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 d etails about essential nutrients for Clostridium butyricum. Batch ferm entations were performed with glycerol or industrial glycerin as a car bon source. It was shown that only 4 mu g/l of biotin was sufficient t o 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 gl ycerol used) and 65 g/l (0.66 mol/mol), respectively. In addition, wit h the proposed medium, evidence was provided that nitrogen could const itute a limiting factor for glycerol fermentation, especially when the C/N ratio was less than 81:1. Despite its simple composition, the syn thetic medium described here gives the same performance for C. butyric um on industrial glycerin as does a rich medium (RM) based on yeast ex tract. (C) 1998 Elsevier Science Ltd. All rights reserved.