Sun Yaqin

Separation of 1,3-propanediol from glycerol-based fermentations of Klebsiella pneumoniae by alcohol precipitation and dilution crystallization

The separation of 1,3-propanediol from the glycerol-based fermentation broth of Klebsiella pneumoniae plays an important role during the microbial production of 1,3-propanediol. In this paper, the separation of 1,3-propanediol from fermentative broth by a combination of ultrafiltration and alcohol dilution crystallization was investigated. The broth was first filtered by ultrafiltration, and 99% of cells, 89.4% of proteins and 69% of nucleic acids were removed. The obtained broth was further condensed by vacuum distillation, and then alcohol was added. The macromolecular impurities, such as nucleic acids, polysaccharides and proteins, were precipitated, and inorganic and organic salts were crystallized. The optimal volume ratio of alcohol added to the condensed fermentation broth was determined to be 2:1. As a result, proteins, nucleic acids and electric conductivity decreased by 97.4%, 89.7% and 95.8%, respectively, compared with the fermentative broth. The influences of pH and water content in condensed broth on alcohol precipitation and dilution crystallization were also investigated. The experimental results indicated that alcohol precipitation and dilution crystallization was feasible and effective for the separation of 1,3-propanediol from actual fermentation broth.