THE ROLE OF HYDROGEN MASS-TRANSFER FOR THE GROWTH-KINETICS OF METHANOBACTERIUM-THERMOAUTOTROPHICUM IN BATCH AND CHEMOSTAT CULTURES

Hydrogen concentration was determined in batch and chemostat cultures of Methanobacterium thermoautotrophicum, both in the headspace and in the medium using mass spectrometry. The calculated dissolved hydrogen concentration in the medium as derived from the headspace hydrogen con centration when equilibrium conditions between gas and liquid phase we re assumed, was ten times higher than the experimentally determined hy drogen concentration, Variation of the partial pressure of hydrogen re sulted in different values for substrate affinity for hydrogen (K-s) a nd yield (Y) of the cells. Upon hydrogen limitation, K-s decreased whi le the yield coefficient for hydrogen increased, indicating a change i n the affinity of the cells towards hydrogen.