Showing papers in "Biofouling in 2001"

The environmental fate and behaviour of antifouling paint booster biocides: A review.

Abstract: Antifouling paint booster biocides are a group of organic compounds added to antifouling paints to improve their efficacy. They have become prevalent since the requirement for alternative antifouling paints formulations for small boats (< 25 m). This need followed a ban on the use of triorganotin biocides in antifouling paints for small boats, in the late 1980's. Worldwide, around eighteen compounds are currently used as antifouling biocides, viz. benzmethylamide, chlorothalonil, copper pyrithione, dichlofluanid, diuron, fluorofolpet, Irgarol 1051, Sea‐Nine 211, Mancozeb, Polyphase, pyridine‐triphenyl‐borane, TCMS (2,3,5,6‐tetrachloro‐4‐methylsulfonyl) pyridine, TCMTB [2‐(thiocyanomethylthio)benzothia‐zole], Thiram, tolyfluanid, zinc pyrithione (ZPT), ziram and Zineb. Any booster biocide released into the environment is subjected to a complex set of processes. These processes include transport mechanisms, transformation, degradation, cross media partitioning, and bioaccumulation. This paper reviews the fa...

The relationship between substratum surface roughness and microbiological and organic soiling: A review

Abstract: Substratum surface roughness has a well documented effect on the retention of microorganisms. Implications of this encompass problems in hygiene, infection, fouling, equipment function, corrosion and cleanability. This paper reviews methods used for visualising surface topography and measuring roughness which are pertinent to microbiologists, and notes limitations of some of the descriptors of surface roughness. A major issue is the scale on which the surface defects are examined: measurements may now be made in nanometers, but the significance of surface texture at this scale in terms of microbial retention has yet to be investigated in detail. Stainless steel and ceramics are commonly used as hygienic food preparation surfaces. Their wear has been visualised, with roughness measured on a nanometer scale using the atomic force microscope (AFM), and the effect on surface wear of cleanability using microbial and organic soil investigated. Surface analytical methods such as X-ray photoelectron spectroscopy (XPS) and time of flight secondary ion mass spectroscopy (ToFSIMS) provided information on the chemical structure at the uppermost atomic layer and demonstrate that microorganisms were removed more rapidly than organic material from the worn surfaces, and that organic soil conditioned the surfaces prior to microbial contamination. On this scale, the dimensions of surface defects were more suited to soil retention than to microbial cell retention. Traditional microscopic methods were not able to differentiate adequately between soil and microbial removal. Surface analytical techniques provide the opportunity to measure and visualise surface roughness and its effect on microbial and organic soiling on a hitherto unavailable level of detection.

Kinetics of conditioning layer formation on stainless steel immersed in seawater

Abstract: Adhesion of microorganisms to surfaces in marine environments leads to biofouling. The deleterious effects of biofilm growth in the marine environment are numerous and include energy losses due to increased fluid frictional resistance or to increased heat transfer resistance, the risk of corrosion induced by microorganisms, loss of optical properties, and quality control and safety problems. Antifouling agents are generally used to protect surfaces from such a biofilm. These agents are toxic and can be persistent, causing harmful environmental and ecological effects. Moreover, the use of biocides and regular cleaning considerably increase the maintenance costs of marine industries. An improved knowledge of biofilm adhesion mechanisms is needed for the development of an alternative approach to the currently used antifouling agents. The aim of this study is to characterise the chemical composition of the molecules first interacting with stainless steel during the period immediately following immersion in natural seawater and to elucidate the kinetics of the adsorbtion process. Proteins are shown to adhere very rapidly, closely followed by carbohydrates. The distribution on the surface of organic molecules is also examined. The adsorbate on the surface is not a continuous film but a heterogeneous deposit, whose average thickness varies widely. The cleaning procedures used affect the adsorption kinetics. In particular, cleaning with hexane results in slower adsorption of nitrogen-containing species than does cleaning in acetone.

