Solasodine production from self-immobilised Solanum aviculare cells

Procedures were developed for 'self-immobilisation' of Solanum aviculare cells to eliminate the need for artificial immobilisation supports. Depending on the cytokinin used in liquid medium, compact aggregates 0.4-2.0 cm in diameter were formed without dispersed cells also being present. Histochemical analysis showed that the aggregates were structurally organised to facilitate nutrient transport. Growth, sugar uptake and solasodine production were measured in shake-flask cultures. Most of the product was stored in the aggregates to reach a maximum concentration of 0.3% dry weight; this is between 1.5 and 10 times the levels reported for suspended cells under similar conditions. A substantial amount of solasodine was produced after growth ceased. The maximum rate of solasodine production was about 0.22 mg g-1 d-1. A simple air-driven bioreactor was tested for culture of the aggregates; solasodine yields were comparable to those measured in shake flasks.