46 Fermentation and Biochemical Engineering Handbook tissue culture nurseries throughout the world. Most of these tissue culture nurseries are using flasks or bottles containing agar medium for commercial propagation, but the efficiency is also low. In order to improve the efficiency, use of a bioreactor is desirable. Using a small bioreactor (4 to 10 liters), the author has produced over 4, 000 to 10, 000 plantlets within I to 2 months. The bioreactor system allows the induction of somatic embryos from vegetative cells which then leads to the production of artificial seeds(Rodenbaugh et al 1987).2 3. 4 Bioreactors-Hardware Configuration The configuration of bioreactors most frequently used for plant cell tissue, and organ cultures is fundamentally the sameas that used for microbial or animal cell cultures. However, in plants, the cells, tissues, and organs are all susceptible to mechanical stresses by medium aeration and agitation. At times, the production of both cells mass and metabolites is repressed severely and the bioreactor must therefore have the characteristics of low shear stresses and efficient oxygen supply. For these reasons, different bioreactors (Fig. 18)have been investigated in order to select the most suitable design Wagner and Vogelmann( 1977)3 have studied the comparison of different types of bioreactors for the yield and productivity of cell mass and anthraqui- none(Fig. 19). Among different types of bioreactors, the yield of anthraqui- nones in the air-lift bioreactor was about double that found in those bioreactors with flat blade turbine impellers, perforated disk impellers, or draft tube bioreactors with Kaplan turbine impellers. It was also about 30% higher than that of a shake flask culture. Thus, the configuration of the bioreactor is very important and development efforts are underway for both bench scale and pilot scale bioreactors Aeration-Agitation Bioreactor. This type of bioreactor(Fig. 20)is popular and is fundamentally the same as that used with microbial cultures For small scale experiments, the aeration-agitation type bioreactors is widely used. However, when the culture volume is increased, many problems arise The following are some of the scale-up problems in large aeration-agitation bioreactors: (i)increasing mechanical stresses by impeller agitation and (ii) increasing foaming and adhesion of cells on the inner surface of the bioreactor. Despite these problems, a large scale pilot bioreactor(volume 20 kl)was constructed. It successfully produced both cell mass and metabolites This bioreactor is therefore the most important type for bioreactor systems
46 Fermentation and Biochemical Engineering Handbook tissue culture nurseries throughout the world. Most of these tissue culture nurseries are using flasks or bottles containing agar medium for commercial propagation, but the efficiency is also low. In order to improve the efficiency, use of a bioreactor is desirable. Using a small bioreactor (4 to 10 liters), the author has produced over 4,000 to 10,000 plantlets within 1 to 2 months. The bioreactor system allows the induction of somatic embryos from vegetative cells which then leads to the production of artificial seeds (Redenbaugh et al., 1987).['*] 3.4 Bioreactors-Hardware Configuration The configuration of bioreactors most frequently used for plant cell, tissue, and organ cultures is hndamentally the same as that used for microbial or animal cell cultures. However, in plants, the cells, tissues, and organs are all susceptible to mechanical stresses by medium aeration and agitation. At times, the production of both cells mass and metabolites is repressed severely and the bioreactor must therefore have the characteristics of low shear stresses and efficient oxygen supply. For these reasons, different bioreactors (Fig. 18) have been investigated in order to select the most suitable design. Wagner and Vogelmann ( 1977)[131 have studied the comparison of different types of bioreactors for the yield and productivity ofcell mass and anthraquinone (Fig. 19). Among different types of bioreactors, the yield of anthraquinones in the air-lift bioreactor was about double that found in those bioreactors with flat blade turbine impellers, perforated disk impellers, or draft tube bioreactors with Kaplan turbine impellers. It was also about 30% higher than that of a shake flask culture. Thus, the configuration of the bioreactor is very important and development efforts are underway for both bench scale and pilot scale bioreactors. Aeration-Agitation Bioreactor. This type of bioreactor (Fig. 20) is popular and is fundamentally the same as that used with microbial cultures. For small scale experiments, the aeration-agitation type bioreactors is widely used. However, when the culture volume is increased, many problems arise. The following are some of the scale-up problems in large aeration-agitation bioreactors: (i) increasing mechanical stresses by impeller agitation and (ii) increasing foaming and adhesion of cells on the inner surface of the bioreactor. Despite these problems, a large scale pilot bioreactor (volume 20 kl) was constructed. It successfully produced both cell mass and metabolites. This bioreactor is therefore the most important type for bioreactor systems