Variation in adhesion strength of Balanus eburneus, crassostrea virginica and hydroides dianthus to fouling‐release coatings

Abstract: This study compared the shear adhesion strength of barnacles, oysters and tubeworms on eight RTV 11‐based silicone fouling‐release coatings containing different silicone oil additives It was found that adhesion strength differed among species and coating types In most cases, oysters and tubeworms had higher adhesion strengths than barnacles Barnacle adhesion strength was reduced on all coatings containing oil additives; however, this was not generally true for oysters and tubeworms The difference in the adhesion strength among the three organisms tested in this study emphasizes the importance of understanding the fundamental interaction between marine invertebrate adhesives and the substratum

Bacterial attachment to stainless steel welds: Significance of substratum microstructure

Abstract: AISI Type 304 L stainless steel (SS) is a widely used material in industry due to its strength and resistance to corrosion. However, corrosion on SS is reported largely at welds or adjacent areas. Bacteria were observed to colonize preferentially near welds as a result of surface roughness. In the present study, the influence of another important metal surface condition on bacterial adhesion has been evaluated, i.e. substratum microstructure. Type 304 L SS weld samples were prepared and machined to separate weld metal, the heat affected zone (HAZ) and base metal regions. The coupons were molded in resin so that only the surfaces polished to a 3 p.m finish were exposed to the experimental medium with Pseudomonas sp. isolated from a corrosive environment in Japan. The coupons were exposed for varying durations. The area of bacterial attachment showed significant differences with time of exposure and; the type of coupons. Generally, the weld metal samples showed more attachment whilst the base metal showed t...

Effect of cyprid age on the settlement of balanus amphitrite darwin in response to natural biofilms

Abstract: Larval settlement of the barnacle Balanus amphitrite Darwin (Cirripedia, Balanidae) is influenced by natural biofilms. In previous work by others, discriminatory settlement of aged cyprids has been observed in response to biofilms of different age. This study extends prior work by considering the effect of the age of cyprids on the outcome of settlement assays. Settlement was investigated with 0‐day‐old (newly metamorphosed) and 5‐day‐old cyprids. Biofilms under investigation were developed in the field for periods of 5 d and 1 month, and were subsequently included in laboratory settlement assays with a choice between a filmed and an unfilmed substratum. The bioassay was modified from the conventional horizontal dish design in order to generate a low water surface‐to‐volume ratio, which served to suppress larval entrapment in an organic layer on the water surface. Irrespective of cyprid age, a clear discrimination between a filmed and an unfilmed substrata was observed, and the preference for filmed or un...

Marine antifoulants from Bifurcaria bifurcata (Phaeophyceae, Cystoseiraceae) and other brown macroalgae

Abstract: In this study, the antifouling activity of a series of extracts and linear diterpenes isolated from Bifurcaria bifurcata (Velley) Ross, a common brown alga of the Atlantic shores of Europe, and derivatives of these compounds was investigated. Antifouling assays with crude extracts from other brown algae, found abundantly along the coast of South Africa (Bifurcaria brassicaeformis, Bifurcariopsis capensis), the Atlantic shores of Europe (Halidrys siliquosa) and the coast of Mediterranean sea (Cladostephus verticillatus, Halopteris scoparia ), are also reported. The fractions were tested in laboratory assays against representative species of the major groups of fouling organisms, viz. bacteria, fungi, diatoms, spores and zygotes of macroalgae and the blue mussel Mytilus edulis. Several components showed promising levels of activity. The high, albeit variable, level of antifouling activity suggests a potential for novel active ingredients in antifouling preparations.

