Nuôi cấy tế bào Nhân sâm Panax ginseng trong
bioreactor: Vai trò của ôxy trong sản xuất sinh khối và
sản phẩm ginsenoside
Ảnh hưởng của nồng độ ôxy (20.8-50%) đến quá trình nuôi
cấy tế bào Panax ginseng đã được nghiên cứu trong
bioreactor hình cầu với dung tích 5l có chứa 4l môi trường
MS. Ở nồng độ ôxy 40% đã cho thấy là thích hợp cho việc
sản xuất sinh khối và sản phẩm ginsenoside với kết quả thu
được là 12.8 g/L sinh khối khô, và 4.5 mg/g SKK
ginsenoside vào ngày thứ 25. Các nồng độ ôxy 20.8, 30 và
50% là không thích hợp cho quá trình nuôi cấy tế bào cũng
như sự tích lũy sản phẩm ginsenoside. Kết quả trên đây
cũng chỉ ra rằng ôxy là nhân tố hữu hiệu trong sản xuất
sinh khối và sản phẩm ginsenoside ở quy mô lớn hơn.
I. ABSTRACT

The effects of oxygen supply within the range of 20.8%-
50% (along with purified air), on high-density cell culture
of Panax ginseng were investigated in an balloon type
bioreactor (5 l capacity and containing 4 l of MS medium).
A 40% oxygen supply was found optimal for the
production of cell mass and ginsenoside with
corresponding values of 12.8 g l
-1
DW, 4.5-mg/g DW on
day 25, respectively. A low (20.8%, 30%) and well as high
concentration of oxygen (50%) supply was unfavorable to
the cell cultures and they affect the cell growth and

(Rao and Ravishankar, 2002). Growth and accumulation of
secondary metabolites in large-scale bioreactors is
influenced by various factors such as shear stress, oxygen
supply, and gas composition. A conventional stirred-tank
bioreactor can produce a high shear region, while in many
cases airlift and bubble column reactors are used for
providing shear environment compared to turbine-agitated
reactors. As reported, oxygen supply is also significant in
affecting secondary metabolites formation in cell cultures
(Gao and Lee, 1992; Zhong et al., 1993; Han and Zhong,
2003). Gas exchange between the gas and liquid phases is
another important factor that may affect the scale-up of
plant cell cultures. In bioreactors, forced aeration is needed
to supply oxygen and to improve fluid mixing. However, it
may also lead to the removal of some known (such as CO
2

and ethylene) or unknown gaseous compounds. Such
gaseous metabolites were proven or suggested to be
important for cell growth and/or synthesis of secondary
metabolites in plant cell cultures (Gao and Lee, 1992). The concentration of dissolved oxygen can be easily
controlled in bubble/airlift bioreactors and interaction
between O
2
supply, cell growth and metabolite biosynthesis
can be observed. In this study, we have used balloon type
bioreactors for cell cultures of ginseng and the interaction

(control), 30%, 40%, and 50%. The schematic diagram of
the whole experimental system is shown in Fig. 1. The
cultivation temperature was controlled at 25±2
o
C and
continuous darkness was maintained. Three identical
cultivation vessels were operated under each condition, and
the cultivation data shown represent average values with
standard deviations. The bioreactor cultures were
maintained up to 30 days.

Sampling and analyses of cell weight, medium sugar,
conductivity A sample of 30 ml of cell culture was taken once from each
bioreactor at an interval of every five days. The cell
suspensions were filtered and washed several times with
distilled water for the measurement of cell weights (fresh
and dry weights). The culture supernatants were used for
analysis residual sugar, using HPLC by following
analytical procedures described by Zhang and Zhong,
(1997) and Woragidbum-rang et al., (2001). The electrical
conductivity was from the exhausted medium using
conductivity meter Wiss-teelm-werkstalten model LF-54
(WTW GmbH, Wielhalm, Germany).


and turbine reactors cultures (Zhong et al., 1999). The
maximum fresh weight with the supply of 20.8% oxygen
(control) was 267 g l
-1
and corresponding dry weight was
11.5 g l
-1
(Fig. 2A-B). It was found that optimum
accumulation of fresh (316 g l
-1
) and dry biomass (12.8 g l
-
1
) was with the supply 40% oxygen in the bioreactors. The
biomass accumulation comparatively declined with the
increase in oxygen concentration to 50% (255 g l
-1
FW and
9.0 g l
-1
DW). Fig. 2. Time profiles of fresh cell weight (A), dry cell
weight (B) in high-density culture
of Panax ginseng cells in a 5 l balloon type bioreactor.


2
supply was lower than that of control (11.5 g l
-1
versus
9.5 g l
-1
on day 25) and it means that carbon flux was
altered by O
2
concentration. A similar phenomenon has
also been reported during cell culture in Catharathus roseus
(Tate and Payne, 1991) and in P. notoginseng (Han and
Zhong, 2003). Fig. 3. Time profiles of medium conductivity (A), residual
sugar (B) in high-density cultures
of Panax ginseng cells in a 5 l balloon type bioreactor. Effect of oxygen concentration on metabolite
production The kinetic profile of total ginsenosides (saponin)
production is shown in Fig. 4. Highest saponin
accumulation was on day 20 to 25 and later it declined.

productivity because of the stripping of CO
2
and other
essential volatiles from the system. An alternative approach
is improving the quality of incoming air by with oxygen
concentration. In the present experiment we have
supplemented the incoming air with different ratios of pure
oxygen, which facilitates oxygen transfer rates, improves
the accumulation of biomass of cultured cell and in turn
accumulation of metabolites. Fig. 4. Kinetics of production of ginseng saponin of Panax
ginseng cells in high-density bioreactor cultivations.

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