Showing papers in "Biofouling in 2011"
TL;DR: The results of this study provide guidance as to the amount of money that can be reasonably spent for research, development, acquisition, and implementation of new technologies or management strategies to combat hull fouling.
Abstract: In the present study, the overall economic impact of hull fouling on a mid-sized naval surface ship (Arleigh Burke-class destroyer DDG-51) has been analyzed. A range of costs associated with hull fouling was examined, including expenditures for fuel, hull coatings, hull coating application and removal, and hull cleaning. The results indicate that the primary cost associated with fouling is due to increased fuel consumption attributable to increased frictional drag. The costs related to hull cleaning and painting are much lower than the fuel costs. The overall cost associated with hull fouling for the Navy's present coating, cleaning, and fouling level is estimated to be $56M per year for the entire DDG-51 class or $1B over 15 years. The results of this study provide guidance as to the amount of money that can be reasonably spent for research, development, acquisition, and implementation of new technologies or management strategies to combat hull fouling.
1,066 citations
TL;DR: This review will discuss the mechanisms identified as playing a role in biofilm resistance to disinfectants, as well as novel anti-biofilm strategies that have recently been explored.
Abstract: A biofilm can be defined as a community of microorganisms adhering to a surface and surrounded by a complex matrix of extrapolymeric substances. It is now generally accepted that the biofilm growth mode induces microbial resistance to disinfection that can lead to substantial economic and health concerns. Although the precise origin of such resistance remains unclear, different studies have shown that it is a multifactorial process involving the spatial organization of the biofilm. This review will discuss the mechanisms identified as playing a role in biofilm resistance to disinfectants, as well as novel anti-biofilm strategies that have recently been explored.
695 citations
TL;DR: Research on the defence of marine organisms against fouling and the technologies they are defining is reviewed and is promoted by advances in nano- and micro-scale patterning.
Abstract: Nature provides many examples of mechanisms to control fouling. These defences can be copied (biomimetic) or tailored (bioinspired) to solve problems of fouling on manmade structures. With increasing research in this area over the last two decades, it is timely to review this burgeoning subject, in particular as the biofouling field shifts focus towards novel, physical mechanisms to prevent and control fouling. This change is being promoted by advances in nano- and micro-scale patterning as well as in a variety of nano-biotechnologies, which are transforming the translation of natural surfaces into experimental materials. In this article, research on the defence of marine organisms against fouling and the technologies they are defining is reviewed.
283 citations
TL;DR: Silver nanoparticles (SN) may have the potential to be an effective alternative to conventional antifungal agents for future therapies in Candida-associated denture stomatitis.
Abstract: The aim of this study was to evaluate the effect of silver nanoparticles (SN) against Candida albicans and Candida glabrata adhered cells and biofilms. SN (average diameter 5 nm) were synthesized by silver nitrate reduction with sodium citrate and stabilized with ammonia. Minimal inhibitory concentration (MIC) tests were performed for C. albicans (n ¼ 2) and C. glabrata (n ¼ 2) grown in suspension following the Clinical Laboratory Standards Institute microbroth dilution method. SN were applied to adhered cells (2 h) or biofilms (48 h) and after 24 h of contact their effect was assessed by enumeration of colony forming units (CFUs) and quantification of total biomass (by crystal violet staining). The MIC results showed that SN were fungicidal against all strains tested at very low concentrations (0.4–3.3 m gm l 71 ). Furthermore, SN were more effective in reducing biofilm biomass when applied to adhered cells (2 h) than to pre-formed biofilms (48 h), with the exception of C. glabrata ATCC, which in both cases showed a reduction *90%. Regarding cell viability, SN were highly effective on adhered C. glabrata and respective biofilms. On C. albicans the effect was not so evident but there was also a reduction in the number of viable biofilm cells. In summary, SN may have the potential to be an effective alternative to conventional antifungal agents for future therapies in Candida-associated denture stomatitis.
176 citations
TL;DR: It is suggested that natural products with QS inhibitory properties can be used for controlling biofouling communities and to prevent microfOUling by one of the compounds screened in this study.
