Actinomycetes scale‐up for the production of the antibacterial,nocathiacin |
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Authors: | Beth Junker Andre Walker Michelle Hesse Mike Lester Jens Christensen Neal Connors |
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Affiliation: | Fermentation Development and Operations, Bioprocess Research and Development, Merck Research Laboratories, Rahway, NJ 07065 |
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Abstract: | 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 (Ro 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/cm2) 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. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009 |
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Keywords: | Amycolatopsis pilot‐scale fermentation scale‐up antibacterial secondary metabolite |
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