Over the summer, Yale IGEM member Cathy Ren interviewed Mr. James S.C. Tai, Technical Director and General Manager of Fleet Management Department, Orion Overseas Container Line Limited (OOCL). We asked about the importance of biofouling in the shipping industry and the possible application of our antimicrobial coating.

(Disclaimer: The interview was translated from Mandarin, so some terms/translations may not be completely correct.)

CR: What is biofouling and why does it matter to OOCL?
JT:Marine paint has always been focused on protecting against water damage, which is called anti-corrosive, but more recently has moved more towards anti-fouling.
Biofouling can be caused by both micro- and macro-organisms. Microorganisms like bacterial slime can adhere to ships' hulls, while the macro-organisms include barnacles and algae. Barnacles in particular can be extremely corrosive. They release a type of acid that will eat through the paint and even the metal, embedding themselves deep in the hulls so that even scraping them off may not be effective. Usually, after scraping, another layer of paint will be applied, but the paint cannot adhere well to a hull that still has these embedded barnacles attached, as the organisms chemically react with the paint.
Biofouling is an important problem because the organisms that attach to the hull will increase the weight of the ship, sometimes enough to double fuel costs if the ship remains in warm waters for an extended period of time and organisms really begin to build up. In just a few days, barnacles can attach and build up enough to pose an enormous challenge to the removal process.

CR: What are the anti-fouling methods that OOCL employs?
JT:There are two main anti-fouling methods currently in use. One is application of a particularly slippery paint, to make the surface mirror-like, so that organisms can't attach to the hull in the first place. However, this paint is very expensive, and application must be done in very specific conditions, like a specific temperature of water, and so on. However, if ships remain immobile, the slipperiness of the paint is not enough to prevent biofouling. And it would be nearly impossible for us to run a shipping company if the ships never docked for unloading. Ships will have to stop eventually, so this method is not completely effective. Also, any damages to the surface, for example from bumping into something while docking the ship, will render the slippery properties useless.
Furthermore, this mirror-like surface, while it can prevent barnacles from attaching, cannot escape things like slime.
Another anti-fouling mechanism is through the use of biocides, which kill organisms like barnacles, but these will also kill other marine organisms so they are not environmentally-friendly. Tin was once the standard biocide, but the industry has since moved to copper, which is supposed to be less harmful to the environment somehow. These biocides are incorporated into a type of paint that will fall off the ship when the ship moves at a certain speed, so any barnacles that have somehow adhered will fall off. One problem is that even if the organisms are killed by the biocides, a process that requires a certain amount of time, their shells may still stick to the ship so the paint- falling-off process is necessary. Then this paint will fall and remain in the ocean, killing other organisms.

CR: What are some other methods for preventing biofouling that are currently being explored?
JT: Some people have proposed regular polishing of the hull to work quickly and prevent heavy buildup of barnacles, but this is both time-consuming and expensive. Although anti-fouling measures are necessary, we can't forget that shipping is the main service, and too much cleaning may not be profitable.
A strategy not yet on the market, still undergoing research, is using a paint that signals to the barnacles that it is attaching to something not stable, like water, so that it will not try to adhere to the hull. However, it is uncertain how this would apply to things like slime and algae.

CR: Yale iGEM is currently trying to produce an anti-microbial protein that could be used in the field of anti-fouling. What are some things we should consider with our approach?
JT:IGEM's protein product is exploring an area of opportunity and innovation. You will need to consider how the protein will affect different types of organisms -- algae, slime, barnacles -- and whether it will work in various temperatures. You will have to consider how the coating will be created and applied to the ship, like will you incorporate it into the paint? Also, even though the main purpose of the protein is anti-fouling, it must not interfere with the anti-corrosive paint, which is considered to be more important than biofouling.
The anti-microbial properties of the protein will need to work before the barnacles release acid and attach to the ship because even if barnacles die, their shells will remain.
Hopefully, the protein will be biodegradable, as that would make it more likely to be accepted by environmental authorities.
The paints and coatings applied to ships are very specific. Different coatings are used for ships that travel in different waters with different organisms, so any protein product used for the treatment and prevention of biofouling would optimally be able to work in a wide range of temperatures and waters.
You could also look at bridges: barnacles also attach to bridges, and their acid corrodes the metal, making the bridges less stable. Bridges are also immobile, so you can't use the slippery-paint method.

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