Zosteric acid—An effective antifoulant for reducing fresh water bacterial attachment on coatings

Abstract

Zosteric acid, a natural product present in eelgrass, has been found to prevent the attachment of some bacteria and barnacles. The results indicate that it may also be effective at reducing the early stages of biofouling, such as the attachment of bacteria that lead to a biofilm. In this study, the ability of zosteric acid in reducing the early stages of fouling was evaluated using attachment studies of fresh water bacteria via two approaches. First, plain coatings were submersed in water containing zosteric acid and either enriched Lake Erie bacteria or Pseudomonas putida, a model fresh water bacteria. It was found that zosteric acid with a concentration one-tenth of its EC50 (the concentration eliminates 50% of the bacteria) was able to reduce bacterial attachment by more than 90%. The second approach incorporated zosteric acid into silicone coatings in the presence of a common solvent to achieve the slow release of zosteric acid; such coatings were then subjected to the bacterial attachment. A ∼75% reduction in bacterial attachment was found for 1 wt% zosteric acid entrapped Sylgard® 184, a model silicone coating, but the reduction only achieved ∼55% for 1 wt% zosteric acid entrapped in a commercial silicone coating, RTV11.