Biodeterioration of Mayan buildings at uxmal and tulum, Mexico

Abstract: Uxmal and Tulum are two important Mayan sites in the Yucatan peninsula. The buildings are mainly composed of limestone and grey/black discoloration is seen on exposed walls and copious greenish biofilms on inner walls. The principal microorganisms detected on interior walls at both Uxmal and Tulum were cyanobacteria; heterotrophic bacteria and filamentous fungi were also present. A dark‐pigmented mitosporic fungus and Bacillus cereus, both isolated from Uxmal, were shown to be acidogenic in laboratory cultures. Cyanobacteria belonging to rock‐degrading genera Synechocystis and Gloeocapsa were identified at both sites. Surface analysis previously showed that calcium ions were present in the biofilms on buildings at Uxmal and Tulum, suggesting the deposition of biosolubilized stone. Apart from their potential to degrade the substrate, the coccoid cyanobacteria supply organic nutrients for bacteria and fungi, which can produce organic acids, further increasing stone degradation.

Extracellular polymeric substances of the marine fouling diatom amphora rostrata Wm.Sm

Abstract: Amphora rostrata was grown under continuous illumination at 27°C in batch cultures using f/2 medium Cell biomass (measured as chllorophyll a and cell counts) reached a maximum on day 7 Thereafter, cell biomass as chl a showed a small decrease Planktonic('free') and biofilm extracellular polymeric substances (EPS) from the adherent cells of A rostrata were studied Both types of EPS were produced during the logarithmic phase of growth However, production was higher during the stationary growth phase Enhanced EPS production was associated with nutrient deficient conditions Planktonic and biofilm EPS were purified by gel filtration using Sephadex G‐200 and ion exchange chromatography using DEAE‐cellulose Both polymers showed the presence of a single peak Capillary gas Chromatographie analysis of both planktonic and biofilm EPS showed that fucose (367%) and galactose (276%) were the most abundant monosaccharides, with small quantities of rhamnose, xylose, arabinose, mannose and glucose Other chemi

Effects of the interactions between glutaraldehyde and the polymeric matrix on the efficacy of the biocide against Pseudomonas fluorescens biofilms

Abstract: Glutaraldehyde (GTA) is a widely used biocide due to its high effectiveness. The experimental work reported here was carried out to assess the effectiveness of GTA in controlling biofilms formed by Pseudomonas fluorescens on stainless steel slides, and to compare efficacy against both planktonic and sessile micro‐rganisms. The tests were performed using two concentrations of GTA (50 and 100mg 1‐1), biofilms of two ages (7 and 15 d), several pH values (5,7 and 9) and a range of exposure times (from 0 (control) to 1,3,7 and 24 h). The action of GTA on biofilm and planktonic populations was assessed by means of activity tests, zeta potential, and the wet weight of the biofilms. Biofilms were not completely removed after treatment with GTA in any of the conditions studied. The higher GTA concentration was more effective in reducing the bacterial activity of the biofilm. The biocide proved to be more effective for longer exposure times. GTA showed good antimicrobial activity against P. fluorescens in suspensio...

Salivary protein adsorption onto hydroxyapatite and SDS-mediated elution studied by in situ ellipsometry

Abstract: Whole unstimulated saliva from two donors was investigated both with respect to adsorption characteristics and SDS‐induced elutability. Salivary protein adsorption onto hydroxyapatite (HA) discs was studied by means of in situ ellipsometry in the concentration range 0.1–20% saliva. The adsorbed amounts on HA were found to be similar to those on silica, but the rates of adsorption were lower. Protein adsorption was virtually unaffected by the presence of Na+, whereas Ca2+ induced nucleation of calcium phosphate at the surface, the deposition rate being influenced by the pellicle age but not by the presence of saliva in bulk solution. The SDS elutability of adsorbed pellicles was determined on HA as well as on silica surfaces. Desorption from both surfaces was found to occur in the same SDS concentration range, although a residual layer was observed on HA. The slight net positive charge and lower charge density of HA as compared to the strongly negatively charged silica, may, at least partly, account for th...

