ABSTRACT
OBJECTIVE: To explore the regulation effects of oxygen carriers on Poria cocos submerged fermentation system which usually can be seriously inhibited by dissolved oxygen limitation. METHODS: One-factor-at-a-time design was employed to determine the oxygen carrier addition strategy through analyzing the effects of different oxygen carries, concentration and adding time of oxygen carrier on Poria cocos submerged fermentation. Then the oxygen carrier addition strategy was established and the metabolic processes of Poria cocos submerged fermentation were investigated comprehensively. RESULTS: The optimal oxygen carrier addition strategy was adding 1% (V/V) Tween-80 at 48 h after inoculation. Under this optimized condition, dry cell weight of Poria cocos reached 13.43 g/L in a 10 L bioreactor, while yields of exopolysaccharides and pachymic acid were 8.58 g/L and 989.52 µg/L, respectively, which exhibited obvious promoting effects compared with no addition oxygen carrier fermentation process. CONCLUSION: Tween-80 can remarkably increase the levels of cell growth, exopolysaccharides biosynthesis and pachymic acid in Poria cocos submerged fermentation system, which may provide new reference for further exploring dissolved oxygen limitation in high density fermentation of medical fungi efficiently.
