Enhanced fed-batch fermentation of 2,3-butanediol by Paenibacillus polymyxa DSM 365.

Fed-batch fermentations for the production of 2,3-butanediol (BDL) with Paenibacillus polymyxa DSM 365 were investigated in 2-L-fermenters. A suitable micro-aerobic set-up enabled high product selectivity of up to 98% R,R-BDL towards meso-BDL and acetoin. Up to 111 g L(-1)R,R-BDL within 54 h could be achieved with sufficient supply of complex medium (yeast extract). To the best of the knowledge of the authors, this is the highest titer so far reported for P. polymyxa indicating its high potential as a non pathogenic BDL-producer. Fermentation in low nutritional medium (5 g L(-1) yeast extract) yielded up to 72 g L(-1) BDL+acetoin (79% R,R-BDL), yet was affected by formation of exopolysaccharides (EPS). In the range of 30-40°C EPS formation decreased with raising temperature although growth rate and BDL-production remained similar. Additionally, Tween80® was found to be a good additive to reduce viscosity caused by EPS.