Abstract: Seventy eight natural products from chemical libraries containing compounds from marine organisms (sponges, algae, fungi, tunicates and cyanobacteria) and terrestrial plants, were screened for the inhibition of bacterial quorum sensing (QS) using a reporter strain Chromobacterium violaceum CV017. About half of the natural products did not show any QS inhibition. Twenty four percent of the tested compounds inhibited QS of the reporter without causing toxicity. The QS inhibitory activities of the most potent and abundant compounds were further investigated using the LuxR-based reporter E. coli pSB401 and the LasR-based reporter E. coli pSB1075. Midpacamide and tenuazonic acid were toxic to the tested reporters. QS-dependent luminescence of the LasR-based reporter, which is normally induced by N-3-oxo-dodecanoyl-L-homoserine lactone, was reduced by demethoxy encecalin and hymenialdisin at concentrations >6.6 μM and 15 μM, respectively. Hymenialdisin, demethoxy encecalin, microcolins A and B and kojic acid inhibited responses of the LuxR-based reporter induced by N-3-oxo-hexanoyl-L-homoserine lactone at concentrations >0.2 μM, 2.2 μM, 1.5 μM, 15 μM and 36 μM, respectively. The ability to prevent microfouling by one of the compounds screened in this study (kojic acid; final concentrations 330 μM and 1 mM) was tested in a controlled mesocosm experiment. Kojic acid inhibited formation of microbial communities on glass slides, decreasing the densities of bacteria and diatoms in comparison with the control lacking kojic acid. The study suggests that natural products with QS inhibitory properties can be used for controlling biofouling communities.
157 citations
TL;DR: The results suggest that until a certain thickness was reached nutrient availability dictated biofilm architecture but when that critical thickness was exceeded mechanical resistance to shear stress became more important.
Abstract: Biofilm formation is a major factor in the growth and spread of both desirable and undesirable bacteria as well as in fouling and corrosion. In order to simulate biofilm formation in industrial settings a flow cell system coupled to a recirculating tank was used to study the effect of a high (550 mg glucose l⁻¹) and a low (150 mg glucose l⁻¹) nutrient concentration on the relative growth of planktonic and attached biofilm cells of Escherichia coli JM109(DE3). Biofilms were obtained under turbulent flow (a Reynolds number of 6000) and the hydrodynamic conditions of the flow cell were simulated by using computational fluid dynamics. Under these conditions, the flow cell was subjected to wall shear stresses of 0.6 Pa and an average flow velocity of 0.4 m s⁻¹ was reached. The system was validated by studying flow development on the flow cell and the applicability of chemostat model assumptions. Full development of the flow was assessed by analysis of velocity profiles and by monitoring the maximum and average wall shear stresses. The validity of the chemostat model assumptions was performed through residence time analysis and identification of biofilm forming areas. These latter results were obtained through wall shear stress analysis of the system and also by assessment of the free energy of interaction between E. coli and the surfaces. The results show that when the system was fed with a high nutrient concentration, planktonic cell growth was favored. Additionally, the results confirm that biofilms adapt their architecture in order to cope with the hydrodynamic conditions and nutrient availability. These results suggest that until a certain thickness was reached nutrient availability dictated biofilm architecture but when that critical thickness was exceeded mechanical resistance to shear stress (ie biofilm cohesion) became more important.
134 citations
TL;DR: A tropical marine bacterium isolated from the hard coral, Symphyllia sp.
Abstract: A tropical marine bacterium isolated from the hard coral, Symphyllia sp. was identified as Serratia marcescens on the basis of morphological, biochemical and 16S rDNA analysis. The bacterium showed antimicrobial activity towards the pathogens Candida albicans and Pseudomonas aeruginosa and the marine biofouling bacterium Bacillus pumilus. S. marcescens displayed biosurfactant activity as evidenced by drop collapse, blood hemolysis and surface tension reduction (52.0-27 mN m(-1)). The active compound was purified by solvent extraction and silicic acid chromatography. Characterization was by thin layer chromatography, gas chromatography mass spectroscopy (GC-MS), Fourier transform infrared (FTIR) spectroscopy and (1)H as well as (13)C nuclear magnetic resonance (NMR) analysis. The surfactant was found to be a glycolipid composed of glucose and palmitic acid. The glycolipid prevented adhesion of C. albicans BH, P. aeruginosa PAO1 and B. pumilus TiO1. The glycolipid also disrupted preformed biofilms of these cultures in microtitre plates. Confocal laser scanning microscopy and electron microscopy confirmed the effective removal of biofilms from glass surfaces. The glycolipid derived from S. marcescens could thus serve as a potential anti-biofilm agent.
