Biofouling and microbial corrosion are two physico-chemical naturally occuring processes that affect ship hulls, pipes, heat exchangers and underwater harbour infrastructures. The economic impact of these two phenomenons is estimated around tens of billions of euros every year for both civilian and military infrastructures. The existing techniques to fight against fouling and corrosion are not satisfactory as they are poorly efficient and/or toxic for the environment. Several alternatives, less toxic, have been appearing in the past few years. Among them, the use of enzymes seems very promising. For instance, enzymes that directly degrade biofilm or that degrade bacteria responsible for biofilm formation have been used to decrease biofouling and microbial corrosion. Nevertheless, limited enzyme stability has considerably hindered the use of enzymes beyond the laboratory scale. To circumvent these limitations, Pr. Eric Chabrière's team working at URMITE laboratory in the Marseille IHU investigated microorganisms living in extreme environments such as Mount Vesuvius hot springs to identify robust enzymes. SsoPox lactonase was thereby isolated from a hyperthermophilic archaea. SsoPox harbours outstanding properties such as resistance to solvent and detergent exposure as well as resistance to heating conferring important assets for biotechnological applications. Furthermore this enzyme can be stored while retaining its activity on long-term periods. The team showed that the lactonase prevents communication between bacteria that are involved in biofilm formation. The ability of the enzyme to inhibit biofilm formation thereby reducing biofouling and corrosion was put forward. Based on these proofs of concept, the project presented here will aim to set up enzyme based formulations to develop antifouling (AF) and anticorrosion paints or coatings. The use of the enzyme is of prime interest as it acts by preventing bacterial communication without killing bacteria. The enzyme also presents a very limited toxicity unlike other anti-bacterial agents classically used in AF paints such as copper. URMITE and MAPIEM, a laboratory specialised in AF coating formulations from Toulon University, have decided to collaborate to set up a technological breakthrough that would be both efficient and environmentally friendly. An experimental approach to determine how the enzyme impacts microbial communities in vitro and in situ will lead to a better understanding of the lactonase mode of action and consequently to adapt formulations for a larger scale evaluation campaign.

Marine biofouling on materials and equipments leads to fatal effects in numerous civil or military marine applications: sailing ships, race ships, tankers and military vessels, offshore platforms, aquaculture installations, oceanographic equipments, and optical sensors. Their consequences are estimated at several billion euros a year, including the costs of maintenance. This colonization leads to an increase of drag resistance and therefore of energy consumption in particular in the sea transport. Antifouling coatings are used on surfaces in contact with marine fouling organisms. Such coating compositions comprise generally polymer matrixes called binders and biocides which inhibit the settlement of marine organisms. The most successful antifouling (AF) paints for several years have been tributyltin (TBT)-based self-polishing paints and have been banned because of environmental concerns. The combination of its widespread use, persistence and toxicity led the International Maritime Organisation (IMO) to introduce the AFS Convention, banning the application of TBT-containing antifoulings to all vessels. New types of antifouling coatings are now under development. Nevertheless, these commercially available tin-free self-polishing paints contain high amounts of copper oxide (Cu2O) combined with booster biological active compounds. Today different countries impose some restrictions on the use of these active materials, and so while they may be chosen to suit national markets in the pleasure boat business, operators of international shipping have to consider where their vessels will sail, or restrict their choice of toxicants to those internationally approved. In Europe, the Biocidal Products Directive (BPD) 98/8/EC entered into force in 1998 and requires all biocidal products to be authorized for use, and this will certainly restrict the choice of marine biocides further. The aim of this project is to develop new non-toxic or ecological AF paints combining self-polishing properties and an AF activity without any toxicants release. New polymer coatings containing electroactive micro(nano)domains will be prepared and characterized for civil and military applications. The specific objectives are the synthesis of acrylic block copolymers which could self-assemble and lead to micro(nano)-structured surfaces acting on the adhesion or the release of settled marine organisms. Besides the expected non-wetting effect of these structured surfaces, the reversible oxidation/reduction of micro(nano)electroactive domains will inhibit the settlement and the adhesion strength of marine organisms. In addition, electrochemical domains will slow down or inhibit the formation of the initial biofilm according to their redox states. A complete hard fouling elimination could be obtained to avoid maintenance for seawater immersed sensors or ship hulls. The work is an interdisciplinary venture to discover novel polymer binders for paint technologies with long-time efficiency, low volatile organic compounds and limiting biocidal substances. The two academic research teams (MAPIEM and MOLTECH laboratories) involved in this project therefore provide a mix of basic and applied scientific knowledge, which will significantly strengthen the current collaboration and the outcomes of the project.

The societal demand is more and more urgent to know the quality of the water, sea waters as river waters, from bacteriological risks, accidental pollution as malicious. Traditional analyses by collecting and analysing samples in laboratory provide important information on the quality of the water but do not allow in situ and real-time monitoring. To overcome this disadvantage, manufacturers turned to submerged sensors to monitor parameters such as dissolved oxygen, turbidity, conductivity, pH and fluorescence. However, these sensors suffer a drift of their measurements due to the invasion of surfaces by bacteria, micro or micro-organisms, which is commonly called biofouling. In this context, antifouling solutions should be developed in order to maintain reliable measurements for as long as possible before maintenance is carried out. The PIEZOVIB project, between the CEA, the MAPIEM and the IFREMER, fits into this context. The proposed solution uses the vibration of the measuring surface by the use of piezoelectric actuators, outside the measuring periods. The surfaces will be transparent or not depending on the type of measurement. This project is based on the conclusive experience acquired in this field for three years, between the MAPIEM laboratory of the University of Toulon and the CEA Grenoble. the surfaces may be, in a second step, micro-textured in order to have a combination of approaches acting synergistically. The developed system will be tested in situ, both in Brest and Toulon, to prove the full benefit of our solution.

Accurate monitoring of trace metals in water is of outmost importance for the environment preservation and for human health. Therefore, there are increasing concerns to develop novel and robust portable sensors in order to control their levels. IDEALWATER project aims to design a novel in-situ device based on fluorescence and electrochemical dual-mode detection to measure trace metal ions in natural water. The advantage of such chemosensors combining dual transduction mode is that they can ensure enhanced diagnostic accuracy by data coupling, mutual verification and elimination of interferences. IDEALWATER project will target lead, cadmium and copper as trace metals representative of various contaminated environmental waters in France and worldwide. Selective detection of these latter metals will be achieved by functionalizing working electrodes with original ion imprinted polymers (IIPs) as recognition elements. IIPs are materials able to selectively recognize a target ion used for their synthesis. For IDEALWATER project, smart IIPs will be specially designed in order to provide a fluorescence signal correlated to the metals binding, and will accumulate metals for the electrochemical measurement. Combining these unique polymers with the double fluorescence and electrochemical detection on a same platform designed to be incorporated in a fluidic device aims to provide accurate, selective, sensitive and portable sensors. These detectors will be capable to evaluate trace metal levels in natural water quickly with no need for any additional step such as sampling and storage. They will represent a versatile platform for other metal detections by adapting the IIP synthesis to other targets.