A study of mycelial growth and exopolysaccharide production from a submerged culture of Mycoleptodonoides aitchisonii in an air-lift bioreactor

Abstract

We determined the optimal culture and medium conditions for effective production of mycelial mass and exopolysaccharide from a liquid culture of Mycoleptodonoides aitchisonii in an air-lift bioreactor. The mycelial growth and exopolysaccharide production were found to be optimal at a temperature of 25 °C and pH of 6.5. When 60 g/L of lactose was used as a carbon source, the maximum mycelial growth and exopolysaccharide production were obtained. The polypeptone and yeast extract were the most appropriate nitrogen sources for mycelial growth and exopolysaccharide production. In addition, when a mixture of 20 g/L of polypeptone and 5 g/L of yeast extract was used, the exopolysaccharide production increased 50% compared to that of the sole nitrogen source. CaCl2·2H2O (1.0 g/L) was the most effective mineral source. Using the optimal culture and medium conditions, batch cultures with basal and designed medium on mycelial growth and exopolysaccharide production in a 5 L air-lift bioreactor were carried out for 16 days. The mycelial growth and exopolysaccharide production increased with an increase of culture time at 14 days, and the maximum mycelial growth and exopolysaccharide production were 20.3 and 6.2 g/L, respectively, after 14 days of culture. The developed model in an air-lift bioreactor showed good agreement with experimental data. These results indicate that exopolysaccharide production is associated with the mycelial growth of M. aitchisonii in an air-lift bioreactor.