Optimization of biomass productivity and substrate utility of a hydrogen bacterium, Alcaligenes hydrogenophilus

Optimizations of cell productivity and utility of gaseous substrates were investigated for Alcaligenes hydrogenophilus. Theoretical analyses for the cell productivity and substrate utility were discussed in the light of experimental data. It was proved from the theoretical analyses that the maximum cell productivity was at the following conditions: D = 0.21 h(-1), R(1) ( = H(2) partial pressure/O(2) partial pressure) = 2.25 and R(2) ( =CO(2) partial pressure/O(2) partial pressure) = 0.09, i.e., a molal ratio, H(2):O(2):CO(2) = 67.4:29.9:2,7. The Condition which gave the maximum cell productivity also gave high utilities of gaseous substrates. The growth yield for oxygen increased with increasing R(1) in chemostat culture, and the growth yield for hydrogen slightly increased with increasing R(1). Theoretical cell productivity and substrate and substrate utility were in good agreement with experimental values, taking into account the change of growth yield for oxygen.