Johnston Wayne A, Stewart Meredith, Lee Peter, Cooney Michael J
Hawaii Natural Energy Institute, University of Hawaii-Manoa, 1680 East West Road, POST 109, Honolulu, HI 96822, USA.
Biotechnol Bioeng. 2003 Nov 5;84(3):314-23. doi: 10.1002/bit.10772.
DO-transient nutrient controllers use the dissolved oxygen signal to attempt acetate threshold tracking during fed-batch cultivation of recombinant E. coli. Here we apply DO-transient control to the production of Jembrana disease virus protein in complex Super Luria medium and compare performance against a high-limit pH-stat controller. For induction at medium cell density (harvest between 31 and 32.5 g dcw L) a total productivity of 0.27 g L h was achieved as compared to 0.24 g L h with the high-limit pH-stat. For induction at high cell density (harvest at 60 g dcw L), decreased productivity (0.12 g L h) was attributed to the effect of acetate accumulation on recombinant protein formation and a concomitant lowering of the critical growth rate. Our results suggest that complex media provides a difficult environment for the application of acetate threshold tracking DO-transient control because of difficulties in re-oxidizing acetate, and apparent localized production of acetate below the production threshold (as detected by the DO-transient controller as SPOUR(crit)). Configuring the DO-transient controller to avoid aggressive threshold probing is suggested as a means to improve performance and reduce acetate accumulation in complex media.
溶解氧瞬态营养物控制器利用溶解氧信号，试图在重组大肠杆菌的补料分批培养过程中跟踪乙酸盐阈值。在此，我们将溶解氧瞬态控制应用于在复杂的超级鲁里亚培养基中生产詹氏病病毒蛋白，并将其性能与高限pH稳态控制器进行比较。对于在中等细胞密度下诱导（收获时细胞干重为31至32.5 g/L），总生产率达到0.27 g/(L·h)，而高限pH稳态控制下为0.24 g/(L·h)。对于在高细胞密度下诱导（收获时细胞干重为60 g/L），生产率降低（0.12 g/(L·h)）归因于乙酸盐积累对重组蛋白形成的影响以及临界生长速率的相应降低。我们的结果表明，由于乙酸盐再氧化困难以及在生产阈值以下明显的局部乙酸盐产生（溶解氧瞬态控制器检测为SPOUR(crit)），复杂培养基为应用乙酸盐阈值跟踪溶解氧瞬态控制提供了一个困难的环境。建议配置溶解氧瞬态控制器以避免激进的阈值探测，作为提高性能和减少复杂培养基中乙酸盐积累的一种手段。
