Bartlett 9714292 Many regions of the solar system where life is postulated to exist, such as the oceans of Europa, are characterized by pressures far greater than those experienced at Earth's surface. Because pressure exerts a fundamental influence on the properties and distribution of life, the effects of high pressure on living systems needs to be understood. Unfortunately, despite the isolation of high pressure-loving (barophilic) microbes from certain deep-sea environments, relatively little data exists on the nature of barophily or the pressure boundaries within which life may exist. The mechanisms and limits of growth at high pressure are being investigated by using a collection of bacteria of differing high pressure growth abilities, and by isolating and characterizing additional barophiles from the environment capable of growing at unprecedented. pressures. Mutants derived from two genetically manipulatable bacteria, barotolerant Escherichia coli, and moderately barophilic Photobacterium species strain SS9, will be obtained following a series of stepwise high pressure selection regimes under various culture conditions. Genes associated with high pressure growth will be identified and characterized. In addition, increased high pressure growth ability will be selectively evolved in the extreme barophile Shewanella species strain PT99, and "hyper" barophiles will be selected for, using sediments freshly obtained from a high pressure location within the Japan Trench. The phylotypes of those isolated microorganisms displaying greatest high pressure growth capability will be ascertained following 16S rDNA sequencing.
