An economical biorefinery process for propionic acid production from glycerol and potato juice using high cell density fermentation

Abstract

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−1h−1, respectively, from 50gL−1 glycerol at initial cell density of 23.7gCDWL−1. 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−1, respectively, 43.8 and 50.8gL−1 propionic acid were obtained at a rate of 0.88 and 0.29gL−1h−1 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.