Therefore, studies on the production of useful metabolite by plant cell culture have been carried out on an increasing scale since the end of the 1950's. The large scale cultivation of tobacco and various vegetable cells was examined in the late 1950's and early 1960's in the U.S., Canada, and Europe. Their results stimulated more recent studies on the industrial application of this technology in many countries.

Since plant cells can be cultivated in various fermentors in a similar way to microbial fermentations, many industrial companies in Japan have tried to apply this technology to commercial production of useful compounds because Japan has a highly developed fermentation technology. At present, two Japanese firms are manufacturing a plant pigment, shikonin, and ginseng cell biomass on a commercial scale and several other products including anti-cancer drugs seem to be close to commercialization.

However, there are still a few barriers which must be overcome before commercialization of many other products can occur. The production cost of metabolites is one of the problems because of the low productivity of cultured plant cells. In order to decrease the cost, increase of production efficiency per cell is an essential factor, which means that higher amounts of products must be produced as quickly as possible. A variety of approaches to improve the productivity of the culture have been tried and some of them were very effective.

In this review, the background of plant cell culture research, cost analysis, methods and facilities, various approaches to improve the productivity, and studies on production of a number of commercially interesting products which have currently been investigated are described.