Development of a biofilm technology for the production of 1,3-propanediol (1,3-PDO) from crude glycerol

Glycerol is the main by-product of transesterification of fats in the biodiesel production. 1,3-Propanediol (1,3-PDO) is a valuable chemical that can be obtained from glycerol by microbial conversion. A number of Enterobacteriaceae species are able to produce 1,3-PDO from glycerol in stirred tank freely suspended cell bioreactors. Little is known about the use of crude glycerol in the production of 1,3-PDO and about the opportunity to intensify the process via strain immobilization in packed bed bioreactors. In this work, Citrobacter freundii, strain DSM 15979, and Pantoea agglomerans, strain DSM 30077, were tested for their ability to produce 1,3-PDO from crude glycerol in shaken flask batch conditions and in packed bed biofilm reactors operating under continuous conditions. Three different hydraulic retention times (HRT) were comparatively tested (8, 4 and 2 h) in order to understand its effects on 1,3-PDO production under immobilized cell conditions. The study revealed that HRT significantly influenced the process performances. The best productivities were observed when a HRT of 2 h was applied. However, both strains were found to be good candidates for 1,3-PDO production in biofilm reactors, even though P. agglomerans displayed quite higher productivities (3.6 g/(L h)) than the other strain.