Accumulative Component Analysis of Polysaccharide in CC Protocorm of Dendrobium candidum

Accumulative polysaccharide in Dendrobium candidum protocorms was studied using the temporary immersion bioreactor system (TIBS). The polysaccharide concentration and monosaccharide ratios in D. candidum protocorms were compared with those in D. candidum stems. The results showed that the accumulative polysaccharide in D. candidum protocorms was not grown synchronously with the accumulation of protocorm biomass. The best harvest period for the production of polysaccharides from protocorm was the first 70 days. The polysaccharide concentration in protocorm was 59.11 mg/g . DW, which was 1/3 of that in D. candidum stem (174.93 mg/g . DW). The analysis of concentration and monosaccharide ratios showed that the main polysaccharide in D. candidum stem was acidic heteropolysaccharide which was composed of two monosaccharides (D-mannose, and D-glucose) and one D-glucuronic acid with D-glucuronic acid and D-mannose as the main components. The polysaccharide in protocorm was also acidic heteropolysaccharide, mainly composed of five hexose sugars (glucose, mannose, galactose, rhamnose and arabinose) and two uronic acids (galacturonic acid and glucuronic acid), with glucuronic acid and mannose as the main components. In addition, the two kinds of polysaccharides contained high content of uronic acid, which may be related to the drying of raw materials at high temperature for a long time. The results may provide a reference strategy for the large-scale production of protocorm tissues by temporary immersion bioreactor system.