초록
An economically sustainable process was developed for propionic acid production by fermentation of glycerol using Propionibacterium acidipropionici and potato juice, a by-product of starch processing, as a nitrogen/vitamin source. The fermentation was done as high-cell-density sequential batches with cell recycle. Propionic acid production and glycerol consumption rates were dependent on initial biomass concentration, and reached a maximum of 1.42 and 2.30gL<SUP>-1</SUP>h<SUP>-1</SUP>, respectively, from 50gL<SUP>-1</SUP> glycerol at initial cell density of 23.7g<SUB>CDW</SUB>L<SUP>-1</SUP>. Halving the concentration of nitrogen/vitamin source resulted in reduction of acetic and succinic acids yields by ~39% each. At glycerol concentrations of 85 and 120gL<SUP>-1</SUP>, respectively, 43.8 and 50.8gL<SUP>-1</SUP> propionic acid were obtained at a rate of 0.88 and 0.29gL<SUP>-1</SUP>h<SUP>-1</SUP> and yield of 84 and 78mol%. Succinic acid was 13g% of propionic acid and could represent a potential co-product covering the cost of nitrogen/vitamin source.