Contamination of soil with heavy metals poses a serious health threat to people and the environment. One way researchers are exploring the effects of this contamination is through the interactions between soil bacteria and the viruses that infect them. A new study reports on these interactions in soils contaminated with high levels of chromium. Overall, the results indicate that as chromium pollution increases, the bacteria–virus relationship changes from one of antagonistic parasitism to one of beneficial mutualism. For example, viruses associated with bacteria tolerant to heavy metals increased in abundance as did viruses with the ability to infect a broad range of bacterial hosts. These correlated increases in abundance could facilitate the sharing of heavy metal resistance genes among members of bacterial communities. These correlated increases in abundance could facilitate the sharing of heavy metal resistance genes among members of bacterial communities, which is made possible by the way viruses use bacterial hosts to replicate their own genetic material. The study demonstrates that viruses have a profound effect on how soil microbes respond to environmental stress. The findings could lead to ways of exploiting bacteria–virus interactions to remediate and restore areas contaminated with heavy metals.