Fed-batch cultures of Hansenula polymorpha were studied
to develop an efficient biosystem to produce recombinant
human serum albumin (HSA). To comply with this
purpose, we used a high-purity oxygen-supplying strategy
to increase the viable cell density in a bioreactor and
enhance the production of target protein. A mutant strain,
H. polymorpha GOT7, was utilized in this study as a host
strain in both 5-l and 30-l scale fermentors. To supply
high-purity oxygen into a bioreactor, nearly 100% highpurity
oxygen from a commercial bomb or higher than
93% oxygen available in situ from a pressure swing
adsorption (PSA) oxygen generator was employed. Under
the optimal fermentation of H. polymorpha with highpurity
oxygen, the final cell densities and produced HSA
concentrations were 24.6 g/l and 5.1 g/l in the 5-l
fermentor, and 24.8 g/l and 4.5 g/l in the 30-l fermentor,
respectively. These were about 2-10 times higher than
those obtained in air-based fed-batch fermentations. The
discrepancies between the 5-l and 30-l fermentors with air
supply were presumably due to the higher contribution of
surface aeration over submerged aeration in the 5-l
fermentor. This study, therefore, proved the positive effect
of high-purity oxygen in enhancing viable cell density as
well as target recombinant protein production in microbial
fermentations.