128 citations
TL;DR: The excellent fouling-release (FR) properties of these new coatings against the macroalga Ulva linza essentially resulted from the inclusion of the amphiphilic block copolymer, while the addition of CNT did not appear to improve the FR properties.
Abstract: Amphiphilic diblock copolymers, Sz6 and Sz12, consisting of a poly(dimethylsiloxane) block (average degree of polymerisation = 132) and a PEGylated-fluoroalkyl modified polystyrene block (Sz, average degree of polymerisation = 6, 12) were prepared by atom transfer radical polymerization (ATRP). Coatings were obtained from blends of either block copolymer (1–10 wt%) with a poly(dimethylsiloxane) (PDMS) matrix. The coating surface presented a simultaneous hydrophobic and lipophobic character, owing to the strong surface segregation of the lowest surface energy fluoroalkyl chains of the block copolymer. Surface chemical composition and wettability of the films were affected by exposure to water. Block copolymer Sz6 was also blended with PDMS and a 0.1 wt% amount of multiwall carbon nanotubes (CNT). The excellent fouling-release (FR) properties of these new coatings against the macroalga Ulva linza essentially resulted from the inclusion of the amphiphilic block copolymer, while the addition of CNT did not ap...
122 citations
TL;DR: Increasing the temperature of river water might lead to faster biofilm recolonization after disturbances, with a distinct biofilm community structure that might affect the trophic web.
Abstract: River biofilms that grow on wet benthic surface are mainly composed of bacteria, algae, cyanobacteria and protozoa embedded in a polysaccharide matrix. The effects of increased river water temperature on biofilm formation were investigated. A laboratory experiment was designed employing two temperatures (11.1–13.2°C, night–day; 14.7–16.0°C, night–day) and two nutrient levels (0.054 mg P l−1, 0.75 mg N l−1; 0.54 mg P l−1, 7.5 mg N l−1). Biofilm formation at the higher temperature was faster, while the biomass of the mature biofilm was mainly determined by nutrient availability. The specific response of the three microbial groups that colonized the substrata (algae, bacteria and ciliates) was modulated by interactions between them. The greater bacterial growth rate and earlier bacterial colonization at the higher temperature and higher nutrient status was not translated into the accrual of higher bacterial biomass. This may result from ciliates grazing on the bacteria, as shown by an earlier increase in per...
110 citations
TL;DR: There is a considerable body of information regarding bacterially enhanced corrosion, however, this review focuses on diatoms (unicellular algae) whose contribution to biocorrosion is less well studied.
Abstract: There is a considerable body of information regarding bacterially enhanced corrosion, however, this review focuses on diatoms (unicellular algae) whose contribution to biocorrosion is less well studied. The reasons why diatoms have been neglected in studies of biocorrosion in natural waters are discussed and the question whether diatoms should be considered as inert with respect of electrochemical processes is considered. A particular focus is given to the case of stainless steels (SS), which are widely used in variety of applications in natural waters. Basic information on the cell biology of diatoms is included in the review, particularly with respect to their ability to ‘sense’ and adhere to surfaces. Investigations at the nanoscale are reviewed as these studies provide information about the behavior of cells at interfaces. Recent advances include the use of atomic force microscopy (AFM), although only a few studies have been applied to diatoms. Regarding the electrochemical behavior of SS, the mechani...
106 citations
TL;DR: To the authors' knowledge, this study showed for the first time that S. aureus biofilm could be efficiently eradicated with the mixture of phage and an antimicrobial agent, especially rifampicin.
Abstract: Lytic bacteriophages (phages) have been investigated as treatments for bacterial infectious diseases. An induced phage, SAP-26, was isolated from a clinical isolate of Staphylococcus aureus. It belongs to the family Siphoviridae and its genome consists of double-stranded 41,207 bp DNA coding for 63 open reading frames. The phage SAP-26 showed a wide spectrum of lytic activity against both methicillin-resistant S. aureus and methicillin-susceptible S.aureus. Furthermore, combined treatment with a phage and antimicrobial agents showed a strong biofilm removal effect which induced structural changes in the biofilm matrix and a substantial decrease in the number of bacteria. Such a broad host range in S. aureus and biofilm removal activity of the phage SAP-26 suggests the possibility of its use as a therapeutic phage in combination with appropriate antimicrobial agent(s). Among the three antimicrobial agents combined with phage, the combination of rifampicin showed the best biofilm removal effect. To the authors' knowledge, this study showed for the first time that S. aureus biofilm could be efficiently eradicated with the mixture of phage and an antimicrobial agent, especially rifampicin.
