New anti-fouling paints with natural biocides for ships
01 / 2000 - 12 / 2004
OBJECTIVE: Biofouling is an enormous problem for sea-going ships. Due to increased resistance fuel costs can rise by as much as 40%, which adds considerably to air pollution. On a global base about 100.000 tons of anti-fouling paints are produced for ships. These paints contain tributyl tin or copper, which act as biocides. However, they have undesirable toxic environmental effects. The use of these paints will be forbidden in 2003. The objective of this project will be the development of new environmentally safe paints that prevent the attachment and growth of organisms. The paints that will be developed have three mechanisms to achieve biofouling prevention. (i) organized layers of polyethyleneglycol (PEG) inhibit attachment of polysaccharides and proteins (ii) slow self-polishing coating that remove organisms that have attached and (iii) natural biocides in the coating that prevent attachment or kill organisms that have attached. The research at MM will focus on the processes that are involved in the development of microbial biofilms. We will investigate the initial attachment of micro-organisms at a surface and the spatial and temporal development of organisms that inhabit these biofilms as well as their extracellular matrix components. We will test a range of newly developed anti-fouling paints based on self-organized PEG layers that are linked with natural biocides for their potential to interfere with biofilm formation on hard substrata. APPROACH: The kinetics of the formation of natural biofilms will be investigated in time and space under different conditions. These include seasonal differences, differences in light conditions, flow regimes and water exchange rates. Biofilm development will be followed using a variety of microscopic techniques, molecular taxonomy and chemical analysis. The development of biofilms will be studied by using confocal laser scanning microscopy (CLSM). Fluorescent probes will be used to detect and localize various biofilm components. Fluorescent lectins will be used to study EPS and molecular taxonomic probes (FISH) will be used for the localization and detection of specific organisms. Microbial biomass will be quantified and identified by using phospholipid fatty acid analysis (PLFA). The dominant or otherwise relevant microorganisms will be isolated and their properties will be studied in detail, with particular reference to the exudation of EPS. Extracellular polymers will be isolated and their composition analysed. The properties of this EPS with respect to binding to different surfaces will be studied. Also the attachment of microorganisms such as diatoms, cyanobacteria, and bacteria will be studied. Different types of surfaces will be tested and different conditions will be employed. These include seawater with different nutrient concentrations (N, P, Si), the presence or absence of light, temperature and shear stress. Finally, we will test a number of natural and already used biocides for their potential to inhibit the attachment of microorganisms to surfaces and we will study the nature of this inhibition. On the basis of the results the promising active compound will be selected for its application in paints. The project is an interdisciplinary collaboration with the Section Physical-Organic Chemistry of the University of Utrecht (Prof. Jenneskens) and Agrotechnology & Food Innovations, Wageningen. PLANNING 2003: Experiments will be carried out to study seasonal development of natural biofilms and the effect of light on the kinetics and composition of biofilms. Also the effect of water discharge rates on biofilm growth will be studied. Furthermore, the fouling properties of various highly ordered PEG-layers anchored to glass substrata as self assembled monolayers will be investigated. In addition, the EPS dynamics for key species of micro-organisms will be studied in liquid cultures as well as in flow cells with respect to various environmental conditions.