Growth and Secondary Metabolite Production by Hairy Roots of Tagetes Patula in Aqueous Two-Phase Systems

Hairy roots of Tagetes patula have been grown in aqueous two-phase systems. After selecting suitable polymers from single-phase experiments (in which salt phases were unable to support growth in the desired concentrations) several two-phase systems were tested for their influence on cell growth and thiophene production. Cell growth occurred in all aqueous two-phase systems, but the highest growth rate was achieved in normal medium. There was no difference in thiophene production between medium and aqueous two-phase systems. The partition of thiophenes favoured slightly the more hydrophobic top phase in most cases, while the cells were confined to the bottom phase. One aqueous two-phase system (15% polyethyleneglycol 10,000 and 15% Reppal PES 200) was tested in a stirred tank reactor with normal medium as a control. The growth rate in medium was higher than in the aqueous two-phase system, while the thiophene production per unit cell weight was in the same range for both systems. The excretion of thiophenes in the reactor with the aqueous two-phase system was about ten times as high as in the control reactor. The amount excreted was however still not more than 3% of the total production.