EFFECT OF SUCROSE, EXOGENOUS PRODUCT CONCENTRATION, AND OTHER CULTURECONDITIONS ON GROWTH AND STEROIDAL ALKALOID PRODUCTION BY SOLANUM AVICULARE HAIRY ROOTS

Growth and steroidal alkaloid production by Solanum aviculare hairy ro ots were investigated as a function of temperature, initial sucrose an d exogenous solasodine concentrations, and medium osmolality. Root gro wth measured as dry weight was significantly affected by initial sucro se concentrations between 2 and 12%; however, sucrose levels below 6-9 % did not significantly alter the specific alkaloid content. Biomass p roduction was maximum and about 60% higher than in 3% sucrose medium w hen the initial sucrose concentration was 4-6%. The effect of sucrose concentration on growth could not be attributed to osmotic effects, st arch accumulation in the roots, or sugar depletion at the lower sugar levels. No significant difference at the 0.01 level in growth rate or alkaloid yield was found between seven root clones cultured in either 3 or 6% sucrose medium. The minimum root doubling time occurred at 25 degrees C; doubling times at 20 degrees C, 30 degrees C, and 37 degree s C were between 1.1 and 3.4 times higher. Experiments with exogenous solasodine added to the medium revealed that growth is strongly inhibi ted by extracellular product concentrations as low as 2 mg l(-1). Nett steroidal alkaloid production declined to negative values when more t han 10 mg l(-1) solasodine was added, indicating that degradation or c onversion of solasodine occurred. As extracellular concentrations can reach at least this level in batch culture, in situ removal of product is recommended for solasodine production systems.