Deep sea biosphere represents the largest ecosystem on earth. It is characterized by extreme physical and chemical conditions and especially by high hydrostatic pressures. Even though ocean depths (cold / hot) harbour a wide community of prokaryots with different metabolic traits within the two domains of life (Bacteria & Archaea), only a few of them are piezophiles up to strict piezophiles. Let's now have a closer look on how the LM2E explores those mechanisms of adaptation.