Alginate immobilization as a strategy for improving succinate production during autofermentation using cyanobacteria Synechocystis sp. PCC 6803

Abstract

This study focused on immobilization of a cyanobacterial strain for succinate production. Recombinant cyanobacterium Synechocystis sp. PCC 6803, with an overexpressed endogenous PEPC gene, was immobilized on calcium alginate beads. This immobilization technology improved succinate production during a continuous autofermentation cycle compared with that produced using a free-cell culture. In addition, the immobilized cells achieved a higher dry cell weight than the free cells. Furthermore, this process permitted cultivation within a shorter timeframe than in a free-cell culture. During continuous succinate production, the immobilized cells increased the succinate yield by 1.4-fold, whereas the use of free-cells resulted in a 50 % decrease in the succinate yield. Continuous batch culture offers a convenient strategy for the use of immobilized cyanobacteria, resulting in a simpler and faster process that achieves a higher rate of succinate production with each cycle.