apple/pear juice), the sugar concentration (6/12 °Bx) and the hydrodynamic conditions (static/turbulent flow). A range of environmental cues were included as the mechanical properties of biofilms are complex. Yeast counts were significantly higher in turbulent flow compared with under static conditions...
December 12, 2017: Biofouling
Xiaochun Huang, Chang Chen, Chunhua Ren, Yingying Li, Yiqin Deng, Yiying Yang, Xiongqi Ding
Colanic acid (CA) is a group I extracellular polysaccharide (EPS) that contributes to resistance against adverse environments in many members of the Enterobacteriaceae. In the present study, a genetic locus EPSC putatively involved in CA biosynthesis was identified in Vibrio alginolyticus ZJ-51, which undergoes colony morphology variation between translucent/smooth (ZJ-T) and opaque/rugose (ZJ-O). EPSC in ZJ-T carries 21 ORFs and resembles the CA cluster of Escherichia coli K-12. The deletion of EPSC led to decreased EPS and biofilm formation in both genetic backgrounds but no alternation of lipopolysaccharide...
December 6, 2017: Biofouling
Santosh Pandit, Ji-Eun Jung, Hyeon-Mi Choi, Jae-Gyu Jeon
The present study investigated the effect of periodic 1-min fluoride treatments on Streptococcus mutans biofilms and then determined the relationship between anti-biofilm activity, treatment frequency, and fluoride concentration using a linear-fitting procedure. S. mutans biofilms were periodically treated (1-min/treatment) with fluoride during biofilm formation and analyzed using microbiological methods, confocal microscopy, and real-time PCR. The results indicated that reductions in the dry weight and acidogenicity of biofilms due to periodic fluoride treatment occurred in a concentration dependent manner...
December 4, 2017: Biofouling
Dongwei Wang, Xia Wu, Lixia Long, Xubo Yuan, Qinghua Zhang, Shengzhang Xue, Shumei Wen, Chenghu Yan, Jianming Wang, Wei Cong
To improve the antifouling (AF) properties of photobioreactors (PBR) for microalgal cultivation, using trihydroxymethyl aminomethane (tris) as the linking agent, a series of polyethylene (PE) films grafted with sulfobetaine (PE-SBMA) with grafting density ranging from 23.11 to 112 μg cm-2 were prepared through surface-initiated atom transfer radical polymerization (SI-ATRP). It was found that the contact angle of PE-SBMA films decreased with the increase in the grafting density. When the grafting density was 101...
November 28, 2017: Biofouling
Cátia Vilas-Boas, Emília Sousa, Madalena Pinto, Marta Correia-da-Silva
Many studies have shown that natural marine compounds can prevent biofouling by a broad spectrum of organisms without toxic effects, encouraging their use in antifouling (AF) coatings. Studies over the past 25 years of the natural product zosteric acid (ZA) are systematically organized in this review. ZA is a sulfated phenolic acid produced by the seagrass Zostera marina that has very promising AF potential against several micro- and macrofouling organisms. ZA was shown to have appropriate environmental fate parameters such as high water solubility, a low log P, low bioaccumulation, and no ecotoxicity, which demonstrated the potential of ZA as a safe AF agent...
November 24, 2017: Biofouling
Hye Young Yoon, Si Young Lee
In this study, a laboratory model to reproduce dental unit waterline (DUWL) biofilms was developed using a CDC biofilm reactor (CBR). Bacteria obtained from DUWLs were filtered and cultured in Reasoner's 2A (R2A) for 10 days, and were subsequently stored at -70°C. This stock was cultivated on R2A in batch mode. After culturing for five days, the bacteria were inoculated into the CBR. Biofilms were grown on polyurethane tubing for four days. Biofilm accumulation and thickness was 1.3 × 10(5) CFU cm(-2) and 10-14 μm respectively, after four days...
November 21, 2017: Biofouling
Natasha C Dickenson, Jason S Krumholz, Kelli Z Hunsucker, Michael Radicone
Biofouling is a significant economic and ecological problem, causing reduced vessel performance and increases in fuel consumption and emissions. Previous research has shown iodine vapor (I2)-infused aeration to be an environmentally friendly method for deterring the settlement of fouling organisms. An aeration system was deployed on a vessel with hull sections coated with two types of antifoulant coatings, Intersleek® 1100 (fouling-release) and Interspeed® BRA-640 (ablative copper biocide), as well as an inert epoxy barrier coating, to assess the effectiveness of aeration in conjunction with common marine coatings...
