MICROBIAL GROWTH AND RESPONSE TO SUPERCRITICAL CO2: ADAPTATION OF HYDROTHERMAL APPARATUS FOR MICROBIAL EXPERIMENTATION

At high pressures equivalent to hydrostatic conditions in geologic reservoirs the geochemical environment experienced by microbes can be dramatically different than the chemical and physical properties obtainable in bench-top culture experiments. In addition to vast differences in chemical solubility of gases, the physical state of certain components such as a separate CO₂ phase can change dramatically over narrow temperature conditions around the critical point. We have adapted existing flexible gold-cell vessels within hydrothermal autoclaves as a means to overcome the physical and chemical limits of bench-top microbial experimentation. Using model organisms and serial aqueous sampling, we describe the procedure for aseptic sampling, inoculation, growth, and sterilization. Liquid and gas-phase samples can be obtained in pressure-tight steel coils for later extraction and analysis of the microbial products, moreover this procedure is adaptable for a wide range of natural and pure culture experimentation.