Tianjin University of Science and Technology, China.
Appl Biochem Biotechnol. 2010 Jan;160(2):552-60. doi: 10.1007/s12010-008-8428-4. Epub 2008 Nov 19.
The liquid suspension culture of dissociated Nostoc flagelliforme cells was investigated. It was found that the growth rate of N. flagelliforme cells and the accumulation of exopolysaccharides (EPS) increased prominently when NaNO(3) and KH(2)PO(4) were added in the liquid BG-11culture medium though phosphate had little effect on EPS yield for specific mass of cells. N. flagelliforme cells grew well at 25 degrees C and neutral pH, however, a lower or higher temperature and weak alkaline can promote EPS accumulation. With the increase of the light intensity, the growth rate of N. flagelliforme cells and the EPS accumulation increase accordingly. When N. flagelliforme cells was cultured in BG-11 medium added with 2.5 g L(-1) of NaNO(3) and 0.956 g L(-1) of KH(2)PO(4) at 25 degrees C with 60 micromol photon m(-2) s(-1) of light intensity, 1.05 g L(-1) cell density and 89.9 mg L(-1) EPS yield were achieved respectively. Adopting the optimal conditions established in flask culture, the liquid culture of N. flagelliforme cells in 20-L photobioreactor for 16 days was conducted and a maximum biomass of 1.32 g L(-1) was achieved, which was about 17.6-fold of that in the initial inoculation. The yield of EPS was 228.56 mg L(-1)and about 2.23-fold of that in flask culture. Moreover, the polysaccharides' material was released into the culture medium during cell growth. These released polysaccharides (RPSs), which can be easily recovered from the medium, are favorable for industrial applications.
已分化的念珠藻细胞液体悬浮培养的研究。结果表明，当在 BG-11 液体培养基中添加 NaNO3 和 KH2PO4 时，念珠藻细胞的生长速度和胞外多糖（EPS）的积累明显增加，尽管磷酸盐对细胞比产率的 EPS 产量影响很小。念珠藻细胞在 25℃和中性 pH 条件下生长良好，但较低或较高的温度和弱碱性条件可以促进 EPS 积累。随着光照强度的增加，念珠藻细胞的生长速度和 EPS 的积累相应增加。当在 BG-11 培养基中培养念珠藻细胞，添加 2.5 g/L 的 NaNO3 和 0.956 g/L 的 KH2PO4，在 25℃下，光照强度为 60 μmol 光子 m-2 s-1 时，细胞密度达到 1.05 g/L，EPS 产率达到 89.9 mg/L。采用在摇瓶培养中建立的最佳条件，在 20-L 光生物反应器中进行了念珠藻细胞的液体培养 16 天，获得了最大生物量 1.32 g/L，是初始接种量的 17.6 倍。EPS 的产率为 228.56 mg/L，是摇瓶培养的 2.23 倍。此外，细胞生长过程中多糖物质被释放到培养基中。这些释放的多糖（RPS）可从培养基中轻易回收，有利于工业应用。
