Barophiles are microorganisms adapted to:
Barophiles also called piezophiles specialized for high hydrostatic pressure exceeding 10 megapascals up to 110 MPa in hadal trenches. Pressure increases ordering of acyl chains reducing membrane fluidity similar to low temperature. Adaptations include increased proportion unsaturated polyunsaturated fatty acids EPA DHA introducing kinks maintaining fluidity, branched iso anteiso fatty acids, shorter chain length, incorporation cholesterol like molecules and carotenoids. Proteins exhibit reduced void volume due to compact packing, increased multimerization, reduced compressibility. Piezolytes beta hydroxybutyrate accumulate stabilizing. Many isolates Colwellia psychrerythraea, Moritella yayanosii, Shewanella benthica are psychropiezophiles requiring both cold and pressure. Obligate barophiles fail to grow at atmospheric pressure indicating pressure dependent enzyme function, ribosome assembly, and transcription complexes. Study of barophiles informs limits biosphere, pressure sterilization pascalization preserving food nutrients, origins life hypothesis that deep sea vents could be cradle where high pressure stabilizes biomolecules. Their cytochromes and ATP synthases adapted maintaining proton motive force under compression in deep ocean habitats.
Ref: Madigan et al., Brock Biology of Microorganisms, Chapter 19: Barophiles - High hydrostatic pressure adaptation.