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

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 degrees C was initially faster than at either 25 degrees C or 35 degrees C and by day 12, the drained weight of roots in the fermentor at 30 degrees C was about fourfold greater than at 25 degrees C and twice that at 35 degrees C. The ultimate hyoscyamine levels attained (approximately 0.5 mg.g-1 wet weight) were similar at both 25 degrees C and 30 degrees C but some 40% lower at 35 degrees C. Final packing densities of 70% w/v were achieved for roots after 37 days growth at 25 degrees C and the highest production rate of 8.2 mg hyoscyamine 1(-1) per day was obtained for roots grown at 30 degrees C. In continuous fermentation at 25 degrees 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 degrees C or 35 degrees C.