TL;DR: The higher antifouling efficacy of IS900 over IS700 may lead to lower roughness and thus lower fuel consumption for those vessels that utilise the IS900 fouling-release coating.
Abstract: The antimicrobial performance of two fouling-release coating systems, Intersleek 700® (IS700; silicone technology), Intersleek 900® (IS900; fluoropolymer technology) and a tie coat (TC, control surface) was investigated in a short term (10 days) field experiment conducted at a depth of ca 05 m in the Marina Bandar Rawdha (Muscat, Oman) Microfouling on coated glass slides was analyzed using epifluorescence microscopy and adenosine-5'-triphosphate (ATP) luminometry All the coatings developed biofilms composed of heterotrophic bacteria, cyanobacteria, seven species of diatoms (2 species of Navicula, Cylindrotheca sp, Nitzschia sp, Amphora sp, Diploneis sp, and Bacillaria sp) and algal spores (Ulva sp) IS900 had significantly thinner biofilms with fewer diatom species, no algal spores and the least number of bacteria in comparison with IS700 and the TC The ATP readings did not correspond to the numbers of bacteria and diatoms in the biofilms The density of diatoms was negatively correlated with the density of the bacteria in biofilms on the IS900 coating, and, conversely, diatom density was positively correlated in biofilms on the TC The higher antifouling efficacy of IS900 over IS700 may lead to lower roughness and thus lower fuel consumption for those vessels that utilise the IS900 fouling-release coating
TL;DR: The results suggest that adsorbed EPS layers could be beneficial to anti-corrosion by hindering the reduction of oxygen, however, the accumulation of an EPS film could stimulate the anodic dissolution of the underlying steel by chelation of Fe2+ ions.
Abstract: Extracellular polymeric substances (EPS) were isolated by centrifugation of thermophilic sulphate-reducing bacteria (SRB) grown in API-RP38 culture medium. The protein and polysaccharide fractions were quantified and the highest concentrations were extracted from a 14-day old culture. The effect of EPS on carbon steel corrosion was investigated by electrochemical techniques. At 30°C, a small amount of EPS in 3% NaCl solution inhibited corrosion, whilst excessive amounts of EPS facilitated corrosion. In addition, the inhibition efficiency of EPS decreased with temperature due to thermal desorption of the EPS. The results suggest that adsorbed EPS layers could be beneficial to anti-corrosion by hindering the reduction of oxygen. However, the accumulation of an EPS film could stimulate the anodic dissolution of the underlying steel by chelation of Fe2+ ions.
TL;DR: Results show coatings can be significantly influenced by geographical area, highlighting the need to test ship hull coatings in locations similar to where they will be utilized.
Abstract: Diatoms are primary colonizers of both antifouling and fouling-release ship hull coatings. There are few published studies which report on diatom community development on modern ship hull coatings. This study reports diatom communities on eight commercial marine ship hull coatings exposed at three static immersion sites along the east coast of Florida, viz. Daytona, Sebastian, and Miami. The coatings tested were three ablative copper systems (Ameron ABC-3, International BRA-640, and Hempel Olympic 76600), two copper-free biocidal systems (E-Paint SN-1, Sherwin Williams HMF), and three fouling-release (FR) systems (International Intersleek 700, International Intersleek 900, and Hempel Hempasil). One hundred and twenty-seven species comprising 44 genera were identified, including some of the more commonly known foulers, viz. Achnanthes, Amphora, Cocconeis, Entomoneis, Licmophora, Melosira, Navicula, Nitzschia, Synedra, and Toxarium. A significant difference was seen among sites, with the more estuarine site...
TL;DR: The results suggest that alginate contributes to steric hindrance and shielding of cell surface features and adhesins that are known to promote cell attachment in Pseudomonas aeruginosa biofilms.