tt B D E (12 Rs H Figure 18. Different types of bioreactors for plant cells, tissues and organs. (A)Shake Flask.(B) Aeration-Agitation. (C) Percolated Impeller.(D) Draught Tube Air-lift.(E Draft Tube with Kaplan Turbine. (F) Air-lift loop.(G)Rotating Drum. (B) Light Emittir Draught Tube. ( )Spin Filter. () Bubble Column. (K) Aeration.()Gaseous Phase
Fermentation Pilot Plant 47
48 Fermentation and Biochemical Engineering Handbook 目 dry weight四 metabolite口 dry weight■ metabolite productivity ity for cell mass and anthraquinones in systems.(1)Shake Fla Flat Blade Turbine. ()Perfolated Disk (4 Draft Tube Bioreactor with Turbine, (5)Air-lift Bioreactor. Air Driven Bioreactors. The simplest design is the air-driven bioreactor equipped with sparger at the bottom of the vessel. It is widely used for plant cell, tissue, and organ cultures. In cases wherethe cells grow rapidly and the cell mass occupies 40-60% of the reactor volume, the flow charac teristics become non Newtonian and the culture medium can no longer be agitated by simple aeration Rotating Drum bioreactor The rotating drum bioreactor(Fig. 21) turns on rollers and the oxygen supply mechanism is entirely different from either the mechanically agitated or the air-lift bioreactor. Tanaka et al (1983), 4) reported that the oxygen transfer coefficient is affected by a change of airflow rate under all rotational speeds(Fig. 22). This character istic is suitable not only for the growth of plant cell, tissue, and organs but also for the production of metabolites under high viscosity and high density cultures. It is superior to the cultures using either mechanically agitated air-lift bioreactors since the cultures are supplied ample oxygen and are only used for a pilot scale experiment (Tanaka 1987). ye was constructed and weakly stressed. Recently a I kl bioreactor of this typ
48 Fermentation and Biochemical Engineering Handbook 10 I 0.5 wrn 100 rprn I 101 0.5 wm 100 rprn I u4 75 I 0.33 vvm 350 rprn dry weight metabolite JJ dry weight metabolite yield productivity Figure 19. Comparison of yield and productivity for cell mass and anthraquinones in various bioreactor systems. (1) Shake Flask. (2) Flat Blade Turbine. (3) Perfolated Disk Impeller. (4) Draft Tube Bioreactor with Kaplan Turbine. (5) Air-lift Bioreactor. Air Driven Bioreactors. The simplest design is the air-driven bioreactor equipped with sparger at the bottom ofthe vessel. It is widely used for plant cell, tissue, and organ cultures. In cases where the cells grow rapidly and the cell mass occupies 40-60% of the reactor volume, the flow characteristics become non-Newtonian and the culture medium can no longer be agitated by simple aeration, Rotating Drum Bioreactor. The rotating drum bioreactor (Fig. 21) turns on rollers and the oxygen supply mechanism is entirely different from either the mechanically agitated or the air-lift bioreactor. Tanaka et al., ( 1983),[14] reported that the oxygen transfer coefficient is affected by a change of airflow rate under all rotational speeds (Fig. 22). This characteristic is suitable not only for thegrowth ofplant cell, tissue, and organs but also for the production of metabolites under high viscosity and high density cultures. It is superior to the cultures using either mechanically agitated or air-lift bioreactors since the cultures are supplied ample oxygen and are only weakly stressed. Recently a 1 kl bioreactor of this type was constructed and used for a pilot scale experiment (Tanaka 1987).[15]
fermentation pilot plant 49 99 Figure 20. Ninety-five liter automated bioreactor for plant cell, tissue and organ cultures Photo courtesy ofK. F. Engineering Co, Ltd, Tokyo) BAFFLE PLATE SENSOR AIR一 Figure 21. Schematic diagram of the rotating drum bioreactor(Tanaka, H, et al., 1983)
Fermentation Pilot Plant 49 Figure 20. Ninety-five liter automated bioreactor for plant cell, tissue and organ cultures. (photo courtesy ofK. F. Engineering Co., Ltd., Tokyo). BAFFLE OXYGEN PLATE SENSOR ¥ ~8 AIR-~ (!) Figure 21. Schematic diagram of the rotating drum bioreactor (Tanaka, H., et al., 1983)