Research Of Polysaccharide Produced By Chlorella EC04 And DC01

Microalgaes possess potential value in many aspects because of its simple structure, rapidly breeding and high bioactive substances productivity. Microalgae polysaccharide has antivirus, regulating immune, antitumor, antioxidation and other biological activity.The culture conditions of polysaccharide production for the two Chlorellas were studied. The results showed that the most suitable conditions for Chlorella EC04 extracellular polysaccharide production were as follows:NaNO₃ 1.1g L-1, MgSO₄·7H₂O 100mg L-1, NaHCO₃1.33g L-1. Under this condition, the extracellular polysaccharide content is 229.22mg L-1 and the biomass is 42.193·10⁶ cells per mL. The most suitable conditions for Chlorella DC01 extracellular polysaccharide production were as follows:NaNO₃ 1.O₃g L-1, MgSO₄·7H₂O 105mg L-1, NaHCO₃ 1.48g L-1. Under this condition, the extracellular polysaccharide content is 159.61mg L-1 and the biomass is 49.425·10⁶ cells per mL. The optimum culture conditions for Chlorella EC04 intracellular polysaccharide production were MgSO₄·7H₂O 112.5mg L-1, K₂HPO₄ 60mg L-1, NaNO 31.2g L-1, VB₁ 0.5mg L-1, VB₁₂ 0.1 ?g L-1 respectively. In this conditions, the polysaccharide production and biomass were 271.74mg g-1 and 48.027·10⁶ cells per mL respectively. The optimum culture conditions for Chlorella DC01 intracellular polysaccharide production were MgSO₄·7H₂O 90mg L-1, K₂HPO₄ 80mg L-1, NaNO₃0.8g L-1, VBi 0.5mg L-1, VB₁₂ 0.1 ug L-1. In this conditions, the polysaccharide production and biomass were 268.O₃ mg g-1 and 39.42·10⁶ cells per mL respectively.Two purified polysaccharide named EEP-la and DEP-la were separated by DEAE Cellulose-52 column then applied for further purification by Sephadex G-100 column. Free radical scavenging rate of the two purified polysaccharide was studied. The results showed that they have good ability for scavenging DPPH radical and hydroxyl radical. The Gas chromatography analysis showed that the monosaccharide compositions of EEP-la were L-rhamnose ?8.20%?, L-arabinose ?7.58%?, D-xylose ?3.89%?, D-mannose ?2.79%?, D-glucose?5.51%?, D-galactose?5.12%? and three unknown monosaccharide which accounts for 4.15%, 33.74% and 23.52% respectively.The monosaccharide compositions of DEP-la were L-arabinose?4.51%?, D-xylose?8.46%?, D-mannose?3.99%?, D-glucose ?64.72%?, D-galactose ?18.31%?.Two intracellular polysaccharide named EIP and DIP were studied by FTIR and Free radical scavenging experiments. The results showed that they all contain uronic acid group and good ability for scavenging DPPH radical and hydroxyl radical. The maximum scavenging rate of DPPH radical were 82.32% and 82.02%, the maximum scavenging rate of hydroxyl radical were 66.37% and 53.57% respectively.