Figure 2

Process overview for two-compartment scale-down cultivations of C. glutamicum ATCC13032. First phase: oscillating oxygen supply at substrate excess (batch, from t = −4 h until t = 0 h); second phase: oscillating oxygen/substrate supply (feed, after t = 0 h); scale-down cultivations with residence time τ = 45 s (TCR1) and τ = 87 s (TCR2); reference experiment without oscillation in aerobic stirred tank (REF); cell dry weight (CDW, left axis, samples taken from stirred tank compartment), glucose feed rate (feed, right axis), oxygen transfer rate (OTR, right axis, same unit as feed); initial batch phase from t = −8 until t = 0 with 22 g/L glucose, fed-batch phase started at t = 0; dissolved oxygen (DO) levels were always > 30% for aerobic stirred tank compartment and absence of DO signals at all sensors in the plug flow compartment showed anaerobic conditions.