Notoginseng Cells Research Articles

Effect of Bottom Clearance on Performance of Airlift Bioreactor in High-Density Culture of Panax notoginseng Cells.

A fed-batch cultivation of Panax notoginseng cells in a concentric-tube airlift reactor was performed to study the effects of bottom clearance on cell growth and the production of ginseng saponin and polysaccharide. At a bottom clearance of 4.0 cm, the highest cell density of 29.1+/-1.6 g/l by dry weight was obtained, and the accumulation of saponin and polysaccharide also reached a maximum, i.e., 2.39+/-0.43 and 2.73+/-0.40 g/l, respectively. Cell growth and metabolite production were limited at a small (2.5 cm) or large (5.0 cm) bottom clearance. By analyzing the time constants of mixing, mass transfer and oxygen consumption, bulk gas-liquid oxygen transfer was found to be responsible for the growth limitation at a small bottom clearance (2.5 cm). The decrease in cell density at a large bottom clearance (5.0 cm) was related to cell sedimentation at the reactor bottom. This work is beneficial for the scale-up and efficient operation of the airlift reactor in cell cultures.

Effect of bottom clearance on performance of airlift bioreactor in high-density culture of Panax notoginseng cells

A fed-batch cultivation of Panax notoginseng cells in a concentric-tube airlift reactor was performed to study the effects of bottom clearance on cell growth and the production of ginseng saponin and polysaccharide. At a bottom clearance of 4.0 cm, the highest cell density of 29.1±1.6 g/ l by dry weight was obtained, and the accumulation of saponin and polysaccharide also reached a maximum, i.e., 2.39±0.43 and 2.73±0.40 g/ l, respectively. Cell growth and metabolite production were limited at a small (2.5 cm) or large (5.0 cm) bottom clearance. By analyzing the time constants of mixing, mass transfer and oxygen consumption, bulk gas-liquid oxygen transfer was found to be responsible for the growth limitation at a small bottom clearance (2.5 cm). The decrease in cell density at a large bottom clearance (5.0 cm) was related to cell sedimentation at the reactor bottom. This work is beneficial for the scale-up and efficient operation of the airlift reactor in cell cultures.

High density cultivation of Panax notoginseng cells in stirred bioreactors for the production of ginseng biomass and ginseng saponin

A novel centrifugal impeller bioreactor (Wang SJ, Zhong JJ. A novel centrifugal impeller bioreactor. I. Fluid circulation, mixing and liquid velocity profiles, Biotechnol. Bioeng. 1996;51:511–519) was used for high-density suspension cultivation of Panax notoginseng cells and its performance was compared with a conventional turbine reactor and a shake flask. The maximum cell density reached 28.9, 26.0 and 22.7 g/l (by dry weight) in the shake flask (SF), centrifugal impeller bioreactor (CIB) and turbine reactor (TR), respectively; and their corresponding biomass productivity was 1103, 900 and 822 mg/(l·day). The total production of ginseng saponin reached about 0.92, 0.80, and 0.49 g/l in the SF, CIB and TR, respectively, and their corresponding saponin productivity was 34, 29 and 21 mg/(l·day). High cell densities (>20 g/l) of P. notoginseng cells were produced in the stirred reactors. It can be concluded that from the viewpoint of biomass production and saponin accumulation, the CIB was better than the TR, and the flask culture results can be well reproduced in the CIB.

Hyperproduction of ginseng saponin and polysaccharide by high density cultivation of Panax notoginseng cells

A high-density culture (HDC) of Panax notoginseng cells for simultaneous production of ginseng saponin (secondary metabolite) and polysaccharide (primary metabolite) was performed in Erlenmeyer flasks. An increase in the initial phosphate concentration up to 3.75 m m was found to be beneficial to the production of these two useful metabolites. The most suitable medium was ascertained to be Murashige and Skoog medium with 1 μ m Cu 2+, 3.75 m m phosphate, and 50 g sucrose l −1. The inoculum size in a range of 2.53–10.2 g dry weight (DW) l −1 had significant effect on the cell growth and metabolite accumulation. By investigating the kinetics and optimizing the environmental conditions of the cell cultures, a cell density of 24 g DW l −1 was obtained in a batch culture. Furthermore, a fedbatch cultivation was attempted to further enhance the cell density and metabolite production. A high cell concentration of 35 g DW l −1 and high production of ginseng saponin (1.57 g l −1) and polysaccharide (5.22 g l −1) were successfully achieved by intermittent feeding of sucrose to keep its medium level below 20 g l −1 in the later part of the cultivation. As observed, the cell sedimentation volume reached almost 100%. The cell density attained may be the upper limit of the suspension cultures of P. notoginseng. The productivities of ginseng saponin and polysaccharide were 2.8 and 3.4-fold higher than those obtained in a conventional batch cultivation.

