Growth and hyoscyamine production of ‘hairy root’ cultures of Datura stramonium in a modified stirred tank reactor

Summary

The growth and hyoscyamine production of transformed roots of Datura stramonium have been examined in a modified 14-1 stirred tank reactor in both batch and continuous fermentations on media containing half or full strength Gamborg's B5 salts and at three different temperatures. Under a range of conditions, roots grown on half strength B5 salts with 3% w/v sucrose had a higher dry matter content (up to 8.3% w/w) and a higher hyoscyamine content (up to 0.52 mg·g⁻¹ wet weight) than roots grown on full strength B5 salts with the same level of sucrose (up to 4.6% w/w dry matter and up to 0.33 mg hyoscyamine g⁻¹ wet weight). Growth at 30°C was initially faster than at either 25°C or 35°C and by day 12, the drained weight of roots in the fermentor at 30°C was about fourfold greater than at 25°C and twice that at 35°C. The ultimate hyoscyamine levels attained (approximately 0.5 mg·g⁻¹ wet weight) were similar at both 25°C and 30°C but some 40% lower at 35°C. Final packing densities of 70% w/v were achieved for roots after 37 days growth at 25°C and the highest production rate of 8.2 mg hyoscyamine l⁻¹ per day was obtained for roots grown at 30°C. In continuous fermentation at 25°C, the release of hyoscyamine into the culture medium was low (less than 0.5% w/w of the total) but was up to sevenfold higher in fermentors operated at 30°C or 35°C.