Bioconversion of residual glycerol from biodiesel synthesis into 1,3-propanediol using immobilized cells of Klebsiella pneumoniae BLh-1

The bioconversion of residual glycerol obtained from biodiesel synthesis into 1,3-propanediol (1,3-PD) was carried out using Ca-alginate immobilized-cells cultures of Klebsiella pneumoniae BLh-1. The immobilization parameters bead size and cell concentration were determined for the best possible productivity and were found to be 3.4 mm and 100 mg mL−1, respectively. In 12 h-batch cultivations, immobilized cultures showed a 1,3-PD productivity of 1.85 g L−1 h−1, up from 1.22 g L−1 h−1 obtained in 16 h-batch cultivations using free-suspended cells. The possibility of reuse of the biocatalysts was tested in 5-cycles repeated batch cultures, with entrapped cells keeping their operational stability and biological activity, with 1,3-PD productivities as high as 4.48 g L−1 h−1. Other important metabolites such as 2,3-butanediol and ethanol were also produced (10.11 g L−1 and 3.71 g L−1, respectively) during the repeated batches. These results show the feasibility of using and further developing immobilized-cell systems of K. pneumoniae for the efficient bioprocessing of residual glycerol.