November 17, 2017: Biofouling
Rosana Alves, Sandra Mota, Sónia Silva, Célia F Rodrigues, Alistair J P Brown, Mariana Henriques, Margarida Casal, Sandra Paiva
Candida albicans has the ability to adapt to different host niches, often glucose-limited but rich in alternative carbon sources. In these glucose-poor microenvironments, this pathogen expresses JEN1 and JEN2 genes, encoding carboxylate transporters, which are important in the early stages of infection. This work investigated how host microenvironments, in particular acidic containing lactic acid, affect C. albicans biofilm formation and antifungal drug resistance. Multiple components of the extracellular matrix were also analysed, including their impact on antifungal drug resistance, and the involvement of both Jen1 and Jen2 in this process...
November 2, 2017: Biofouling
Claudia Ventura, Andrew J Guerin, Osama El-Zubir, Antonio J Ruiz-Sanchez, Luke I Dixon, Kevin J Reynolds, Marie L Dale, James Ferguson, Andrew Houlton, Benjamin R Horrocks, Anthony S Clare, David A Fulton
Zwitterionic materials display antifouling promise, but their potential in marine anti-biofouling is still largely unexplored. This study evaluates the effectiveness of incorporating small quantities (0-20% on a molar basis) of zwitterions as sulfobetaine methacrylate (SBMA) or carboxybetaine methacrylate (CBMA) into lauryl methacrylate-based coatings whose relatively hydrophobic nature encourages adhesion of the diatom Navicula incerta, a common microfouling organism responsible for the formation of 'slime'...
October 30, 2017: Biofouling
David J McElroy, Dieter F Hochuli, Martina A Doblin, Richard J Murphy, Robert J Blackburn, Ross A Coleman
Copper based paints are used to prevent fouling on the hulls of ships. The widely documented effect of copper on hull assemblages may be primarily due to direct effects on the invertebrates themselves or indirect effects from copper absorbed into the microbial biofilm before settlement has commenced. Artificial units of habitat were exposed to varied regimes of copper to examine (1) the photosynthetic efficiency and pigments of early-colonising biofilms, and (2) subsequent macroinvertebrate assemblage change in response to the different regimes of copper...
October 30, 2017: Biofouling
Santi M Mandal, Jahangir Khan, Denial Mahata, Suman Saha, Jayangshu Sengupta, Osmar N Silva, Subhayan Das, Mahitosh Mandal, Octavio L Franco
Amniotic membrane (AM) is frequently used in ophthalmologic surgery for rapid ocular surface reconstruction. Sometimes it may create a major problem with associated infections after biofilm formation over the membrane. To overcome this problem, AM was coated with the antimicrobial peptide clavanin A. The antifungal activity of clavanin A in the native and self-assembled form was determined against the common ocular surface pathogens Candida albicans, Aspergillus fumigatus, Alternaria sp. and Fusarium sp. Biofilm formation over the coated surface was significantly reduced in comparison with the uncoated membrane...
October 19, 2017: Biofouling
Erica B Ricker, Eric Nuxoll
Upon formation of a biofilm, bacteria undergo several changes that prevent eradication with antimicrobials alone. Due to this resistance, the standard of care for infected medical implants is explantation of the infected implant and surrounding tissue, followed by eventual reimplantation of a replacement device. Recent studies have demonstrated the efficacy of heat shock for biofilm eradication. To minimize the heat required for in situ biofilm eradication, this study investigated the hypothesis that antibiotics, while ineffective by themselves, may substantially increase heat shock efficacy...
October 17, 2017: Biofouling
Chi Guan, Delphine Parrot, Jutta Wiese, Frank D Sönnichsen, Mahasweta Saha, Deniz Tasdemir, Florian Weinberger
A bioassay-guided approach was used to identify defense compounds that are present on the surface of Zostera marina and which inhibit settlement of microfoulers at natural concentrations. Moderately polar eelgrass surface extracts inhibited the settlement of seven marine bacteria and one yeast that originated from non-living substrata. In contrast, five other bacterial strains that had been directly isolated from eelgrass surfaces were all insensitive, which suggested a selective effect of surface metabolites on the microbial communities present on eelgrass...