Combined effect of cyprid age and lipid content on larval attachment and metamorphosis of Balanus amphitrite darwin

Abstract: Various algal diets of different lipid content and composition were used to rear batches of naupliar larvae of Balanus amphitrite. The cyprids in these larval batches differed in lipid content and were used to investigate the combined effect of cyprid lipid content and cyprid age on attachment and metamorphosis. For this purpose, cyprids were aged for 0,3 and 6 d at 8°C prior to utilization in laboratory attachment assays. The percentage attachment of cyprids with similar lipid content differed significantly among the three age categories. A strong and a weak positive relationship between cyprid lipid content and attachment were monitored in young and old cyprids, respectively. A significant interaction (two‐way ANOVA) between cyprid age and lipid content was observed, indicating that these factors jointly affect larval attachment and metamorphosis in B. amphitrite from the beginning of the cyprid stage.

An in vitro study of initial adsorption from human parotid and submandibular/sublingual resting saliva at solid/liquid interfaces

Abstract: The influence of saliva concentration, saliva total protein content and the wetting characteristics of exposed solids on in vitro film formation was studied by the technique of in situ ellipsometry. The rates and plateau values of adsorption (45 min) at solid/liquid interfaces (hydrophilic silica and hydrophobic methylated silica surfaces) were determinated for human parotid (HPS) and submandibular/sublingual (HSMSLS) resting saliva solutions (0.1 and 1.0%, (v/v), saliva in phosphate buffered saline). Adsorption rates were related to a model assuming mass transport through an unstirred layer adjacent to the surface. The results showed that the adsorption was rapid, concentration dependent and higher on hydrophobic than on hydrophilic surfaces. Analysis of the influence of protein concentration on the adsorbed amounts demonstrated an interaction between protein concentration and the two surfaces for HPS and HSMSLS, respectively. This may indicate differences in binding mode. Inter‐individual differences we...

Adhesion of the marine fouling diatom Amphora coffeaeformis to non-solid gel surfaces

Abstract: Diatom adhesion to different gel surfaces was tested under different shear conditions, using the fouling marine diatom Amphora coffeaeformis as test organism. Four polymers were selected to obtain a test matrix containing gels with different surface charge as well as different surface energies, viz. agarose, alginate, chitosan and chemically modified polyvinylalcohol (PVA‐SbQ). Three experimental systems were applied to obtain different shear rates. Experimental system 1 consisted of gels cast in a cell culturing well plate for comparing initial adhesion as well as long term biofilm development in the absence of shear. In experimental system 2, microscope slide based test surfaces were tested in aquaria under low shear conditions. A rotating annular biofilm reactor was used to obtain high and controlled shear rates. At high shear rates A. coffeaeformis cells adhered better to the charged polymer gels (alginate and chitosan) than to the low charged polymer gels (agarose and PVA‐SbQ). In the system where sh...

Resistance of biofilms containing alginate-producing bacteria to disintegration by an alginate degrading enzyme (algl)

Abstract: Pure culture biofilms of Pseudomonas aeruginosa (strains 8830 and ATCC 700829) and mixed population biofilms composed of Pseudomonas aeruginosa (ATCC 700829), Pseudomonas fluorescens (ATCC 700830), and Klebsiellapneumoniae (ATCC 700831) were treated with an alginate‐degrading enzyme (AlgL). The enzyme effectively depolymerized the mannuronic acid rich (92%), partially O‐acetylated bacterial alginate produced by P. aeruginosa (8830), both in dilute solution and in a gel‐like, concentrated state. However, both biofilms were unaffected by the presence of the enzyme. These findings suggest either that bacterial alginates do not contribute significantly to the cohesiveness of biofilms or that the alginate is protected from enzymatic degradation in biofilms.

Attachment strength of Limnoperna fortunei on substrates, and their surface properties

Abstract: The attachment strength of the freshwater mussel Limnoperna fortunei was studied. The force and energy required for the mussel to detach from various substrata (coatings and materials) were measured by a load test method, and the results were compared and discussed with regard to the surface properties of the substrata (surface roughness and surface free energy). The detachment force and energy were measured from 0.02 to 2.56 N, and from 0.02 to 14.3 mJ, respectively, depending on the type of coating and material used. The mussel attached strongly to polar surfaces, such as glass, and attached weakly to non‐polar surfaces, such as silicone. There was a fairly good correlation between the detachment force and the detachment energy, and the detachment force and energy correlated well with the number of secreted threads. The unit detachment energy (the detachment energy divided by the number of secreted threads) was low when the mussel detached through adhesive failure of byssal pads, whereas it was high whe...

