Nutrient requirements for glycerol conversion to 1,3-propanediol by Clostridium butyricum

A low-nutrient medium (LNM) based on biotin as the sole growth factor was defined to extend nutritional knowledge and to give more precise details about essential nutrients for Clostridium butyricum. Batch fermentations were performed with glycerol or industrial glycerin as a carbon source. It was shown that only 4 μg/l of biotin was sufficient to convert up to 129 g/l of glycerol and 121 g/l of industrial glycerin into a large amount of 1,3-propanediol; up to 67 g/l (0.63 mol/mol glycerol used) and 65 g/l (0.66 mol/mol), respectively. In addition, with the proposed medium, evidence was provided that nitrogen could constitute a limiting factor for glycerol fermentation, especially when the C/N ratio was less than 81:1. Despite its simple composition, the synthetic medium described here gives the same performance for C. butyricum on industrial glycerin as does a rich medium (RM) based on yeast extract.