Abstract: Among various functions, extracellular polymeric substances (EPS) provide microbial biofilms with mechanical stability and affect initial cell attachment, the first stage in the biofilm formation process. The role of alginate, an abundant polysaccharide in Pseudomonas aeruginosa biofilms, in the viscoelastic properties and adhesion kinetics of EPS was analyzed using a quartz crystal microbalance with dissipation (QCM-D) monitoring technology. EPS was extracted from two P. aeruginosa biofilms, a wild type strain, PAO1, and a mucoid strain, PAOmucA22 that over-expresses alginate production. The higher alginate content in the EPS originating from the mucoid biofilms was clearly shown to increase both the rate and the extent of attachment of the EPS, as well as the layer's thickness. Also, the presence of calcium and elevated ionic strength increased the thickness of the EPS layer. Dynamic light scattering (DLS) showed that the presence of calcium and elevated ionic strength induced intermolecular attractive interactions in the mucoid EPS molecules. For the wild type EPS, in the presence of calcium, an elevated shift in the distribution of the diffusion coefficients was observed with DLS due to a more compacted conformation of the EPS molecules. Moreover, the alginate over-expression effect on EPS adherence was compared to the effect of alginate over-expression on P. aeruginosa cell attachment. In a parallel plate flow cell, under similar hydraulic and aquatic conditions as those applied for the EPS adsorption tests in the QCM-D flow cell, reduced adherence of the mucoid strain was clearly observed compared to the wild type isogenic bacteria. The results suggest that alginate contributes to steric hindrance and shielding of cell surface features and adhesins that are known to promote cell attachment.
TL;DR: Fluorine-free mixed amphiphilic block copolymers with mixtures of short side groups of polydimethyl siloxane and polyethylene glycol were synthesized and studied for their ability to influence the surface properties and control the adhesion of marine organisms to coated surfaces.
Abstract: Fluorine-free mixed amphiphilic block copolymers with mixtures of short side groups of polydimethyl siloxane (PDMS) and polyethylene glycol (PEG) were synthesized and studied for their ability to influence the surface properties and control the adhesion of marine organisms to coated surfaces. The settlement (attachment) and strength of adhesion of two different marine algae, the green seaweed Ulva and the diatom Navicula, were evaluated against the surfaces. It is known that hydrophobic coatings based on polydimethyl siloxane elastomers (PDMSe) are prone to protein adsorption and accumulation of strongly adherent diatom slimes, in contrast to PEG-based hydrophilic surfaces that inhibit protein adsorption and moderate only weak adhesion of diatoms. By incorporating both PDMS and PEG side chains into the polymers, the effect of incorporating both polar and non-polar groups on fouling-release could be studied. The dry surfaces were characterized by X-ray photoelectron spectroscopy (XPS) and near-edge X-ray a...
TL;DR: This study for the first time, reports a novel anti-biofilm compound from a marine bacterium with wide application in medicine and the aquaculture industry, 4-phenylbutanoic acid, which showed potential activity against a wide range of biofilms.
Abstract: Biofilm formation is a critical problem in nosocomial infections and in the aquaculture industries and biofilms show high resistance to antibiotics. The aim of the present study was to reveal a novel anti-biofilm compound from marine bacteria against antibiotic resistant gram-positive and gram-negative biofilms. The bacterial extract (50 μg ml(-1)) of S6-01 (Bacillus indicus = MTCC 5559) showed 80-90% biofilm inhibition against Escherichia coli, Shigella flexneri, Proteus mirabilis and S6-15 (Bacillus pumilus = MTCC 5560) showed 80-95% biofilm inhibition against all the 10 tested organisms. Furthermore, they also reduced the hydrophobicity index and extracellular polymeric substances (EPS) production. Structural elucidation of the active principle in S6-15 using GC-MS, (1)H NMR, and (13)C NMR spectral data revealed it to be 4-phenylbutanoic acid. This is the first report of 4-phenylbutanoic acid as a natural product. The purified compound (10-15 μg ml(-1)) showed potential activity against a wide range of biofilms. This study for the first time, reports a novel anti-biofilm compound from a marine bacterium with wide application in medicine and the aquaculture industry.
TL;DR: Honey, at a low concentration of 0.5% (v/v), significantly reduced biofilm formation in enterohemorrhagic Escherichia coli O157:H7 without inhibiting the growth of planktonic cells, and Transcriptome analyses showed that honey significantly repressed curli genes, quorum sensing genes, and virulence genes.
