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Chemical signalling between microbial films and spores of the marine macroalga Ulva

Final Activity Report Summary - Bact2alga (Chemical signalling between microbial films and spores of the marine macroalga Ulva)

Biofouling, the growth of marine organisms on hard substrata, is a major problem for marine industries causing large economical and environmental costs. Fouling on a ship hull leads to higher fuel consumption, contributing to more CO2 from the burning of fossil fuels. The current antifouling technology is primarily based on the application of toxic substances that are harmful to the natural environment. Novel, environmentally friendly approaches for solving the biofouling problem are urgently needed.

The approach taken within this project was to learn from nature. Solving the biofouling problem could be achieved with increased understanding of the involved biological processes. The critical part was to understand the mechanism that mediated the interactions among fouling organisms. In the project ‘Bact2alga’ the interactions between marine bacterial films and alga were investigated. The green alga ulva was one of the most important biofouling organisms on ship hulls worldwide. Bacterial films were, during previous research efforts by Joint lab group, observed to play a major role in the development of this alga. Furthermore, flow conditions seemed to be important for settlement and attachment of this ulva spores and plants, as determined by Granhag lab group.

In the first part of this project, the importance of flow for the interactions between bacteria and alga was studied. As synthetic bacterial signals proved difficult to include and measure in the micro flow cells, the research concentrated on natural bacterial biofilms that produced signal molecules. In the second project part, the composition of natural bacterial films was investigated with fluorescent probes in a microscopy technique called fluorescent in situ hybridisation (FISH). This technique worked very well and bacterial films with intact three-dimensional structure could be viewed. Results showed that the composition of bacterial groups was of great importance for the first growth, i.e. germination, in the fouling alga ulva. This new knowledge could offer important help for mitigating the problems of biofouling.