Subatomic bacteria were a type of bacteria that could be found in space and fed on several compounds that make up the hull of starships.
In 2365, these were found feeding on the tritanium plating of both the USS Enterprise-D's and the IKS Pagh's hull, eventually creating a hole. They were safely removed from both vessels via the use of a tunneling neutrino beam. (TNG: "A Matter Of Honor")