Abstract: Bacterial biofilms are associated with persistent infections due to their high resistance to antimicrobial agents. Hence, controlling pathogenic biofilm formation is important in bacteria-related diseases. Honey, at a low concentration of 0.5% (v/v), significantly reduced biofilm formation in enterohemorrhagic Escherichia coli O157:H7 without inhibiting the growth of planktonic cells. Conversely, this concentration did not inhibit commensal E. coli K-12 biofilm formation. Transcriptome analyses showed that honey significantly repressed curli genes (csgBAC), quorum sensing genes (AI-2 importer and indole biosynthesis), and virulence genes (LEE genes). Glucose and fructose in the honeys were found to be key components in reducing biofilm formation by E. coli O157:H7 through the suppression of curli production and AI-2 import. Furthermore, honey, glucose and fructose decreased the colonization of E. coli O157:H7 cells on human HT-29 epithelial cells. These results suggest that low concentrations of honey, su...
TL;DR: The paper introduces the concept of the microbial electrochemical snorkel (MES), a simplified design of a “short-circuited” microbial fuel cell (MFC) that cannot provide current but it is optimized for wastewater treatment.
Abstract: The paper introduces the concept of the microbial electrochemical snorkel (MES), a simplified design of a “short-circuited” microbial fuel cell (MFC). The MES cannot provide current but it is optimized for wastewater treatment. An electrochemically active biofilm (EAB) was grown on graphite felt under constant polarization in an urban wastewater. Controlling the electrode potential and inoculating the bioreactor with a suspension of an established EAB improved the performance and the reproducibility of the anodes. Anodes, colonized by an EAB were tested for the chemical oxygen demand (COD) removal from urban wastewater using a variety of bio-electrochemical processes (microbial electrolysis, MFC, MES). The MES technology, as well as a short-circuited MFC, led to a COD removal 57% higher than a 1000 Ω-connected MFC, confirming the potential for wastewater treatment.
TL;DR: This is the first report of a detailed characterisation of the EPS produced by V. parahaemolyticus, which could be further explored for biotechnological and industrial use.
Abstract: A marine bacterial strain identified as Vibrio parahaemolyticus by 16S rRNA gene (HM355955) sequencing and gas chromatography (GC) coupled with MIDI was selected from a natural biofilm by its capability to produce extracellular polymeric substances (EPS). The EPS had an average molecule size of 15.278 μm and exhibited characteristic diffraction peaks at 5.985°, 9.150° and 22.823°, with d-spacings of 14.76661, 9.29989 and 3.89650 A, respectively. The Fourier-transform infrared spectroscopy (FTIR) spectrum revealed aliphatic methyl, primary amine, halide groups, uronic acid and saccharides. Gas chromatography mass spectrometry (GCMS) confirmed the presence of arabinose, galactose, glucose and mannose. 1HNMR (nuclear magnetic resonance) revealed functional groups characteristic of polysaccharides. The EPS were amorphous in nature (CIxrd 0.092), with a 67.37% emulsifying activity, thermostable up to 250°C and displayed pseudoplastic rheology. MALDI-TOF–TOF analysis revealed a series of masses, exhibiting low-...
TL;DR: The finding that surface charge, rather than total surface energy, may be responsible for surface selection by cyprids, will have significant implications for the design of future fouling-resistant materials.
Abstract: Gibbs surface energy has long been considered to be an important parameter in the design of fouling-resistant surfaces for marine applications. Rigorous testing of the hypothesis that settlement is ...
TL;DR: Results suggest that 10 slide-replicates immersed at a depth of 1 m may be an optimal sampling strategy for analyzing the colonization dynamics of biofilm-dwelling ciliate communities in marine habitats.
Abstract: A new approach to determining sampling effort for analyzing biofilm-dwelling ciliate colonization was studied in the coastal waters of the Yellow Sea, northern China, from May to June 2010. The optimal sample size for evaluating biofilm-dwelling ciliate colonization increased with shortening exposure time, and can be determined according to the probability of recovering those species with a specified cumulative contribution to communities. More slide-replicates were required at a depth of 3 m than at 1 m to recover equivalent proportions of the ciliate communities. For routine colonization dynamics analyses, 10 slide-replicates (175 cm2) were sufficient to achieve a 95% probability of recovering those species with a cumulative contribution of >90% to the ciliate communities at a depth of 1 m. These results suggest that 10 slide-replicates immersed at a depth of 1 m may be an optimal sampling strategy for analyzing the colonization dynamics of biofilm-dwelling ciliate communities in marine habitats.
TL;DR: The preferential interfacial aggregation of the larger PEG segments enables the coating surface to have a substantially enhanced resistance to settlement of spores of the green seaweed Ulva, cells of the diatom Navicula and cypris larvae of the barnacle Balanus amphitrite as well as low adhesion of sporelings (young plants) of UlvA.
