Silver

Silver compounds are toxic to bacteria, viruses, fungi and algae.

An excerpt from the article 24 facts about silver

Compounds of other heavy metals, such as copper, lead, or mercury, also have such properties, but silver compounds are not as harmful to humans. They kill many microorganisms in vitro. Silver ions can change the structure of cell walls and the nuclear envelope, disorganizing bacterial cells. Silver also binds to bacterial DNA and RNA, preventing them from replicating.