Potential of Klebsiella oxytoca for 1,3-propanediol production from glycerol under excess substrate conditions
Glycerol, a by-product of biodiesel, is a source of carbon for the bioproduction of chemical intermediates with high commercial value, such as 1,3-propanediol. One strain of Klebsiella oxytoca, isolated from soil samples, was tested to determine its potential to produce 1,3-propanediol through fermentation of a glycerol solution, under excess substrate conditions. The microbial growth curve was evaluated by optical density reading using a spectrophotometer (600 nm), while glycerol consumption and concentration of the products were determined by high performance liquid chromatography (HPLC) with HPX 87H column (BioRad). Formate, 3-hydroxypropionaldehyde and ethanol were produced in the early hours of fermentation. The increased rate of glycerol consumption and the formation of 1,3-propanediol coincides with formate degradation. This indicates that formate degradation likely works as an alternative means to generate part of the nicotine adenine dinucleotide (NADH) used by the 1,3-propanediol-dehydrogenase enzyme. Yield in mole of product per 100 mol of substrate reached 48.5, which is higher than that of previously investigated K. oxytoca strains.
Keywords: Klebsiella oxytoca, glycerol, fermentation, 1,3-propanediol, biodiesel