Abstract: The facile preparation of amphiphilic network coatings having a hydrophobic dimethacryloxy-functionalized perfluoropolyether (PFPE-DMA; M w = 1500 g mol−1) crosslinked with hydrophilic monomethacryloxy functionalized poly(ethylene glycol) macromonomers (PEG-MA; M w = 300, 475, 1100 g mol−1), intended as non-toxic high-performance marine coatings exhibiting antifouling characteristics is demonstrated. The PFPE-DMA was found to be miscible with the PEG-MA. Photo-cured blends of these materials containing 10 wt% of PEG-MA oligomers did not swell significantly in water. PFPE-DMA crosslinked with the highest molecular weight PEG oligomer (ie PEG1100) deterred settlement (attachment) of algal cells and cypris larvae of barnacles compared to a PFPE control coating. Dynamic mechanical analysis of these networks revealed a flexible material. Preferential segregation of the PEG segments at the polymer/air interface resulted in enhanced antifouling performance. The cured amphiphilic PFPE/PEG films showed decreased a...
TL;DR: The photosynthetic pigment fucoxanthin appears to be ecologically relevant as a surface-associated antimicrobial agent, acting against the settlement of bacteria on the surface of the macroalga F. vesiculosus.
Abstract: The chemical defence against microfouling in the brown seaweed Fucus vesiculosus was investigated and an inhibitor of bacterial settlement was isolated by bioassay-guided fractionation of non-polar surface extracts. UV-vis and mass spectrometry were used to identify the compound as the carotenoid fucoxanthin. The metabolite was tested at the natural concentration (in a surface volume based assay) against the settlement of four bacterial strains isolated from F. vesiculosus and 11 strains isolated from co-occurring algae and marine sediment. Surface concentrations between 1.4 and 6 μg cm(-2) resulted in 50% inhibition of four of these isolates, which were studied in more detail using a surface area-based assay, while a fifth isolate proved to be less sensitive. The presence of fucoxanthin on the surface of F. vesiculosus was demonstrated with two different surface extraction methods. Fucoxanthin was detected at concentrations between 0.7 and 9 μg cm(-2) on the algal surface. Fucoxanthin was still present at the algal surface after removal of associated diatoms through mechanical cleaning and germanium dioxide treatment and was thus mainly produced by F. vesiculosus rather than by diatoms. Thus, the photosynthetic pigment fucoxanthin appears to be ecologically relevant as a surface-associated antimicrobial agent, acting against the settlement of bacteria on the surface of the macroalga F. vesiculosus.
TL;DR: There was no correspondence between the responses of the two different types of biofilms to a particular treatment, which underscores the distinction between the killing power of an antimicrobial agent and its ability to alter biofilm mechanical properties and thereby influence biofilm removal.
Abstract: Changes in the viscoelastic material properties of bacterial biofilms resulting from chemical and antimicrobial treatments were measured by rheometry. Colony biofilms of Staphylococcus epidermidis or a mucoid Pseudomonas aeruginosa were subjected to a classical creep test performed using a parallel plate rheometer. Data were fit to the 4-parameter Burger model to quantify the material properties. Biofilms were exposed to the chloride salts of several common mono-, di-, and tri- valent cations, and to urea, industrial biocides, and antibiotics. Many of these treatments resulted in statistically significant alterations in the material properties of the biofilm. Multivalent cations stiffened the P. aeruginosa biofilm, while ciprofloxacin and glutaraldehyde weakened it. Urea, rifampin, and a quaternary ammonium biocide weakened the S. epidermidis biofilm. In general, there was no correspondence between the responses of the two different types of biofilms to a particular treatment. These results underscore the distinction between the killing power of an antimicrobial agent and its ability to alter biofilm mechanical properties and thereby influence biofilm removal. Understanding biofilm rheology and how it is affected by chemical treatment could lead to improvements in biofilm control.
TL;DR: Based on the laboratory-scale investigations, detachment of pipe wall biofilms due to cell death or flow dynamics could release the entrapped Fe and Mn into the bulk water, which could lead to a discoloured water event and managing biofilm growth on drinking water pipelines should be considered by water utilities to minimize accumulation of Fe andmn in distribution networks.