Attachment strength of an adhesive nuisance mussel, limnoperna fortunei, against water flow

Abstract: The attachment strength of the freshwater mussel Limnoperna fortunei against water flow was studied. Newton's expression successfully described the hydrodynamic drag force acting on the mussel with a drag coefficient value of 1.03. The drag‐resistant force (defined as hydrodynamic drag force at mussel detachment) was smaller than the detachment force measured using a tensile load test. A fairly good correlation was obtained between the drag‐resistant force and the number of secreted threads. The drag‐resistant force divided by the number of threads increased with shell size, suggesting that byssal thread strength increased with mussel growth. For the mussel specimens obtained from a water transmission pipe, thread width increased with shell size. However, thread width was not dependent on current velocity. There was no correlation between the number of secreted threads and shell length, which indicated that the number of secreted threads did not change with mussel size. Therefore, the water velocity neede...

Settlement inhibition of fouling invertebrate larvae by metabolites of the marine bacterium Halomonas marina within a polyurethane coating

Abstract: The marine bacterium, Halomonas marina (ATCC 27129), was shown to inhibit settlement and development of the sessile invertebrates Balanus amphitrite and Bugula neritina. Different bacterial treatments were employed to investigate this interaction. Filmed bacteria and liquid suspensions of whole cells, lysed cells and culture filtrate all reduced settlement of B. amphitrite. Polyurethane coatings containing whole cells were partially inhibitory while lysed cells caused complete inhibition of B. amphitrite larval settlement. In contrast, culture filtrate in a polyurethane matrix stimulated settlement of B. amphitrite larvae. Whole cells, culture filtrate, and lysed cells embedded in a polyurethane coating also controlled B. neritina settlement and maturation.

The influence of environmental factors on the rate and extent of stainless steel ennoblement mediated by manganese-oxidizing biofilms

Abstract: The increase in the open circuit potential of passive metals in natural waters due to biofilm formation at the metal surface, termed ennoblement, has been reported for nearly 30 years. Although its occurrence is undoubtedly associated with microbial colonization, the underlying mechanism of ennoblement remains controversial. Recent work produced in the authors’ laboratory has provided convincing experimental evidence that ennoblement can be caused by deposition of biomineralized manganese produced by manganese‐oxidizing biofilms. The purpose of this study was to determine the effects of environmental factors on the rate and extent of ennoblement of 316L stainless steel exposed to natural waters. This was accomplished by exposing corrosion coupons to four freshwater systems over a 4‐yearperiod. The rate and extent of ennoblement observed in these locations was correlated with dissolved manganese concentrations, the mass of accumulated manganese oxides, organic carbon concentration, dissolved oxygen concent...

Adsorption of Flavobacterium breve and Pseudomonas fluorescens P17 on different metals: Electrochemical polarization effect

Abstract: The electrochemical polarization effect on early adsorption of Flavobacterium breve and Pseudomonas fluorescens P17 to platinum, titanium, stainless steel, copper, aluminum alloy and mild steel was studied. A well‐defined peak characterized the bacterial adsorption dependence on externally applied potential. Maximal adsorption occurred in the potential range of ‐0.5 to 0.5 V (SCE) for all tested metals. A shift of applied potential towards both a positive and a negative direction from the maximal adsorption potential (Emax,ad) was accompanied by a gradual decrease in bacterial adsorption. The extent of bacterial adsorption strongly depended on the nature of the metallic substratum and decreased accordingly as follows: platinum > titanium > stainless steel > aluminum alloy > carbon steel > copper. Adsorption on all tested metals was approximately two orders of magnitude higher with the relatively more hydrophobic F. breve compared to the less hydrophobic P. fluorescens P17. The effect of electrochemical po...

