Transgenic "hairy" roots of Hyoscyamus muticus, immobilized within an ebb-and-flow bioreactor (EFBR), were cultured for a period of 18 d. The growth results showed that a 2.5-L EFBR, with a productivity of 0.481 g DW/L-d and an average specific growth rate (μ) of 0.211/d, duplicated the growth performance of the standard 50-mL shake-flask control, successfully demonstrating scale up at 50x scale. The 250-mL shake flask, the 2.5-L sparged submerged-phase bioreactor (SSBR), and the 2.0-L SSBR all failed to accomplish the same. The growth performance of the EFBR was also investigated in a treatment where the normal EFBR treatment's liquid-phase duration (μt L) of 4 min was increased to 7 min (called the LDT treatment) and in another treatment where the normal EFBR treatment's gas-phase duration (ΔtG) of 4 min was increased to 10 min (called the GDT treatment). The resulting intermediate growth performance exhibited by the LDT treatment or the GDT treatment, which was neither significantly lower than that of the normal EFBR treatment nor significantly greater than that of the SSBR control, demonstrated that the tested values of (ΔtL) max = 7 min and (ΔtG)max = 10 min coincided, if roughly, with the empirical EFBR phase-duration limits beyond which the EFBR regime would fail to satisfy the physiological requirements of the growing root culture. The results also suggested that increasing the liquid-phase duration to ΔtL = 7 min or the gas-phase duration to ΔtG = 10 min caused a limitation in the mass transfer of oxygen within the EFBR. In each case, oxygen mass-transfer limitation preceded sugar mass-transfer limitation, underscoring that oxygen delivery through forced convective flow is the critical variable in the scale up of the EFBR. The acceptable (ΔtL)max and (Δt G)max for the EFBR were demonstrated to fall between 4 and 7 min.
|Number of pages
|Transactions of the American Society of Agricultural Engineers
|Published - Sep 2003
All Science Journal Classification (ASJC) codes
- Agricultural and Biological Sciences (miscellaneous)