Rethinking the makeup of antifouling paint

Henrik Meyer: Cysbio is a biotech company making existing and novel molecules by fermentation. The technology is the metabolic engineering of microbes, that creates microbial strains that can transform sugar and other renewable substrates into the desired materials. This is a fermentation process, just like brewing beer. We do not make alcohol but we do make other interesting products. 

This method is by definition part of the green revolution, where previously fossil fuel-based chemicals are made by much more sustainable methods, using renewable substrates such as glucose, maltose, or glycerol, and made into products by simple biology – fermentation. The fermentation method often also replaces the need for many chemicals in production and thereby reduces a lot of pollution and the need for harmful chemicals and waste products. 

We replace fossil fuel-based and polluting production methods with much more sustainable production methods, and we also invent biobased safe products that by their functionality can replace other more polluting alternatives. Zosteric acid is a good example as we can replace more harmful biocides that can be a problem when released in water in large amounts as the situation is with current antifouling technology.

The very nature of our technology means that we practically always will contribute technology that replaces something less desirable. Our main strategy is just to be good at our core business: making existing and novel fermentation-based molecules. 

We will seek to drive products that also can make a real difference by offering solutions from nature’s own arsenal of great products. Zosteric acid is one, as it is identical to the antifouling product that some plants use, thereby making it safe and biodegradable and without pollution risk even if used in big amounts. 

We are especially seeking products that exist in nature. Our next product will be one of nature’s own preservation products.

Metals, like copper, are quite toxic for many marine living organisms. It is a biocide that works by killing or inhibiting many different organisms and even larger organisms, thereby reducing the amount that will grow on the vessels’ bottoms and resulting in reduced speed and extra fuel costs. 

Copper is said to be problematic in inland waters, lakes, and shallow waters, so many countries are looking to ban or limit the use of copper-based antifouling products. The very principle with the bottom paint with copper is that copper is slowly released into the environment, and this can lead to unwanted concentrations of this biocide in water.

The principle is that we genetically engineer a selected microbe – we normally work with Ecoli – changing the metabolic pathways so that the bacteria is forced to make a lot of the compound we need to produce. 

The bacteria strain is then fed a substrate – normally glucose or similar sugars. This happens in large steel tanks in an isolated environment, from which no live bacteria gets out. The fermentation liquid is then separated from the bacteria biomass, which is dried and all bacteria dies – the material can be used as fertiliser or can be burned. 

The fermentation broth  now has the desired product in solution, and by filtration and other methods, the final desired product is concentrated and purified as the final product. This is what we sell. Companies can buy our ingredient and use it to create final products like paint coating products for the maritime sector. 

We can make eelgrass acid in the scale of tonnes [by mid-2023] and we aim at getting to a cost where the inclusion rate in paint will be similar to the current cost of copper and other biocides, which it will replace. We will make it competitive, but the price will not be the driver. Sustainability and environmental consciousness will be the driver.

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Eelgrass acid is a unique compound because of the way it works to prevent the fouling growth of microbes and larger organisms. It prevents spores and fungi from attaching and growing on surfaces where the product is placed. 

The exact “prevention mechanism” is still not fully understood. The exciting part is that, unlike biocides, eelgrass acid does not kill any organisms. It is non-toxic to everything – but microbes don’t like to be near the product. It has a very unique repellent-like effect. 

Thirty years of research into the compound have demonstrated that it really works very effectively. Until now though the compound has been too expensive to produce for commercial use. 

Cysbio is based on two genetic engineering technology platforms that are very well patented globally. The one we use to make eelgrass acid is the one we call the sulfation platform. 

Here, we can take phenolic compounds that are normally toxic to the production organism and sulphate them, thereby making them both non-toxic and water-soluble. This enables us to make novel compounds that it is normally impossible to make otherwise.

There are few products available. The use of zinc was mostly replaced by less harmful copper. Other biocides are also used, though copper is still prevailing as it is effective, releases slowly, and is quite cost-effective. 

There are a lot of experiments and good developments with surface materials that are less prone to fouling. There are also attempts to make natural, non-toxic solutions such as eelgrass acid – one that exists specifically for barnacles – but the effect is often not good and nothing is broadly effective against most microbes and larger organisms. Eelgrass acid is unique, being broadly harmless.

The challenge is to create effective slow-release or fixed coating paint systems, which is the work that is going on now. Eelgrass acid is not toxic, so it might not solve all antifouling challenges as effectively as toxic materials. 

But the work to build better coating systems and paint systems will make eelgrass acid one of the key materials that can be used to replace some of the currently more problematic products used. The combination of eelgrass acid with other products will also be a smart way to strongly reduce the more harmful components making a two-way functioning antifouling protection system.