There are many textbooks describing very sophisticated laboratory systems for plant cell cultures. However, it is not always necessary to design special laboratories for this technology, but general microbiology laboratories can be used, although aseptic conditions are a prerequisite for incubation of plant cells as well as microbial cultures.

The following equipment is required:

Laminar air flow cabinets: The cabinets are commercially available in different sizes. They are placed in the laboratory where needed. If there is a sterile room, the cabinets are not always necessary.

Autoclave: Autoclaves in different sizes are commercially available.

Oven for dry sterilization: Although autoclaves can be used for dry sterilization, an oven is useful for sterilization of scalpels and glass-wares such as petri-dishes, pipets and others.

Equipment for sterilization by filtration: The medium containing carbon sources and growth regulators are simultaneously sterilized using a autoclave but sometimes aseptic filtration is favorable to avoid decomposition of unstable chemicals. The equipment is also commercially available.

Water distillation apparatus or pure water demineralizer: To prepare media, distilled water or deionized water is generally used although tap water can be used particularly in large-scale cultivation of plant cells in a large fermentor from an economical point of view.

Culture rooms and/or Cabinets: To cultivate the plant cells, culture rooms under different temperature or and/or cabinet-type incubators are essential facilities. Temperature and light intensity as well as a duration of lighting in the room and/or in the cabinet are controlled under the optimal conditions.

Shelves: Shelves built from rigid wire mesh to allow maximum air movement and minimize shading should be used in the culture room.

Shakers: A rotary shaker or a reciprocal shaker is necessary for suspension cultures.

5.2 Fermentors or bioreactors

In order to cultivate plant cells in a large-scale, fermentors with different sizes are useful. Various types of fermentors have been designed by many researchers since the end of 1950's as seen in Fig. 3. The most simple vessel is a carboy system described by Tulecke and Nickell in 1959 (10) which consists of a rubber-stoppered 20 L carboy fitted with four tubes (air-in, air-out, medium-in and sample-out). Filtered compressed air is employed for oxygen supply, aeration and agitation of the medium. A roller-bottled system using a round flask was used by Lamport (31) in 1964. A V-shape fermentor was proposed by Veliky and Martin (32). It is an inverted flask carrying two teflon-coated stirring bars on a glass pin situated at the bottom of the flask. A drain/sample port is also located at the bottom. The top of the flask is fitted with four standard taper penetrations.

However, the most common types of system on the bench is a stirred-jar fermentor which is used for microbial cultivation although some minor alteration is made. For example Martin et al. (33) increased the size of each impeller blade to 1 inch with a commercially available 7.5 L New Brunswick Microferm Fermentor.

Kato et al. (34) suggested that an agitation speed of 50 to 100 r.p.m. was most appropriate for the growth of tobacco cells in stirred-jar fermentors. It is true that cultured plant cells are more fragile than bacterial cells, however, Martin noted: "it seems obvious that cell lines differ in their resistance to shear effects and that a single optimum agitation speed cannot be designed for all lines" (35).

Wagner et al. (36) compared a variety of fermentor types equipped with different agitation and aeration systems with various productivities of cell mass and anthraquinones using Morinda citrofolia cells, and recommended the air-lift type fermentor as the most suitable system (Fig. 4). Tanaka et al. (37) designed a rotary-drum type fermentor having an in-let and an out-let at the side of the fermentor (Fig. 5). The fermentor itself rotates slowly like as a rotary bottle. Recently, Ten Hoopen et al. (38) discussed the problems and profiles of large-scale plant cell culture. However, fermentors installed with agitators which are similar to those of microbial culture have been employed for commercial production of shikonin and ginseng cells although some modification in equipment was made to optimize physical conditions.