High-pressure-temperature bioreactor for studying pressure-temperature relationships in bacterial growth and productivity.

Thermophilic organisms offer many potential advantages for biotechnological processes; however, realization of the promise of thermophiles will require extensive research on bacterial thermophily and high-temperature cultivation systems. This article describes a novel bioreactor suitable for precise studies of microbial growth and productivity at temperatures up to 260 degrees C and pressures up to 350 bar. The apparatus is versatile and corrosion resistant, and enables direct sampling of both liquids and gases from a transparent culture vessel without altering the reaction conditions. Gas recirculation through the culture can be controlled through the action of a magnetically driven pump. Initial studies in this bioreactor of Methanococcus jannaschii, an extremely thermophilic methanogen isolated from a deep-sea hydrothermal vent, revealed that increasing the pressure from 7.8 to 100 bar accelerated the production of methane and cellular protein by this archaebacterium at 90 degrees C, and raised the maximum temperature allowing growth from 90 to 92 degrees C. Further increases in pressure had little effect on the growth rate at 90 degrees C.