Regulation of apparent viscosity and O transfer coefficient by osmotic pressure in cell suspensions of Panax notoginseng

As the dry weight to fresh weight ratio of Panax notoginseng cells is related to the medium sugar concentration, the osmotic pressure can be increased by adding glucose to change cells' water content. When the apparent viscosity was decreased from 80.1 to 10 cp the surface O transfer coefficient (K a) increased from 4.80 to 5.68 h by adding 1.23 g glucose to 50 ml culture medium after 24 h.

Enhancement of ginseng saponin production in suspension cultures of Panax notoginseng: manipulation of medium sucrose

The effect of initial sucrose concentration (i.e. 20, 30, 40 and 60 g 1 −1) was investigated in suspension cultures of Panax notoginseng for production of ginseng saponin (secondary metabolite) and polysaccharide (primary metabolite). The final dry cell weight was increased from 8.9 to 11.9 g 1 −1 with an increase of initial sucrose concentration from 20 to 40 g 1 −1, but an even higher sucrose concentration of 60 g 1 −1 seemed to repress the cell growth. The specific growth rate based on active biomass was reduced from 0.084 to 0.067 day −1 with an increase of initial sucrose from 20 to 60 g 1 −1. The initial sucrose amount also had a significant effect on sugar metabolism as well as consumption of nitrate and phosphate. Furthermore, it was found that a high sugar level was favorable to the synthesis of ginseng saponin, which may be due to the high osmotic pressure and reduced nutrient uptake (especially nitrate) under these conditions. The content of ginseng polysaccharide was not apparently affected by initial sucrose levels. The maximum production of ginseng saponin (0.86 g 1 −1) and polysaccharide (1.98 g 1 −1) was achieved at an initial sucrose concentration of 40 g l −1 on day 26. Based on the above findings, a sugar feeding strategy was formulated to enhance the saponin accumulation by P. notoginseng cells. The highest saponin production of 1.77 g 1 −1 (on day 26) was obtained by intermittent sugar feeding during cultivation; the production and productivity of ginseng saponin increased 2.3- and 2.1-fold compared with those of control, respectively.

Effect of Nitrogen Source on Cell Growth and Production of Ginseng Saponin and Polysaccharide in Suspension Cultures of Panax notoginseng

AbstractThe effects of the nitrate to ammonium ratio on the cell growth, the production of ginseng saponin (secondary metabolite) and polysaccharide (primary metabolite), as well as consumption of major nutrients by suspension cultures of Panax notoginseng cells were investigated at a total nitrogen (N) of 60 mM in a 250‐mL Erlenmeyer flask. The results indicate that the ratio of nitrate to ammonium had a great influence on the cell growth and consumption of carbon and N sources. It was found that biosynthesis of saponin was more susceptible to the ratio of NO3−/NH4+ than that of polysaccharide. Ammonium was unfavorable to saponin formation. The maximum production of ginseng saponin and polysaccharide was attained when nitrate was the sole N source. The effect of total N amount (using nitrate as the sole N source) on the cell cultures was also studied, and the result shows that the dry cell weight was increased from 4.9 to 10.9 g/L with increase of initial nitrate concentration from 0 to 60 mM. The relationship between initial nitrate concentration (including both intracellular and medium nitrate) and specific cell growth rate based on active biomass could be described by Monod equation, in which the kinetic parameters μmax and Ks were determined to be 0.066 d−1 and 4.84 mM, respectively. The maximum production of ginseng saponin and polysaccharide was 0.85 and 1.59 g/L, respectively, with initial nitrate concentration of 60 mM.

Effect of osmotic pressure on cell growth and production of ginseng saponin and polysaccharide in suspension cultures of Panax notoginseng

The effects of initial osmotic pressure (IOP) on the production of ginseng polysaccharide and ginseng saponin were studied in suspension cultures of Panax notoginseng cells. At higher IOP, the specific saponin production and intracellular carbohydrate storage were increased, while the plant cell volume, the consumption rates of major medium components and the specific cell growth rate were decreased. The specific production of polysaccharide was reduced with an increase of IOP from 4.45 to 5.18 atm, and levelled off at an even higher IOP.

A simple and modified manometric method for measuring oxygen uptake rate of plant cells in flask cultures

A simple and convenient technique was developed based on the principle of Warburg manometric method to measure O2 uptake rate (OUR) and CO2 evolution rate (CER) of suspended cells in a shake flask culture. It was successfully applied to suspension cultures of rice (Oryza sativa) and Panax notoginseng cells, and some important bioprocess parameters, such as OUR, CER, respiratory quotient (RQ), specific OUR (SOUR) and specific CER (SCER), were quantitatively obtained. The measuring system is easy to operate, able to treat many samples simultaneously and is economical.