October 16, 2017: Biofouling
Karina Sampaio Caiaffa, Loiane Massunari, Marcelle Danelon, Gabriel Flores Abuna, Telma Blanca Lombardo Bedran, Norival Alves Santos-Filho, Denise Madalena Palomari Spolidorio, Natalia Leal Vizoto, Eduardo Maffud Cilli, Cristiane Duque
This study evaluated the cytotoxicity and antimicrobial activity of analogs of cationic peptides against microorganisms associated with endodontic infections. L-929 fibroblasts were exposed to LL-37, KR-12-a5 and hBD-3-1C(V) and chlorhexidine (CHX, control), and cell metabolism was evaluated with MTT. The minimal inhibitory concentration (MIC) and the minimal bactericidal/fungicidal concentration (MBC/MFC) of the peptides and CHX were determined against oral pathogens associated with endodontic infections. Enterococcus faecalis and Streptococcus mutans biofilms were cultivated in bovine dentin blocks, exposed to different concentrations of the most efficient antimicrobial peptide and analyzed by confocal laser scanning microscopy...
October 12, 2017: Biofouling
Noe T Alvarez, Ryan Noga, So-Ryong Chae, George A Sorial, Hodon Ryu, Vesselin Shanov
Membrane filtration is one of the most reliable methods for water treatment. However, wider application is limited due to biofouling caused by accumulation of microorganisms on the membrane surface. This report details a heatable carbon nanotube composite membrane with self-cleaning properties for sustainable recovery from biofouling. Microfiltration polycarbonate/carbon-nanotubes hybrid membranes were fabricated using drawable nanotubes that maintained the porosity and provided electrical conductivity to the membrane...
October 10, 2017: Biofouling
L Di Gregorio, V Tandoi, R Congestri, S Rossetti, F Di Pippo
In this study, next generation sequencing and catalyzed reporter deposition fluorescence in situ hybridization, combined with confocal microscopy, were used to provide insights into the biodiversity and structure of biofilms collected from four full-scale European cooling systems. Water samples were also analyzed to evaluate the impact of suspended microbes on biofilm formation. A common core microbiome, containing members of the families Sphingomonadaceae, Comamonadaceae and Hyphomicrobiaceae, was found in all four biofilms, despite the water of each coming from different sources (river and groundwater)...
October 10, 2017: Biofouling
Yigit Kemal Demirel, Dogancan Uzun, Yansheng Zhang, Ho-Chun Fang, Alexander H Day, Osman Turan
Predictions of added resistance and the effective power of ships were made for varying barnacle fouling conditions. A series of towing tests was carried out using flat plates covered with artificial barnacles. The tests were designed to allow the examination of the effects of barnacle height and percentage coverage on the resistance and effective power of ships. The drag coefficients and roughness function values were evaluated for the flat plates. The roughness effects of the fouling conditions on the ships' frictional resistances were predicted...
October 5, 2017: Biofouling
B R da Silva, A J S Conrado, A L Pereira, F F V Evaristo, F V S Arruda, M A Vasconcelos, E N Lorenzón, E M Cilli, E H Teixeira
The aims of this study were to describe the synthesis of a novel synthetic peptide based on the primary structure of the KR-12 peptide and to evaluate its antimicrobial and anti-biofilm activities against Streptococcus mutans. The antimicrobial effect of KR-12 and [W(7)]KR12-KAEK was assessed by determining the minimum inhibitory (MIC) and minimum bactericidal (MBC) concentrations. The evaluation of anti-biofilm activity was assessed through total biomass quantification, colony forming unit counting and scanning electron microscopy...
October 2, 2017: Biofouling
Barry I Cayford, Guangming Jiang, Jurg Keller, Gene Tyson, Philip L Bond
This study investigated the variation in microbially induced concrete corrosion communities at different circumferential locations of a real sewer pipe and the effects of a wastewater flooding event on the community. Three distinct microbial community groups were found in different corrosion samples. The physico-chemical properties of the corrosion layers and the microbial communities were distinct for the cross-sectional positions within the pipe, ie ceiling, wall and tidal zones. The microbial communities detected from the same positions in the pipe were consistent over the length of the pipe, as well as being consistent between the replicate pipes...
September 28, 2017: Biofouling
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