The ocean is full of crap, and it's our fault. We've been dumping crap into it for centuries, so it's not surprising that some areas boast 335,000 pieces of floating junk per square km. Cleaning it all up by hand isn't feasible, so a group of students are trying to engineer synthetic bacteria to do the job instead.
Cleaning up ocean garbage would be easy (or, easier) if the garbage consisted of large objects, but it doesn't. The ocean does a pretty good job of breaking down things like plastics into small pieces about the size of confetti, but those pieces stick around for a long, long time. And when fish eat them (fish aren't the most discriminating creatures), these plastic shards work their way up the food chain, causing havoc as they go. It's a bad situation for the fish, the fish that eat those fish, the birds that eat the fish that eat the fish, and so on all the way up to the apex predators: sharks, giant squid, the Loch Ness monster, and us.
Students from University College London have decided that the way to tackle a bunch of little tiny pieces of plastic is with an even bigger bunch of little tiny synthetic bacteria. The bacteria will be customized with three genetic 'modules:' module one is detection, which uses a human oestrogen receptor that binds to different types of plastics. Once the bacteria finds itself some plastic, the aggregation module kicks in, inducing the bacteria to to extrude a sticky substance. Gradually, all of the little tiny bits of sticky plastic will glom on to each other, forming 'islands' that float up to the surface and can be easily collected and recycled, or stuck to each other to make a giant garbage island that is apparently suitable for habitation by monkeys (viz. video below).
This project is an entry for iGEM, the world's largest synthetic biology competition, and if you think the idea has merit, you can help the students reach their funding goal of 1,500 quid at the link below.