Abstract:

The production of 1,3-propanediol from glycerol by Klebsiella pneumoniae encapsulated in NaCS/PDMDAAC capsules with a liquid core was investigated.The cell growth, glycerol consumption,1,3-propanediol accumulation by encapsulated K.pneumoniae were compared with free culture in flasks.The immobilized K.pneumoniae was also cultured in a packed bed reactor.The biomass in microcapsules reached 6 g·L^-1, far higher than 2.5 g·L^-1 in flask for free culture.Glycerol was consumed completely in 12 h for immobilized cells, compared with 27 h for free cells.The encapsulated cells produced 1,3-propanediol of 13 g·L^-1 in fermentation broth, lower than 17.5 g·L^-1 in free culture.If 1,3-propanediol in microcapsules was considered, the yield (Y_P/S) for immobilized cell was 0.613 mol·mol^-1, which was higher than 0.545 mol·mol^-1 for free culture.For batch fermentations in the packed bed reactor, the method of increasing substrate concentration was adopted to increase the final 1,3-propanediol concentration, and the maximal 1,3-propanediol concentration reached 58.1 g·L^-1 with molar yield of 0.596 mol·mol^-1 and productivity of 5.28 g·L^-1·h^-1 at the initial glycerol concentration of 120 g·L^-1.Six batches of fermentation in packed bed reactor was carried out and the results could be reproduced.