The rapid accumulation of glycerol during biodiesel synthesis has attracted much interest on the potential usage. One of the promising applications is the conversion of glycerol to 1,3-propanediol (PDO), as well 2,3-butanediol (BDO), by using Klebsiella pneumonia. The results of this study indicate that the dissolved oxygen level (DO) is a determining factor in the distribution of PDO and BDO. The batch with a low DO could achieve a much higher PDO/BDO ratio than the high DO batch, with results of 9.9 and 0.2, respectively. The enzyme activity of glycerol dehydratase (GDHt) in the low DO batch was about three times that of the high DO batch, and this might be the cause of the enhanced PDO production. In conclusion, the results of this work show that high DO was beneficial to the production of BDO when using glycerol as the carbon source, while low DO could enhance PDO production. (C) 2013 Elsevier Ltd. All rights reserved.