 The study provides experimental evidence that candidates methanoperidons nitro reducans and ANME acclimated to nitrate reduction uses surface localized redox active cytochromes for metal reduction through cytochrome-mediated extracellular electron transfer, EET, from ANME to different electron sinks. This article was authored by Xu Weqin Zhong, Georgina H. Joyce, Andy Olu, and others.