Bacterial communities collected on the surface of stainless steels samples exposed to seawater heated from 30°C to 40°C.

Stainless steels exposed to seawater undergo a several hundred millivolt increase of the open circuit potential called ennoblement. That phenomenon is caused by the bacteria present on the surface of the stainless steel. There is a critical temperature of 38°C above which the ennoblement is inhibited despite the presence of bacteria. We collected bacteria from samples exposed to a range of temperature: 30°C, 33°C, 36°C, 38°C and 40°C in order to compared the conditions leading to ennoblement (under 40°C). We found the presence of the electro-active bacteria Candidatus Tenderia electrophaga, an electro-autotrophic bacteria able to use an electrode as an electron donor to reduce oxygen. We propose a model for which electrotroph bacteria are associated with ennoblement.