Glycerol or other reduced carbon sources may be used as a feedstock for the microbial production of chemical products under certain microaerobic conditions. For example, such production may occur under microaerobic or microrespiratory conditions in which electron acceptors are consumed in the reaction as quickly as they are added. In such reactions, the reaction product is at least as reduced as carbon source. Further, during such a reaction, at least some of the carbon source is used to generate cell mass. In addition, microorganisms with modified genomes are provided for carrying out the methods herein.