Biotechnological Investigation for the Prevention of Biofouling. I

MARINE ECOLOGY PROGRESS SERIES Vol. 123: 301-312, 1995 Published July 20 ' Mar Ecol Prog Ser 1 REVIEW Biotechnological investigation for the prevention of biofouling. I. Biological and biochemical principles for the prevention of biofouling Sibylle Abarzua, Sabiene Jakubowski Universitat Rostock, Fachbereich Biologie, Lehrstuhl Biochemie, Doberaner StraRe 143, D-18051 Rostock, Germany ABSTRACT The most important b~ologicaland biochemcal methods with potential for the prevention of biofouling are descnbed Among these methods, the isolation of biogenic agents produced by several species of micro- and macroalgae and inanne invertebrates with antibacterial, antialgal, anh- protozoan and antlmacrofouhng properties may be the most promising and effective method for the prevention of biofoul~ng The isolated substances with the most potent ant~oulantactlvlty are fatty ac~ds,terpenes terpenoids, hpoproteins, glycolipids, phenols, lactons, peptides and steroids The advantage of the utilization of micro- and macroalgae for the isolation of biogenic agents is that algae can be cultivated m a short tlme in mass culture, independent of season Furthermore, they can be manipulated to a large extent in the direct~onof the 'production of biogenic agents' However, the cul- tivation of mcro- and macroalgae is very expensive Manne Invertebrates must be collected In certain seasons This collection of manne invertebrates could lead to an uncontrolled explo~tationof marlne organisms and to a change in the balance of marine ecosystems. Therefore, determination of the chemical structure and the subsequent synthesis of the deterrmned biogenic agents is necessary if marine invertebrates are to be used as producers of biogenic agents. Ant~foulingsystems must be both envi- ronmentally safe and effective for at least 3 yr when formulated as antifoul~ngpaints. There have been a few attempts at th~s,but no applicable successes have been reported to date KEY WORDS Antifouling . Biofouling Growth inhibition Marine bioactive agents . Macrofoulers . Microfoulers . Settlement INTRODUCTION 1978). This process occurs in the first minutes of the biological settlement (Fig. 1).After approximately 1 to What is biofouling? 2 h, the colonization of bacteria involving 2 distinct phases, a reversible approach phase ('adsorption')and Biofouling is one of the most important problems a nonreversible attachment phase ('adhesion'), occurs currently facing marine technology. In the marine (Marshall 1980, Wahl 1989) (Fig 1).The first, reversible environment any solid surface will become fouled. adsorption, is an instantaneous attraction which holds Materials submerged in seawater experience a series bacteria near the surface. The bacterial adsorption is of discrete physical, chemical and biological events essentially governed by physical forces: Brownian which results in the formation of a complex layer of motion, electrostatic interaction, gravity, and van-der- attached organisms known as biofouling. Waal forces (Fletcher & Loeb 1979, Walt et al. 1985). Loeb & Neihof (1975),Baier (1984) and Lewin (1984) The phenomenon is termed reversible because the have shown that the first event is the accumulation organisms can easily be removed before substantial of an organic 'conditioning' film consisting of chemical contact of cell surface has been made. The second, compounds (mostly protein, proteoglycans and poly- irreversible attachment phase can be made by bacteria sacchandes) mahng the surface wettable (Dexter that produce extracellular bridging polymer (e.g. poly- O Inter-Research 1995 Resale of full article not permitted 302 Mar Ecol Prog Ser 123: 301-312, 1995 macrofouling microfouling tenlary colonizers -------...---------- secondary colonlzen tt"ttm*****ttl-*mm*t*t+mN***~mtfm..** pnmary colonizers 11111/11/111111~11111111~11111111111~////////////l//l/////l///////l///////////////l////////////////////////////////l organlc f~lm ............................................................................... subnrate l min 1-24h l week 2 - 3 weeks adhesion of bacter~a spores of macroalgae larvae of macrofoulerr organic parti- (e.g Pseudo- (e.g.Enterornorpha mtestinabs, (e.g.Balanus arnphrtrife [Cnrstacea] cles (e g protein) monas pufrefaciens. Ulothnx zonala Electra crustulenta [Bryozoa] ViMo aQinolyticus) [Cnloropnyta]) Laorned~aflexuosa [Coelenterata] Myirlus edulis [Molluscs] diatoms protozoa Spirorbis borealis [Polychaeta] (e g Achnantes brevrpes (e.g. Vaginicola sp.. Sfyela coriacea [Tun~cata]) Amphrprora paludosa. Vort~cellasp.. Amphora coffeaefom~s. Zoothamniu.r! sp., Licmophora abbfeviata [Cillata]) Fig. 1. Temporal struc- Nirzschra pusilla) ture of settlement saccharide fibrils consisting mostly of glucose and fruc- (Von Oertzen et al. 1989). therefore