Microbial Production of 2,3- Butanediol From Waste Glycerol

Abstract

An inevitable waste from biodiesel production is glycerol, contaminated by alkaline catalyst, water and methanol and released in quite big amounts, exceeding its market demand. One way of its utilization is production of different bulk and fine chemicals, for example 2,3- butanediol. The latter is used as a precursor for manufacturing of plastics, synthetic rubber, some pharmaceuticals, etc. In the present paper the ability of the strain Klebsiella oxytoca VA 8391 to produce this compound under batch and fed-batch conditions was studied at initial glycerol concentrations between 10 and 30 g dm^-3. Experiments have been carried out in shaking flasks. The bacteria cultivation was at 37oC and stirred conditions at 200 rpm, whereas the product formation was studied both under stirred and still conditions. It was found out that the used strain is capable to produce selectively 2,3- butanediol with very high yields of practical importance (up to 92 %) and no contamination by other products. The optimum glycerol concentration was 20 g dm-3. At higher initial
concentrations substrate inhibition started to occur. It was established that the studied fermentation process required aerobic bacteria cultivation followed by anoxic period of product formation by the developed culture. Only in this case high yields were attained.