Microbial adaptations to the psychrosphere/piezosphere.

Low temperature and high pressure deep-sea environments occupy the largest fraction of the biosphere. Nevertheless, the molecular adaptations that enable life to exist under these conditions remain poorly understood. This article will provide an overview of the current picture on high pressure adaptation in cold oceanic environments, with an emphasis on genetic experiments performed on Photobacterium profundum. Thus far genes which have been found or implicated as important for pressure-sensing or pressure-adaptation include genes required for fatty acid unsaturation, the membrane protein genes toxR and rseC and the DNA recombination gene recD. Many deep-sea bacteria possess genes for the production of omega-3 polyunsaturated fatty acids. These could be of biotechnological significance since these fatty acids reduce the risk of cardiovascular disease and certain cancers and are useful as dietary supplements.