Fermentation of extremophilic microorganisms

The cultivation of the hyperthermophile Pyrococcus furiosus, the thermoacidophile Sulfolobus shibatae and the halophile Marinococcus M52 in dialysis membrane reactors resulted in cell yields of 2.6 g l(-1), 114 g l(-1) and 132 g l(-1) (cell dry weight), respectively. In the case of P. furiosus neither hydrogen (up to 160 mu mol l(-1)) nor the metabolic products were found to be responsible for growth cessation at a cultivation temperature of 90 degrees C. The low cell yield at an agitation speed of above 1800 rpm demonstrates the sensitivity of P. furiosus to hydrodynamic stress. The oxygen transfer rate into culture medium at extreme temperatures was shown to be equal or even greater than that under mesophilic condition.