Biosynthesis of 1,3-propanodiol and 2,3-butanodiol from residual glycerol in continuous cell-immobilized Klebsiella pneumoniae bioreactors

Abstract

In recent years, residual glycerol from biodiesel synthesis made this chemical a cheap, readily available carbon source to bioprocess, which is also a form to reduce costs in the fuel industry. We propose and describe a bioprocess using fluidized and packed-bed continuous bioreactors to convert this residual glycerol into value-added products such as 1,3-propanediol (1,3-PD) and 2,3-butanediol (2,3-BD), largely used in the chemical industry. The bacterium Klebsiella pneumoniae BLh-1, strain isolated by us, was immobilized in the permeable support of polyvinyl alcohol (LentiKats®). After testing different dilution rates (D) for all bioreactor configurations, the best obtained productivities of 1,3-PD was 8.69 g L^-1 h^-1 at a D = 0.45 h^-1 , and 2.99 g L^-1 h^-1 at a D = 0.30 h^-1 for 2,3-BD, both in the packed-bed configuration. In the fluidized-bed reactor, the highest productivity values achieved were 4.48 and 1.16 g L^-1 h^-1 for 1,3-PD and 2,3-BD, respectively, both at D = 0.33 h^-1 . These results show the potential of setting up a bioprocess based on continuous cultures using immobilized K. pneumoniae BLh-1 in PVA matrices in order to efficiently convert the abundant surplus of glycerol into commercially important chemicals such as 1,3-PD and 2,3-BD.

Keywords: 1,3-propanediol; 2,3-butanediol; Klebsiella pneumoniae BLh-1; LentiKats®; fluidized-bed bioreactor; packed-bed bioreactor.