Effects of supplementation of succinic acid on the production and molecular weight distribution of exopolysaccharides by Antrodia camphorata in batch cultures

The effects of organic acid supplementation on both yields and molecular weight distributions of exopolysaccharide (EPS) of Antrodia camphorata were investigated in shaker flasks and air-lift bioreactors. In the shaker flask study, five out of six organic acid-supplemented cultures showed negative effects on cell growth, the exception being pyruvic acid-supplemented culture; lower number average molecular weights (Mn) of EPS were obtained in all the supplemented cultures. EPS production was enhanced by 31% due to the addition of succinic acid. Optimum product yield was obtained between 2.0 and 3.0 g dm^-3 succinic acid; however, the specific production of EPS increased monotonically as succinic acid concentration was increased From 0 to 5 g dm^-3. Enhancement of EPS yield by 28% and a higher Mn of EPS (around 310 kDa) due to the addition of succinic acid were also demonstrated in an air-lift bioreactor. In addition, a novel fermentation process resistant to EPS degradation is proposed, based on the inhibition of β-glucanase activity by the supplementation with succinic acid.