Transient studies of nutrient uptake, growth, and indole alkaloid accumulation in heterotrophic cultures of hairy roots of Catharanthus roseus

✍ Scribed by Rajiv Bhadra; Jacqueline V. Shanks

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 218 KB
• Volume: 55
• Category: Article
• ISSN: 0006-3592
• DOI: 10.1002/(sici)1097-0290(19970805)55:3<527::aid-bit9>3.0.co;2-e

✦ Synopsis

The kinetics of growth, the uptake of macronutrients, and the accumulation of indole alkaloids were investigated in long-term, heterotrophically cultured transgenic (''hairy'') roots of Catharanthus roseus. Tabersonine, ajmalicine, and serpentine were monitored over a 70-day period. The doubling time [dry-weight (DW) basis] of C. roseus hairy roots in B5/2 nutrients supplemented with 3% sucrose was 3.6 days. NH 4 + , NO 3 , -and P i were depleted sequentially from culture medium by hairy roots, while sugars remained undepleted. The growth-limiting nutrient was inorganic nitrogen, NH 4 + and NO 3 -, with exponential-phase overall biomass yields of 34.1 and 5.0 g DW/g nutrient, respectively. Extracellular pH decreased to 4.8 in early exponential phase of culture growth from the initially adjusted value of 5.7, increased subsequently to a maximum of 7.7 in late exponential phase of growth coincident with the maximum of fresh weight (FW)/DW ratio, before decreasing to 5.5-5.0. The organic acids, pyruvate, formate, lactate, and succinate were excreted by hairy roots starting in late phase of exponential growth, possibly resulting in the late-culture pH decrease. Tabersonine accumulation was distinctly growth associated with maximum specific and total yields of 1.15 mg/g DW and 5.6 mg/L, respectively, in late-exponential phase of growth. Serpentine accumulation was non-growth associated with increasing specific and total levels in stationary growth phase: 1.3 mg/g DW and 10.5 mg/L, respectively. The accumulation of ajmalicine also appeared growth associated.