Pichia pastoris growth in the BioFlo 110 was successful. Culture density of 91.0 g/L DCW was achieved, and when oxygen supplementation was added (see Appendix, page 5), cell density reached 177.4 g/L DCW.
Temperature control was excellent using unchilled (55F) tap water as the coolant. Nevertheless, fermentors with large-area stainless-steel heat exchangers, such as the New Brunswick Scientifics BioFlo 3000, have an advantage in temperature control at high cell density compared to systems with immersed coils (like the BioFlo 110 used here); or when compared to systems that rely on waterjackets made of glass. Glass has poorer thermal conductivity than stainless steel, but glass jackets have larger surface areas than immersed coils. Both immersed coils and glass jackets can work well, but the advantage of a fermentor like the BioFlo 3000 with a large stainless steel heat exchanger becomes significant at higher cell densities or with higher coolant temperatures.
Overall, our protocol and the BioFlo 110 performed extremely well. The BioFlo 110 Advanced Fermentation Kit is a suitable instrument for culturing Pichia pastoris . Furthermore, we expect that similar results can be achieved when using BioFlo 110 fermentation vessels in other sizes (1.3, 3.0 or 14 L liters), as well as when using a water-jacket configuration.
Effect of Gas Mix Controller and Oxygen Supplementation
A second continuous-batch was performed, this time adding the BioFlo 110 Gas Mix Controller, , M1273- 3104, to demonstrate the impact of oxygen supplementation on final dry ce