Substrate gradients in bioreactors: origin and consequences

摘要: Gradients of glucose in time and space are shown a 30 m3 cultivation Saccharomyces cerevisiae grown minimal medium to cell density 20 gl−1. The fed-batch concept was used with as the limiting component which fed continuously process. As mean concentration declined throughout process, level at all times different three sampling ports (bottom/middle/top) reactor. These gradients were furthermore depend on feed position. This means that if supplied relatively stagnant mixing zone above top impeller, more pronounced than by well mixed bottom impeller zone. A rapid system constructed, continuous samples every 0.15 s analysed from point Fifty collected this system, but amount frequency is possible change. results these series show variance where one stage, peak appeared relative difference 40 mgl−1. pattern fluctuations turbulence location feed. It shown, when localised area well-mixed area, deviation negligible. fluid flow, (gassed ungassed) bulk (ungassed) reactor, characterised measurements using thermal anemometry. types areas resembles mentioned above. turbulent frequencies range 10−1 104 Hz highest amplitudes low frequencies. spectra depicts uniform scale for zones, especially dominance frequency, high amplitude flow variations observed short-time oscillations substrate support hypothesis transport over fairly long distances without substantial both especially,