The conversion of glycerol to 1,3-propanediol (1,3-PD) using Klebsiella pneumoniae CGMCC 1.6366 under aerobic condition was scaled up from scale 5 to 50,000 l in series. Several parameters including power input P/V(1), agitation rate n, impeller tip speed nD, superficial gas velocity u(s), and Re(s) were investigated as the criteria for scaling up. Impeller tip speed was chosen as the main criterion. It was also noticed less aeration was favored in that less electron will be shunted to electron transfer chain. The fermentation in 500 l bioreactor produced 66.8 g 1,3-PD with the yield of 0.55 mol mol(-1) at agitation rate and aeration of 130 rpm and 0.14 vvm air flow. Using these empirically obtained control concepts we successfully scaled up in 500-50,000 l pilot-scale reactors. The final 1,3-PD concentrations in 50,000 1 bioreactor amounted to 63.3 g l(-1) with the yield of 0.5 mol mol(-1). (C) 2009 Elsevier Ltd. All rights reserved.