Abstract: Although health risk due to discoloured water is minimal, such water continues to be the source of one of the major complaints received by most water utilities in Australia. Elevated levels of iron (Fe) and/or manganese (Mn) in bulk water are associated with discoloured water incidents. The accumulation of these two elements in distribution systems is believed to be one of the main causes for such elevated levels. An investigation into the contribution of pipe wall biofilms towards Fe and Mn deposition, and discoloured water events is reported in this study. Eight laboratory-scale reactors were operated to test four different conditions in duplicate. Four reactors were exposed to low Fe (0.05 mg l−1) and Mn (0.02 mg l−1) concentrations and the remaining four were exposed to a higher (0.3 and 0.4 mg l−1 for Fe and Mn, respectively) concentration. Two of the four reactors which received low and high Fe and Mn concentrations were chlorinated (3.0 mg l−1 of chlorine). The biological activity (measured in term...
TL;DR: A review looks at the current preventive strategies often used to decrease the risk of CRIs due to colonization and biofilm formation on catheter surfaces, as well as at the more recent approaches under investigation.
Abstract: Central venous catheters (CVCs) nowadays constitute critical devices used in medical care, namely in intensive care units. However, CVCs also represent one of the indwelling medical devices with enhanced risk of nosocomial device-related infection. Catheter-related infections (CRIs) are a major cause of patient morbidity and mortality, often justifying premature catheter removal and an increase in costs and use of resources. Adhesion and subsequent biofilm formation on the surfaces of indwelling catheters is elemental to the onset of pathogenesis. Seeking the prevention of CVC colonisation and CRI, a variety of approaches have been studied, tested and, in some cases, already applied in clinical practice. This review looks at the current preventive strategies often used to decrease the risk of CRIs due to colonization and biofilm formation on catheter surfaces, as well as at the more recent approaches under investigation.
TL;DR: The results showed that concrete sewer biofilms are more diverse than previously reported and a more comprehensive molecular database will be needed to better study the dynamics of concreteBiofilms.
Abstract: The microbial composition of concrete biofilms within wastewater collection systems was studied using molecular assays. SSU rDNA clone libraries were generated from 16 concrete surfaces of manholes, a combined sewer overflow, and sections of a corroded sewer pipe. Of the 2457 sequences analyzed, α-, β-, γ-, and δ-Proteobacteria represented 15%, 22%, 11%, and 4% of the clones, respectively. β-Proteobacteria (47%) sequences were more abundant in the pipe crown than any of the other concrete surfaces. While 178 to 493 Operational Taxonomic Units (OTUs) were associated with the different concrete samples, only four sequences were shared among the different clone libraries. Bacteria implicated in concrete corrosion were found in the clone libraries while archaea, fungi, and several bacterial groups were also detected using group-specific assays. The results showed that concrete sewer biofilms are more diverse than previously reported. A more comprehensive molecular database will be needed to better study the d...
TL;DR: Video microscopy of cyprids of Balanus amphitrite was used to monitor the action of antennular setae during the exploratory behaviour prior to attachment and a revised description of all antennularity setae for that species was provided.
Abstract: Video microscopy of cyprids of Balanus amphitrite was used to monitor the action of antennular setae during the exploratory behaviour prior to attachment. In addition, SEM was used to provide a rev...
TL;DR: L.f. biosurfactant showed substantial anti-biofouling activity because it reduced the process of attachment and biofilm production and also showed a reduction in gtfB/C gene expression (P value < 0.05).
Abstract: Biofouling in the oral cavity often causes serious problems. The ability of Streptococcus mutans to synthesize extracellular glucans from sucrose using glucosyltransferases (gtfs) is vital for the initiation and progression of dental caries. Recently, it was demonstrated that some biological compounds, such as secondary metabolites of probiotic bacteria, have an anti-biofouling effect. In this study, S. mutans was investigated for the anti-biofouling effect of Lactobacillus fermentum (L.f.)-derived biosurfactant. It was hypothesized that two enzymes produced by S. mutans, glucosyltransferases B and C, would be inhibited by the L.f.-biosurfactant. When these two enzymes were inhibited, fewer biofilms (or none) were formed. RNA was extracted from a 48-h biofilm of S. mutans formed in the presence or absence of L.f. biosurfactant, and the gene expression level of gtfB/C was quantified using the real-time polymerase chain reaction (RT-PCR). L.f. biosurfactant showed substantial anti-biofouling activity becaus...