there is an over- iusej. it is itnown that these polysaccharide fibrils lapping between micro- and macrofouling (Fig. 1).Lar- (slimes) are anchored to their chemical counterparts in vae of macrofoulers (sessile marine organisms such as the macromolecular film by lectins or divalent cations tunicates, coelenterates, bryozoans, barnacles, mus- (Ca++,Mg++) (Costerton et al. 1978).With the establish- sels, polychaetes), which are called tertiary colonizers, ment of covalent bonds between the bacterial glyco- then attach to the microfouling film (Fig. 1) (Takazawa calix and the macromolecular film the adsorption et al. 1992). Larvae of macrofoulers prefer to settle on phase blends into the adhesion phase (Wahl1989).The surfaces coated with microbial and algal films (Col- growing bacterial lawn, composed of dead and living well 1983). cells and their secreted 'slime', together with the macro- According to micro- and macrofouling processes the molecular film, constitutes the so-called primary film following overlapping time sequence is observed: bac- (slime film) (Wahl 1989). teria appear after approximately 1 to 2 h, diatoms after Diatoms, spores of macroalgae and protozoa appear 24 h, spores of macroalgae and protozoa after 1 wk and after the development of the primary film (Fig. 1) with larvae of macrofoulers after 2 to 3 wk (Von Oertzen et a clear quantitative dominance of the diatoms (Mar- al. 1989).It seems that all micro- and macrofoulers pro- shall et al. 1971, Caron & Sieburth 1981, Cuba & Blake duce adhesive substances necessary for their attach- 1983, Zahuranec 1991). Benthic diatoms are attached ment to solid surfaces such as the hull of a ship (Cook- by mucus secretion (Cooksey et al. 1984, Ferreira & sey et al. 1984).In the literature there are contradictory Seeliger 1985) and may densely cover wide substratum opinions on the question whether this sequence of areas. While in the majority of observed events diatom events constitutes a real ecological succession or not colonization was always preceded by bacterial attach- (Little 1984). ment (Little 1984), there may be exceptions (Sieburth The settlement of micro- and macrofoulers on the & Tootle 1981, Maki et al. 1988). Attachment of spores hulls of ships must be prevented for both economic and of macroalgae is realized by species such as Entero- ecological reasons. The bacterial slime films and the morpha intestinalis and Ulothrix zonata; protozoan large numbers of barnacles, mussels and tunicates colonizers belong mostly to the sessile or hemisessile which accumulate on ships increase drag forces and forms [e.g. Ciliata) or are mobile predators of micro- surface corrosion, thereby causing additional fuel, CO, organisms, not being considered to be true epibionts. emissions and maintenance costs (Gitlitz 1981). Bacteria and diatoms represent the primary colonizers and spores of macroalgae and protozoa constitute the secondary colonizers in the process of microfouling Effect of the utilization of antifouling paints (Fig. 1). A clear separation between microfouling and macrofouling is impossible because the spores of In the efforts to avoid marine biofouling, antifoul- macroalgae belong to the macrofouling organisms ing paints are used, mostly with copper and tri-n- Abarzua & Jakubowski Prevention of biofouling 303 butyltin (TBT) as very effective active agents Alternative methods for the prevention of biofouling (Willemsen & Ferrarl 1993). The antifouling paints prevent blofouling by releasing effective biocides at Due to present and expected future restrictive regu- a constant rate. Since the early 1970s, triaryltin and lation on the use of TBT (Dalley 1987) and probably trialkyltin compounds have been increasingly used in other polluting antifouling compounds there is a grow- antifouling paints because of their excellent ability to ing need for other methods of the prevention of biofoul- prevent marine organisms from becoming encrusted ing. Several physical/mechanical, physical/chemical on ship bottoms and culturing nets (Suzuki et al. and biological/biochemical principles for the pre- 1992). vention of biofouling were used in the last 30 yr TBT is used as a biocide in coatings in 3 different (Gerencser et al. 1962, Schulz & Subklev 1964, Kuhl & ways: in free association paints (biocide dispersed in a Neumann 1969, Loeb & Neihof 1975, Characklis 1981, resinous matrix), in ablative paints (biocide is bonded Dhar et al. 1981, Branscomb & Rittschof 1984, Fletcher in a less permeable matrix that gradually flakes off) & Baier 1984, Humphries et al. 1986). and in self-polishing copolymers (SPC) (biocide is It is the aim of the present work to describe and chemically bonded). Self-polishing 01-ganotin copoly- evaluate the most important biological/biochemical mer

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