Junker Beth, Walker Andre, Hesse Michelle, Lester Mike, Christensen Jens, Connors Neal
Fermentation Development and Operations, Bioprocess Research and Development, Merck Research Laboratories, Rahway, NJ 07065, USA.
Biotechnol Prog. 2009 Jan-Feb;25(1):176-88. doi: 10.1002/btpr.122.
An Amycolatopsis fastidiosa culture, which produces the nocathiacin class of antibacterial compounds, was scaled up to the 15,000 L working volume. Lower volume pilot fermentations (600, 900, and 1,500 L scale) were conducted to determine process feasibility at the 15,000 L scale. The effects of inoculum volume, impeller tip speed, volumetric gas flow rate, superficial gas velocity, backpressure, and sterilization heat stress were examined to determine optimal scale-up operating conditions. Inoculum volume (6 vs. 2 vol %) and medium sterilization (R(o) of 68 vs. 92 min(-1)) had no effect on productivity or titer, and higher impeller tip speeds (2.1 vs. 2.9 m/s) had a slight effect (20% decrease). In contrast, higher backpressure, incorporating increased head pressure at the 15,000 L scale (1.2 vs. 0.7 kg/cm(2)) and low gas flow rates (0.25 vs. 0.8 vvm), appeared to be problematic (40-50% decrease). High off-gas CO2 levels were likely reasons for observed lower productivity. Consequently, air flow rate for this 25-fold scale-up (600-15,000 L) was controlled to match off-gas CO2 profiles of acceptable smaller scale batches to maintain levels below 0.5%. The 15,000 L-scale fermentation achieved an expected nocathiacin I titer of 310 mg/L after 7 days. Other on-line data (i.e., pH, oxygen uptake rate, and CO2 evolution rate) and off-line data (i.e., analog production, glucose utilization, ammonium production, and dry cell weight) at the 15,000 L scale also tracked similarly to the smaller scale, demonstrating successful fermentation scale-up.
一种产生诺卡硫霉素类抗菌化合物的苛求无枝酸菌培养物被扩大到15000升的工作体积。进行了较低体积的中试发酵（600升、900升和1500升规模），以确定15000升规模下的工艺可行性。研究了接种量、叶轮尖端速度、体积气体流速、表观气体流速、背压和灭菌热应激的影响，以确定最佳的放大操作条件。接种量（6%对2%体积）和培养基灭菌（R₀为68对92分钟⁻¹）对生产率或效价没有影响，较高的叶轮尖端速度（2.1对2.9米/秒）有轻微影响（降低20%）。相比之下，较高的背压，包括在15000升规模下增加的压头压力（1.2对0.7千克/平方厘米）和低气体流速（0.25对0.8体积/体积·分钟），似乎存在问题（降低40 - 50%）。尾气中高二氧化碳水平可能是观察到生产率较低的原因。因此，将这种25倍放大（600 - 15000升）的空气流速控制为与可接受的较小规模批次的尾气二氧化碳曲线相匹配，以将水平维持在0.5%以下。15000升规模的发酵在7天后达到了预期的诺卡硫霉素I效价310毫克/升。15000升规模下的其他在线数据（即pH值、氧气摄取率和二氧化碳释放率）和离线数据（即类似物产量、葡萄糖利用、铵产量和干细胞重量）也与较小规模相似，表明发酵放大成功。
