Studies On Liquid Suspension Culture Proudced Polysaccharides Of Dendrobium Candium

Dendrobium candium was a rare precious Chinese herb. It has been in severe danger. In order to realize its sustaninable utilization by mass propagation of protocorm-like bodies(PLBS) in bioreactor, these experiment compared the advantage-disadvantage of solid culture and liquid suspension culture, PLBS was used as material, the best culture condition for PLBS growth,multiplication and polysaccharides synthesize were investigated systemicly. Osmotic pressure and intermittent feed were also studied. Polysaccharides contents and Amino acid content of D. candidum with wild material were also compared. The paper provided theory basis for PLBS tissue culture in mass propagation. The main results were showed as follows:The liquid suspension culture was superior to solid culture not only in dry weigh but also production of polysaccharides. In liquid suspension culture, dry weight and polysaccharide production of PLBS reached to its maximum 17.64 g /L and 3081.2 mg/L after 50 days and 40 days, while solid culture reached to its maximum 13.40g /L and 2412.5mg/L after 60 days and 40 days, dry weight and polysaccharide production of PLBS of solid culture less 4.24g/L and 568.7 mg/L than liquid suspension culture. Comparing with morphological, PLBS was green , bud obviously differentiated, the embrionic shape body was small and weak in solid culture, but in liquid suspension culture, PLBS was yellow with little green, bud differentiation was not obviously, the embrionic shape body was even and sturdy. Results showed that: the probable way of producing protocorms was provided by liquid suspension culture.The growth of protocorms closely correlated with the consumption of sugar, nitrate and phosphate, sugar was absorbed almost at 40d, indicated that PLBS used carbon sources completely. In nitrogen consumption, NH₄⁺ was superior to NO₃^-, the both were almost line dropped. PO₄^3- was absorbed almost at 30d. In exponential phase, the medium conductivity decreased linearly relative to the biomass accumulation.There were different effects on the growth of protocorms and the accumulation of polysaccharides in five basic medium MS, 1/2 MS, B5, N6 and White, N6 was best medium for the accumulation of polysaccharides. White was best medium for growth of the protocorms. 1/2 MS and N6 were the best medium for the dry weight of protocorms and the accumulation of polysaccharides after synthesis considered.Sucrose, glucose and fructose were used as carbon sources to test their influences on growth and polysaccharide accumulation in the protocorms, and sucrose, glucose were better than fructose for protocorms growth and polysaccharide accumulation. Sucrose was the best carbon sources for the dry weight of protocorms and price after synthesis considered. 30g/L sucrose was the best concentration.The medium with 10%coconut milk, nitrogen concentration was 30-60 mmol/L, the ratio NO₃^- to NH₄⁺ was 40: 20, 30: 30, 10001ux-15001ux, 12hours per day were advantageous to the growth of protocorms and the accumulation of polysaccharides. The order of effect factors to the accumulation of polysaccharides was rotation speed, pH value and inoculum amount, Of which pH5.0, 110r/min rotation speed and 50g/LFW inoculum amount. The order of effect factors to the dry weight was pH value, rotation speed, and inoculum amount. Of which pH7.0, 110r/min rotation speed and 30 g/L·FW or 40 g/L·FW. inoculum amount.The Polysaccharide and Amino acid contents of PLBS and wild material were rich, their contents were close.So, the best medium and culture condition for the dry weight of protocorms and the accumlation of polysaccharides was: 1/2MS+30g/Lsources+0.1mg/LNAA+10%conut milk, adjusted nitrogen concentration to 30-60 mmol/L, the ratio NO₃^- to NH₄⁺ was 40: 20,30:30, pH7.0, 110r/min rotation speed and 30g/L·FW or 40g/LFW innculum amount, 10001ux-15001ux, 12 hours per day.