Mass Propagation of Multiple Shoots Using a Large Bioreactor

The shoot primordium is a suitable inoculant for large scale culture of shoots comparing with the shoot. itself. A culture method of multiple shoots starting from the shoot primordium was established. The influence of scale up conditions on the growth of multiple shoots originating from the primordia was also investigated. Shoot primordium of Stevia rebaudiana has been induced and maintained in modified MS liquid medium containing NAA and BA. The primordia grew constantly by about 7 times in 1 month in the liquid shake culture. The multiple shoots were then induced efficiently from the primordia by eliminating the growth hormones from the MS medium. They grew constantly by about 20 times in 1 month in the liquid shake culture. The growth of shoots in culture vessels of different sizes, 0.3 l (flask), 6 l (jar fermentor) and 500 l (bioreactor), were compared by inoculating the primordia at a fixed density of about 10 gl-1. The shoots grew actively to fill up culture vessels within a month, and the final weight of shoots per unit volume of medium was similar in each culture vessel. This result strongly suggests that multiple shoots can be mass propagated in a large scale without affecting the culture efficiency.