The production of propionic acid from sugars by fermentation through lactic acid as an intermediate

Abstract

AbstractAs an alternative to propionic acid production from sugars by species of propionibacteria, propionic acid may be produced from sugars through lactate as an intermediate. Propionibacteria are actually able to utilize lactate as a substrate much more rapidly than glucose. In this study, Lactobacillus xylosus and Propionibacterium shermanii were utilized to convert glucose and xylose to propionate through lactate as an intermediate. Pure culture batch studies were carried out to obtain fermentation parameters for the two cultures. The pure cultures were then combined in a mixed culture series arrangement designed to prevent nutrient limitation. Finally, propionic acid production from lactate was demonstrated in a cross‐linked immobilized cell reactor using lactate added to the medium and produced by L. xylosus in a continuous stirred tank reactor. Productivities of 14 g dm−3 h−1 at a 9 min residence time (2·1 g dm−3 propionate) and 2 g dm−3 h−1 at a 9·9 h residence time (19·7 g dm−3 propionate) were obtained without pH control.