Correlated XPS, AFM and bacterial adhesion studies on milk and milk proteins adherent to stainless steel

Abstract: Adhesion of Staphylococcus aureus and Listeria mono‐cytogenes to a stainless steel surface increased as the amount of surface‐adsorbed milk proteins decreased, as indicated by the x‐ray photoelectron spectroscopy (XPS) N Is signal. The iron signal was inversely related to the nitrogen signal, a decrease indicating either thinner surface coverage with protein or increased exposure of the alloy surface. Stainless steel samples were further studied using Tapping Mode™ atomic force microscopy (TM‐AFM) following a number of protein treatments. Both skimmed milk and the individual milk‐protein k‐casein provided AFM images consistent with a high level of surface coverage, confirming the XPS and bacterial adhesion data. Conversely, α‐lactalbumin exhibited sparse coverage as determined by both AFM and XPS analysis. Consequently this protein was less effective at reducing bacterial adhesion to the stainless steel. This study has shown that correlated surface analytical techniques can be successfully applied to inve...

Effective use of monitoring techniques for use in detecting and controlling MIC in cooling water systems

Abstract: The effective use of both oxidizing and non‐oxidizing biocides for control of MIC in cooling water systems was evaluated. A patented localized corrosion monitor was used to monitor changes in localized corrosion rates within laboratory scale and pilot cooling tower systems under various biocide treatment regimes. Under many of these conditions the changes in localized corrosion rates can be directly correlated with specific biocide feed. In particular, bromine based biocides exhibited the greatest control of MIC and corresponding recovery in localized corrosion rates.

Antifouling substances of natural origin: Activity of benzoquinone compounds from Maesa Lanceolata against marine crustaceans

Abstract: A screening of antifouling activity from plants extracts led to selection and further study of Maesa lanceolata Forssk. Two p‐benzoquinone compounds were isolated from the fruits and found to be active against Artemia salina. The anti‐crustacean activity of both p‐benzoquinones is reported for the first time.

Colonization of aerobic biofilms by sulfate‐reducing bacteria

Abstract: The ability of the SRB Desulfovibrio desulfuricans to colonize aerobic heterotrophic or nitrifying biofilms on stainless steel surfaces was investigated by fluorescence in situ hybridization (FISH) in combination with confocal laser scanning microscopy (CLSM), the polymerase chain reaction (PCR) directed to the dissimilatory sulfite reductase and by oxygen microelectrodes. Biofilms of heterotrophic bacteria and of nitrifying bacteria pregrown on steel coupons in laboratory devices were not invaded by cells of D. desulfuricans within 1 week, even though large pores as possible entry paths and anoxic zones and sulfate in the medium as prerequisites for activity of D. desulfuricans existed in the biofilms. On the contrary, coinoculation of D. desulfuricans and aerobic heterotrophic bacteria from water of a cooling water system led to immediate establishment of a small but detectable population of D. desulfuricans distributed over the whole biofilm depth. The fact that individual SRB attached efficiently and ...

Volatile substances from adult extracts induce larval settlement of the barnacle balanus amphitrite

Abstract: The volatile substance extracted from conspecific adults induces larval settlement of the barnacle Balanus amphitrite. The settlement inducing activity of the volatile fractions was checked monthly from June, 1997 to December, 1998. Both water soluble extracts and volatile fractions from the barnacle were prepared by the steam distillation. The active cue in the volatile fraction was always extracted with n‐pentane under acidic conditions, although settlement inducing activity varied with the sample. GC‐MS analysis of the active and inactive pentane fractions revealed 1, 2, 3‐trimethyl‐benzene as the settlement inducing substance. Commercially available 1, 2, 3‐trimethylbenzene also showed high settlement inducing activity at a concentration of 0.8 × 10‐12 M (100 pg 1‐1). This substance was detected at concentrations of more than 7 ng g‐1 of wet barnacle (equivalent to 0.6 × 10‐12M, equal to 70pg1‐1) by GC analysis. These results indicate that 1,2,3‐trimethylbenzene in the volatile fractions acts as a che...