Abstract:

The effects of carbon source and inorganic nitrogen source on the biosynthesis of polysaccharides by
Cordyceps militaris in shaking flask cultivation were investigated. The culture medium for polysaccharide production
from Cordyceps militaris was optimized by orthogonal array design. The results showed that glucose was beneficial
to the accumulation of intracellular polysaccharides (IPS) while galactose was propitious to the biosynthesis of
exopolysaccharides (EPS). Monosaccharides participated in the biosynthesis of Cordyceps militaris polysaccharides in the
lag phase or stationary phase of cell growth while oligosaccharides markedly improved the biosynthesis of EPS during the
early log phase. The presence of NH4
+ was beneficial to the accumulation of IPS. The optimal culture medium contained
80 g/L of glucose, 10 g/L of peptone and 10 mmol/L of (NH4)2HPO4. The maximal production of total polysaccharides
reached (1.197 ± 0.032) g/L with an EPS/IPS ratio of 1:3.4. The accumulation of EPS after optimization was doubled.

Key words: Cordyceps militaris, polysaccharides, biosynthesis, orthogonal array design, medium optimization