DURING EARTH'S HISTORY LIFE HAS FACED A SUCCESSION OF EVER-EVOLVING ENVIRONMENTS EACH EXERTING SELECTIVE PRESSURES TO WHICH IT MUST ADAPT OR PERISH. EARTH LIFE HAS BEEN CHALLENGED BY BOTH GRADUAL AND ABRUPT ENVIRONMENTAL CHANGES (E.G. VARIABLE SOLAR OUTPUT BOLIDE IMPACTS TECTONICS VOLCANISM). IN TURN LIFE PROCESSES HAVE BROUGHT ABOUT GLOBAL ENVIRONMENTAL CHANGES (E.G. NITROGEN CYCLING OXYGENIC PHOTOSYNTHESIS CO2 SEQUESTRATION CARBONATE DEPOSITION). BOTH ABIOTIC AND BIOTIC CHEMISTRY IS GOVERNED BY THE FUNDAMENTAL PHYSICAL PARAMETERS OF PRESSURE (P) AND TEMPERATURE (T). PHYLOGENETICS SUGGEST THAT THE FIRST LIFE MAY HAVE EVOLVED IN ANOXIC HIGH-P ENVIRONMENTS SUCH AS OCCUR AT MODERN-DAY HYDROTHERMAL VENTS. BY APPROXIMATELY 3.5 GYA MICROBES HAD MIGRATED TO THE OCEAN/AIR AND LAND/AIR INTERFACES WHERE RECENT RESEARCH INDICATES THAT BY APPROXIMATELY 2.7 GYA EARTH'S ATMOSPHERE MAY HAVE ACTUALLY BEEN THINNER THAN THAT OF PRESENT-DAY EARTH. THUS MICROBIAL LIFE HAS EVOLVED TO FUNCTION AT WIDE EXTREMES OF P. INDEED MODERN MICROBES CAN BE FOUND IN NICHES RANGING OVER 6 LOGS IN P FROM LESS THAN 103 PA IN THE UPPER TROPOSPHERE TO GREATER THAN 108 PA IN THE OCEAN DEPTHS.HOW DID MICROBES EVOLVE THE ABILITY TO FUNCTION AT SUCH A WIDE RANGE OF P'S? TO STUDY THIS QUESTION WE PROPOSE TO USE STRAINS OF THE GENUS CARNOBACTERIUM WHICH ARE PSYCHROTOLERANT FACULTATIVELY ANAEROBIC GRAM-POSITIVE BACTERIA THAT GROW AT BOTH LOW-P AND HIGH-P EXTREMES. PI NICHOLSON HAS SHOWN THAT TWO SIBERIAN PERMAFROST STRAINS (WN1359 WN1374) AND 11 CARNOBACTERIUM TYPE SPECIES WERE CAPABLE OF GROWTH AT 0 DEGREES C AND LOW P FROM 7X102-105 PA. CO-I BARTLETT HAS ISOLATED CARNOBACTERIUM STRAIN AT7 FROM 2 500 M DEPTH IN THE ALEUTIAN TRENCH WHICH IS CAPABLE OF GROWTH AT 1.8 DEGREES C AND HIGH P FROM 105-6X107 PA. WITH DOE-JGI (PI) AND THE J. CRAIG VENTER INSTITUTE (CO-I) WE HAVE OBTAINED THE GENOME SEQUENCES FROM ALL 14 OF THESE CARNOBACTERIUM STRAINS. THE COMPLETE LOW-P AND HIGH-P LIMITS FOR GROWTH OF THESE BACTERIA AND HOW CHANGES IN P AFFECT THEIR GENE EXPRESSION ARE UNKNOWN. IT HAS RECENTLY BEEN SHOWN THAT MICROBES CAN ADAPT TO CHANGING ENVIRONMENTS BY ALTERING THEIR GLOBAL PATTERN OF DNA METHYLATION (THE METHYLOME) WHICH IN TURN CAN INFLUENCE GLOBAL GENE TRANSCRIPTION (THE TRANSCRIPTOME). WE FOUND THAT THE METHYLOME OF PERMAFROST STRAIN WN1359 DIFFERED WHEN CELLS WERE GROWN AT 7X102 VS. 105 PA. FROM THESE OBSERVATIONS WE HAVE DEVELOPED THE WORKING HYPOTHESIS THAT: BACTERIA ADAPT TO THE P ENVIRONMENT BY ALTERING THEIR METHYLOMES AND TRANSCRIPTOMES.