Enzymatic profiles of 11 barophilic bacteria under in situ conditions: evidence for pressure modulation of phenotype.

Barophilic bacteria are microorganisms that grow preferentially (facultative barophiles) or exclusively (obligate barophiles) under elevated hydrostatic pressure. Barophilic bacteria have been isolated from a variety of deep-sea environments. Attempts to characterize these organisms have been hampered by a lack of appropriate methodologies. A colorimetric method for the detection of 19 constitutively expressed enzymes under in situ conditions of pressure and temperature has been devised, using a simple modification of the commercially available API ZYME enzyme assay kit. By using this method, enzyme profiles of 11 barophilic isolates, including an obligate barophile, were determined. Nine of the 10 facultatively barophilic isolates examined exhibited a change of phenotype in at least one enzyme reaction when tested at 1 atm (1 atm = 101.29 kPa), compared with results obtained under in situ pressure. The assay is simple and rapid and allows for direct determination of enzyme activity under conditions of high pressure and low temperature.