Piezophilic or Barophilic Microorganisms

Abstract

Piezophilic microorganisms grow optimally under high hydrostatic pressure as 10 MPa (Mega Pascal unit) when tested over all permissible temperatures. Barophiles was the term originally used. They thrive in extreme high-pressure environments, exceeding up to 150 MPa (1 MPa = 10 bar). They are found in marine trenches, deep-sea sediments, hydrothermal vents, ocean floors, and rocks deep under the Earth. They can also resist extreme temperature, pH, and high salt concentration; thus they are polyextremophiles. Their barostability is attributed to genomic adaptation (robust DNA repair systems), proteomic adaptations (substitution of all other amino acids with arginine), stabilization, and activation of enzymes by high pressures. Pyrococcus yayanosii is the most pressure-resistant organism while Thermococcus barophilus is both thermophilic and barophilic; Psychromonas hadalis is obligately piezophilic and optimally grows at 6 °C and pressure 60 MPa.

In India, piezophilic microorganisms such as nitrifying bacteria are reported from Central Indian Basin; some fungi like Aspergillus, Trichothesium, and Sagenomella from deep-sea sediments of Central Indian Basin; and bacteria like Acinetobacter, Halomonas, Sphingomonas, and Shewanella from deep drilling at Koyana, Western India. One novel genus and one novel species of piezophilic microorganism new to Science have been reported from India.