Application of bioreactors for large-scale micropropagation systems of plants

The application of bioreactor culture techniques for plant micropropagation is regarded as one of the ways to reduce production cost by scaling-up and automation. Recent experiments are restricted to a small number of species that, however, demonstrate the feasibility of this technology. Periodic im mersion liquid culture using ebb and flood system and column-type bubble bi oreactors equipped with a raft support system to maintain plant tissues at the air and liquid interface were found to be suitable for micropropagation of plants via the organogenic pathway. Balloon-type bubble bioreactors pro ved to be fit for micropropagation via somatic embryogenesis with less shea r stress on cultured cells. Several cultivars of Lilium were successfully p ropagated using a two-stage culture method in one bioreactor. A large numbe r of small-scale segments were cultured for 4 wk with periodic immersion li quid culture to induce multiple bulblets from each segment, then the bulble t induction medium was changed into bulblet growth medium by employing a su bmerged liquid bioreactor system. This culture method resulted in a nearly 10-fold increase in bulblet growth compared to conventional culture with so lid medium. About 20 000 cuttings of virus-free potato could be obtained fr om 120 single-node explants in a 20-liter balloon-type bubble bioreactor af ter 8 wk of culture. The percentage of ex vitro survival and root induction of the cuttings was more than 95%. Other successful results were obtained from the micropropagation and transplant production Of chrysanthemum, sweet potato, Chinese foxglove. Propagation systems via somatic embryogenesis in Acanthopanax koreanum and thornless Aralia elata were established using a l iquid suspension of embryogenic. determined cells. More than 500 000 somati c embryos in different stages were harvested from a 10-liter balloon-type b ubble bioreactor after a 6-wk culture. Further development of these embryos in solid medium and eventually in the field was successful. The bioreactor system could reduce initial and operational cost for micropropagation, but further development of sophisticated technology might be needed to apply t his system to plant micropropagation industries.