from Chiaki Kato writing in Extremophiles: Microbiology and Biotechnology:
Piezophilic microorganisms, which are defined as "pressure-loving" microorganisms, are isolated and characterized from high pressure environments. They grow better at high-hydrostatic pressures than at atmospheric pressures, and only exist at deeper water column environments, particularly in the deep-sea bottoms. Therefore, piezophilic microorganisms are typical deep-sea microorganisms that are well adapted to deep-sea pressure and temperature conditions. These microorganisms have special strategies for surviving in such extreme environments, where gene expression and enzyme activities could be controlled by pressure. Studies on adaptations to high pressure environments have recently been studied in detail, and the mechanisms involved are being elucidated. In this chapter, the distribution, taxonomy, cultivation and molecular characters of piezophiles are described.
Further reading: Extremophiles: Microbiology and Biotechnology