Defense Mechanism Employed by Algae Can Effectively and Safely Inhibit Marine Fouling
Cerium dioxide nanoparticles block communication between bacteria and prevent the formation of biofilms.
MAINZ, Germany - Chemists at Johannes Gutenberg University Mainz (JGU), Mainz, Germany, have developed a method that reliably hinders hazardous seawater fouling and is effective, affordable and easy on the environment. Fouling can occur, for example, as the result of the growth of bacteria, algae or mollusks in harbor facilities, on boat hulls and aquaculture netting. The resultant damage and consequential costs can be significant. It is estimated that these are equivalent to $200 billion annually in the shipping industry alone. Protective coatings applied to vessels usually contain copper-based biocides. These have the disadvantage that they harm the environment while resistance to them can also develop. In order to find an alternative, the research team of Professor Wolfgang Tremel decided to simulate a defense mechanism employed by algae and established that cerium dioxide nanoparticles can effectively prevent fouling. This discovery could contribute to the development of new protective coatings that are much less environmentally harmful than the hull coatings in use now.
Marine algae utilize secondary metabolic products in order to provide themselves with a form of chemical defense against micro-organisms and predators. These halogenated secondary metabolites specifically prevent bacterial biofilms, other algae, and even barnacles from becoming attached to and developing on larger formations of algae, sponges and other creatures. Halogenated compounds produced by the red seaweed Delisea pulchra, for instance, inhibit bacterial fouling but are neither toxic nor growth retarding. Instead, they scupper what is known as quorum sensing, i.e, a system used by bacteria to communicate with the help of messenger substances that results in the formation of biofilms. The structures of the halogenated compounds synthesized by seaweeds are similar to those of these substances, so they cause a blockade of the bacterial receptors and suppress the switchover of bacterial gene regulation to biofilm formation. This form of interference with bacterial gene regulation is also of pharmaceutical interest as it is known that pathogenic bacteria can protect themselves against attack by the immune system and the effect of antibiotics by forming biofilms, for instance on the epithelium of the respiratory system.